Human evolution is the evolutionary process that led to the emergence of anatomically modern humans, beginning with the evolutionary history of primates—in particular genus Homo—and leading to the emergence of Homo sapiens as a distinct species of the hominid family, which includes the great apes. This process involved the gradual development of traits such as human bipedalism and language, as well as interbreeding with other hominins, which indicate that human evolution was not linear but a web.
The study of human evolution involves several scientific disciplines, including physical anthropology, primatology, archaeology, paleontology, neurobiology, ethology, linguistics, evolutionary psychology, embryology and genetics. Genetic studies show that primates diverged from other mammals about , in the Late Cretaceous period, and the earliest fossils appear in the Paleocene, around .
Within the superfamily Hominoidea, the family Hominidae diverged from the family Hylobatidae some 15–20 million years ago; subfamily Homininae (African apes) diverged from Ponginae (orangutans[a]) about 14 million years ago; the tribe Hominini (including humans, Australopithecus, and chimpanzees) parted from the tribe Gorillini (gorillas) between 8–9 million years ago; and, in turn, the subtribes Hominina (humans and extinct biped ancestors) and Panina (chimpanzees) separated 4–7 million years ago.
Human evolution from its first separation from the last common ancestor of humans and chimpanzees is characterized by a number of morphological, developmental, physiological, and behavioral changes. The most significant of these adaptations are bipedalism, increased brain size, lengthened ontogeny (gestation and infancy), and decreased sexual dimorphism. The relationship between these changes is the subject of ongoing debate.[page needed] Other significant morphological changes included the evolution of a power and precision grip, a change first occurring in H. erectus.
Bipedalism is the basic adaptation of the hominid and is considered the main cause behind a suite of skeletal changes shared by all bipedal hominids. The earliest hominin, of presumably primitive bipedalism, is considered to be either Sahelanthropus or Orrorin, both of which arose some 6 to 7 million years ago. The non-bipedal knuckle-walkers, the gorillas and chimpanzees, diverged from the hominin line over a period covering the same time, so either Sahelanthropus or Orrorin may be our last shared ancestor. Ardipithecus, a full biped, arose approximately 5.6 million years ago.
The early bipeds eventually evolved into the australopithecines and still later into the genus Homo. There are several theories of the adaptation value of bipedalism. It is possible that bipedalism was favored because it freed the hands for reaching and carrying food, saved energy during locomotion, enabled long-distance running and hunting, provided an enhanced field of vision, and helped avoid hyperthermia by reducing the surface area exposed to direct sun; features all advantageous for thriving in the new savanna and woodland environment created as a result of the East African Rift Valley uplift versus the previous closed forest habitat. A 2007 study provides support for the hypothesis that walking on two legs, or bipedalism, evolved because it used less energy than quadrupedal knuckle-walking. However, recent studies suggest that bipedality without the ability to use fire would not have allowed global dispersal. This change in gait saw a lengthening of the legs proportionately when compared to the length of the arms, which were shortened through the removal of the need for brachiation. Another change is the shape of the big toe. Recent studies suggest that australopithecines still lived part of the time in trees as a result of maintaining a grasping big toe. This was progressively lost in habilines.
Anatomically, the evolution of bipedalism has been accompanied by a large number of skeletal changes, not just to the legs and pelvis, but also to the vertebral column, feet and ankles, and skull. The femur evolved into a slightly more angular position to move the center of gravity toward the geometric center of the body. The knee and ankle joints became increasingly robust to better support increased weight. To support the increased weight on each vertebra in the upright position, the human vertebral column became S-shaped and the lumbar vertebrae became shorter and wider. In the feet the big toe moved into alignment with the other toes to help in forward locomotion. The arms and forearms shortened relative to the legs making it easier to run. The foramen magnum migrated under the skull and more anterior.
The most significant changes occurred in the pelvic region, where the long downward facing iliac blade was shortened and widened as a requirement for keeping the center of gravity stable while walking; bipedal hominids have a shorter but broader, bowl-like pelvis due to this. A drawback is that the birth canal of bipedal apes is smaller than in knuckle-walking apes, though there has been a widening of it in comparison to that of australopithecine and modern humans, permitting the passage of newborns due to the increase in cranial size but this is limited to the upper portion, since further increase can hinder normal bipedal movement.
The shortening of the pelvis and smaller birth canal evolved as a requirement for bipedalism and had significant effects on the process of human birth which is much more difficult in modern humans than in other primates. During human birth, because of the variation in size of the pelvic region, the fetal head must be in a transverse position (compared to the mother) during entry into the birth canal and rotate about 90 degrees upon exit. The smaller birth canal became a limiting factor to brain size increases in early humans and prompted a shorter gestation period leading to the relative immaturity of human offspring, who are unable to walk much before 12 months and have greater neoteny, compared to other primates, who are mobile at a much earlier age. The increased brain growth after birth and the increased dependency of children on mothers had a major effect upon the female reproductive cycle, and the more frequent appearance of alloparenting in humans when compared with other hominids. Delayed human sexual maturity also led to the evolution of menopause with one explanation providing that elderly women could better pass on their genes by taking care of their daughter's offspring, as compared to having more children of their own.
The human species eventually developed a much larger brain than that of other primates—typically 1,330 cm3 (81 cu in) in modern humans, nearly three times the size of a chimpanzee or gorilla brain. After a period of stasis with Australopithecus anamensis and Ardipithecus, species which had smaller brains as a result of their bipedal locomotion, the pattern of encephalization started with Homo habilis, whose 600 cm3 (37 cu in) brain was slightly larger than that of chimpanzees. This evolution continued in Homo erectus with 800–1,100 cm3 (49–67 cu in), and reached a maximum in Neanderthals with 1,200–1,900 cm3 (73–116 cu in), larger even than modern Homo sapiens. This brain increase manifested during postnatal brain growth, far exceeding that of other apes (heterochrony). It also allowed for extended periods of social learning and language acquisition in juvenile humans, beginning as much as 2 million years ago.
The temporal lobes, which contain centers for language processing, have increased disproportionately, as has the prefrontal cortex, which has been related to complex decision-making and moderating social behavior. Encephalization has been tied to increased meat and starches in the diet, and the development of cooking, and it has been proposed that intelligence increased as a response to an increased necessity for solving social problems as human society became more complex. Changes in skull morphology, such as smaller mandibles and mandible muscle attachments, allowed more room for the brain to grow.
The increase in volume of the neocortex also included a rapid increase in size of the cerebellum. Its function has traditionally been associated with balance and fine motor control, but more recently with speech and cognition. The great apes, including hominids, had a more pronounced cerebellum relative to the neocortex than other primates. It has been suggested that because of its function of sensory-motor control and learning complex muscular actions, the cerebellum may have underpinned human technological adaptations, including the preconditions of speech.
The immediate survival advantage of encephalization is difficult to discern, as the major brain changes from Homo erectus to Homo heidelbergensis were not accompanied by major changes in technology. It has been suggested that the changes were mainly social and behavioural, including increased empathic abilities, increases in size of social groups, and increased behavioural plasticity. Encephalization may be due to a dependency on calorie-dense, difficult-to-acquire food.
The reduced degree of sexual dimorphism in humans is visible primarily in the reduction of the male canine tooth relative to other ape species (except gibbons) and reduced brow ridges and general robustness of males. Another important physiological change related to sexuality in humans was the evolution of hidden estrus. Humans are the only hominoids in which the female is fertile year round and in which no special signals of fertility are produced by the body (such as genital swelling or overt changes in proceptivity during estrus).
Nonetheless, humans retain a degree of sexual dimorphism in the distribution of body hair and subcutaneous fat, and in the overall size, males being around 15% larger than females. These changes taken together have been interpreted as a result of an increased emphasis on pair bonding as a possible solution to the requirement for increased parental investment due to the prolonged infancy of offspring.
The ulnar opposition—the contact between the thumb and the tip of the little finger of the same hand—is unique to the genus Homo, including Neanderthals, the Sima de los Huesos hominins and anatomically modern humans. In other primates, the thumb is short and unable to touch the little finger. The ulnar opposition facilitates the precision grip and power grip of the human hand, underlying all the skilled manipulations.
A number of other changes have also characterized the evolution of humans, among them an increased importance on vision rather than smell; a longer juvenile developmental period and higher infant dependency; a smaller gut; faster basal metabolism; loss of body hair; evolution of sweat glands; a change in the shape of the dental arcade from being u-shaped to being parabolic; development of a chin (found in Homo sapiens alone); development of styloid processes; and the development of a descended larynx.
History of study
The word homo, the name of the biological genus to which humans belong, is Latin for "human".[b] It was chosen originally by Carl Linnaeus in his classification system.[c] The word "human" is from the Latin humanus, the adjectival form of homo. The Latin "homo" derives from the Indo-European root *dhghem, or "earth". Linnaeus and other scientists of his time also considered the great apes to be the closest relatives of humans based on morphological and anatomical similarities.
The possibility of linking humans with earlier apes by descent became clear only after 1859 with the publication of Charles Darwin's On the Origin of Species, in which he argued for the idea of the evolution of new species from earlier ones. Darwin's book did not address the question of human evolution, saying only that "Light will be thrown on the origin of man and his history."
The first debates about the nature of human evolution arose between Thomas Henry Huxley and Richard Owen. Huxley argued for human evolution from apes by illustrating many of the similarities and differences between humans and other apes, and did so particularly in his 1863 book Evidence as to Man's Place in Nature. Many of Darwin's early supporters (such as Alfred Russel Wallace and Charles Lyell) did not initially agree that the origin of the mental capacities and the moral sensibilities of humans could be explained by natural selection, though this later changed. Darwin applied the theory of evolution and sexual selection to humans in his 1871 book The Descent of Man, and Selection in Relation to Sex.
A major problem in the 19th century was the lack of fossil intermediaries. Neanderthal remains were discovered in a limestone quarry in 1856, three years before the publication of On the Origin of Species, and Neanderthal fossils had been discovered in Gibraltar even earlier, but it was originally claimed that these were the remains of a modern human who had suffered some kind of illness. Despite the 1891 discovery by Eugène Dubois of what is now called Homo erectus at Trinil, Java, it was only in the 1920s when such fossils were discovered in Africa, that intermediate species began to accumulate. In 1925, Raymond Dart described Australopithecus africanus. The type specimen was the Taung Child, an australopithecine infant which was discovered in a cave. The child's remains were a remarkably well-preserved tiny skull and an endocast of the brain.
Although the brain was small (410 cm3), its shape was rounded, unlike that of chimpanzees and gorillas, and more like a modern human brain. Also, the specimen showed short canine teeth, and the position of the foramen magnum (the hole in the skull where the spine enters) was evidence of bipedal locomotion. All of these traits convinced Dart that the Taung Child was a bipedal human ancestor, a transitional form between apes and humans.
The East African fossils
During the 1960s and 1970s, hundreds of fossils were found in East Africa in the regions of the Olduvai Gorge and Lake Turkana. These searches were carried out by the Leakey family, with Louis Leakey and his wife Mary Leakey, and later their son Richard and daughter-in-law Meave, fossil hunters and paleoanthropologists. From the fossil beds of Olduvai and Lake Turkana they amassed specimens of the early hominins: the australopithecines and Homo species, and even Homo erectus.
These finds cemented Africa as the cradle of humankind. In the late 1970s and the 1980s, Ethiopia emerged as the new hot spot of paleoanthropology after "Lucy", the most complete fossil member of the species Australopithecus afarensis, was found in 1974 by Donald Johanson near Hadar in the desertic Afar Triangle region of northern Ethiopia. Although the specimen had a small brain, the pelvis and leg bones were almost identical in function to those of modern humans, showing with certainty that these hominins had walked erect. Lucy was classified as a new species, Australopithecus afarensis, which is thought to be more closely related to the genus Homo as a direct ancestor, or as a close relative of an unknown ancestor, than any other known hominid or hominin from this early time range; see terms "hominid" and "hominin". (The specimen was nicknamed "Lucy" after the Beatles' song "Lucy in the Sky with Diamonds", which was played loudly and repeatedly in the camp during the excavations.) The Afar Triangle area would later yield discovery of many more hominin fossils, particularly those uncovered or described by teams headed by Tim D. White in the 1990s, including Ardipithecus ramidus and Ardipithecus kadabba.
In 2013, fossil skeletons of Homo naledi, an extinct species of hominin assigned (provisionally) to the genus Homo, were found in the Rising Star Cave system, a site in South Africa's Cradle of Humankind region in Gauteng province near Johannesburg. As of September 2015, fossils of at least fifteen individuals, amounting to 1,550 specimens, have been excavated from the cave. The species is characterized by a body mass and stature similar to small-bodied human populations, a smaller endocranial volume similar to Australopithecus, and a cranial morphology (skull shape) similar to early Homo species. The skeletal anatomy combines primitive features known from australopithecines with features known from early hominins. The individuals show signs of having been deliberately disposed of within the cave near the time of death. The fossils were dated close to 250,000 years ago, and thus are not a direct ancestor but a contemporary with the first appearance of larger-brained anatomically modern humans.
The genetic revolution
The genetic revolution in studies of human evolution started when Vincent Sarich and Allan Wilson measured the strength of immunological cross-reactions of blood serum albumin between pairs of creatures, including humans and African apes (chimpanzees and gorillas). The strength of the reaction could be expressed numerically as an immunological distance, which was in turn proportional to the number of amino acid differences between homologous proteins in different species. By constructing a calibration curve of the ID of species' pairs with known divergence times in the fossil record, the data could be used as a molecular clock to estimate the times of divergence of pairs with poorer or unknown fossil records.
In their seminal 1967 paper in Science, Sarich and Wilson estimated the divergence time of humans and apes as four to five million years ago, at a time when standard interpretations of the fossil record gave this divergence as at least 10 to as much as 30 million years. Subsequent fossil discoveries, notably "Lucy", and reinterpretation of older fossil materials, notably Ramapithecus, showed the younger estimates to be correct and validated the albumin method.
Progress in DNA sequencing, specifically mitochondrial DNA (mtDNA) and then Y-chromosome DNA (Y-DNA) advanced the understanding of human origins. Application of the molecular clock principle revolutionized the study of molecular evolution.
On the basis of a separation from the orangutan between 10 and 20 million years ago, earlier studies of the molecular clock suggested that there were about 76 mutations per generation that were not inherited by human children from their parents; this evidence supported the divergence time between hominins and chimpanzees noted above. However, a 2012 study in Iceland of 78 children and their parents suggests a mutation rate of only 36 mutations per generation; this datum extends the separation between humans and chimpanzees to an earlier period greater than 7 million years ago (Ma). Additional research with 226 offspring of wild chimpanzee populations in eight locations suggests that chimpanzees reproduce at age 26.5 years on average; which suggests the human divergence from chimpanzees occurred between 7 and 13 million years ago. And these data suggest that Ardipithecus (4.5 Ma), Orrorin (6 Ma) and Sahelanthropus (7 Ma) all may be on the hominid lineage, and even that the separation may have occurred outside the East African Rift region.
Furthermore, analysis of the two species' genes in 2006 provides evidence that after human ancestors had started to diverge from chimpanzees, interspecies mating between "proto-human" and "proto-chimpanzees" nonetheless occurred regularly enough to change certain genes in the new gene pool:
- A new comparison of the human and chimpanzee genomes suggests that after the two lineages separated, they may have begun interbreeding... A principal finding is that the X chromosomes of humans and chimpanzees appear to have diverged about 1.2 million years more recently than the other chromosomes.
The research suggests:
- There were in fact two splits between the human and chimpanzee lineages, with the first being followed by interbreeding between the two populations and then a second split. The suggestion of a hybridization has startled paleoanthropologists, who nonetheless are treating the new genetic data seriously.
The quest for the earliest hominin
In the 1990s, several teams of paleoanthropologists were working throughout Africa looking for evidence of the earliest divergence of the hominin lineage from the great apes. In 1994, Meave Leakey discovered Australopithecus anamensis. The find was overshadowed by Tim D. White's 1995 discovery of Ardipithecus ramidus, which pushed back the fossil record to .
In 2000, Martin Pickford and Brigitte Senut discovered, in the Tugen Hills of Kenya, a 6-million-year-old bipedal hominin which they named Orrorin tugenensis. And in 2001, a team led by Michel Brunet discovered the skull of Sahelanthropus tchadensis which was dated as , and which Brunet argued was a bipedal, and therefore a hominid—that is, a hominin (cf Hominidae; terms "hominids" and hominins).
Anthropologists in the 1980s were divided regarding some details of reproductive barriers and migratory dispersals of the genus Homo. Subsequently, genetics has been used to investigate and resolve these issues. According to the Sahara pump theory evidence suggests that the genus Homo have migrated out of Africa at least three and possibly four times (e.g. Homo erectus, Homo heidelbergensis and two or three times for Homo sapiens). Recent evidence suggests these dispersals are closely related to fluctuating periods of climate change.
Recent evidence suggests that humans may have left Africa half a million years earlier than previously thought. A joint Franco-Indian team has found human artifacts in the Siwalk Hills north of New Delhi dating back at least 2.6 million years. This is earlier than the previous earliest finding of genus Homo at Dmanisi, in Georgia, dating to 1.85 million years. Although controversial, tools found at a Chinese cave strengthen the case that humans used tools as far back as 2.48 million years ago. This suggests that the Asian "Chopper" tool tradition, found in Java and northern China may have left Africa before the appearance of the Acheulian hand axe.
Dispersal of modern Homo sapiens
Up until the genetic evidence became available, there were two dominant models for the dispersal of modern humans. The multiregional hypothesis proposed that the genus Homo contained only a single interconnected population as it does today (not separate species), and that its evolution took place worldwide continuously over the last couple of million years. This model was proposed in 1988 by Milford H. Wolpoff. In contrast, the "out of Africa" model proposed that modern H. sapiens speciated in Africa recently (that is, approximately 200,000 years ago) and the subsequent migration through Eurasia resulted in the nearly complete replacement of other Homo species. This model has been developed by Chris B. Stringer and Peter Andrews.
Sequencing mtDNA and Y-DNA sampled from a wide range of indigenous populations revealed ancestral information relating to both male and female genetic heritage, and strengthened the "out of Africa" theory and weakened the views of multiregional evolutionism. Aligned in genetic tree differences were interpreted as supportive of a recent single origin. Analyses have shown a greater diversity of DNA patterns throughout Africa, consistent with the idea that Africa is the ancestral home of mitochondrial Eve and Y-chromosomal Adam, and that modern human dispersal out of Africa has only occurred over the last 55,000 years.
"Out of Africa" has thus gained much support from research using female mitochondrial DNA and the male Y chromosome. After analysing genealogy trees constructed using 133 types of mtDNA, researchers concluded that all were descended from a female African progenitor, dubbed Mitochondrial Eve. "Out of Africa" is also supported by the fact that mitochondrial genetic diversity is highest among African populations.
A broad study of African genetic diversity, headed by Sarah Tishkoff, found the San people had the greatest genetic diversity among the 113 distinct populations sampled, making them one of 14 "ancestral population clusters". The research also located a possible origin of modern human migration in southwestern Africa, near the coastal border of Namibia and Angola. The fossil evidence was insufficient for archaeologist Richard Leakey to resolve the debate about exactly where in Africa modern humans first appeared. Studies of haplogroups in Y-chromosomal DNA and mitochondrial DNA have largely supported a recent African origin. All the evidence from autosomal DNA also predominantly supports a Recent African origin. However, evidence for archaic admixture in modern humans, both in Africa and later, throughout Eurasia has recently been suggested by a number of studies.
Recent sequencing of Neanderthal and Denisovan genomes shows that some admixture with these populations has occurred. All modern human groups outside Africa have 1–4% or (according to more recent research) about 1.5–2.6% Neanderthal alleles in their genome, and some Melanesians have an additional 4–6% of Denisovan alleles. These new results do not contradict the "out of Africa" model, except in its strictest interpretation, although they make the situation more complex. After recovery from a genetic bottleneck that some researchers speculate might be linked to the Toba supervolcano catastrophe, a fairly small group left Africa and interbred with Neanderthals, probably in the Middle East, on the Eurasian steppe or even in North Africa before their departure. Their still predominantly African descendants spread to populate the world. A fraction in turn interbred with Denisovans, probably in southeastern Asia, before populating Melanesia. HLA haplotypes of Neanderthal and Denisova origin have been identified in modern Eurasian and Oceanian populations. The Denisovan EPAS1 gene has also been found in Tibetan populations. Studies of the human genome using machine learning have identified additional genetic contributions in Eurasians from an "unknown" ancestral population potentially related to the Neanderthal-Denisovan lineage.
There are still differing theories on whether there was a single exodus from Africa or several. A multiple dispersal model involves the Southern Dispersal theory, which has gained support in recent years from genetic, linguistic and archaeological evidence. In this theory, there was a coastal dispersal of modern humans from the Horn of Africa crossing the Bab el Mandib to Yemen at a lower sea level around 70,000 years ago. This group helped to populate Southeast Asia and Oceania, explaining the discovery of early human sites in these areas much earlier than those in the Levant. This group seems to have been dependent upon marine resources for their survival.
Stephen Oppenheimer has proposed a second wave of humans may have later dispersed through the Persian Gulf oases, and the Zagros mountains into the Middle East. Alternatively it may have come across the Sinai Peninsula into Asia, from shortly after 50,000 yrs BP, resulting in the bulk of the human populations of Eurasia. It has been suggested that this second group possibly possessed a more sophisticated "big game hunting" tool technology and was less dependent on coastal food sources than the original group. Much of the evidence for the first group's expansion would have been destroyed by the rising sea levels at the end of each glacial maximum. The multiple dispersal model is contradicted by studies indicating that the populations of Eurasia and the populations of Southeast Asia and Oceania are all descended from the same mitochondrial DNA L3 lineages, which support a single migration out of Africa that gave rise to all non-African populations.
On the basis of the early date of Badoshan Iranian Aurignacian, Oppenheimer suggests that this second dispersal may have occurred with a pluvial period about 50,000 years before the present, with modern human big-game hunting cultures spreading up the Zagros Mountains, carrying modern human genomes from Oman, throughout the Persian Gulf, northward into Armenia and Anatolia, with a variant travelling south into Israel and to Cyrenicia.
Recent genetic evidence suggests that all modern non-African populations, including those of Eurasia and Oceania, are descended from a single wave that left Africa between 65,000 and 50,000 years ago.
The evidence on which scientific accounts of human evolution are based comes from many fields of natural science. The main source of knowledge about the evolutionary process has traditionally been the fossil record, but since the development of genetics beginning in the 1970s, DNA analysis has come to occupy a place of comparable importance. The studies of ontogeny, phylogeny and especially evolutionary developmental biology of both vertebrates and invertebrates offer considerable insight into the evolution of all life, including how humans evolved. The specific study of the origin and life of humans is anthropology, particularly paleoanthropology which focuses on the study of human prehistory.
Evidence from molecular biology
The closest living relatives of humans are bonobos and chimpanzees (both genus Pan) and gorillas (genus Gorilla). With the sequencing of both the human and chimpanzee genome, as of 2012 estimates of the similarity between their DNA sequences range between 95% and 99%. By using the technique called the molecular clock which estimates the time required for the number of divergent mutations to accumulate between two lineages, the approximate date for the split between lineages can be calculated.
The gibbons (family Hylobatidae) and then the orangutans (genus Pongo) were the first groups to split from the line leading to the hominins, including humans—followed by gorillas (genus Gorilla), and, ultimately, by the chimpanzees (genus Pan). The splitting date between hominin and chimpanzee lineages is placed by some between , that is, during the Late Miocene. Speciation, however, appears to have been unusually drawn out. Initial divergence occurred sometime between , but ongoing hybridization blurred the separation and delayed complete separation during several millions of years. Patterson (2006) dated the final divergence at .
Genetic evidence has also been employed to resolve the question of whether there was any gene flow between early modern humans and Neanderthals, and to enhance our understanding of the early human migration patterns and splitting dates. By comparing the parts of the genome that are not under natural selection and which therefore accumulate mutations at a fairly steady rate, it is possible to reconstruct a genetic tree incorporating the entire human species since the last shared ancestor.
Each time a certain mutation (single-nucleotide polymorphism) appears in an individual and is passed on to his or her descendants, a haplogroup is formed including all of the descendants of the individual who will also carry that mutation. By comparing mitochondrial DNA which is inherited only from the mother, geneticists have concluded that the last female common ancestor whose genetic marker is found in all modern humans, the so-called mitochondrial Eve, must have lived around 200,000 years ago.
Human evolutionary genetics studies how one human genome differs from the other, the evolutionary past that gave rise to it, and its current effects. Differences between genomes have anthropological, medical and forensic implications and applications. Genetic data can provide important insight into human evolution.
Evidence from the fossil record
There is little fossil evidence for the divergence of the gorilla, chimpanzee and hominin lineages. The earliest fossils that have been proposed as members of the hominin lineage are Sahelanthropus tchadensis dating from , Orrorin tugenensis dating from , and Ardipithecus kadabba dating to . Each of these have been argued to be a bipedal ancestor of later hominins but, in each case, the claims have been contested. It is also possible that one or more of these species are ancestors of another branch of African apes, or that they represent a shared ancestor between hominins and other apes.
The question then of the relationship between these early fossil species and the hominin lineage is still to be resolved. From these early species, the australopithecines arose around robust (also called Paranthropus) and gracile branches, one of which (possibly A. garhi) probably went on to become ancestors of the genus Homo. The australopithecine species that is best represented in the fossil record is Australopithecus afarensis with more than 100 fossil individuals represented, found from Northern Ethiopia (such as the famous "Lucy"), to Kenya, and South Africa. Fossils of robust australopithecines such as Au. robustus (or alternatively Paranthropus robustus) and Au./P. boisei are particularly abundant in South Africa at sites such as Kromdraai and Swartkrans, and around Lake Turkana in Kenya.and diverged into
The earliest member of the genus Homo is Homo habilis which evolved around  Homo habilis is the first species for which we have positive evidence of the use of stone tools. They developed the Oldowan lithic technology, named after the Olduvai Gorge in which the first specimens were found. Some scientists consider Homo rudolfensis, a larger bodied group of fossils with similar morphology to the original H. habilis fossils, to be a separate species, while others consider them to be part of H. habilis—simply representing intraspecies variation, or perhaps even sexual dimorphism. The brains of these early hominins were about the same size as that of a chimpanzee, and their main adaptation was bipedalism as an adaptation to terrestrial living..
During the next million years, a process of encephalization began and, by the arrival (about) of Homo erectus in the fossil record, cranial capacity had doubled. Homo erectus were the first of the hominins to emigrate from Africa, and, from , this species spread through Africa, Asia, and Europe. One population of H. erectus, also sometimes classified as a separate species Homo ergaster, remained in Africa and evolved into Homo sapiens. It is believed that these species, H. erectus and H. ergaster, were the first to use fire and complex tools.
The earliest transitional fossils between H. ergaster/erectus and archaic H. sapiens are from Africa, such as Homo rhodesiensis. These descendants of African H. erectus spread through Eurasia from ca. 500,000 years ago, evolving into H. antecessor, H. heidelbergensis and H. neanderthalensis. The earliest fossils of anatomically modern humans are from the Middle Paleolithic, about 300–200,000 years ago such as the Herto and Omo remains of Ethiopia, Jebel Irhoud remains of Morocco, and Florisbad remains of South Africa; later fossils from Es Skhul cave in Israel and Southern Europe begin around 90,000 years ago ( ).
As modern humans spread out from Africa, they encountered other hominins such as Homo neanderthalensis and the Denisovans, who may have evolved from populations of Homo erectus that had left Africa around . The nature of interaction between early humans and these sister species has been a long-standing source of controversy, the question being whether humans replaced these earlier species or whether they were in fact similar enough to interbreed, in which case these earlier populations may have contributed genetic material to modern humans.
This migration out of Africa is estimated to have begun about 70–50,000 years BP and modern humans subsequently spread globally, replacing earlier hominins either through competition or hybridization. They inhabited Eurasia and Oceania by 40,000 years BP, and the Americas by at least 14,500 years BP.
The hypothesis of interbreeding, also known as hybridization, admixture or hybrid-origin theory, has been discussed ever since the discovery of Neanderthal remains in the 19th century. The linear view of human evolution began to be abandoned in the 1970s as different species of humans were discovered that made the linear concept increasingly unlikely. In the 21st century with the advent of molecular biology techniques and computerization, whole-genome sequencing of Neanderthal and human genome were performed, confirming recent admixture between different human species. In 2010, evidence based on molecular biology was published, revealing unambiguous examples of interbreeding between archaic and modern humans during the Middle Paleolithic and early Upper Paleolithic. It has been demonstrated that interbreeding happened in several independent events that included Neanderthals and Denisovans, as well as several unidentified hominins. Today, approximately 2% of DNA from all non-African populations (including Europeans, Asians, and Oceanians) is Neanderthal, with traces of Denisovan heritage. Also, 4–6% of modern Melanesian genetics are Denisovan. Comparisons of the human genome to the genomes of Neandertals, Denisovans and apes can help identify features that set modern humans apart from other hominin species. In a 2016 comparative genomics study, a Harvard Medical School/UCLA research team made a world map on the distribution and made some predictions about where Denisovan and Neanderthal genes may be impacting modern human biology.
For example, comparative studies in the mid-2010s found several traits related to neurological, immunological, developmental, and metabolic phenotypes, that were developed by archaic humans to European and Asian environments and inherited to modern humans through admixture with local hominins.
Although the narratives of human evolution are often contentious, several discoveries since 2010 show that human evolution should not be seen as a simple linear or branched progression, but a mix of related species. In fact, genomic research has shown that hybridization between substantially diverged lineages is the rule, not the exception, in human evolution. Furthermore, it is argued that hybridization was an essential creative force in the emergence of modern humans.
Early evolution of primates
The evolutionary history of the primates can be traced back 65 million years. One of the oldest known primate-like mammal species, the Plesiadapis, came from North America; another, Archicebus, came from China. Other similar basal primates were widespread in Eurasia and Africa during the tropical conditions of the Paleocene and Eocene.
David R. Begun concluded that early primates flourished in Eurasia and that a lineage leading to the African apes and humans, including to Dryopithecus, migrated south from Europe or Western Asia into Africa. The surviving tropical population of primates—which is seen most completely in the Upper Eocene and lowermost Oligocene fossil beds of the Faiyum depression southwest of Cairo—gave rise to all extant primate species, including the lemurs of Madagascar, lorises of Southeast Asia, galagos or "bush babies" of Africa, and to the anthropoids, which are the Platyrrhines or New World monkeys, the Catarrhines or Old World monkeys, and the great apes, including humans and other hominids.
The earliest known catarrhine is Kamoyapithecus from uppermost Oligocene at Eragaleit in the northern Great Rift Valley in Kenya, dated to 24 million years ago. Its ancestry is thought to be species related to Aegyptopithecus, Propliopithecus, and Parapithecus from the Faiyum, at around 35 million years ago. In 2010, Saadanius was described as a close relative of the last common ancestor of the crown catarrhines, and tentatively dated to 29–28 million years ago, helping to fill an 11-million-year gap in the fossil record.
In the Early Miocene, about 22 million years ago, the many kinds of arboreally adapted primitive catarrhines from East Africa suggest a long history of prior diversification. Fossils at 20 million years ago include fragments attributed to Victoriapithecus, the earliest Old World monkey. Among the genera thought to be in the ape lineage leading up to 13 million years ago are Proconsul, Rangwapithecus, Dendropithecus, , Nacholapithecus, Equatorius, Nyanzapithecus, Afropithecus, Heliopithecus, and Kenyapithecus, all from East Africa.
The presence of other generalized non-cercopithecids of Middle Miocene from sites far distant—Otavipithecus from cave deposits in Namibia, and Pierolapithecus and Dryopithecus from France, Spain and Austria—is evidence of a wide diversity of forms across Africa and the Mediterranean basin during the relatively warm and equable climatic regimes of the Early and Middle Miocene. The youngest of the Miocene hominoids, Oreopithecus, is from coal beds in Italy that have been dated to 9 million years ago.
Molecular evidence indicates that the lineage of gibbons (family Hylobatidae) diverged from the line of great apes some 18–12 million years ago, and that of orangutans (subfamily Ponginae) diverged from the other great apes at about 12 million years; there are no fossils that clearly document the ancestry of gibbons, which may have originated in a so-far-unknown Southeast Asian hominoid population, but fossil proto-orangutans may be represented by Sivapithecus from India and Griphopithecus from Turkey, dated to around 10 million years ago.
Divergence of the human clade from other great apes
Species close to the last common ancestor of gorillas, chimpanzees and humans may be represented by Nakalipithecus fossils found in Kenya and Ouranopithecus found in Greece. Molecular evidence suggests that between 8 and 4 million years ago, first the gorillas, and then the chimpanzees (genus Pan) split off from the line leading to the humans. Human DNA is approximately 98.4% identical to that of chimpanzees when comparing single nucleotide polymorphisms (see human evolutionary genetics). The fossil record, however, of gorillas and chimpanzees is limited; both poor preservation – rain forest soils tend to be acidic and dissolve bone – and sampling bias probably contribute to this problem.
Other hominins probably adapted to the drier environments outside the equatorial belt; and there they encountered antelope, hyenas, dogs, pigs, elephants, horses, and others. The equatorial belt contracted after about 8 million years ago, and there is very little fossil evidence for the split—thought to have occurred around that time—of the hominin lineage from the lineages of gorillas and chimpanzees. The earliest fossils argued by some to belong to the human lineage are Sahelanthropus tchadensis (7 Ma) and Orrorin tugenensis (6 Ma), followed by Ardipithecus (5.5–4.4 Ma), with species Ar. kadabba and Ar. ramidus.
It has been argued in a study of the life history of Ar. ramidus that the species provides evidence for a suite of anatomical and behavioral adaptations in very early hominins unlike any species of extant great ape. This study demonstrated affinities between the skull morphology of Ar. ramidus and that of infant and juvenile chimpanzees, suggesting the species evolved a juvenalised or paedomorphic craniofacial morphology via heterochronic dissociation of growth trajectories. It was also argued that the species provides support for the notion that very early hominins, akin to bonobos (Pan paniscus) the less aggressive species of the genus Pan, may have evolved via the process of self-domestication. Consequently, arguing against the so-called "chimpanzee referential model" the authors suggest it is no longer tenable to use chimpanzee (Pan troglodytes) social and mating behaviors in models of early hominin social evolution. When commenting on the absence of aggressive canine morphology in Ar. ramidus and the implications this has for the evolution of hominin social psychology, they wrote:
Of course Ar. ramidus differs significantly from bonobos, bonobos having retained a functional canine honing complex. However, the fact that Ar. ramidus shares with bonobos reduced sexual dimorphism, and a more paedomorphic form relative to chimpanzees, suggests that the developmental and social adaptations evident in bonobos may be of assistance in future reconstructions of early hominin social and sexual psychology. In fact the trend towards increased maternal care, female mate selection and self-domestication may have been stronger and more refined in Ar. ramidus than what we see in bonobos.:128
The authors argue that many of the basic human adaptations evolved in the ancient forest and woodland ecosystems of late Miocene and early Pliocene Africa. Consequently, they argue that humans may not represent evolution from a chimpanzee-like ancestor as has traditionally been supposed. This suggests many modern human adaptations represent phylogenetically deep traits and that the behavior and morphology of chimpanzees may have evolved subsequent to the split with the common ancestor they share with humans.
The genus Australopithecus evolved in eastern Africa around 4 million years ago before spreading throughout the continent and eventually becoming extinct 2 million years ago. During this time period various forms of australopiths existed, including Australopithecus anamensis, Au. afarensis, Au. sediba, and Au. africanus. There is still some debate among academics whether certain African hominid species of this time, such as Au. robustus and Au. boisei, constitute members of the same genus; if so, they would be considered to be Au. robust australopiths whilst the others would be considered Au. gracile australopiths. However, if these species do indeed constitute their own genus, then they may be given their own name, Paranthropus.
- Australopithecus (4–1.8 Ma), with species Au. anamensis, Au. afarensis, Au. africanus, Au. bahrelghazali, Au. garhi, and Au. sediba;
- Kenyanthropus (3–2.7 Ma), with species K. platyops;
- Paranthropus (3–1.2 Ma), with species P. aethiopicus, P. boisei, and P. robustus
A new proposed species Australopithecus deyiremeda is claimed to have been discovered living at the same time period of Au. afarensis. There is debate if Au. deyiremeda is a new species or is Au. afarensis. Australopithecus prometheus, otherwise known as Little Foot has recently been dated at 3.67 million years old through a new dating technique, making the genus Australopithecus as old as afarensis. Given the opposable big toe found on Little Foot, it seems that he was a good climber, and it is thought given the night predators of the region, he probably, like gorillas and chimpanzees, built a nesting platform at night, in the trees.
Evolution of genus Homo
The earliest documented representative of the genus Homo is Homo habilis, which evolved around , and is arguably the earliest species for which there is positive evidence of the use of stone tools. The brains of these early hominins were about the same size as that of a chimpanzee, although it has been suggested that this was the time in which the human SRGAP2 gene doubled, producing a more rapid wiring of the frontal cortex. During the next million years a process of rapid encephalization occurred, and with the arrival of Homo erectus and Homo ergaster in the fossil record, cranial capacity had doubled to 850 cm3. (Such an increase in human brain size is equivalent to each generation having 125,000 more neurons than their parents.) It is believed that Homo erectus and Homo ergaster were the first to use fire and complex tools, and were the first of the hominin line to leave Africa, spreading throughout Africa, Asia, and Europe between .
According to the recent African origin of modern humans theory, modern humans evolved in Africa possibly from Homo heidelbergensis, Homo rhodesiensis or Homo antecessor and migrated out of the continent some 50,000 to 100,000 years ago, gradually replacing local populations of Homo erectus, Denisova hominins, Homo floresiensis, Homo luzonensis and Homo neanderthalensis. Archaic Homo sapiens, the forerunner of anatomically modern humans, evolved in the Middle Paleolithic between 400,000 and 250,000 years ago. Recent DNA evidence suggests that several haplotypes of Neanderthal origin are present among all non-African populations, and Neanderthals and other hominins, such as Denisovans, may have contributed up to 6% of their genome to present-day humans, suggestive of a limited interbreeding between these species. The transition to behavioral modernity with the development of symbolic culture, language, and specialized lithic technology happened around 50,000 years ago, according to some anthropologists, although others point to evidence that suggests that a gradual change in behavior took place over a longer time span.
Homo sapiens is the only extant species of its genus, Homo. While some (extinct) Homo species might have been ancestors of Homo sapiens, many, perhaps most, were likely "cousins", having speciated away from the ancestral hominin line. There is yet no consensus as to which of these groups should be considered a separate species and which should be a subspecies; this may be due to the dearth of fossils or to the slight differences used to classify species in the genus Homo. The Sahara pump theory (describing an occasionally passable "wet" Sahara desert) provides one possible explanation of the early variation in the genus Homo.
Based on archaeological and paleontological evidence, it has been possible to infer, to some extent, the ancient dietary practices of various Homo species and to study the role of diet in physical and behavioral evolution within Homo.
Some anthropologists and archaeologists subscribe to the Toba catastrophe theory, which posits that the supereruption of Lake Toba on Sumatran island in Indonesia some 70,000 years ago caused global consequences, killing the majority of humans and creating a population bottleneck that affected the genetic inheritance of all humans today. The genetic and archaeological evidence for this remains in question however.
H. habilis and H. gautengensis
Homo habilis lived from about 2.8 to 1.4 Ma. The species evolved in South and East Africa in the Late Pliocene or Early Pleistocene, 2.5–2 Ma, when it diverged from the australopithecines. Homo habilis had smaller molars and larger brains than the australopithecines, and made tools from stone and perhaps animal bones. One of the first known hominins was nicknamed 'handy man' by discoverer Louis Leakey due to its association with stone tools. Some scientists have proposed moving this species out of Homo and into Australopithecus due to the morphology of its skeleton being more adapted to living on trees rather than to moving on two legs like Homo sapiens.
H. rudolfensis and H. georgicus
These are proposed species names for fossils from about 1.9–1.6 Ma, whose relation to Homo habilis is not yet clear.
- Homo rudolfensis refers to a single, incomplete skull from Kenya. Scientists have suggested that this was another Homo habilis, but this has not been confirmed.
- Homo georgicus, from Georgia, may be an intermediate form between Homo habilis and Homo erectus, or a subspecies of Homo erectus.
H. ergaster and H. erectus
The first fossils of Homo erectus were discovered by Dutch physician Eugene Dubois in 1891 on the Indonesian island of Java. He originally named the material Anthropopithecus erectus (1892–1893, considered at this point as a chimpanzee-like fossil primate) and Pithecanthropus erectus (1893–1894, changing his mind as of based on its morphology, which he considered to be intermediate between that of humans and apes). Years later, in the 20th century, the German physician and paleoanthropologist Franz Weidenreich (1873–1948) compared in detail the characters of Dubois' Java Man, then named Pithecanthropus erectus, with the characters of the Peking Man, then named Sinanthropus pekinensis. Weidenreich concluded in 1940 that because of their anatomical similarity with modern humans it was necessary to gather all these specimens of Java and China in a single species of the genus Homo, the species Homo erectus. Homo erectus lived from about 1.8 Ma to about 70,000 years ago – which would indicate that they were probably wiped out by the Toba catastrophe; however, nearby Homo floresiensis survived it. The early phase of Homo erectus, from 1.8 to 1.25 Ma, is considered by some to be a separate species, Homo ergaster, or as Homo erectus ergaster, a subspecies of Homo erectus.
In Africa in the Early Pleistocene, 1.5–1 Ma, some populations of Homo habilis are thought to have evolved larger brains and to have made more elaborate stone tools; these differences and others are sufficient for anthropologists to classify them as a new species, Homo erectus—in Africa. The evolution of locking knees and the movement of the foramen magnum are thought to be likely drivers of the larger population changes. This species also may have used fire to cook meat. Richard Wrangham suggests that the fact that Homo seems to have been ground dwelling, with reduced intestinal length, smaller dentition, "and swelled our brains to their current, horrendously fuel-inefficient size", suggest that control of fire and releasing increased nutritional value through cooking was the key adaptation that separated Homo from tree-sleeping Australopithecines.
A famous example of Homo erectus is Peking Man; others were found in Asia (notably in Indonesia), Africa, and Europe. Many paleoanthropologists now use the term Homo ergaster for the non-Asian forms of this group, and reserve Homo erectus only for those fossils that are found in Asia and meet certain skeletal and dental requirements which differ slightly from H. ergaster.
H. cepranensis and H. antecessor
These are proposed as species that may be intermediate between H. erectus and H. heidelbergensis.
- H. antecessor is known from fossils from Spain and England that are dated 1.2 Ma–500 ka.
- H. cepranensis refers to a single skull cap from Italy, estimated to be about 800,000 years old.
H. heidelbergensis ("Heidelberg Man") lived from about 800,000 to about 300,000 years ago. Also proposed as Homo sapiens heidelbergensis or Homo sapiens paleohungaricus.
H. rhodesiensis, and the Gawis cranium
- H. rhodesiensis, estimated to be 300,000–125,000 years old. Most current researchers place Rhodesian Man within the group of Homo heidelbergensis, though other designations such as archaic Homo sapiens and Homo sapiens rhodesiensis have been proposed.
- In February 2006 a fossil, the Gawis cranium, was found which might possibly be a species intermediate between H. erectus and H. sapiens or one of many evolutionary dead ends. The skull from Gawis, Ethiopia, is believed to be 500,000–250,000 years old. Only summary details are known, and the finders have not yet released a peer-reviewed study. Gawis man's facial features suggest its being either an intermediate species or an example of a "Bodo man" female.
Neanderthal and Denisovan
Homo neanderthalensis, alternatively designated as Homo sapiens neanderthalensis, lived in Europe and Asia from 400,000 to about 28,000 years ago. There are a number of clear anatomical differences between anatomically modern humans (AMH) and Neanderthal populations. Many of these relate to the superior adaptation to cold environments possessed by the Neanderthal populations. Their surface to volume ratio is an extreme version of that found amongst Inuit populations, indicating that they were less inclined to lose body heat than were AMH. From brain Endocasts, Neanderthals also had significantly larger brains. This would seem to indicate that the intellectual superiority of AMH populations may be questionable. More recent research by Eiluned Pearce, Chris Stringer, R.I.M. Dunbar, however, have shown important differences in brain architecture. For example, in both the orbital chamber size and in the size of the occipital lobe, the larger size suggests that the Neanderthal had a better visual acuity than modern humans. This would give a superior vision in the inferior light conditions found in Glacial Europe. It also seems that the higher body mass of Neanderthals had a correspondingly larger brain mass required for body care and control.
The Neanderthal populations seem to have been physically superior to AMH populations. These differences may have been sufficient to give Neanderthal populations an environmental superiority to AMH populations from 75,000 to 45,000 years BP. With these differences, Neanderthal brains show a smaller area was available for social functioning. Plotting group size possible from endocranial volume, suggests that AMH populations (minus occipital lobe size), had a Dunbars number of 144 possible relationships. Neanderthal populations seem to have been limited to about 120 individuals. This would show up in a larger number of possible mates for AMH humans, with increased risks of inbreeding amongst Neanderthal populations. It also suggests that humans had larger trade catchment areas than Neanderthals (confirmed in the distribution of stone tools). With larger populations, social and technological innovations were easier to fix in human populations, which may have all contributed to the fact that modern Homo sapiens replaced the Neanderthal populations by 28,000 BP.
Earlier evidence from sequencing mitochondrial DNA suggested that no significant gene flow occurred between H. neanderthalensis and H. sapiens, and that the two were separate species that shared a common ancestor about 660,000 years ago. However, a sequencing of the Neanderthal genome in 2010 indicated that Neanderthals did indeed interbreed with anatomically modern humans circa 45,000 to 80,000 years ago (at the approximate time that modern humans migrated out from Africa, but before they dispersed into Europe, Asia and elsewhere). The genetic sequencing of a 40,000-year-old human skeleton from Romania showed that 11% of its genome was Neanderthal, and it was estimated that the individual had a Neanderthal ancestor 4–6 generations previously, in addition to a contribution from earlier interbreeding in the Middle East. Though this interbred Romanian population seems not to have been ancestral to modern humans, the finding indicates that interbreeding happened repeatedly.
All modern non-African humans have about 1% to 4% or, according to more recent data, about 1.5% to 2.6% of their DNA derived from Neanderthal DNA, and this finding is consistent with recent studies indicating that the divergence of some human alleles dates to one Ma, although the interpretation of these studies has been questioned. Neanderthals and Homo sapiens could have co-existed in Europe for as long as 10,000 years, during which human populations exploded vastly outnumbering Neanderthals, possibly outcompeting them by sheer numerical strength.
In 2008, archaeologists working at the site of Denisova Cave in the Altai Mountains of Siberia uncovered a small bone fragment from the fifth finger of a juvenile member of Denisovans. Artifacts, including a bracelet, excavated in the cave at the same level were carbon dated to around 40,000 BP. As DNA had survived in the fossil fragment due to the cool climate of the Denisova Cave, both mtDNA and nuclear DNA were sequenced.
While the divergence point of the mtDNA was unexpectedly deep in time, the full genomic sequence suggested the Denisovans belonged to the same lineage as Neanderthals, with the two diverging shortly after their line split from the lineage that gave rise to modern humans. Modern humans are known to have overlapped with Neanderthals in Europe and the Near East for possibly more than 40,000 years, and the discovery raises the possibility that Neanderthals, Denisovans, and modern humans may have co-existed and interbred. The existence of this distant branch creates a much more complex picture of humankind during the Late Pleistocene than previously thought. Evidence has also been found that as much as 6% of the DNA of some modern Melanesians derive from Denisovans, indicating limited interbreeding in Southeast Asia.
Alleles thought to have originated in Neanderthals and Denisovans have been identified at several genetic loci in the genomes of modern humans outside of Africa. HLA haplotypes from Denisovans and Neanderthal represent more than half the HLA alleles of modern Eurasians, indicating strong positive selection for these introgressed alleles. Corinne Simoneti at Vanderbilt University, in Nashville and her team have found from medical records of 28,000 people of European descent that the presence of Neanderthal DNA segments may be associated with a likelihood to suffer depression more frequently.
The flow of genes from Neanderthal populations to modern humans was not all one way. Sergi Castellano of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, has in 2016 reported that while Denisovan and Neanderthal genomes are more related to each other than they are to us, Siberian Neanderthal genomes show similarity to the modern human gene pool, more so than to European Neanderthal populations. The evidence suggests that the Neanderthal populations interbred with modern humans possibly 100,000 years ago, probably somewhere in the Near East.
Studies of a Neanderthal child at Gibraltar show from brain development and teeth eruption that Neanderthal children may have matured more rapidly than is the case for Homo sapiens.
H. floresiensis, which lived from approximately 190,000 to 50,000 years before present (BP), has been nicknamed the hobbit for its small size, possibly a result of insular dwarfism. H. floresiensis is intriguing both for its size and its age, being an example of a recent species of the genus Homo that exhibits derived traits not shared with modern humans. In other words, H. floresiensis shares a common ancestor with modern humans, but split from the modern human lineage and followed a distinct evolutionary path. The main find was a skeleton believed to be a woman of about 30 years of age. Found in 2003, it has been dated to approximately 18,000 years old. The living woman was estimated to be one meter in height, with a brain volume of just 380 cm3 (considered small for a chimpanzee and less than a third of the H. sapiens average of 1400 cm3).
However, there is an ongoing debate over whether H. floresiensis is indeed a separate species. Some scientists hold that H. floresiensis was a modern H. sapiens with pathological dwarfism. This hypothesis is supported in part, because some modern humans who live on Flores, the Indonesian island where the skeleton was found, are pygmies. This, coupled with pathological dwarfism, could have resulted in a significantly diminutive human. The other major attack on H. floresiensis as a separate species is that it was found with tools only associated with H. sapiens.
The hypothesis of pathological dwarfism, however, fails to explain additional anatomical features that are unlike those of modern humans (diseased or not) but much like those of ancient members of our genus. Aside from cranial features, these features include the form of bones in the wrist, forearm, shoulder, knees, and feet. Additionally, this hypothesis fails to explain the find of multiple examples of individuals with these same characteristics, indicating they were common to a large population, and not limited to one individual.
A small number of specimens from the island of Luzon, dated 50,000 to 67,000 years ago, have recently been assigned by their discoverers, based on dental characteristics, to a novel human species, H. luzonensis.
H. sapiens (the adjective sapiens is Latin for "wise" or "intelligent") emerged in Africa around 300,000 years ago, likely derived from Homo heidelbergensis or a related lineage. In September 2019, scientists reported the computerized determination, based on 260 CT scans, of a virtual skull shape of the last common human ancestor to modern humans/H. sapiens, representative of the earliest modern humans, and suggested that modern humans arose between 260,000 and 350,000 years ago through a merging of populations in East and South Africa.
Between 400,000 years ago and the second interglacial period in the Middle Pleistocene, around 250,000 years ago, the trend in intra-cranial volume expansion and the elaboration of stone tool technologies developed, providing evidence for a transition from H. erectus to H. sapiens. The direct evidence suggests there was a migration of H. erectus out of Africa, then a further speciation of H. sapiens from H. erectus in Africa. A subsequent migration (both within and out of Africa) eventually replaced the earlier dispersed H. erectus. This migration and origin theory is usually referred to as the "recent single-origin hypothesis" or "out of Africa" theory. H. sapiens interbred with archaic humans both in Africa and in Eurasia, in Eurasia notably with Neanderthals and Denisovans.
The Toba catastrophe theory, which postulates a population bottleneck for H. sapiens about 70,000 years ago, was controversial from its first proposal in the 1990s and by the 2010s had very little support. Distinctive human genetic variability has arisen as the result of the founder effect, by archaic admixture and by recent evolutionary pressures.
Use of tools
The use of tools has been interpreted as a sign of intelligence, and it has been theorized that tool use may have stimulated certain aspects of human evolution, especially the continued expansion of the human brain. Paleontology has yet to explain the expansion of this organ over millions of years despite being extremely demanding in terms of energy consumption. The brain of a modern human consumes about 13 watts (260 kilocalories per day), a fifth of the body's resting power consumption. Increased tool use would allow hunting for energy-rich meat products, and would enable processing more energy-rich plant products. Researchers have suggested that early hominins were thus under evolutionary pressure to increase their capacity to create and use tools.
Precisely when early humans started to use tools is difficult to determine, because the more primitive these tools are (for example, sharp-edged stones) the more difficult it is to decide whether they are natural objects or human artifacts. There is some evidence that the australopithecines (4 Ma) may have used broken bones as tools, but this is debated.
Many species make and use tools, but it is the human genus that dominates the areas of making and using more complex tools. The oldest known tools are flakes from West Turkana, Kenya, which date to 3.3 million years ago. The next oldest stone tools are from Gona, Ethiopia, and are considered the beginning of the Oldowan technology. These tools date to about 2.6 million years ago. A Homo fossil was found near some Oldowan tools, and its age was noted at 2.3 million years old, suggesting that maybe the Homo species did indeed create and use these tools. It is a possibility but does not yet represent solid evidence. The third metacarpal styloid process enables the hand bone to lock into the wrist bones, allowing for greater amounts of pressure to be applied to the wrist and hand from a grasping thumb and fingers. It allows humans the dexterity and strength to make and use complex tools. This unique anatomical feature separates humans from apes and other nonhuman primates, and is not seen in human fossils older than 1.8 million years.
Bernard Wood noted that Paranthropus co-existed with the early Homo species in the area of the "Oldowan Industrial Complex" over roughly the same span of time. Although there is no direct evidence which identifies Paranthropus as the tool makers, their anatomy lends to indirect evidence of their capabilities in this area. Most paleoanthropologists agree that the early Homo species were indeed responsible for most of the Oldowan tools found. They argue that when most of the Oldowan tools were found in association with human fossils, Homo was always present, but Paranthropus was not.
In 1994, Randall Susman used the anatomy of opposable thumbs as the basis for his argument that both the Homo and Paranthropus species were toolmakers. He compared bones and muscles of human and chimpanzee thumbs, finding that humans have 3 muscles which are lacking in chimpanzees. Humans also have thicker metacarpals with broader heads, allowing more precise grasping than the chimpanzee hand can perform. Susman posited that modern anatomy of the human opposable thumb is an evolutionary response to the requirements associated with making and handling tools and that both species were indeed toolmakers.
Stone tools are first attested around 2.6 million years ago, when hominins in Eastern Africa used so-called core tools, choppers made out of round cores that had been split by simple strikes. This marks the beginning of the Paleolithic, or Old Stone Age; its end is taken to be the end of the last Ice Age, around 10,000 years ago. The Paleolithic is subdivided into the Lower Paleolithic (Early Stone Age), ending around 350,000–300,000 years ago, the Middle Paleolithic (Middle Stone Age), until 50,000–30,000 years ago, and the Upper Paleolithic, (Late Stone Age), 50,000–10,000 years ago.
Archaeologists working in the Great Rift Valley in Kenya have discovered the oldest known stone tools in the world. Dated to around 3.3 million years ago, the implements are some 700,000 years older than stone tools from Ethiopia that previously held this distinction.
The period from 700,000 to 300,000 years ago is also known as the Acheulean, when H. ergaster (or erectus) made large stone hand axes out of flint and quartzite, at first quite rough (Early Acheulian), later "retouched" by additional, more-subtle strikes at the sides of the flakes. After 350,000 BP the more refined so-called Levallois technique was developed, a series of consecutive strikes, by which scrapers, slicers ("racloirs"), needles, and flattened needles were made. Finally, after about 50,000 BP, ever more refined and specialized flint tools were made by the Neanderthals and the immigrant Cro-Magnons (knives, blades, skimmers). Bone tools were also made by H. sapiens in Africa by 90–70,000 years ago and are also known from early H. sapiens sites in Eurasia by about 50,000 years ago.
Transition to behavioral modernity
Until about 50,000–40,000 years ago, the use of stone tools seems to have progressed stepwise. Each phase (H. habilis, H. ergaster, H. neanderthalensis) started at a higher level than the previous one, but after each phase started, further development was slow. Currently paleoanthropologists are debating whether these Homo species possessed some or many of the cultural and behavioral traits associated with modern humans such as language, complex symbolic thinking, technological creativity etc. It seems that they were culturally conservative maintaining simple technologies and foraging patterns over very long periods.
Around 50,000 BP, modern human culture started to evolve more rapidly. The transition to behavioral modernity has been characterized by some as a "Great Leap Forward", or as the "Upper Palaeolithic Revolution", due to the sudden appearance of distinctive signs of modern behavior and big game hunting in the archaeological record. Evidence of behavioral modernity significantly earlier also exists from Africa, with older evidence of abstract imagery, widened subsistence strategies, more sophisticated tools and weapons, and other "modern" behaviors, and many scholars have recently argued that the transition to modernity occurred sooner than previously believed. Some other scholars consider the transition to have been more gradual, noting that some features had already appeared among archaic African Homo sapiens since 300–200,000 years ago. Recent evidence suggests that the Australian Aboriginal population separated from the African population 75,000 years ago, and that they made a sea journey of up to 160 km 60,000 years ago, which may diminish the evidence of the Upper Paleolithic Revolution.
Modern humans started burying their dead, using animal hides to make clothing, hunting with more sophisticated techniques (such as using trapping pits or driving animals off cliffs), and engaging in cave painting. As human culture advanced, different populations of humans introduced novelty to existing technologies: artifacts such as fish hooks, buttons, and bone needles show signs of variation among different populations of humans, something that had not been seen in human cultures prior to 50,000 BP. Typically, H. neanderthalensis populations do not vary in their technologies, although the Chatelperronian assemblages have been found to be Neanderthal innovations produced as a result of exposure to the Homo sapiens Aurignacian technologies.
Among concrete examples of modern human behavior, anthropologists include specialization of tools, use of jewellery and images (such as cave drawings), organization of living space, rituals (for example, burials with grave gifts), specialized hunting techniques, exploration of less hospitable geographical areas, and barter trade networks. Debate continues as to whether a "revolution" led to modern humans ("the big bang of human consciousness"), or whether the evolution was more "gradual".
Recent and ongoing human evolution
Anatomically modern human populations continue to evolve, as they are affected by both natural selection and genetic drift. Although selection pressure on some traits, such as resistance to smallpox, has decreased in the modern age, humans are still undergoing natural selection for many other traits. Some of these are due to specific environmental pressures, while others are related to lifestyle changes since the development of agriculture (10,000 years ago), urbanization (5,000), and industrialization (250 years ago). It has been argued that human evolution has accelerated since the development of agriculture 10,000 years ago and civilization some 5,000 years ago, resulting, it is claimed, in substantial genetic differences between different current human populations, and more recent research indicates that for some traits, the developments and innovations of human culture have driven a new form of selection that coexists with, and in some cases has largely replaced, natural selection.
Particularly conspicuous is variation in superficial characteristics, such as Afro-textured hair, or the recent evolution of light skin and blond hair in some populations, which are attributed to differences in climate. Particularly strong selective pressures have resulted in high-altitude adaptation in humans, with different ones in different isolated populations. Studies of the genetic basis show that some developed very recently, with Tibetans evolving over 3,000 years to have high proportions of an allele of EPAS1 that is adaptive to high altitudes.
Other evolution is related to endemic diseases: the presence of malaria selects for sickle cell trait (the heterozygous form of sickle cell gene), while in the absence of malaria, the health effects of sickle-cell anemia select against this trait. For another example, the population at risk of the severe debilitating disease kuru has significant over-representation of an immune variant of the prion protein gene G127V versus non-immune alleles. The frequency of this genetic variant is due to the survival of immune persons. Some reported trends remain unexplained and the subject of ongoing research in the novel field of evolutionary medicine: polycystic ovary syndrome (PCOS) reduces fertility and thus is expected to be subject to extremely strong negative selection, but its relative commonality in human populations suggests a counteracting selection pressure. The identity of that pressure remains the subject of some debate.
Recent human evolution related to agriculture includes genetic resistance to infectious disease that has appeared in human populations by crossing the species barrier from domesticated animals, as well as changes in metabolism due to changes in diet, such as lactase persistence.
Culturally-driven evolution can defy the expectations of natural selection: while human populations experience some pressure that drives a selection for producing children at younger ages, the advent of effective contraception, higher education, and changing social norms have driven the observed selection in the opposite direction. However, culturally-driven selection need not necessarily work counter or in opposition to natural selection: some proposals to explain the high rate of recent human brain expansion indicate a kind of feedback whereupon the brain's increased social learning efficiency encourages cultural developments that in turn encourage more efficiency, which drive more complex cultural developments that demand still-greater efficiency, and so forth. Culturally-driven evolution has an advantage in that in addition to the genetic effects, it can be observed also in the archaeological record: the development of stone tools across the Palaeolithic period connects to culturally-driven cognitive development in the form of skill acquisition supported by the culture and the development of increasingly complex technologies and the cognitive ability to elaborate them.
In contemporary times, since industrialization, some trends have been observed: for instance, menopause is evolving to occur later. Other reported trends appear to include lengthening of the human reproductive period and reduction in cholesterol levels, blood glucose and blood pressure in some populations.
This list is in chronological order across the table by genus. Some species/subspecies names are well-established, and some are less established – especially in genus Homo. Please see articles for more information.
- Adaptive evolution in the human genome
- Amity-enmity complex
- Dual inheritance theory
- Evolution of human intelligence
- Evolution of morality
- Evolutionary medicine
- Evolutionary neuroscience
- Evolutionary origin of religions
- Human behavioral ecology
- Human evolution (origins of society and culture)
- Human origins
- Human vestigiality
- List of human evolution fossils
- Molecular paleontology
- Obstetrical dilemma
- Origin of language
- Origin of speech
- Sexual selection in human evolution
- Transgenerational trauma
- Brian K. Hall; Benedikt Hallgrímsson (2011). Strickberger's Evolution. Jones & Bartlett Publishers. p. 488. ISBN 978-1-4496-6390-2.
- Rogers Ackermann, Rebecca; Mackay, Alex; Arnold, Michael L (October 2015). "The Hybrid Origin of "Modern" Humans". Evolutionary Biology. 43 (1): 1–11. doi:10.1007/s11692-015-9348-1. S2CID 14329491.
- Antrosio, Jason (August 23, 2018). "Denisovans and Neandertals: Rethinking Species Boundaries". Living Anthropologically.
- Human Hybrids. (PDF). Michael F. Hammer. Scientific American, May 2013.
- Yong, Ed (July 2011). "Mosaic humans, the hybrid species". New Scientist. 211 (2823): 34–38. Bibcode:2011NewSc.211...34Y. doi:10.1016/S0262-4079(11)61839-3.
- Heng, Henry H.Q. (May 2009). "The genome-centric concept: resynthesis of evolutionary theory". BioEssays. 31 (5): 512–525. doi:10.1002/bies.200800182. ISSN 0265-9247. PMID 19334004. S2CID 1336952.
- Tyson, Peter (July 1, 2008). "Meet Your Ancestors". Nova ScienceNow. PBS; WGBH Educational Foundation. Retrieved April 18, 2015.
- Planck 2012 harvnb error: no target: CITEREFPlanck2012 (help)
- Boyd & Silk 2003
- Brues & Snow 1965, pp. 1–39
- Brunet, Michel; Guy, Franck; Pilbeam, David; et al. (July 11, 2002). "A new hominid from the Upper Miocene of Chad, Central Africa". Nature. 418 (6894): 145–151. Bibcode:2002Natur.418..145B. doi:10.1038/nature00879. ISSN 0028-0836. PMID 12110880. S2CID 1316969.
- White, T. D.; Asfaw, B.; Beyene, Y.; Haile-Selassie, Y.; Lovejoy, C. O.; Suwa, G.; Woldegabriel, G. (2009). "Ardipithecus ramidus and the Paleobiology of Early Hominids". Science. 326 (5949): 75–86. Bibcode:2009Sci...326...75W. doi:10.1126/science.1175802. PMID 19810190. S2CID 20189444.
- Kwang Hyun, Ko (2015). "Origins of Bipedalism". Brazilian Archives of Biology and Technology. 58 (6): 929–934. arXiv:1508.02739. Bibcode:2015arXiv150802739K. doi:10.1590/S1516-89132015060399. S2CID 761213.
- DeSalle & Tattersall 2008, p. 146
- Curry 2008, pp. 106–109
- "Study Identifies Energy Efficiency As Reason For Evolution Of Upright Walking". ScienceDaily. Rockville, MD: ScienceDaily, LLC. July 17, 2007. Retrieved April 9, 2015.
- "Study identifies energy efficiency as reason for evolution of upright walking". UANews. Tucson, AZ: The University of Arizona Office of University Communications. July 16, 2007. Retrieved April 23, 2015.
- Sockol, Michael D.; Raichlen, David A.; Pontzer, Herman (July 24, 2007). "Chimpanzee locomotor energetics and the origin of human bipedalism". Proc. Natl. Acad. Sci. U.S.A. 104 (30): 12265–12269. Bibcode:2007PNAS..10412265S. doi:10.1073/pnas.0703267104. ISSN 0027-8424. PMC 1941460. PMID 17636134.
- David-Barrett, T.; Dunbar, R.I.M. (2016). "Bipedality and Hair-loss Revisited: The Impact of Altitude and Activity Scheduling". Journal of Human Evolution. 94: 72–82. doi:10.1016/j.jhevol.2016.02.006. PMC 4874949. PMID 27178459.
- Aiello & Dean 1990
- Kondo 1985
- Srivastava 2009, p. 87
- Strickberger 2000, pp. 475–476
- Trevathan 2011, p. 20
- Zuk, Marlene (2014), "Paleofantasy: What Evolution Really Tells Us About Sex, Diet, and How We Live" (W.W. Norton & Company)
- Hrdy, Sarah Blaffer (2011), "Mothers and Others: The Evolutionary Origins of Mutual Understanding" (Harvard Uni Press)
- Wayman, Erin (August 19, 2013). "Killer whales, grandmas and what men want: Evolutionary biologists consider menopause". Science News. ISSN 0036-8423. Retrieved April 24, 2015.
- Schoenemann, P. Thomas (October 2006). "Evolution of the Size and Functional Areas of the Human Brain". Annual Review of Anthropology. 35: 379–406. doi:10.1146/annurev.anthro.35.081705.123210. ISSN 0084-6570. S2CID 7611321.
- Brown, Graham; Fairfax, Stephanie; Sarao, Nidhi. "Tree of Life Web Project: Human Evolution". www.tolweb.org.
- Park, Min S.; Nguyen, Andrew D.; Aryan, Henry E.; et al. (March 2007). "Evolution of the human brain: changing brain size and the fossil record". Neurosurgery. 60 (3): 555–562. doi:10.1227/01.NEU.0000249284.54137.32. ISSN 0148-396X. PMID 17327801. S2CID 19610624.
- Bruner, Emiliano (December 2007). "Cranial shape and size variation in human evolution: structural and functional perspectives". Child's Nervous System. 23 (12): 1357–1365. CiteSeerX 10.1.1.391.288. doi:10.1007/s00381-007-0434-2. ISSN 0256-7040. PMID 17680251. S2CID 16163137.
- Potts, Richard (October 2012). "Evolution and Environmental Change in Early Human Prehistory". Annual Review of Anthropology. 41: 151–167. doi:10.1146/annurev-anthro-092611-145754. ISSN 0084-6570.
- Leonard, William R.; Snodgrass, J. Josh; Robertson, Marcia L. (August 2007). "Effects of brain evolution on human nutrition and metabolism". Annual Review of Nutrition. 27: 311–327. doi:10.1146/annurev.nutr.27.061406.093659. ISSN 0199-9885. PMID 17439362. S2CID 18869516.
- McBroom, Patricia (June 14, 1999). "Meat-eating was essential for human evolution, says UC Berkeley anthropologist specializing in diet" (Press release). Berkeley: University of California Press. Retrieved April 25, 2015.
- Mann, Neil (September 2007). "Meat in the human diet: An anthropological perspective". Nutrition & Dietetics. 64 (Supplement s4): S102–S107. doi:10.1111/j.1747-0080.2007.00194.x. ISSN 1747-0080. Retrieved January 31, 2012.
- Zimmer, Carl (August 13, 2015). "For Evolving Brains, a 'Paleo' Diet Full of Carbs". The New York Times. Retrieved August 14, 2015.
- Organ, Chris; Nunn, Charles L.; Machanda, Zarin; Wrangham, Richard W. (August 30, 2011). "Phylogenetic rate shifts in feeding time during the evolution of Homo". Proc. Natl. Acad. Sci. U.S.A. 108 (35): 14555–14559. Bibcode:2011PNAS..10814555O. doi:10.1073/pnas.1107806108. ISSN 0027-8424. PMC 3167533. PMID 21873223.
- David-Barrett, T.; Dunbar, R.I.M. (2013). "Processing Power Limits Social Group Size: Computational Evidence for the Cognitive Costs of Sociality". Proceedings of the Royal Society B. 280 (1765): 20131151. doi:10.1098/rspb.2013.1151. PMC 3712454. PMID 23804623.
- Bown & Rose 1987
- Barton, Robert A.; Venditti, Chris (October 20, 2014). "Rapid Evolution of the Cerebellum in Humans and Other Great Apes". Current Biology. 24 (20): 2440–2444. doi:10.1016/j.cub.2014.08.056. ISSN 0960-9822. PMID 25283776. S2CID 5041106.
- Starowicz-Filip, Anna; Milczarek, Olga; Kwiatkowski, Stanisław; et al. (2013). "Cerebellar cognitive affective syndrome CCAS – a case report". Archives of Psychiatry and Psychotherapy. 15 (3): 57–64. doi:10.12740/APP/18666. OCLC 220954272.
- Feng Yu; Qing-jun Jiang; Xi-yan Sun; et al. (August 22, 2014). "A new case of complete primary cerebellar agenesis: clinical and imaging findings in a living patient". Brain. 138 (Pt 6): e353. doi:10.1093/brain/awu239. ISSN 1460-2156. PMC 4614135. PMID 25149410.
- Weaver, Anne H. (March 8, 2005). "Reciprocal evolution of the cerebellum and neocortex in fossil humans". Proc. Natl. Acad. Sci. U.S.A. 102 (10): 3576–3580. Bibcode:2005PNAS..102.3576W. doi:10.1073/pnas.0500692102. ISSN 0027-8424. PMC 553338. PMID 15731345.
- Klein, Stefan (2014). Survival of the Nicest. The Experiment. ISBN 978-1615190904.
- Sallet, J.; Mars, R.B.; Noonan, M.P.; Andersson, J.L.; O'Reilly, J.X.; Jbabdi, S.; Croxson, P.L.; Jenkinson, M.; Miller, K.L. (November 4, 2011). "Social Network Size Affects Neural Circuits in Macaques". Science. 334 (6056): 697–700. Bibcode:2011Sci...334..697S. doi:10.1126/science.1210027. ISSN 0036-8075. PMID 22053054. S2CID 206536017.
- Dunbar, R.I.M. (1992). "Neocortex size as a constraint on group size in primates". Journal of Human Evolution. 22 (6): 469–493. doi:10.1016/0047-2484(92)90081-j.
- Dávid-Barrett, T.; Dunbar, R.I.M. (August 22, 2013). "Processing power limits social group size: computational evidence for the cognitive costs of sociality". Proceedings of the Royal Society of London B: Biological Sciences. 280 (1765): 20131151. doi:10.1098/rspb.2013.1151. ISSN 0962-8452. PMC 3712454. PMID 23804623.
- Shultz, Susanne; Dunbar, Robin (December 14, 2010). "Encephalization is not a universal macroevolutionary phenomenon in mammals but is associated with sociality". Proceedings of the National Academy of Sciences. 107 (50): 21582–21586. Bibcode:2010PNAS..10721582S. doi:10.1073/pnas.1005246107. ISSN 0027-8424. PMC 3003036. PMID 21098277.
- Richard, Potts (1998). "Environmental Hypotheses of Hominin Evolution". American Journal of Physical Anthropology. 107: 93–136. doi:10.1002/(sici)1096-8644(1998)107:27+<93::aid-ajpa5>3.0.co;2-x.
- Kaplan, Hillard; Hill, Kim; Lancaster, Jane; Hurtado, Magdelena (August 16, 2000). "A Theory of Human Life History Evolution: Diet, Intelligence, and Longevity" (PDF). Evolutionary Anthropology. 9 (4): 156–185. doi:10.1002/1520-6505(2000)9:4<156::AID-EVAN5>3.0.CO;2-7.
- Tanner, Nancy Makepeace; Tanner (1981). On Becoming Human. CUP Archive. p. 202. ISBN 978-0-521-28028-0.
- Reno, Philip L.; Lovejoy, C. Owen (April 28, 2015). "From Lucy to Kadanuumuu: balanced analyses ofAustralopithecus afarensisassemblages confirm only moderate skeletal dimorphism". PeerJ. 3: e925. doi:10.7717/peerj.925. ISSN 2167-8359. PMC 4419524. PMID 25945314.
- Lovejoy, C. Owen (October 2, 2009). "Reexamining Human Origins in Light of Ardipithecus ramidus" (PDF). Science. 326 (5949): 74–74e8. Bibcode:2009Sci...326...74L. doi:10.1126/science.1175834. ISSN 0036-8075. PMID 19810200. S2CID 42790876.
- Young, Richard W (January 2003). "Evolution of the human hand: the role of throwing and clubbing". Journal of Anatomy. 202 (1): 165–174. doi:10.1046/j.1469-7580.2003.00144.x. ISSN 0021-8782. PMC 1571064. PMID 12587931.
- Miriam Ittyerah (2013). Hand Preference and Hand Ability: Evidence from studies in Haptic Cognition. John Benjamins Publishing. pp. 37–38. ISBN 978-9027271648.
- Frank R. Wilson. "The Hand How Its Use Shapes the Brain, Language, and Human Culture". The New York Times. Pantheon Books. Retrieved July 2, 2017.
- Pontzer, Herman (2016). "Metabolic acceleration and the evolution of human brain size and life history". Nature. 533 (7603): 390–392. Bibcode:2016Natur.533..390P. doi:10.1038/nature17654. PMC 4942851. PMID 27144364.
- American Heritage Dictionaries (editors) 2006
- "Nested Hierarchies, the Order of Nature: Carolus Linnaeus". Understanding Evolution: The History of Evolutionary Thought. The University of California at Berkeley. Retrieved August 2, 2019.
- Darwin, Charles (1859). "On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life". Nature (Full image view 1st ed.). 5 (121): 367–404. Bibcode:1872Natur...5..318B. doi:10.1038/005318a0. PMC 5184128. PMID 30164232. S2CID 4042779.
- Darwin 1981
- Montgomery 1988, pp. 95–96
- Shipman, Pat; Storm, Paul (2002). "Missing links: Eugène Dubois and the origins of paleoanthropology". Evolutionary Anthropology: Issues, News, and Reviews. 11 (3): 108–116. doi:10.1002/evan.10021. ISSN 1520-6505. S2CID 84889438.
- Dart, Raymond (February 7, 1925). "Australopithecus africanus: The Man-Ape of South Africa". Nature. 115 (2884): 195–199. Bibcode:1925Natur.115..195D. doi:10.1038/115195a0. ISSN 0028-0836. S2CID 4142569.
- Johanson & Edey 1981, pp. 20–22, 184–185
- Cartmill, Matt; Fred H. Smith; Kaye B. Brown (2009). The Human Lineage. Wiley-Blackwell. p. 151. ISBN 978-0-471-21491-5.
- Johanson & Edey 1981, p. 22
- Shreeve, Jamie (July 2010). "The Evolutionary Road". National Geographic. ISSN 0027-9358. Retrieved May 28, 2015.
- Berger, LR; et al. (2015). "Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa". eLife. 4. doi:10.7554/eLife.09560. PMC 4559886. PMID 26354291.
- Shreeve, Jamie (September 10, 2015). "This Face Changes the Human Story. But How?". National Geographic News. Retrieved September 10, 2015.
- Dirks et al. (2017): between 335 and 236 ka. The lower limit of 236 ka is due to optically stimulated luminescence dating of sediments with U-Th and palaeomagnetic analyses of flowstones; the upper limit of 335 ka is due to U-series and electron spin resonance (US-ESR) dating of two H. naledi teeth, to 253+82
−70 ka, for an estimated age of the fossils of 253+82
- Dirks, Paul H.G.M.; Roberts, Eric M.; et al. (May 9, 2017). "The age of Homo naledi and associated sediments in the Rising Star Cave, South Africa". eLife. 6: e24231. doi:10.7554/eLife.24231. PMC 5423772. PMID 28483040.Full list of authors
- Paul H.G.M. Dirks
- Eric M. Roberts
- Hannah Hilbert-Wolf
- Jan D. Kramers
- John Hawks
- Anthony Dosseto
- Mathieu Duval
- Marina Elliott
- Mary Evans
- Rainer Grün
- John Hellstrom
- Andy I.R. Herries
- Renaud Joannes-Boyau
- Tebogo V. Makhubela
- Christa J. Placzek
- Jessie Robbins
- Carl Spandler
- Jelle Wiersma
- Jon Woodhead
- Lee R. Berger
- Sarich, V.M.; Wilson, A.C. (1967). "Immunological time scale for hominid evolution". Science. 158 (3805): 1200–1204. Bibcode:1967Sci...158.1200S. doi:10.1126/science.158.3805.1200. PMID 4964406. S2CID 7349579.
- M'charek 2005, p. 96
- Trent 2005, p. 6
- Wade, Nicholas (May 18, 2006). "Two Splits Between Human and Chimp Lines Suggested". The New York Times. Retrieved April 20, 2015.
- Behar, Doron M.; Villems, Richard; Soodyall, Himla; et al. (May 9, 2008). "The Dawn of Human Matrilineal Diversity" (PDF). American Journal of Human Genetics. 82 (5): 1130–1140. doi:10.1016/j.ajhg.2008.04.002. ISSN 0002-9297. PMC 2427203. PMID 18439549. Retrieved April 20, 2015.
- Gonder, Mary Katherine; Mortensen, Holly M.; Reed, Floyd A.; et al. (March 2007). "Whole-mtDNA Genome Sequence Analysis of Ancient African Lineages" (PDF). Molecular Biology and Evolution. 24 (3): 757–768. doi:10.1093/molbev/msl209. ISSN 0737-4038. PMID 17194802. Retrieved April 20, 2015.
- Tishkoff and Reed (2009)
- Templeton, Alan R. (2005). "Haplotype Trees and Modern Human Origins". American Journal of Physical Anthropology. 128 (Supplement 41 (Yearbook of Physical Anthropology)): 33–59. doi:10.1002/ajpa.20351. ISSN 0002-9483. PMID 16369961.
- Peter B. deMenocal, (2016) "Climate Shocks" (Scientific American Vol 25, No 4)
- Barras, Colin (2016), "Stone Tools hint humans reached Asia much earlier" (New Scientist February 6, 2016)
- Wolpoff, Milford H.; Hawks, John; Caspari, Rachel (May 2000). "Multiregional, Not Multiple Origins" (PDF). American Journal of Physical Anthropology. 112 (1): 129–136. doi:10.1002/(SICI)1096-8644(200005)112:1<129::AID-AJPA11>3.0.CO;2-K. hdl:2027.42/34270. ISSN 0002-9483. PMID 10766948.
- Wolpoff, Milford H.; Spuhler, James N.; Smith, Fred H.; et al. (August 12, 1988). "Modern Human Origins". Science. 241 (4867): 772–774. Bibcode:1988Sci...241..772W. doi:10.1126/science.3136545. ISSN 0036-8075. PMID 3136545.
- Owen, James (July 18, 2007). "Modern Humans Came Out of Africa, 'Definitive' Study Says". National Geographic News. Washington, DC: National Geographic Society. Retrieved May 14, 2011.
- Stringer, Chris B.; Andrews, Peter (March 11, 1988). "Genetic and fossil evidence for the origin of modern humans". Science. 239 (4845): 1263–1268. Bibcode:1988Sci...239.1263S. doi:10.1126/science.3125610. ISSN 0036-8075. PMID 3125610. S2CID 39200956.
- Webster 2010, p. 53
- Ramachandran et al. 2010, p. 606
- Kutty 2009, p. 40 harvnb error: no target: CITEREFKutty2009 (help)
- Cann, Rebecca L.; Stoneking, Mark; Wilson, Allan C. (January 1, 1987). "Mitochondrial DNA and human evolution". Nature. 325 (6099): 31–36. Bibcode:1987Natur.325...31C. doi:10.1038/325031a0. ISSN 0028-0836. PMID 3025745. S2CID 4285418. Archived from the original on August 13, 2010. Retrieved April 21, 2015.
- Gill, Victoria (May 1, 2009). "Africa's genetic secrets unlocked". BBC News. London: BBC. Retrieved June 8, 2011. The results were published in the online edition of the journal Science.
- Leakey 1994, pp. 87–89
- Jorde, Lynn B.; Bamshad, Michael; Rogers, Alan R. (February 1998). "Using mitochondrial and nuclear DNA markers to reconstruct human evolution". BioEssays. 20 (2): 126–136. doi:10.1002/(SICI)1521-1878(199802)20:2<126::AID-BIES5>3.0.CO;2-R. ISSN 0265-9247. PMID 9631658.
- Wall, Jeffrey D.; Lohmueller, Kirk E.; Plagnol, Vincent (August 2009). "Detecting Ancient Admixture and Estimating Demographic Parameters in Multiple Human Populations". Molecular Biology and Evolution. 26 (8): 1823–1827. doi:10.1093/molbev/msp096. ISSN 0737-4038. PMC 2734152. PMID 19420049.
- Green, Richard E.; Krause, Johannes; Briggs, Adrian W.; et al. (May 7, 2010). "A Draft Sequence of the Neandertal Genome". Science. 328 (5979): 710–722. Bibcode:2010Sci...328..710G. doi:10.1126/science.1188021. ISSN 0036-8075. PMC 5100745. PMID 20448178.
- Reich, David; Green, Richard E.; Kircher, Martin; et al. (December 23, 2010). "Genetic history of an archaic hominin group from Denisova Cave in Siberia". Nature. 468 (7327): 1053–1060. Bibcode:2010Natur.468.1053R. doi:10.1038/nature09710. hdl:10230/25596. ISSN 0028-0836. PMC 4306417. PMID 21179161.
- Prüfer, K.; de Filippo, C.; Grote, S.; Mafessoni, F.; Korlević, P.; Hajdinjak, M.; et al. (2017). "A high-coverage Neandertal genome from Vindija Cave in Croatia". Science. 358 (6363): 655–58. Bibcode:2017Sci...358..655P. doi:10.1126/science.aao1887. PMC 6185897. PMID 28982794.
- Reich, David; Patterson, Nick; Kircher, Martin; et al. (October 7, 2011). "Denisova Admixture and the First Modern Human Dispersals into Southeast Asia and Oceania". American Journal of Human Genetics. 89 (4): 516–528. doi:10.1016/j.ajhg.2011.09.005. ISSN 0002-9297. PMC 3188841. PMID 21944045.
- Abi-Rached, Laurent; Jobin, Matthew J.; Kulkarni, Subhash; et al. (October 7, 2011). "The Shaping of Modern Human Immune Systems by Multiregional Admixture with Archaic Humans". Science. 334 (6052): 89–94. Bibcode:2011Sci...334...89A. doi:10.1126/science.1209202. ISSN 0036-8075. PMC 3677943. PMID 21868630.
- Huertha Sanchez, Emilia et al. (2014), "Altitude adaptation in Tibetans caused by introgression of Denisovan-like DNA" (Nature Vol 512, August 14, 2014)
- "Artificial intelligence applied to the genome identifies an unknown human ancestor". ScienceDaily. Retrieved January 17, 2019.
- Lahr, Marta Mirazón; Petraglia, Mike; Stokes, Stephen; et al. "Searching for traces of the Southern Dispersal". Leverhulme Centre for Human Evolutionary Studies. Cambridge: University of Cambridge. Archived from the original on May 10, 2012. Retrieved April 21, 2015.
- Simpson, Colin. DNA evidence suggests the whole world is a little bit Arab. The National. 16, June 2020. Archived at The Wayback Machine
- Fernandes V, Alshamali F, Alves M, et al. The Arabian cradle: mitochondrial relicts of the first steps along the southern route out of Africa. Am J Hum Genet. 2012;90(2):347–355. doi:10.1016/j.ajhg.2011.12.010
- Macaulay, Vincent; Hill, Catherine; Achilli, Alessandro; et al. (May 13, 2005). "Single, Rapid Coastal Settlement of Asia Revealed by Analysis of Complete Mitochondrial Genomes" (PDF). Science. 308 (5724): 1034–1036. Bibcode:2005Sci...308.1034M. doi:10.1126/science.1109792. ISSN 0036-8075. PMID 15890885. S2CID 31243109.
- Oppenheimer, Stephen (2012), "Out of Eden: The Peopling of the World" (Robinson; New Ed edition (March 1, 2012))
- Posth C, Renaud G, Mittnik M, Drucker DG, Rougier H, Cupillard C, et al. (2016). "Pleistocene Mitochondrial Genomes Suggest a Single Major Dispersal of Non-Africans and a Late Glacial Population Turnover in Europe". Current Biology. 26 (6): 827–833. doi:10.1016/j.cub.2016.01.037. PMID 26853362. S2CID 140098861.
- Karmin M, Saag L, Vicente M, Wilson Sayres MA, Järve M, Talas UG, et al. (April 2015). "A recent bottleneck of Y chromosome diversity coincides with a global change in culture". Genome Research. 25 (4): 459–66. doi:10.1101/gr.186684.114. PMC 4381518. PMID 25770088.
- Haber M, Jones AL, Connell BA, Arciero E, Yang H, Thomas MG, et al. (August 2019). "A Rare Deep-Rooting D0 African Y-Chromosomal Haplogroup and Its Implications for the Expansion of Modern Humans Out of Africa". Genetics. 212 (4): 1421–1428. doi:10.1534/genetics.119.302368. PMC 6707464. PMID 31196864.
- Stanford, Allen & Antón 2009
- Wood, Bernard A.; Richmond, Brian G. (July 2000). "Human evolution: taxonomy and paleobiology". Journal of Anatomy. 197 (1): 19–60. doi:10.1046/j.1469-7580.2000.19710019.x. ISSN 1469-7580. PMC 1468107. PMID 10999270.
- Ajit, Varki; Nelson, David L. (October 2007). "Genomic Comparisons of Humans and Chimpanzees" (PDF). Annual Review of Anthropology. 36: 191–209. doi:10.1146/annurev.anthro.36.081406.094339. ISSN 0084-6570. Retrieved April 26, 2015.
Sequence differences from the human genome were confirmed to be ∼1% in areas that can be precisely aligned, representing ∼35 million single base-pair differences. Some 45 million nucleotides of insertions and deletions unique to each lineage were also discovered, making the actual difference between the two genomes ∼4%.
- Sayers, Ken; Raghanti, Mary Ann; Lovejoy, C. Owen (October 2012). "Human Evolution and the Chimpanzee Referential Doctrine". Annual Review of Anthropology. 41: 119–138. doi:10.1146/annurev-anthro-092611-145815. ISSN 0084-6570.
- Dawkins 2004
- "Find Time of Divergence: Hominidae versus Hylobatidae". TimeTree. Retrieved April 18, 2015.
- Ruvolo, Maryellen (October 1997). "Genetic Diversity in Hominoid Primates". Annual Review of Anthropology. 26: 515–540. doi:10.1146/annurev.anthro.26.1.515. ISSN 0084-6570.
- Ruvolo, Maryellen (March 1997). "Molecular Phylogeny of the Hominoids: Inferences from Multiple Independent DNA Sequence Data Sets". Molecular Biology and Evolution. 14 (3): 248–265. doi:10.1093/oxfordjournals.molbev.a025761. ISSN 0737-4038. PMID 9066793.
- Patterson, N; Richter, DJ; Gnerre, S; Lander, ES; Reich, D (2006). "Genetic evidence for complex speciation of humans and chimpanzees". Nature. 441 (7097): 1103–1108. Bibcode:2006Natur.441.1103P. doi:10.1038/nature04789. PMID 16710306. S2CID 2325560.
- Begun, David R. (October 2010). "Miocene Hominids and the Origins of the African Apes and Humans". Annual Review of Anthropology. 39: 67–84. doi:10.1146/annurev.anthro.012809.105047. ISSN 0084-6570.
- Ghosh, Pallab (March 4, 2015). "'First human' discovered in Ethiopia". BBC News. London. Retrieved April 19, 2015.
- Wood 2009, pp. 17–27
- Mitchell, Alanna (January 30, 2012). "DNA Turning Human Story Into a Tell-All". The New York Times. Retrieved February 13, 2012.
- Wood, Bernard A. (December 1996). "Human evolution". BioEssays. 18 (12): 945–954. doi:10.1002/bies.950181204. ISSN 0265-9247. PMID 8976151. S2CID 221464189.
- Huxley, T. (1890). "The Aryan Question and Pre-Historic Man". Collected Essays: Volume VII, Man's Place in Nature.
- Our ancestors mated with the mystery ‘Denisovan’ people – twice. Andy Coghlan, New Scientist. March 15, 2018.
- Green, R. E.; Krause, J.; Briggs, A. W.; Maricic, T.; Stenzel, U.; Kircher, M.; Patterson, N.; Li, H.; Zhai, W.; Fritz, M. H. Y.; Hansen, N. F.; Durand, E. Y.; Malaspinas, A. S.; Jensen, J. D.; Marques-Bonet, T.; Alkan, C.; Prufer, K.; Meyer, M.; Burbano, H. A.; Good, J. M.; Schultz, R.; Aximu-Petri, A.; Butthof, A.; Hober, B.; Hoffner, B.; Siegemund, M.; Weihmann, A.; Nusbaum, C.; Lander, E. S.; Russ, C.; Novod, N.; Affourtit, J.; Egholm, M.; Verna, C.; Rudan, P.; Brajkovic, D.; Kucan, Z.; Gusic, I.; Doronichev, V. B.; Golovanova, L. V.; Lalueza-Fox, C.; de la Rasilla, M.; Fortea, J.; Rosas, A.; Schmitz, R. W.; Johnson, P. L. F.; Eichler, E. E.; Falush, D.; Birney, E.; Mullikin, J. C.; Slatkin, M.; Nielsen, R.; Kelso, J.; Lachmann, M.; Reich, D.; Paabo, S. (May 6, 2010). "A Draft Sequence of the Neandertal Genome". Science. 328 (5979): 710–722. Bibcode:2010Sci...328..710G. doi:10.1126/science.1188021. PMC 5100745. PMID 20448178.
- Wei-Haas, Maya (August 22, 2018). "Ancient Girl's Parents Were Two Different Human Species – Born 90,000 years ago, the child is the first direct evidence of interbreeding among Neanderthals and their cousins the Denisovans". National Geographic. Retrieved August 22, 2018.
- A world map of Neanderthal and Denisovan ancestry in modern humans. March 28, 2016.
- Sankararaman, Sriram; Mallick, Swapan; Patterson, Nick; Reich, David (2016). "The Combined Landscape of Denisovan and Neanderthal Ancestry in Present-Day Humans". Current Biology. 26 (9): 1241–7. doi:10.1016/j.cub.2016.03.037. PMC 4864120. PMID 27032491.
- Human-Neandertal Comparisons. Tara Marathe. Science Magazine. 2010.
- Dannemann, M; Andrés, AM; Kelso, J (2016). "Introgression of Neandertal- and Denisovan-like Haplotypes Contributes to Adaptive Variation in Human Toll-like Receptors". Am J Hum Genet. 98 (1): 22–33. doi:10.1016/j.ajhg.2015.11.015. PMC 4716682. PMID 26748514.
- Gittelman, Rachel M.; Schraiber, Joshua G.; Vernot, Benjamin; Mikacenic, Carmen; Wurfel, Mark M.; Akey, Joshua M. (2016). "Archaic Hominin Admixture Facilitated Adaptation to Out-of-Africa Environments". Current Biology. 26 (24): 3375–3382. doi:10.1016/j.cub.2016.10.041. PMC 6764441. PMID 27839976.
- Maxwell 1984, p. 296
- Rui Zhang; Yin-Qiu Wang; Bing Su (July 2008). "Molecular Evolution of a Primate-Specific microRNA Family" (PDF). Molecular Biology and Evolution. 25 (7): 1493–1502. doi:10.1093/molbev/msn094. ISSN 0737-4038. PMID 18417486. Retrieved April 27, 2015.
- Willoughby, Pamela R. (2005). "Palaeoanthropology and the Evolutionary Place of Humans in Nature". International Journal of Comparative Psychology. 18 (1): 60–91. ISSN 0889-3667. Retrieved April 27, 2015.
- Martin 2001, pp. 12032–12038
- Tavaré, Simon; Marshall, Charles R.; Will, Oliver; et al. (April 18, 2002). "Using the fossil record to estimate the age of the last common ancestor of extant primates". Nature. 416 (6882): 726–729. Bibcode:2002Natur.416..726T. doi:10.1038/416726a. ISSN 0028-0836. PMID 11961552. S2CID 4368374.
- Rose, Kenneth D. (1994). "The earliest primates". Evolutionary Anthropology: Issues, News, and Reviews. 3 (5): 159–173. doi:10.1002/evan.1360030505. ISSN 1060-1538. S2CID 85035753.
- Fleagle, John; Gilbert, Chris (2011). Rowe, Noel; Myers, Marc (eds.). "Primate Evolution". All The World's Primates. Charlestown, RI: Primate Conservation, Inc. Retrieved April 27, 2015.
- Roach, John (March 3, 2008). "Oldest Primate Fossil in North America Discovered". National Geographic News. Washington, DC: National Geographic Society. Retrieved April 27, 2015.
- McMains, Vanessa (December 5, 2011). "Found in Wyoming: New fossils of oldest American primate". The Gazette. Baltimore, MD: Johns Hopkins University. Retrieved April 27, 2015.
- Caldwell, Sara B. (May 19, 2009). "Missing link found, early primate fossil 47 million years old". Digital Journal. Toronto, Canada: digitaljournal.com. Retrieved April 27, 2015.
- Watts, Alex (May 20, 2009). "Scientists Unveil Missing Link In Evolution". Sky News Online. London: BSkyB. Archived from the original on July 28, 2011. Retrieved April 27, 2015.
- Wilford, J.N. (June 5, 2013). "Palm-size fossil resets primates' clock, scientists say". The New York Times. Retrieved June 5, 2013.
- Kordos, László; Begun, David R. (January 2001). "Primates from Rudabánya: allocation of specimens to individuals, sex and age categories". Journal of Human Evolution. 40 (1): 17–39. doi:10.1006/jhev.2000.0437. ISSN 0047-2484. PMID 11139358.
- Cameron 2004, p. 76
- Wallace 2004, p. 240
- Zalmout, Iyad S.; Sanders, William J.; MacLatchy, Laura M.; et al. (July 15, 2010). "New Oligocene primate from Saudi Arabia and the divergence of apes and Old World monkeys". Nature. 466 (7304): 360–364. Bibcode:2010Natur.466..360Z. doi:10.1038/nature09094. ISSN 0028-0836. PMID 20631798. S2CID 205220837.
- Clark, G.; Henneberg, M. (June 2015). "The life history of Ardipithecus ramidus: a heterochronic model of sexual and social maturation". Anthropological Review. 78 (2): 109–132. doi:10.1515/anre-2015-0009. S2CID 54900467. Retrieved July 22, 2015.
- Zimmer, Carl (May 27, 2015). "The Human Family Tree Bristles With New Branches". The New York Times. Retrieved May 30, 2015.
- Gardner., Elizabeth K.; Purdue University (April 1, 2015). "New instrument dates old skeleton before 'Lucy'; 'Little Foot' 3.67 million years old". Science Daily. Retrieved April 3, 2015.
- Swisher, Curtis & Lewin 2001
- based on Schlebusch, CM; Malmström, H; Günther, T; Sjödin, P; Coutinho, A; Edlund, H; Munters, AR; Vicente, M; Steyn, M; Soodyall, H; Lombard, M; Jakobsson, M (2017). "Southern African ancient genomes estimate modern human divergence to 350,000 to 260,000 years ago". Science. 358 (6363): 652–655. Bibcode:2017Sci...358..652S. doi:10.1126/science.aao6266. PMID 28971970. S2CID 206663925., Fig. 3 (H. sapiens divergence times) and Stringer, C. (2012). "What makes a modern human". Nature. 485 (7396): 33–35. Bibcode:2012Natur.485...33S. doi:10.1038/485033a. PMID 22552077. S2CID 4420496. (archaic admixture).
- Stringer 1994, p. 242
- McHenry 2009, p. 265
- "Out of Africa Revisited". Science (This Week in Science). 308 (5724): 921. May 13, 2005. doi:10.1126/science.308.5724.921g. ISSN 0036-8075. S2CID 220100436.
- Stringer, Chris (June 12, 2003). "Human evolution: Out of Ethiopia". Nature. 423 (6941): 692–695. Bibcode:2003Natur.423..692S. doi:10.1038/423692a. ISSN 0028-0836. PMID 12802315. S2CID 26693109.
- Johanson, Donald (May 2001). "Origins of Modern Humans: Multiregional or Out of Africa?". actionbioscience. Washington, DC: American Institute of Biological Sciences. Retrieved November 23, 2009.
- Mixon, Bobbie; Ehardt, Carolyn; Hammer, Michael (September 6, 2011). "Evolution's Past Is Modern Human's Present" (Press release). National Science Foundation. Press Release 11-181. Retrieved April 20, 2015.
- O'Neil, Dennis. "Early Modern Homo sapiens". Evolution of Modern Humans: A Survey of the Biological and Cultural Evolution of Archaic and Modern Homo sapiens (Tutorial). San Marcos, CA: Palomar College. Retrieved April 20, 2015.
- "Fossil Reanalysis Pushes Back Origin of Homo sapiens". Scientific American. February 17, 2005. ISSN 0036-8733. Retrieved April 20, 2015.
- Noonan, James P. (May 2010). "Neanderthal genomics and the evolution of modern humans". Genome Research. 20 (5): 547–553. doi:10.1101/gr.076000.108. ISSN 1088-9051. PMC 2860157. PMID 20439435.
- Mellars, Paul (June 20, 2006). "Why did modern human populations disperse from Africa ca. 60,000 years ago? A new model". Proc. Natl. Acad. Sci. U.S.A. 103 (25): 9381–9386. Bibcode:2006PNAS..103.9381M. doi:10.1073/pnas.0510792103. ISSN 0027-8424. PMC 1480416. PMID 16772383.
- Mcbrearty, Sally; Brooks, Alison S. (November 2000). "The revolution that wasn't: a new interpretation of the origin of modern human behavior". Journal of Human Evolution. 39 (5): 453–563. doi:10.1006/jhev.2000.0435. ISSN 0047-2484. PMID 11102266. S2CID 42968840.
- Strait, David S.; Grine, Frederick E.; Moniz, Marc A. (January 1997). "A reappraisal of early hominid phylogeny". Journal of Human Evolution. 32 (1): 17–82. doi:10.1006/jhev.1996.0097. ISSN 0047-2484. PMID 9034954. S2CID 37754799.
- Bryson 2004, pp. 522–543
- Walker 2007, pp. 3–10
- Ungar & Teaford 2002
- Bogin 1997, pp. 96–142
- Barnicot, Nigel A. (April–June 2005). "Human nutrition: Evolutionary perspectives". Integrative Physiological & Behavioral Science. 40 (2): 114–117. doi:10.1007/BF02734246. ISSN 1932-4502. PMID 17393680. S2CID 39549910.
- "The new batch – 150,000 years ago". The evolution of man. London: BBC Science & Nature. Archived from the original on January 18, 2006. Retrieved April 28, 2015.
- Whitehouse, David (June 9, 2003). "When humans faced extinction". BBC News. London: BBC. Retrieved January 5, 2007.
- "Modern humans flourished through ancient supervolcano eruption 74,000 years ago: Modern humans flourished through ancient supervolcano eruption". ScienceDaily. Retrieved January 24, 2019.
- Wood, Bernard; Collard, Mark (1999). "The changing face of Genus Homo". Evolutionary Anthropology: Issues, News, and Reviews. 8 (6): 195–207. doi:10.1002/(SICI)1520-6505(1999)8:6<195::AID-EVAN1>3.0.CO;2-2. ISSN 1060-1538.
- Viegas, Jennifer (May 21, 2010). "Toothy Tree-Swinger May Be Earliest Human". Discovery News. Silver Spring, MD: Discovery Communications, LLC. Retrieved April 28, 2015.
- Wood, Bernard A. (January 1999). "Homo rudolfensis Alexeev, 1986 – fact or phantom?". Journal of Human Evolution. 36 (1): 115–118. doi:10.1006/jhev.1998.0246. ISSN 0047-2484. PMID 9924136.
- Gabounia, Léo; de Lumley, Marie-Antoinette; Vekua, Abesalom; et al. (September 2002). "Découverte d'un nouvel hominidé à Dmanissi (Transcaucasie, Géorgie)" [Discovery of a new hominid at Dmanisi (Transcaucasia, Georgia)]. Comptes Rendus Palevol (in French). 1 (4): 243–253. doi:10.1016/S1631-0683(02)00032-5. ISSN 1631-0683.
- Lordkipanidze, David; Vekua, Abesalom; Ferring, Reid; et al. (November 2006). "A fourth hominin skull from Dmanisi, Georgia". The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology. 288A (11): 1146–1157. doi:10.1002/ar.a.20379. ISSN 1552-4884. PMID 17031841.
- Turner, William (April 1895). "On M. Dubois' Description of Remains recently found in Java, named by him Pithecanthropus erectus. With Remarks on so-called Transitional Forms between Apes and Man". Journal of Anatomy and Physiology. 29 (Pt 3): 424–445. PMC 1328414. PMID 17232143.
- Weidenreich, Franz (July 1940). "Some Problems Dealing with Ancient Man". American Anthropologist. 42 (3): 375–383. doi:10.1525/aa.1940.42.3.02a00010. ISSN 0002-7294.
- Grine, Frederick E.; Fleagle, John G. (2009), "The First Humans: A Summary Perspective on the Origin and Early Evolution of the Genus Homo", Vertebrate Paleobiology and Paleoanthropology, Springer Netherlands, pp. 197–207, doi:10.1007/978-1-4020-9980-9_17, ISBN 9781402099793
- Spoor, Fred; Wood, Bernard A.; Zonneveld, Frans (June 23, 1994). "Implications of early hominid labyrinthine morphology for evolution of human bipedal locomotion". Nature. 369 (6482): 645–648. Bibcode:1994Natur.369..645S. doi:10.1038/369645a0. ISSN 0028-0836. PMID 8208290. S2CID 4344784.
- Ings, Simon (October 4, 2009). "Catching Fire: How Cooking Made Us Human by Richard Wrangham: review". Retrieved February 23, 2016.
- Wrangham, Richard (2011), "Catching Fire: How cooking made us human"
- Bermúdez de Castro, José María; Arsuaga, Juan Luis; Carbonell, Eudald; et al. (May 30, 1997). "A Hominid from the Lower Pleistocene of Atapuerca, Spain: Possible Ancestor to Neandertals and Modern Humans". Science. 276 (5317): 1392–1395. doi:10.1126/science.276.5317.1392. ISSN 0036-8075. PMID 9162001.
- Carbonell, Eudald; Bermúdez de Castro, José María; Parés, Josep M.; et al. (March 27, 2008). "The first hominin of Europe". Nature. 452 (7186): 465–469. Bibcode:2008Natur.452..465C. doi:10.1038/nature06815. hdl:2027.42/62855. ISSN 0028-0836. PMID 18368116. S2CID 4401629.
- Manzi, Giorgio; Mallegni, Francesco; Ascenzi, Antonio (August 14, 2001). "A cranium for the earliest Europeans: Phylogenetic position of the hominid from Ceprano, Italy". Proc. Natl. Acad. Sci. U.S.A. 98 (17): 10011–10016. Bibcode:2001PNAS...9810011M. doi:10.1073/pnas.151259998. ISSN 0027-8424. PMC 55569. PMID 11504953.
- Czarnetzki, Alfred; Jakob, Tina; Pusch, Carsten M. (April 2003). "Palaeopathological and variant conditions of the Homo heidelbergensis type specimen (Mauer, Germany)". Journal of Human Evolution. 44 (4): 479–495. doi:10.1016/S0047-2484(03)00029-0. ISSN 0047-2484. PMID 12727464.
- Semaw, Sileshi; Toth, Nicholas; Schick, Kathy; et al. (March 27, 2006). "Scientists discover hominid cranium in Ethiopia" (Press release). Bloomington: Indiana University. Retrieved November 26, 2006.
- Harvati, Katerina (January 2003). "The Neanderthal taxonomic position: models of intra- and inter-specific craniofacial variation". Journal of Human Evolution. 44 (1): 107–132. doi:10.1016/S0047-2484(02)00208-7. ISSN 0047-2484. PMID 12604307.
- Herrera, K.J.; Somarelli, J.A.; Lowery, R.K.; Herrera, R.J. (2009). "To what extent did Neanderthals and modern humans interact?". Biological Reviews. 84 (2): 245–257. doi:10.1111/j.1469-185X.2008.00071.x. PMID 19391204. S2CID 25787484.
- Finlayson, Clive; Giles Pacheco, Francisco; Rodríguez-Vidal, Joaquín; Fa, Darren A; María Gutierrez López, José; Santiago Pérez, Antonio; Finlayson, Geraldine; Allue, Ethel; Baena Preysler, Javier; Cáceres, Isabel; Carrión, José S; Fernández Jalvo, Yolanda; Gleed-Owen, Christopher P; Jimenez Espejo, Francisco J; López, Pilar; Antonio López Sáez, José; Antonio Riquelme Cantal, José; Sánchez Marco, Antonio; Giles Guzman, Francisco; Brown, Kimberly; Fuentes, Noemí; Valarino, Claire A; Villalpando, Antonio; Stringer, Christopher B; Martinez Ruiz, Francisca; Sakamoto, Tatsuhiko (2006). "Late survival of Neanderthals at the southernmost extreme of Europe". Nature. 443 (7113): 850–853. Bibcode:2006Natur.443..850F. doi:10.1038/nature05195. hdl:10261/18685. PMID 16971951. S2CID 4411186.
- Pearce, Eiluned; Stringer, Chris; Dunbar, R.I.M. (2013). "New insights into differences in brain organization between Neanderthals and anatomically modern humans (Proceedings of the Royal Society)". Proceedings of the Royal Society of London B: Biological Sciences. 280 (1758): 20130168. doi:10.1098/rspb.2013.0168. PMC 3619466. PMID 23486442.
- Krings, Matthias; Stone, Anne; Schmitz, Ralf W.; et al. (July 11, 1997). "Neandertal DNA sequences and the origin of modern humans". Cell. 90 (1): 19–30. doi:10.1016/S0092-8674(00)80310-4. hdl:11858/00-001M-0000-0025-0960-8. ISSN 0092-8674. PMID 9230299. S2CID 13581775.
- Green, Richard E.; Malaspinas, Anna-Sapfo; Krause, Johannes; et al. (August 8, 2008). "A Complete Neandertal Mitochondrial Genome Sequence Determined by High-Throughput Sequencing". Cell. 134 (3): 416–426. doi:10.1016/j.cell.2008.06.021. ISSN 0092-8674. PMC 2602844. PMID 18692465.
- Serre, David; Langaney, André; Chech, Mario; et al. (March 2004). "No Evidence of Neandertal mtDNA Contribution to Early Modern Humans". PLOS Biology. 2 (3): e57. doi:10.1371/journal.pbio.0020057. ISSN 1545-7885. PMC 368159. PMID 15024415.
- Viegas, Jennifer (May 6, 2010). "Neanderthals, Humans Interbred, DNA Proves". Discovery News. Silver Spring, MD: Discovery Communications, LLC. Archived from the original on May 8, 2015. Retrieved April 30, 2015.
- Calloway, Ewan (May 13, 2015). "Early European may have had Neanderthal great-great-grandparent". Nature. doi:10.1038/nature.2015.17534. S2CID 181973496.
- Sample, Ian (June 22, 2015). "My Neanderthal sex secret: modern European's great-great grandparent link". The Guardian. Retrieved July 27, 2018.
- Gutiérrez, Gabriel; Sánchez, Diego; Marín, Antonio (August 2002). "A Reanalysis of the Ancient Mitochondrial DNA Sequences Recovered from Neandertal Bones". Molecular Biology and Evolution. 19 (8): 1359–1366. doi:10.1093/oxfordjournals.molbev.a004197. ISSN 0737-4038. PMID 12140248.
- Hebsgaard, Martin B.; Wiuf, Carsten; Gilbert, M. Thomas; et al. (January 2007). "Evaluating Neanderthal Genetics and Phylogeny" (PDF). Journal of Molecular Evolution. 64 (1): 50–60. Bibcode:2007JMolE..64...50H. CiteSeerX 10.1.1.174.8969. doi:10.1007/s00239-006-0017-y. ISSN 0022-2844. PMID 17146600. S2CID 2746487. Archived from the original (PDF) on April 1, 2011. Retrieved October 24, 2017.
- Mellars, Paul; French, Jennifer C. (July 29, 2011). "Tenfold Population Increase in Western Europe at the Neandertal–to–Modern Human Transition Paul". Science. 333 (6042): 623–627. Bibcode:2011Sci...333..623M. doi:10.1126/science.1206930. ISSN 0036-8075. PMID 21798948. S2CID 28256970.
- Brown, Terence A. (April 8, 2010). "Human evolution: Stranger from Siberia". Nature. 464 (7290): 838–839. Bibcode:2010Natur.464..838B. doi:10.1038/464838a. ISSN 0028-0836. PMID 20376137. S2CID 4320406.
- Krause, Johannes; Qiaomei Fu; Good, Jeffrey M.; et al. (April 8, 2010). "The complete mitochondrial DNA genome of an unknown hominin from southern Siberia". Nature. 464 (7290): 894–897. Bibcode:2010Natur.464..894K. doi:10.1038/nature08976. ISSN 0028-0836. PMID 20336068. S2CID 4415601.
- Katsnelson, Alla (March 24, 2010). "New hominin found via mtDNA". The Nutshell (Blog). Philadelphia, PA: The Scientist. ISSN 0890-3670. Retrieved May 1, 2015.
- "Kaufman, Danial (2002), "Comparisons and the Case for Interaction among Neanderthals and Early Modern Humans in the Levant" (Oxford Journal of Anthropology)
- Bokma, Folmer; van den Brink, Valentijn; Stadler, Tanja (September 2012). "Unexpectedly many extinct hominins". Evolution. 66 (9): 2969–2974. doi:10.1111/j.1558-5646.2012.01660.x. ISSN 0014-3820. PMID 22946817. S2CID 13145359.
- Martinón-Torres, María; Dennell, Robin; Bermúdez de Castro, José María (February 2011). "The Denisova hominin need not be an out of Africa story". Journal of Human Evolution. 60 (2): 251–255. doi:10.1016/j.jhevol.2010.10.005. ISSN 0047-2484. PMID 21129766.
- Simonti, C.N.; Vernot, B.; Bastarache, L.; Bottinger, E.; Carrell, D.S.; Chisholm, R.L.; Crosslin, D.R.; Hebbring, S.J.; Jarvik, G. P.; Kullo, I.J.; Li, R.; Pathak, J.; Ritchie, M.D.; Roden, D.M.; Verma, S.S.; Tromp, G.; Prato, J.D.; Bush, W.S.; Akey, J.M.; Denny, J.C.; Capra, J.A. (2016). "The phenotypic legacy of admixture between modern humans and Neandertals". Science. 351 (6274): 737–741. Bibcode:2016Sci...351..737S. doi:10.1126/science.aad2149. PMC 4849557. PMID 26912863.
- Kuhlwilm, M; Gronau, I; Hubisz, MJ; de Filippo, C; Prado-Martinez, J; Kircher, M; Fu, Q; Burbano, HA; Lalueza-Fox, C; de la Rasilla, M; Rosas, A; Rudan, P; Brajkovic, D; Kucan, Ž; Gušic, I; Marques-Bonet, T; Andrés, AM; Viola, B; Pääbo, S; Meyer, M; Siepel, A; Castellano, S (2016). "Ancient gene flow from early modern humans into Eastern Neanderthals". Nature. 530 (7591): 429–433. Bibcode:2016Natur.530..429K. doi:10.1038/nature16544. PMC 4933530. PMID 26886800.
- Dean, MC, Stringer, CB et al, (1986) "Age at death of the Neanderthal child from Devil's Tower, Gibraltar and the implications for studies of general growth and development in Neanderthals" (American Journal of Physical Anthropology, Vol 70 Issue 3, July 1986)
- Brown, Peter; Sutikna, Thomas; Morwood, Michael J.; Soejono, Raden Panji; et al. (October 28, 2004). "A new small-bodied hominin from the Late Pleistocene of Flores, Indonesia". Nature. 431 (7012): 1055–1061. Bibcode:2004Natur.431.1055B. doi:10.1038/nature02999. ISSN 0028-0836. PMID 15514638. S2CID 26441.
- Argue, Debbie; Donlon, Denise; Groves, Colin; et al. (October 2006). "Homo floresiensis: Microcephalic, pygmoid, Australopithecus, or Homo?". Journal of Human Evolution. 51 (4): 360–374. doi:10.1016/j.jhevol.2006.04.013. ISSN 0047-2484. PMID 16919706.
- Martin, Robert D.; Maclarnon, Ann M.; Phillips, James L.; et al. (November 2006). "Flores hominid: New species or microcephalic dwarf?". The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology. 288A (11): 1123–1145. doi:10.1002/ar.a.20389. ISSN 1552-4884. PMID 17031806.
- Détroit, F.; Mijares, A. S.; Corny, J.; Daver, G.; Zanolli, C.; Dizon, E.; Robles, E.; Grün, R. & Piper, P. J. (2019). "A new species of Homo from the Late Pleistocene of the Philippines". Nature. 568 (7751): 181–186. Bibcode:2019Natur.568..181D. doi:10.1038/s41586-019-1067-9. PMID 30971845. S2CID 106411053.
- Schlebusch, Carina M; Malmström, Helena; Günther, Torsten; Sjödin, Per; Coutinho, Alexandra; Edlund, Hanna; Munters, Arielle R; Vicente, Mário; Steyn, Maryna; Soodyall, Himla; Lombard, Marlize; Jakobsson, Mattias (2017). "Southern African ancient genomes estimate modern human divergence to 350,000 to 260,000 years ago". Science. 358 (6363): 652–655. Bibcode:2017Sci...358..652S. doi:10.1126/science.aao6266. PMID 28971970. S2CID 206663925.
- Sample, Ian (June 7, 2017). "Oldest Homo sapiens bones ever found shake foundations of the human story". The Guardian. Retrieved June 7, 2017.
- Zimmer, Carl (September 10, 2019). "Scientists Find the Skull of Humanity's Ancestor — on a Computer – By comparing fossils and CT scans, researchers say they have reconstructed the skull of the last common forebear of modern humans". The New York Times. Retrieved September 10, 2019.
- Mounier, Aurélien; Lahr, Marta (2019). "Deciphering African late middle Pleistocene hominin diversity and the origin of our species". Nature Communications. 10 (1): 3406. Bibcode:2019NatCo..10.3406M. doi:10.1038/s41467-019-11213-w. PMC 6736881. PMID 31506422.
- Ambrose, Stanley H. (June 1998). "Late Pleistocene human population bottlenecks, volcanic winter, and differentiation of modern humans". Journal of Human Evolution. 34 (6): 623–651. doi:10.1006/jhev.1998.0219. ISSN 0047-2484. PMID 9650103. S2CID 33122717.
- Huff, Chad. D; Xing, Jinchuan; Rogers, Alan R.; Witherspoon, David; Jorde, Lynn B. (January 19, 2010). "Mobile Elements Reveal Small Population Size in the Ancient Ancestors of Homo Sapiens". Proceedings of the National Academy of Sciences. 107 (5): 2147–2152. Bibcode:2010PNAS..107.2147H. doi:10.1073/pnas.0909000107. PMC 2836654. PMID 20133859.
- Ko, Kwang Hyun (2016). "Origins of human intelligence: The chain of tool-making and brain evolution" (PDF). Anthropological Notebooks. 22 (1): 5–22.
- Jabr, Ferris (July 18, 2012). "Does Thinking Really Hard Burn More Calories?". Scientific American. ISSN 0036-8733. Retrieved May 3, 2015.
- Gibbons, Ann (May 29, 1998). "Solving the Brain's Energy Crisis". Science. 280 (5368): 1345–1347. doi:10.1126/science.280.5368.1345. ISSN 0036-8075. PMID 9634409. S2CID 28464775.
- Robinson 2008, p. 398
- Harmand, Sonia; Lewis, Jason E.; Feibel, Craig S.; Lepre, Christopher J.; Prat, Sandrine; Lenoble, Arnaud; Boës, Xavier; Quinn, Rhonda L.; Brenet, Michel (May 20, 2015). "3.3-million-year-old stone tools from Lomekwi 3, West Turkana, Kenya". Nature. 521 (7552): 310–315. Bibcode:2015Natur.521..310H. doi:10.1038/nature14464. ISSN 0028-0836. PMID 25993961. S2CID 1207285.
- Semaw, Sileshi; Rogers, Michael J.; Quade, Jay; Renne, Paul R.; Butler, Robert F.; Dominguez-Rodrigo, Manuel; Stout, Dietrich; Hart, William S.; Pickering, Travis; Simpson, Scott W. (August 1, 2003). "2.6-Million-year-old stone tools and associated bones from OGS-6 and OGS-7, Gona, Afar, Ethiopia". Journal of Human Evolution. 45 (2): 169–177. doi:10.1016/S0047-2484(03)00093-9. ISSN 0047-2484. PMID 14529651.
- Freeman & Herron 2007, pp. 786–788
- Ward, Carol V.; Tocheri, Matthew W.; Plavcan, J. Michael; et al. (January 7, 2014). "Early Pleistocene third metacarpal from Kenya and the evolution of modern human-like hand morphology". Proc. Natl. Acad. Sci. U.S.A. 111 (1): 121–124. Bibcode:2014PNAS..111..121W. doi:10.1073/pnas.1316014110. ISSN 0027-8424. PMC 3890866. PMID 24344276.
- Plummer, Thomas (2004). "Flaked stones and old bones: Biological and cultural evolution at the dawn of technology". American Journal of Physical Anthropology. Supplement 39 (Yearbook of Physical Anthropology): 118–164. doi:10.1002/ajpa.20157. ISSN 0002-9483. PMID 15605391.
- Wong, Kate (April 15, 2015). "Archaeologists Take Wrong Turn, Find World's Oldest Stone Tools". Scientific American (Blog). ISSN 0036-8733. Retrieved May 3, 2015.
- Balter, Michael (April 14, 2015). "World's oldest stone tools discovered in Kenya". Science (News). doi:10.1126/science.aab2487. ISSN 0036-8075. Retrieved May 3, 2015.
- Drake, Nadia (April 16, 2015). "Oldest Stone Tools Discovered in Kenya". National Geographic News. Washington, DC: National Geographic Society. Retrieved May 3, 2015.
- Henshilwood, Christopher S.; et al. (2002). "Emergence of Modern Human Behavior: Middle Stone Age Engravings from South Africa". Science. 295 (5558): 1278–1280. Bibcode:2002Sci...295.1278H. doi:10.1126/science.1067575. PMID 11786608. S2CID 31169551.
- Yellen, JE; AS Brooks; E Cornelissen; MJ Mehlman; K Stewart (April 28, 1995). "A middle stone age worked bone industry from Katanda, Upper Semliki Valley, Zaire". Science. 268 (5210): 553–556. Bibcode:1995Sci...268..553Y. doi:10.1126/science.7725100. PMID 7725100.
- Diamond 1999, p. 39
- Bar-Yosef, Ofer (October 2002). "The Upper Paleolithic Revolution". Annual Review of Anthropology. 31: 363–393. doi:10.1146/annurev.anthro.31.040402.085416. ISSN 0084-6570.
- McBrearty, Sally; Brooks, Allison (2000). "The revolution that wasn't: a new interpretation of the origin of modern human behavior". Journal of Human Evolution. 39 (5): 453–563. doi:10.1006/jhev.2000.0435. PMID 11102266. S2CID 42968840.
- Henshilwood, Christopher; Marean, Curtis (2003). "The Origin of Modern Human Behavior: Critique of the Models and Their Test Implications". Current Anthropology. 44 (5): 627–651. doi:10.1086/377665. PMID 14971366. S2CID 11081605.
- Henshilwood, C. S.; d'Errico, F.; Yates, R.; Jacobs, Z.; Tribolo, C.; Duller, G. A. T.; Mercier, N.; Sealy, J. C.; Valladas, H.; Watts, I.; Wintle, A. G. (2002). "Emergence of modern human behavior: Middle Stone Age engravings from South Africa". Science. 295 (5558): 1278–1280. Bibcode:2002Sci...295.1278H. doi:10.1126/science.1067575. PMID 11786608. S2CID 31169551.
- Backwell, L; d'Errico, F; Wadley, L (2008). "Middle Stone Age bone tools from the Howiesons Poort layers, Sibudu Cave, South Africa". Journal of Archaeological Science. 35 (6): 1566–1580. doi:10.1016/j.jas.2007.11.006.
- Nowell, April (October 2010). "Defining Behavioral Modernity in the Context of Neandertal and Anatomically Modern Human Populations". Annual Review of Anthropology. 39: 437–452. doi:10.1146/annurev.anthro.012809.105113. ISSN 0084-6570.
- d'Errico, Francesco; Stringer, Chris B. (April 12, 2011). "Evolution, revolution or saltation scenario for the emergence of modern cultures?". Philosophical Transactions of the Royal Society B. 366 (1567): 1060–1069. doi:10.1098/rstb.2010.0340. ISSN 0962-8436. PMC 3049097. PMID 21357228.
- (March 15, 2018). "Scientists Are Amazed By Stone Age Tools They Dug Up In Kenya". NPR. Retrieved March 15, 2018.
- Yong, Ed (March 15, 2018). "A Cultural Leap at the Dawn of Humanity – New finds from Kenya suggest that humans used long-distance trade networks, sophisticated tools, and symbolic pigments right from the dawn of our species". The Atlantic. Retrieved March 15, 2018.
- Brooks AS, Yellen JE, Potts R, Behrensmeyer AK, Deino AL, Leslie DE, Ambrose SH, Ferguson JR, d'Errico F, Zipkin AM, Whittaker S, Post J, Veatch EG, Foecke K, Clark JB (2018). "Long-distance stone transport and pigment use in the earliest Middle Stone Age". Science. 360 (6384): 90–94. Bibcode:2018Sci...360...90B. doi:10.1126/science.aao2646. PMID 29545508. S2CID 14051717.
- Rasmussen, M; Guo, X; Wang, Y; Lohmueller, K.E; Rasmussen, S; Albrechtsen, A; Skotte, L; Lindgreen, S; Metspalu, M; Jombart, T; Kivisild, T; Zhai, W; Eriksson, A; Manica, A; Orlando, L; de la Vega, F.M; Tridico, S; Metspalu, E; Nielsen, K; Avila-Arcos, M.C.; Moreno-Mayar, J.V.; Muller, C; Dortch, J; Gilbert, M.T.P.; Lund, O; Wesolowska, A; Karmin, M; Weinert, L.A.; Wang, B; et al. (2011). "An Aboriginal Australian Genome Reveals Separate Human Dispersals into Asia". Science. 334 (6052): 94–98. Bibcode:2011Sci...334...94R. doi:10.1126/science.1211177. PMC 3991479. PMID 21940856.
- Ambrose, Stanley H. (March 2, 2001). "Paleolithic Technology and Human Evolution". Science. 291 (5509): 1748–1753. Bibcode:2001Sci...291.1748A. doi:10.1126/science.1059487. ISSN 0036-8075. PMID 11249821. S2CID 6170692.
- Mellars, P (2010). "Neanderthal symbolism and ornament manufacture: The bursting of a bubble?". Proc Natl Acad Sci USA. 107 (47): 20147–20148. Bibcode:2010PNAS..10720147M. doi:10.1073/pnas.1014588107. PMC 2996706. PMID 21078972.
- Cochran & Harpending 2009
- Bender, Andrea (August 8, 2019). "The Role of Culture and Evolution for Human Cognition". Topics in Cognitive Science. 12 (4): 1403–1420. doi:10.1111/tops.12449. ISSN 1756-8757. PMID 31392845.
- Medical Research Council (UK) (November 21, 2009). "Brain Disease 'Resistance Gene' evolves in Papua New Guinea community; could offer insights Into CJD". ScienceDaily. Rockville, MD: ScienceDaily, LLC. Retrieved November 22, 2009.
- Mead, S.; Whitfield, J.; Poulter, M.; Shah, P.; Uphill, J.; Campbell, T.; Al-Dujaily, H.; Hummerich, H.; Beck, J.; Mein, C.A.; Verzilli, C.; Whittaker, J.; Alpers, M.P.; Collinge, J. (2009). "A Novel Protective Prion Protein Variant that Colocalizes with Kuru Exposure" (PDF). The New England Journal of Medicine. 361 (21): 2056–2065. doi:10.1056/NEJMoa0809716. PMID 19923577.
- Corbett, Stephen; Morin-Papunen, Laure (July 2013). "The Polycystic Ovary Syndrome and recent human evolution". Molecular and Cellular Endocrinology. 373 (1–2): 39–50. doi:10.1016/j.mce.2013.01.001. PMID 23352610. S2CID 13078403.
- Diamond 1999
- Courtiol, Alexandre; Tropf, Felix C.; Mills, Melinda C. (July 12, 2016). "When genes and environment disagree: Making sense of trends in recent human evolution". Proceedings of the National Academy of Sciences. 113 (28): 7693–7695. doi:10.1073/pnas.1608532113. ISSN 0027-8424. PMC 4948334. PMID 27402758.
- Markov, Alexander V.; Markov, Mikhail A. (June 2020). "Runaway brain‐culture coevolution as a reason for larger brains: Exploring the "cultural drive" hypothesis by computer modeling". Ecology and Evolution. 10 (12): 6059–6077. doi:10.1002/ece3.6350. ISSN 2045-7758. PMC 7319167. PMID 32607213.
- Stout, Dietrich (April 12, 2011). "Stone toolmaking and the evolution of human culture and cognition". Philosophical Transactions of the Royal Society B: Biological Sciences. 366 (1567): 1050–1059. doi:10.1098/rstb.2010.0369. ISSN 0962-8436. PMC 3049103. PMID 21357227.
- Byars, S.G.; Ewbank, D.; Govindaraju, D.R.; Stearns, S.C. (2009). "Natural selection in a contemporary human population". Proceedings of the National Academy of Sciences. 107 (suppl_1): 1787–1792. Bibcode:2010PNAS..107.1787B. doi:10.1073/pnas.0906199106. PMC 2868295. PMID 19858476.
- Aiello, Leslie; Dean, Christopher (1990). An Introduction to Human Evolutionary Anatomy. London; San Diego: Elsevier Academic Press. ISBN 978-0-12-045591-1. LCCN 95185095. OCLC 33408268.
- American Heritage Dictionaries (editors) (2006). More Word Histories and Mysteries: From Aardvark to Zombie. Boston, MA: Houghton Mifflin. ISBN 978-0-618-71681-4. LCCN 2006020835. OCLC 70199867.
- Bogin, Barry (1997). "The Evolution of Human Nutrition". In Romanucci-Ross, Lola; Moerman, Daniel E.; Tancredi, Laurence R. (eds.). The Anthropology of Medicine: From Culture to Method (3rd ed.). Westport, CT: Bergin & Garvey. ISBN 978-0-89789-516-3. LCCN 96053993. OCLC 36165190.
- Bown, Thomas M.; Rose, Kenneth D. (1987). Patterns of Dental Evolution in Early Eocene Anaptomorphine Primates (Omomyidae) From the Bighorn Basin, Wyoming (PDF). Memoir (Paleontological Society). 23. Tulsa, OK: Paleontological Society. OCLC 16997265.
- Boyd, Robert; Silk, Joan B. (2003). How Humans Evolved (3rd ed.). New York: W.W. Norton & Company. ISBN 978-0-393-97854-4. LCCN 2002075336. OCLC 49959461.
- Brues, Alice M.; Snow, Clyde C. (1965). "Physical Anthropology". In Siegel, Bernard J. (ed.). Biennial Review of Anthropology 1965. Biennial Review of Anthropology. 4. Stanford, CA: Stanford University Press. ISBN 978-0-8047-1746-5. ISSN 0067-8503. LCCN 59012726. OCLC 01532912.
- Bryson, Bill (2004) [Originally published 2003]. "The Mysterious Biped". A Short History of Nearly Everything. Toronto: Anchor Canada. ISBN 978-0-385-66004-4. LCCN 2003046006. OCLC 55016591.
- Cameron, David W. (2004). Hominid Adaptations and Extinctions. Sydney, NSW: UNSW Press. ISBN 978-0-86840-716-6. LCCN 2004353026. OCLC 57077633.
- Cochran, Gregory; Harpending, Henry (2009). The 10,000 Year Explosion: How Civilization Accelerated Human Evolution. New York: Basic Books. ISBN 978-0-465-00221-4. LCCN 2008036672. OCLC 191926088.
- Curry, James R. (2008). Children of God: Children of Earth. Bloomington, IN: AuthorHouse. ISBN 978-1-4389-1846-4. OCLC 421466369.
- Darwin, Charles (1981) [Originally published 1871; London: John Murray]. The Descent of Man, and Selection in Relation to Sex. Introduction by John Tyler Bonner and Robert M. May (Reprint ed.). Princeton, NJ: Princeton University Press. ISBN 978-0-691-02369-4. LCCN 80008679. OCLC 7197127.
- Dawkins, Richard (2004). The Ancestor's Tale: A Pilgrimage to the Dawn of Evolution. Boston, MA: Houghton Mifflin. ISBN 978-0-618-00583-3. LCCN 2004059864. OCLC 56617123.
- DeSalle, Rob; Tattersall, Ian (2008). Human Origins: What Bones and Genomes Tell Us About Ourselves. Texas A&M University Anthropology Series. 13 (1st ed.). College Station, TX: Texas A&M University Press. ISBN 978-1-58544-567-7. OCLC 144520427.
- Diamond, Jared (1999). Guns, Germs, and Steel: The Fates of Human Societies. New York: W.W. Norton & Company. ISBN 978-0-393-31755-8. LCCN 2005284124. OCLC 35792200.
- Freeman, Scott; Herron, Jon C. (2007). Evolutionary Analysis (4th ed.). Upper Saddle River, NJ: Pearson Prentice Hall. ISBN 978-0-13-227584-2. LCCN 2006034384. OCLC 73502978.
- Galinon-Melenec, Béatrice (2015). "From "Traces" and "Human Trace" to "Human–Trace Paradigm"". In Parrend, Pierre; Bourgine, Paul; Collet, Pierre (eds.). First Complex systems Digital Campus World E-Conference. Tempe, Arizona: Springer.
- Johanson, Donald; Edey, Maitland (1981). Lucy, the Beginnings of Humankind. St Albans: Granada. ISBN 978-0-586-08437-3.
- Montgomery, William M. (1988) [Originally published 1974]. "Germany". In Glick, Thomas F. (ed.). The Comparative Reception of Darwinism. Chicago, Illinois: University of Chicago Press. ISBN 978-0-226-29977-8. LCCN 87035814. OCLC 17328115. "The Conference on the Comparative Reception of Darwinism was held in Austin, Texas, on April 22 and 23, 1972, under the joint sponsorship of the American Council of Learned Societies and the University of Texas at Austin"
- Kondo, Shiro, ed. (1985). Primate Morphophysiology, Locomotor Analyses, and Human Bipedalism. American Journal of Physical Anthropology. 70. Tokyo: University of Tokyo Press. pp. 278–279. doi:10.1002/ajpa.1330700214. ISBN 978-4-13-066093-8. LCCN 85173489. OCLC 12352830.
- Leakey, Richard E. (1994). The Origin of Humankind. Science Masters Series. New York: Basic Books. ISBN 978-0-465-03135-1. LCCN 94003617. OCLC 30739453.
- M'charek, Amade (2005). The Human Genome Diversity Project: An Ethnography of Scientific Practice. Cambridge Studies in Society and the Life Sciences. Cambridge; New York: Cambridge University Press. ISBN 978-0-521-83222-9. LCCN 2004052648. OCLC 55600894.
- Martin, Robert D. (2001). "Primates, Evolution of". In Smelser, Neil J.; Baltes, Paul B. (eds.). International Encyclopedia of the Social & Behavioral Sciences (1st ed.). Amsterdam; New York: Elsevier. pp. 12032–12038. doi:10.1016/B0-08-043076-7/03083-7. ISBN 978-0-08-043076-8. LCCN 2001044791. OCLC 47869490.
- Maxwell, Mary (1984). Human Evolution: A Philosophical Anthropology. New York: Columbia University Press. ISBN 978-0-231-05946-6. LCCN 83024005. OCLC 10163036.
- McHenry, Henry M. (2009). "Human Evolution". In Ruse, Michael; Travis, Joseph (eds.). Evolution: The First Four Billion Years. Foreword by Edward O. Wilson. Cambridge, Massachusetts: Belknap Press of Harvard University Press. ISBN 978-0-674-03175-3. LCCN 2008030270. OCLC 225874308.
- Ramachandran, Sohini; Hua Tang; Gutenkunst, Ryan N.; Bustamante, Carlos D. (2010). "Genetics and Genomics of Human Population Structure". In Speicher, Michael R.; Antonarakis, Stylianos E.; Motulsky, Arno G. (eds.). Vogel and Motulsky's Human Genetics: Problems and Approaches (4th completely rev. ed.). Heidelberg; London; New York: Springer. doi:10.1007/978-3-540-37654-5. ISBN 978-3-540-37653-8. LCCN 2009931325. OCLC 549541244.
- Robinson, J.T. (2008) [Originally published 1963; Chicago, Illinois: Aldine Transaction]. "Adaptive Radiation in the Australopithecines and the Origin of Man". In Howell, F. Clark; Bourlière, François (eds.). African Ecology and Human Evolution. New Brunswick, NJ: Transaction Publishers. ISBN 978-0-202-36136-9. LCCN 2007024716. OCLC 144770218.
- Srivastava, R.P. (2009). Morphology of the Primates and Human Evolution. New Delhi: PHI Learning Private Limited. ISBN 978-81-203-3656-8. OCLC 423293609.
- Stanford, Craig; Allen, John S.; Antón, Susan C. (2009). Biological Anthropology: The Natural History of Humankind (2nd ed.). Upper Saddle River, NJ: Pearson Prentice Hall. ISBN 978-0-13-601160-6. LCCN 2007052429. OCLC 187548835.
- Strickberger, Monroe W. (2000). Evolution (3rd ed.). Sudbury, MA: Jones and Bartlett Publishers. ISBN 978-0-7637-1066-8. LCCN 99032072. OCLC 41431683.
- Stringer, Chris B. (1994) [First published 1992]. "Evolution of Early Humans". In Jones, Steve; Martin, Robert D.; Pilbeam, David (eds.). The Cambridge Encyclopedia of Human Evolution. Foreword by Richard Dawkins (1st paperback ed.). Cambridge, UK: Cambridge University Press. ISBN 978-0-521-32370-3. LCCN 92018037. OCLC 444512451.
- Swisher, Carl C., III; Curtis, Garniss H.; Lewin, Roger (2001) [Originally published 2000]. Java Man: How Two Geologists Changed Our Understanding of Human Evolution. Chicago: University of Chicago Press. ISBN 978-0-226-78734-3. LCCN 2001037337. OCLC 48066180.
- Tishkoff, S.A.; Reed, F.A.; et al. (2009). "The Genetic Structure and History of Africans and African Americans". Science (published May 22, 2009). 324 (5930): 1035–1044. Bibcode:2009Sci...324.1035T. doi:10.1126/science.1172257. PMC 2947357. PMID 19407144.
- Trent, Ronald J. (2005). Molecular Medicine: An Introductory Text (3rd ed.). Burlington, MA: Elsevier Academic Press. ISBN 978-0-12-699057-7. LCCN 2004028087. OCLC 162577235.
- Trevathan, Wenda R. (2011) [Originally published 1987; New York: Aldine De Gruyter]. Human Birth: An Evolutionary Perspective. New Brunswick, NJ: Transaction Publishers. ISBN 978-1-4128-1502-4. LCCN 2010038249. OCLC 669122326.
- Ungar, Peter S.; Teaford, Mark F., eds. (2002). Human Diet: Its Origin and Evolution. Westport, CT: Bergin & Garvey. ISBN 978-0-89789-736-5. LCCN 2001043790. OCLC 537239907.
- Walker, Alan (2007). "Early Hominin Diets: Overview and Historical Perspectives". In Ungar, Peter (ed.). Evolution of the Human Diet: The Known, the Unknown, and the Unknowable. Human Evolution Series. Oxford; New York: Oxford University Press. ISBN 978-0-19-518346-7. LCCN 2005036120. OCLC 132816551.
- Wallace, David Rains (2004). Beasts of Eden: Walking Whales, Dawn Horses, and Other Enigmas of Mammal Evolution. Berkeley: University of California Press. ISBN 978-0-520-24684-3. LCCN 2003022857. OCLC 53254011.
- Webster, Donovan (2010). Meeting the Family: One Man's Journey Through His Human Ancestry. Foreword by Spencer Wells. Washington, DC: National Geographic Society. ISBN 978-1-4262-0573-6. LCCN 2009050471. OCLC 429022321.
- Wood, Bernard A. (2009). "Where Does the Genus Homo Begin, and How Would We Know?". In Grine, Frederick E.; Fleagle, John G.; Leakey, Richard E. (eds.). The First Humans: Origin and Early Evolution of the Genus Homo. Vertebrate Paleobiology and Paleoanthropology. Dordrecht, the Netherlands: Springer Netherlands. pp. 17–28. doi:10.1007/978-1-4020-9980-9_3. ISBN 978-1-4020-9979-3. ISSN 1877-9077. LCCN 2009927083. OCLC 310400980. "Contributions from the Third Stony Brook Human Evolution Symposium and Workshop October 3–7, 2006."
- Alexander, Richard D. (1990). How Did Humans Evolve? Reflections on the Uniquely Unique Species (PDF). Special Publication. Ann Arbor, MI: Museum of Zoology, University of Michigan. pp. 1–38. LCCN 90623893. OCLC 22860997.
- Barton, Nicholas H.; Briggs, Derek E.G.; Eisen, Jonathan A.; et al. (2007). Evolution. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press. ISBN 978-0-87969-684-9. LCCN 2007010767. OCLC 86090399.
- Enard, Wolfgang; Przeworski, Molly; Fisher, Simon E.; et al. (August 22, 2002). "Molecular evolution of FOXP2, a gene involved in speech and language". Nature. 418 (6900): 869–872. Bibcode:2002Natur.418..869E. doi:10.1038/nature01025. ISSN 0028-0836. PMID 12192408. S2CID 4416233.
- Flinn, Mark V.; Geary, David C.; Ward, Carol V. (January 2005). "Ecological dominance, social competition, and coalitionary arms races: Why humans evolved extraordinary intelligence" (PDF). Evolution and Human Behavior. 26 (1): 10–46. doi:10.1016/j.evolhumbehav.2004.08.005. ISSN 1090-5138. Retrieved May 5, 2015.
- Gibbons, Ann (2006). The First Human: The Race to Discover our Earliest Ancestors (1st ed.). New York: Doubleday. ISBN 978-0-385-51226-8. LCCN 2005053780. OCLC 61652817.
- Hartwig, Walter C., ed. (2002). The Primate Fossil Record. Cambridge Studies in Biological and Evolutionary Anthropology. 33. Cambridge; New York: Cambridge University Press. ISBN 978-0-521-66315-1. LCCN 2001037847. OCLC 47254191.
- Heizmann, Elmar P.J.; Begun, David R. (November 2001). "The oldest Eurasian hominoid". Journal of Human Evolution. 41 (5): 463–481. doi:10.1006/jhev.2001.0495. ISSN 0047-2484. PMID 11681862. S2CID 21230992.
- Hill, Andrew; Ward, Steven (1988). "Origin of the hominidae: The record of African large hominoid evolution between 14 my and 4 my". American Journal of Physical Anthropology. 31 (59): 49–83. doi:10.1002/ajpa.1330310505. ISSN 0002-9483.
- Hoagland, Hudson (1964). "Science and the New Humanism". Science. 143 (3602): 111–114. Bibcode:1964Sci...143..111H. doi:10.1126/science.143.3602.111. PMID 17781189.
- Ijdo, Jacob W.; Baldini, Antonio; Ward, David C.; et al. (October 15, 1991). "Origin of human chromosome 2: An ancestral telomere-telomere fusion". Proc. Natl. Acad. Sci. U.S.A. 88 (20): 9051–9055. Bibcode:1991PNAS...88.9051I. doi:10.1073/pnas.88.20.9051. ISSN 0027-8424. PMC 52649. PMID 1924367. – two ancestral ape chromosomes fused to give rise to human chromosome 2
- Johanson, Donald; Wong, Kate (2010). Lucy's Legacy: The Quest for Human Origins. New York: Three Rivers Press. ISBN 978-0-307-39640-2. LCCN 2010483830. OCLC 419801728.
- Jones, Steve; Martin, Robert D.; Pilbeam, David, eds. (1994) [First published 1992]. The Cambridge Encyclopedia of Human Evolution. Foreword by Richard Dawkins (1st paperback ed.). Cambridge, UK: Cambridge University Press. ISBN 978-0-521-32370-3. LCCN 92018037. OCLC 444512451. (Note: this book contains very useful, information dense chapters on primate evolution in general, and human evolution in particular, including fossil history).
- Leakey, Richard E.; Lewin, Roger (1992). Origins Reconsidered: In Search of What Makes us Human. New York: Doubleday. ISBN 978-0-385-41264-3. LCCN 92006661. OCLC 25373161.
- Lewin, Roger (1997). Bones of Contention: Controversies in the Search for Human Origins (2nd ed.). Chicago, Illinois: University of Chicago Press. ISBN 978-0-226-47651-3. LCCN 97000972. OCLC 36181117.
- Morwood, Mike; van Oosterzee, Penny (2007). A New Human: The Startling Discovery and Strange Story of the 'Hobbits' of Flores, Indonesia (1st Smithsonian Books ed.). New York: Smithsonian Books/HarperCollins. ISBN 978-0-06-089908-0. LCCN 2006052267. OCLC 76481584.
- Oppenheimer, Stephen (2003). Out of Eden: The Peopling of the World. london: Constable & Robinson. ISBN 978-1-84119-697-8. LCCN 2005482222. OCLC 52195607.
- Ovchinnikov, Igor V.; Götherström, Anders; Romanova, Galina P.; et al. (March 30, 2000). "Molecular analysis of Neanderthal DNA from the Northern Caucasus". Nature. 404 (6777): 490–493. Bibcode:2000Natur.404..490O. doi:10.1038/35006625. ISSN 0028-0836. PMID 10761915. S2CID 3101375.
- Roberts, Alice M. (2009). The Incredible Human Journey: The Story of How We Colonised the Planet. London: Bloomsbury Publishing. ISBN 978-0-7475-9839-8. OCLC 310156315.
- Shreeve, James (1995). The Neandertal Enigma: Solving the Mystery of Modern Human Origins. New York: Morrow. ISBN 978-0-688-09407-2. LCCN 95006337. OCLC 32088673.
- Stringer, Chris B. (2011). The Origin of Our Species. London: Allen Lane. ISBN 978-1-84614-140-9. LCCN 2011489742. OCLC 689522193.
- Stringer, Chris B.; Andrews, Peter (2005). The Complete World of Human Evolution. London; New York: Thames & Hudson. ISBN 978-0-500-05132-0. LCCN 2004110563. OCLC 224377190.
- Sykes, Rebecca Wragg (2020). Kindred: Neanderthal Life, Love, Death and Art. London: Bloomsbury Sigma. ISBN 978-1-4729-3749-0.
- Stringer, Christopher; McKie, Robin (1997). African Exodus: The Origins of Modern Humanity (1st American ed.). New York: Henry Holt and Company. ISBN 978-0-8050-2759-4. LCCN 96037718. OCLC 36001167.
- Tattersall, Ian (2008). The Fossil Trail: How We Know What We Think We Know About Human Evolution (2nd ed.). New York: Oxford University. ISBN 978-0195367669. LCCN 2008013654. OCLC 218188644.
- van Oosterzee, Penny (1999). Dragon Bones: The Story of Peking Man. St Leonards, New South Wales: Allen & Unwin. ISBN 978-1-86508-123-6. LCCN 00300421. OCLC 45853997.
- Wade, Nicholas (2006). Before the Dawn: Recovering the Lost History of Our Ancestors. New York: Penguin Press. ISBN 978-1-59420-079-3. LCCN 2005055293. OCLC 62282400.
- Walker, Alan; Shipman, Pat (1996). The Wisdom of the Bones: In Search of Human Origins. London: Weidenfeld & Nicolson. ISBN 978-0-297-81670-6. OCLC 35202130.
- Weiss, Mark L.; Mann, Alan E. (1985). Human Biology and Behavior: An Anthropological Perspective (4th ed.). Boston: Little Brown. ISBN 978-0-316-92894-6. LCCN 85000158. OCLC 11726796. (Note: this book contains very accessible descriptions of human and non-human primates, their evolution, and fossil history).
- Wells, Spencer (2003) [Originally published 2002; Princeton, NJ: Princeton University Press]. The Journey of Man: A Genetic Odyssey (Random House trade paperback ed.). New York: Random House Trade Paperbacks. ISBN 978-0-8129-7146-0. LCCN 2003066679. OCLC 53287806