Human evolution

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This article is about the divergence of Homo sapiens from other species. For a complete timeline of human evolution, see Timeline of human evolution. For other uses, see Human evolution (disambiguation).
"Evolution of Man" redirects here. For the album by Example, see The Evolution of Man.

Human evolution is the evolutionary process leading up to the appearance of anatomically modern humans. The topic usually covers the evolutionary history of primates, in particular the genus Homo, and the emergence of Homo sapiens as a distinct species of hominids (or "great apes") rather than studying the evolutionary history that led to primates. The study of human evolution involves many scientific disciplines, including physical anthropology, primatology, archaeology, paleontology, ethology, linguistics, evolutionary psychology, embryology and genetics.[1]

Genetic studies show that primates diverged from other mammals about 85 million years ago, in the Late Cretaceous period, and the earliest fossils appear in the Paleocene, around 55 million years ago.[2] The Hominidae family diverged from the Hylobatidae (gibbon) family 15–20 million years ago, and around 14 million years ago, the subfamily Ponginae (orangutans) diverged from the Hominidae family.[3]

Bipedalism is the basic adaption of the hominin line. The earliest bipedal hominin is considered to be either Sahelanthropus or Orrorin; alternatively, either Sahelanthropus or Orrorin may instead be the last shared ancestor between chimps and humans. Ardipithecus, a full bipedal, arose somewhat later, and the early bipedals eventually evolved into the australopithecines, and later into the genus Homo.

The earliest documented members of the genus Homo are Homo habilis, which evolved around 2.8 million years ago;[4] and it is arguably the earliest species for which there is positive evidence of 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 began, and with the arrival of Homo erectus in the fossil record, cranial capacity had doubled to 850 cm3.[5] This increase in human brain size is equivalent to every generation having an additional 125,000 neurons more than their parents. It is believed that these species were the first to use fire and complex tools. Homo erectus and Homo ergaster were also the first of the hominin line to leave Africa, and these species spread through Africa, Asia, and Europe between 1.3 to 1.8 million years ago.

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 and Homo neanderthalensis.[6][7][8][9][10] Archaic Homo sapiens, the forerunner of anatomically modern humans, evolved between 400,000 and 250,000 years ago.[11][12] 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 inter-breeding between these species.[13][14][15] Anatomically modern humans evolved from archaic Homo sapiens in the Middle Paleolithic, about 200,000 years ago.[16] The transition to behavioral modernity with the development of symbolic culture, language, and specialized lithic technology happened around 50,000 years ago according to many anthropologists[17] although some suggest a gradual change in behavior over a longer time span.[18]

History of study[edit]

Before Darwin[edit]

The word homo, the name of the biological genus to which humans belong, is Latin for "human." It was chosen originally by Carolus Linnaeus in his classification system. 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."[19] 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.

Darwin[edit]

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 apes, and did so particularly in his 1863 book Evidence as to Man's Place in Nature. However, 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 when he published The Descent of Man in 1871.[20]

First fossils[edit]

A major problem at that time 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 human remains of a creature suffering some kind of illness.[21] 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.[citation needed] In 1925, Raymond Dart described Australopithecus africanus.[22] 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 endocranial cast 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 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[edit]

Louis Leakey examining skulls from Olduvai Gorge, Tanzania.

During the 1960s and 1970s, hundreds of fossils were found, particularly in East Africa in the regions of the Olduvai Gorge and Lake Turkana. The driving force in the East African researches was the Leakey family, with Louis Leakey and his wife Mary Leakey, and later their son Richard and daughter in-law Meave being among the most successful fossil hunters and palaeoanthropologists. From the fossil beds of Olduvai and Lake Turkana they amassed fossils of australopithecines, early Homo and even Homo erectus.

These finds cemented Africa as the cradle of humankind. In the 1980s, Ethiopia emerged as the new hot spot of palaeoanthropology as "Lucy," the most complete fossil member of the species Australopithecus afarensis, was found by Donald Johanson in Hadar in the desertic Middle Awash region of northern Ethiopia. This area would be the location of many new hominin fossils, particularly those uncovered by the team headed by Tim D. White in the 1990s, such as Ardipithecus ramidus.

The genetic revolution[edit]

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).[23] 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,[23] 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.[24][25][26] 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 chimps 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 chimps to an earlier period greater than 7 million years ago (Ma). Additional research with 226 offspring of wild chimp populations in 8 locations suggests that chimps reproduce at age 26.5 years, on average; which suggests the human divergence from chimps occurred between 7 to 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 hominin 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 chimps, interspecies mating between "proto-human" and "proto-chimps" nonetheless occurred regularly enough to change certain genes in the new gene pool:

A new comparison of the human and chimp genomes suggests that after the two lineages separated, they may have begun interbreeding... A principal finding is that the X chromosomes of humans and chimps 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 chimp 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.[27]

The quest for the earliest hominin[edit]

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 4.2 million years ago.

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 7.2 million years ago, and which Brunet argued was a bipedal, and therefore a hominid—that is, a hominin (cf Hominidae; terms "hominids" and hominins).

Human dispersal[edit]

Map with arrows emanating from Africa, across Eurasia, to Australia and the Americas.
A global mapping model of human migration, based from divergence of the mitochondrial DNA (which indicates the matrilineage).[28] Timescale (ka) indicated by colours.
Trellis of intermingling populations for the last two million years.
A "trellis" (as Milford H. Wolpoff called it) that emphasizes back-and-forth gene flow among geographic regions.[29]
Different models for the beginning of the present human species.

Anthropologists in the 1980s were divided regarding some details of reproductive barriers and migratory dispersals of the Homo genus. Subsequently, genetics has been used to investigate and resolve these issues. According to the Sahara pump theory evidence suggests that genus Homo have migrated out of Africa at least three times (e.g. Homo erectus, Homo heidelbergensis and Homo sapiens).

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 nearly complete replacement of other Homo species. This model has been developed by Chris B. Stringer and Peter Andrews.[30][31] In contrast, the multiregional hypothesis proposed that Homo genus 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 million years. This model was proposed in 1988 by Milford H. Wolpoff.[32][33]

Sequencing mtDNA and Y-DNA sampled from a wide range of indigenous populations revealed ancestral information relating to both male and female genetic heritage.[34] Aligned in genetic tree differences were interpreted as supportive of a recent single origin.[35] 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.[36]

"Out of Africa" has gained 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.[37]

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 the origin of modern human migration in south-western Africa, near the coastal border of Namibia and Angola.[38] The fossil evidence was insufficient for Richard Leakey to resolve this debate.[39] Studies of haplogroups in Y-chromosomal DNA and mitochondrial DNA have largely supported a recent African origin.[40] Evidence from autosomal DNA also predominantly supports a Recent African origin. However, evidence for archaic admixture in modern humans had been suggested by some studies.[41]

Recent sequencing of Neanderthal[42] and Denisovan[13] genomes shows that some admixture occurred. Modern humans outside Africa have 2–4% 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. After recovery from a genetic bottleneck that might be due to the Toba supervolcano catastrophe, a fairly small group left Africa and briefly interbred with Neanderthals, probably in the middle-east or even North Africa before their departure. Their still predominantly African descendants spread to populate the world. A fraction in turn interbred with Denisovans, probably in south-east Asia, before populating Melanesia.[43] HLA haplotypes of Neanderthal and Denisova origin have been identified in modern Eurasian and Oceanian populations.[15]

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,[44] 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 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.[44]

A second wave of humans may have dispersed across the Sinai Peninsula into Asia, resulting in the bulk of human population for Eurasia. This second group possibly possessed a more sophisticated 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.[44] 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 lineages, which support a single migration out of Africa that gave rise to all non-African populations.[45]

Anatomical changes[edit]

The hominoids are descendants of a common ancestor.

Human evolution is characterized by a number of morphological, developmental, physiological, and behavioral changes that have taken place since the split between the last common ancestor of humans and chimpanzees. 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.[46][page needed] Other significant morphological changes included the evolution of a power and precision grip, a change first occurring in H. erectus.[47]

Bipedalism[edit]

Bipedalism is the basic adaption of the hominin and is considered the main cause behind a suite of skeletal changes shared by all bipedal hominins. The earliest hominin, of presumably primitive bipedalism, is considered to be either Sahelanthropus[48] or Orrorin, both of which arose some 6 to 7 million years ago. The non-bipedal knuckle-walkers, the gorilla and chimpanzee, diverged from the hominin line over a period covering the same time, so either of Sahelanthropus or Orrorin may instead be our last shared ancestor. Ardipithecus, a full bipedal, arose somewhat later.[citation needed]

The early bipedals eventually evolved into the australopithecines and later the genus Homo. There are several theories of the adaptation value of bipedalism. It is possible that bipedalism was favored because it freed up the hands for reaching and carrying food, saved energy during locomotion,[49] enabled long distance running and hunting, enhanced field of vision and helped avoid hyperthermia by reducing the surface area exposed to direct sun; all this mainly for thriving in the new grassland type environment rather than the previous forest type.[25][50] A new study provides support for the hypothesis that walking on two legs, or bipedalism, evolved because it used less energy than quadrupedal knuckle-walking.[51][52]

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.[53] 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.[54]

The most significant changes are in the pelvic region, where the long downward facing iliac blade was shortened and became wide as a requirement for keeping the center of gravity stable while walking;[49] bipedal hominids have a shorter but broad, bowl-like pelvis due to this. A drawback is that the birth canal of these apes is smaller than regular 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.[55]

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.[56] The smaller size of the birth canal became an obstacle when the brain size began to increase in early humans, prompted a shorter gestation period and the reason why humans give birth to immature offspring, who are unable to walk much before 12 months and have greater neoteny, compared to other primates, who are motile at a much earlier age.[50] The increased brain growth after birth and the increased dependency of children on mothers had a big effect upon the female reproductive cycle,[citation needed] and the more frequent appearance of monogamous relationships in humans when compared with other hominids. Delayed human sexual maturity also led to the evolution of menopause with one explanation saying that elderly women could better pass on their genes by taking care of their daughter's offspring, as compared to having more of their own.[57]

Encephalization[edit]

The human species developed a much larger brain than that of other primates—typically 1,330  cm3 in modern humans, over twice the size of that of a chimpanzee or gorilla.[58] The pattern of encephalization started with Homo habilis, which at approximately 600  cm3 had a brain slightly larger than that of chimpanzees, and continued with Homo erectus (800–1,100  cm3), reaching a maximum in Neanderthals with an average size of (1,200–1,900  cm3), larger even than Homo sapiens. The pattern of human postnatal brain growth differs from that of other apes (heterochrony) and allows for extended periods of social learning and language acquisition in juvenile humans. However, the differences between the structure of human brains and those of other apes may be even more significant than differences in size.[59][60][61][62]

The increase in volume over time has affected areas within the brain unequally—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.[58] Encephalization has been tied to an increasing emphasis on meat in the diet,[63][64] or with the development of cooking,[65] 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. The human brain was able to expand because of the changes in the morphology of smaller mandibles and mandible muscle attachments to the skull into allowing more room for the brain to grow.[66]

The increase in volume of the neocortex also included a rapid increase in size of the cerebellum. Traditionally the cerebellum has been associated with a paleocerebellum and archicerebellum as well as a neocerebellum. Its function has also traditionally been associated with balance, fine motor control but more recently speech and cognition. The great apes including humans and its antecessors had a more pronounced development of the cerebellum relative to the neocortex than other primates. It has been suggested that because of its function of sensory-motor control and assisting in learning complex muscular action sequences, the cerebellum may have underpinned the evolution of human's technological adaptations including the preadaptation of speech.[67][68][69][70]

Sexual dimorphism[edit]

The reduced degree of sexual dimorphism 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 and bonobos are the only apes 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 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.

Other changes[edit]

A number of other changes have also characterized the evolution of humans, among them an increased importance on vision rather than smell; a smaller gut; 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.

Evidence[edit]

The evidence on which scientific accounts of human evolution is based comes from many fields of natural science. The main sources 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.[71]

Evidence from molecular biology[edit]

Family tree showing the extant hominoids: humans (genus Homo), chimpanzees and bonobos (genus Pan), gorillas (genus Gorilla), orangutans (genus Pongo), and gibbons (four genera of the family Hylobatidae: Hylobates, Hoolock, Nomascus, and Symphalangus). All except gibbons are hominids.

The closest living relatives of humans are bonobos and chimpanzees (both genus Pan) and gorillas (genus Gorilla).[72] With the sequencing of both the human and chimpanzee genome, current estimates of the similarity between their DNA sequences range between 95% and 99%.[72][73][74] 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 orangutans (genus Pongo) were the first groups to split from the line leading to the hominins, including humans—followed by gorillas, and, ultimately, by the chimpanzees (genus Pan). The splitting date between hominin and chimpanzee lineages is placed by some between 4 to 8 million years ago, that is, during the Late Miocene.[3][75][76]Speciation, however, appears to have been unusually drawn-out. Initial divergence occurred sometime between 7 to 13 million years ago, but ongoing hybridization blurred the separation and delayed complete separation during several millions of years. Patterson (2006) dated the final divergence at 5 to 6 million years ago.[77]

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.

Genetics[edit]

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[edit]

Replica of fossil skull of Homo habilis. Fossil number KNM ER 1813, found at Koobi Fora, Kenya.
Replica of fossil skull of Homo ergaster (African Homo erectus). Fossil number Khm-Heu 3733 discovered in 1975 in Kenya.

There is little fossil evidence for the divergence of the gorilla, chimpanzee and hominin lineages.[78] The earliest fossils that have been proposed as members of the hominin lineage are Sahelanthropus tchadensis dating from 7 million years ago, Orrorin tugenensis dating from 5.7 million years ago, and Ardipithecus kadabba dating to 5.6 million years ago. 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 4 million years ago and diverged into 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 one hundred fossil individuals represented, found from Northern Ethiopia (such as the famous "Lucy"), to Kenya, and South Africa. Fossils of robust australopithecines such as A. robustus (or alternatively Paranthropus robustus) and A./P. boisei are particularly abundant in South Africa at sites such as Kromdraai and Swartkrans, and around Lake Turkana in Kenya.

The earliest member of the genus Homo is Homo habilis which evolved around 2.8 million years ago.[4] 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 species internal 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 1.9 million years ago) 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 1.8 to 1.3 million years ago, this species spread through Africa, Asia, and Europe. One population of H. erectus, also sometimes classified as a separate species Homo ergaster, stayed 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, but seemingly transitional forms were also found at Dmanisi, Georgia. 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 200,000 years ago such as the Omo remains of Ethiopia; later fossils from Es Skhul cave in Israel and Southern Europe begin around 90,000 years ago (0.09 million years ago).

As modern humans spread out from Africa, they encountered other hominins such as Homo neanderthalensis and the so-called Denisovans, who may have evolved from populations of Homo erectus that had left Africa around 2 million years ago. 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.[79][80]

This migration out of Africa is estimated to have begun about 70,000 years BP (Before Present) 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.[81]

Before Homo[edit]

For evolutionary history before primates, see Evolution of mammals, Evolutionary history of life, and Timeline of human evolution.

Early evolution of primates[edit]

Evolutionary history of the primates can be traced back 65 million years.[82] The oldest known primate-like mammal species,[83] the Plesiadapis, came from North America, but they were widespread in Eurasia and Africa during the tropical conditions of the Paleocene and Eocene.

David R. Begun [84] 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 hominins.

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.[85] Its ancestry is thought to be species related to Aegyptopithecus, Propliopithecus, and Parapithecus from the Faiyum, at around 35 million years ago.[86] 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.[87]

Reconstructed tailless Proconsul skeleton

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, Limnopithecus, 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 South East 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.[49]

Divergence of the human clade from other great apes[edit]

A reconstruction of "Lucy," a female Australopithecus afarensis on exhibit in the National Museum of Natural History, Washington, D.C., USA.

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 A. kadabba and A. ramidus.

Genus Australopithecus[edit]

Main article: Australopithecus

The Australopithecus genus 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, A. afarensis, A. sediba, and A. africanus. There is still some debate amongst academics whether certain African hominid species of this time, such as A. robustus and A. boisei, constitute members of the same genus; if so, they would be considered to be A. robust australopiths whilst the others would be considered A. gracile australopiths. However, if these species do indeed constitute their own genus, then they may be given their own name, the Paranthropus.

Genus Homo[edit]

One current view of the temporal and geographical distribution of genus Homo populations.[88] Other interpretations differ mainly in the taxonomy and geographical distribution of hominin species.
A reconstruction of Homo habilis
Skulls of
1. Gorilla 2. Australopithecus 3. Homo erectus 4. Neanderthal (La Chapelle aux Saints) 5. Steinheim Skull 6. modern Homo sapiens. Notice the decreasing prognathism and thickness of the brow ridge, and the increasing size of the forehead.

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.[89][90] There is yet no consensus as to which of these groups should inferred as a separate species and which as subspecies; this may be due to the dearth of fossils or to the slight differences used to classify species in the Homo genus.[90] 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.[62][91][92][93][94]

Some anthropologists and archaeologists subscribe to the Toba catastrophe theory, which posits that the supereruption of Lake Toba on Sumatra island in Indonesia some 70,000 years ago caused global consequences,[95] killing most humans then alive and creating a population bottleneck that affected the genetic inheritance of all humans today.[96]

H. habilis and H. gautengensis[edit]

Homo habilis lived from about 2.8[4] 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, it 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.[97]

In May 2010, a new species, Homo gautengensis was discovered in South Africa.[98]

H. rudolfensis and H. georgicus[edit]

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.[99]
  • Homo georgicus, from Georgia, may be an intermediate form between Homo habilis and Homo erectus,[100] or a sub-species of Homo erectus.[101]

H. ergaster and H. erectus[edit]

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 Pithecanthropus erectus based on its morphology, which he considered to be intermediate between that of humans and apes.[102] 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 ofHomo 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, in 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.[103] The evolution of locking knees and the movement of the foramen magnum (the hole in the skull where the spine enters) are thought to be likely drivers of the larger population changes. This species also may have used fire to cook meat.

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[edit]

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.[104][105]
  • H. cepranensis refers to a single skull cap from Italy, estimated to be about 800,000 years old.[106]

H. heidelbergensis[edit]

Reconstruction of Homo heidelbergensis which may be the direct ancestor of both Homo neanderthalensis and Homo sapiens.

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.[107]

H. rhodesiensis, and the Gawis cranium[edit]

  • 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.[108]

Neanderthal and Denisovan[edit]

Main articles: Neanderthal and Denisovan
Dermoplastic reconstruction of a Neanderthal

Homo neanderthalensis, alternatively designated as Homo sapiens neanderthalensis,[109] lived in Europe and Asia from 400,000[110] to about 30,000 years ago. Evidence from sequencing mitochondrial DNA indicated 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.[111][112][113] 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).[114]

Nearly all modern non-African humans have 1% to 4% of their DNA derived from Neanderthal DNA,[114] 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.[115][116] 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.[117]

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.[118] 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 genomic DNA were sequenced.[13][119]

While the divergence point of the mtDNA was unexpectedly deep in time,[120] the full genomic sequence suggested the Denisovans belonged to the same lineage as Neanderthals, with the two diverging shortly after their line split from that lineage giving rise to modern humans.[13] Modern humans are known to have overlapped with Neanderthals in Europe for more than 10,000 years, and the discovery raises the possibility that Neanderthals, modern humans and the Denisova hominin may have co-existed. The existence of this distant branch creates a much more complex picture of humankind during the Late Pleistocene than previously thought.[119][121] Evidence has also been found that as much as 6% of the genomes of some modern Melanesians derive from Denisovans, indicating limited interbreeding in Southeast Asia.[43][122]

Alleles thought to have originated in Neanderthal and the Denisova hominin 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,[15] indicating strong positive selection for these introgressed alleles.

H. floresiensis[edit]

Main article: Homo floresiensis
Restoration model of Homo floresiensis

H. floresiensis, which lived from approximately 100,000 to 12,000 years before present, has been nicknamed hobbit for its small size, possibly a result of insular dwarfism.[123] 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).[citation needed]

However, there is an ongoing debate over whether H. floresiensis is indeed a separate species.[124] Some scientists hold that H. floresiensis was a modern H. sapiens with pathological dwarfism.[125] 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 possibly create a hobbit-like human. The other major attack on H. floresiensis as a separate species is that it was found with tools only associated with H. sapiens.[125]

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.

H. sapiens[edit]

Main article: Archaic humans

H. sapiens (the adjective sapiens is Latin for "wise" or "intelligent") have lived from about 250,000 years ago to the present. Between 400,000 years ago and the second interglacial period in the Middle Pleistocene, around 250,000 years ago, the trend in skull 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. Current evidence does not preclude some multiregional evolution or some admixture of the migrant H. sapiens with existing Homo populations. This is a hotly debated area of paleoanthropology.

Current research has established that humans are genetically highly homogenous; that is, the DNA of individuals is more alike than usual for most species, which may have resulted from their relatively recent evolution or the possibility of a population bottleneck resulting from cataclysmic natural events such as the Toba catastrophe.[126][127] Distinctive genetic characteristics have arisen, however, primarily as the result of small groups of people moving into new environmental circumstances. These adapted traits are a very small component of the Homo sapiens genome, but include various characteristics such as skin color and nose form, in addition to internal characteristics such as the ability to breathe more efficiently at high altitudes.

H. sapiens idaltu, from Ethiopia, is an extinct sub-species from about 160,000 years ago.

Comparative table of Homo species
Species Temporal range Mya Habitat Adult height Adult mass Cranial capacity (cm³) Fossil record Discovery / publication of name
H. habilis 2.1 – 1.5[128] Africa 150 cm (4 ft 11 in) 33–55 kg (73–121 lb) 510–660 Many 1960/1964
H. erectus 1.9 – 0.07

[129]

Africa, Eurasia (Java, China, India, Caucasus) 180 cm (5 ft 11 in) 60 kg (130 lb) 850 (early) – 1,100 (late) Many[130] 1891/1892
H. rudolfensis
membership in Homo uncertain
1.9 Kenya 700 2 sites 1972/1986
H. gautengensis
also classified as H. habilis
1.9 – 0.6 South Africa 100 cm (3 ft 3 in) 3 individuals[131] 2010/2010
H. ergaster
also classified as H. erectus
1.8 – 1.3[132] Eastern and Southern Africa 700–850 Many 1975
H. antecessor
also classified as H. heidelbergensis
1.2 – 0.8 Spain 175 cm (5 ft 9 in) 90 kg (200 lb) 1,000 2 sites 1997
H. cepranensis
a single fossil, possibly H. erectus
0.9 – 0.35 Italy 1,000 1 skull cap 1994/2003
H. heidelbergensis 0.6 – 0.35[133] Europe, Africa, China 180 cm (5 ft 11 in) 90 kg (200 lb) 1,100–1,400 Many 1908
H. neanderthalensis
possibly a subspecies of H. sapiens
0.35 – 0.04[134] Europe, Western Asia 170 cm (5 ft 7 in) 55–70 kg (121–154 lb) (heavily built) 1,200–1,900 Many (1829)/1864
H. rhodesiensis
also classified as H. heidelbergensis
0.3 – 0.12 Zambia 1,300 Very few 1921
H. tsaichangensis
possibly H. erectus
0.25 – 0.2 Taiwan 1 individual pre-2008/2015
H. sapiens
(modern humans)
0.2[135]

 – present

Worldwide 150 - 190 cm (4 ft 7 in - 6 ft 3 in) 50–100 kg (110–220 lb) 950–1,800 (extant) —/1758
H. floresiensis
classification uncertain
0.10 – 0.012 Indonesia 100 cm (3 ft 3 in) 25 kg (55 lb) 400 7 individuals 2003/2004
Denisova hominin
possible H. sapiens subspecies or hybrid
0.04 Russia 1 site 2010
Red Deer Cave people
possible H. sapiens subspecies or hybrid
0.0145–0.0115 China Very few 2012


Hominin species distributed through time edit

Homo Australopithecus Ardipithecus Paranthropus Homo sapiens Homo neandertalensis Homo heidelbergensis Homo erectus Paranthropus robustus Paranthropus boisei Paranthropus aethiopicus Homo ergaster Homo habilis Australopithecus sediba Australopithecus garhi Australopithecus africanus Australopithecus bahrelghazali Australopithecus afarensis Australopithecus anamensis Orrorin tugenensis Sahelanthropus Pleistocene Pliocene Miocene


Use of tools[edit]

"A sharp rock," an Oldowan pebble tool, the most basic of human stone tools.
The harnessing of fire was a pivotal milestone in human history.
Acheulean hand-axes from Kent. Homo erectus flint work. The types shown are (clockwise from top) cordate, ficron and ovate.
Venus of Willendorf, an example of Paleolithic art, dated 24–26,000 years ago.

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 body's total energy consumption.[136] 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.[137]

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.[138]

It should be noted that 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 the Oldowan stone tools from Ethiopia, 2.5–2.6 million years old. 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.[139] 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.[140]

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.[139]

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.[139]

Stone tools[edit]

Stone tools are first attested around 2.6 Ma, when H. habilis in Eastern Africa used so-called pebble tools, choppers made out of round pebbles that had been split by simple strikes.[141] 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 claim to 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.[142][143][144]

The period from 700,000–300,000 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.[141] 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). In this period they also started to make tools out of bone.

Transition to behavioral modernity[edit]

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 Eurasian "Great Leap Forward,"[145] or as the "Upper Palaeolithic Revolution,"[146] due to the sudden appearance of distinctive signs of modern behavior in the archaeological record. Other scholars consider the transition to have been more gradual, noting that some features had already appeared among archaic African Homo sapiens since 200,000 years ago.[147][148]

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.[149] 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.

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.[18]

Recent and current human evolution[edit]

Natural selection still exerts its ancient methodologies on modern human populations. For 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.[150][151] 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 .[152]

It has been argued that human evolution has accelerated since the development of agriculture and civilization some 10,000 years ago, resulting, it is claimed, in substantial genetic differences between different current human populations.[153] The retention of lactase persistence into adulthood is an example of such recent evolution. Recent human evolution seems to have been largely confined to genetic resistance to infectious disease that have appeared in human populations by crossing the species barrier from domesticated animals.[154]

Without a 'natural selection' pressure or opportunity for speciation—such as geographic isolation of a local human population——recent human evolution has been predominantly subject to genetic drift.[citation needed]

Species list[edit]

This list is in chronological order across the page by genus.

See also[edit]

References[edit]

  1. ^ Heng, Henry H. Q. (May 2009). "The genome-centric concept: resynthesis of evolutionary theory". BioEssays (Hoboken, NJ: John Wiley & Sons) 31 (5): 512–525. doi:10.1002/bies.200800182. ISSN 0265-9247. PMID 19334004. 
  2. ^ Tyson, Peter (July 1, 2008). "Meet Your Ancestors". NOVA scienceNOW. PBS; WGBH Educational Foundation. Retrieved 2015-04-18. 
  3. ^ a b Dawkins 2004
  4. ^ a b c Ghosh, Pallab (March 4, 2015). "'First human' discovered in Ethiopia". BBC News (London: BBC). Retrieved 2015-04-19. 
  5. ^ Swisher, Curtis & Lewin 2001
  6. ^ Stringer 1994, p. 242
  7. ^ McHenry 2009, p. 265
  8. ^ "Out of Africa Revisited". Science (This Week in Science) (Washington, D.C.: American Association for the Advancement of Science) 308 (5724): 921. May 13, 2005. doi:10.1126/science.308.5724.921g. ISSN 0036-8075. 
  9. ^ Stringer, Chris (June 12, 2003). "Human evolution: Out of Ethiopia". Nature (London: Nature Publishing Group) 423 (6941): 692–695. doi:10.1038/423692a. ISSN 0028-0836. PMID 12802315. 
  10. ^ Johanson, Donald (May 2001). "Origins of Modern Humans: Multiregional or Out of Africa?". actionbioscience. Washington, D.C.: American Institute of Biological Sciences. Retrieved 2009-11-23. 
  11. ^ 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 2015-04-20. 
  12. ^ 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 2015-04-20. 
  13. ^ a b c d 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 (London: Nature Publishing Group) 468 (7327): 1053–1060. Bibcode:2010Natur.468.1053R. doi:10.1038/nature09710. ISSN 0028-0836. PMID 21179161. 
  14. ^ Noonan, James P. (May 2010). "Neanderthal genomics and the evolution of modern humans". Genome Research (Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press) 20 (5): 547–553. doi:10.1101/gr.076000.108. ISSN 1088-9051. PMC 2860157. PMID 20439435. 
  15. ^ a b c 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 (Washington, D.C.: American Association for the Advancement of Science) 334 (6052): 89–94. Bibcode:2011Sci...334...89A. doi:10.1126/science.1209202. ISSN 0036-8075. PMC 3677943. PMID 21868630. 
  16. ^ "Fossil Reanalysis Pushes Back Origin of Homo sapiens". Scientific American (Stuttgart: Georg von Holtzbrinck Publishing Group). February 17, 2005. ISSN 0036-8733. Retrieved 2015-04-20. 
  17. ^ 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. (Washington, D.C.: National Academy of Sciences) 103 (25): 9381–9386. Bibcode:2006PNAS..103.9381M.. doi:10.1073/pnas.0510792103. ISSN 0027-8424. PMC 1480416. PMID 16772383. 
  18. ^ a b 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 (Amsterdam, the Netherlands: Elsevier) 39 (5): 453–563. doi:10.1006/jhev.2000.0435. ISSN 0047-2484. PMID 11102266. 
  19. ^ American Heritage Dictionaries (editors) 2006
  20. ^ Darwin 1981
  21. ^ Montgomery 1988, pp. 95–96
  22. ^ Dart, Raymond (February 7, 1925). "Australopithecus africanus: The Man-Ape of South Africa" (PDF). Nature (London: Nature Publishing Group) 115 (2884): 195–199. doi:10.1038/115195a0. ISSN 0028-0836. Retrieved 2015-05-11. 
  23. ^ a b Sarich, V. M.; Wilson, A. C. (1967). "Immunological time scale for hominid evolution". Science 158 (3805): 1200–1203. doi:10.1126/science.158.3805.1200. PMID 4964406.  edit
  24. ^ M'charek 2005, p. 96
  25. ^ a b DeSalle & Tattersall 2008, p. 146
  26. ^ Trent 2005, p. 6
  27. ^ Wade, Nicholas (May 18, 2006). "Two Splits Between Human and Chimp Lines Suggested". The New York Times. Retrieved 2015-04-20. 
  28. ^ Behar, Doron M.; Villems, Richard; Soodyall, Himla et al. (May 9, 2008). "The Dawn of Human Matrilineal Diversity" (PDF). American Journal of Human Genetics (Cambridge, MA: Cell Press on behalf of the American Society of Human Genetics) 82 (5): 1130–1140. doi:10.1016/j.ajhg.2008.04.002. ISSN 0002-9297. PMC 2427203. PMID 18439549. Retrieved 2015-04-20. 
  29. ^ Templeton, Alan R. (2005). "Haplotype Trees and Modern Human Origins". American Journal of Physical Anthropology (Hoboken, NJ: John Wiley & Sons for the American Association of Physical Anthropologists) 128 (Supplement 41 (Yearbook of Physical Anthropology)): 33–59. doi:10.1002/ajpa.20351. ISSN 0002-9483. PMID 16369961. 
  30. ^ Owen, James (July 18, 2007). "Modern Humans Came Out of Africa, 'Definitive' Study Says". National Geographic News (Washington, D.C.: National Geographic Society). Retrieved 2011-05-14. 
  31. ^ Stringer, Chris B.; Andrews, Peter (March 11, 1988). "Genetic and fossil evidence for the origin of modern humans". Science (Washington, D.C.: American Association for the Advancement of Science) 239 (4845): 1263–1268. Bibcode:1988Sci...239.1263S. doi:10.1126/science.3125610. ISSN 0036-8075. PMID 3125610. 
  32. ^ Wolpoff, Milford H.; Hawks, John; Caspari, Rachel (May 2000). "Multiregional, Not Multiple Origins" (PDF). American Journal of Physical Anthropology (Hoboken, NJ: John Wiley & Sons for the American Association of Physical Anthropologists) 112 (1): 129–136. doi:10.1002/(SICI)1096-8644(200005)112:1<129::AID-AJPA11>3.0.CO;2-K. ISSN 0002-9483. PMID 10766948. 
  33. ^ Wolpoff, Milford H.; Spuhler, James N.; Smith, Fred H. et al. (August 12, 1988). "Modern Human Origins". Science (Washington, D.C.: American Association for the Advancement of Science) 241 (4867): 772–774. Bibcode:1988Sci...241..772W. doi:10.1126/science.3136545. ISSN 0036-8075. PMID 3136545. 
  34. ^ Webster 2010, p. 53
  35. ^ Ramachandran et al. 2010, p. 606
  36. ^ Kutty 2009, p. 40
  37. ^ Cann, Rebecca L.; Stoneking, Mark; Wilson, Allan C. (January 1, 1987). "Mitochondrial DNA and human evolution". Nature (London: Nature Publishing Group) 325 (6099): 31–36. Bibcode:1987Natur.325...31C. doi:10.1038/325031a0. ISSN 0028-0836. PMID 3025745. Archived from the original on 2010-08-13. Retrieved 2015-04-21. 
  38. ^ Gill, Victoria (May 1, 2009). "Africa's genetic secrets unlocked". BBC News (London: BBC). Retrieved 2011-06-08.  The results were published in the online edition of the journal Science.
  39. ^ Leakey 1994, pp. 87–89
  40. ^ Jorde, Lynn B.; Bamshad, Michael; Rogers, Alan R. (February 1998). "Using mitochondrial and nuclear DNA markers to reconstruct human evolution". BioEssays (Hoboken, NJ: John Wiley & Sons) 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. 
  41. ^ 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 (Oxford, UK: Oxford University Press on behalf of the Society for Molecular Biology and Evolution) 26 (8): 1823–1827. doi:10.1093/molbev/msp096. ISSN 0737-4038. PMC 2734152. PMID 19420049. 
  42. ^ Green, Richard E.; Krause, Johannes; Briggs, Adrian W. et al. (May 7, 2010). "A Draft Sequence of the Neandertal Genome". Science (Washington, D.C.: American Association for the Advancement of Science) 328 (5979): 710–722. Bibcode:2010Sci...328..710G. doi:10.1126/science.1188021. ISSN 0036-8075. PMID 20448178. 
  43. ^ a b 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 (Cambridge, MA: Cell Press on behalf of the American Society of Human Genetics) 89 (4): 516–528. doi:10.1016/j.ajhg.2011.09.005. ISSN 0002-9297. PMC 3188841. PMID 21944045. Retrieved 2015-04-21. 
  44. ^ a b c Lahr, Marta Mirazón; Petraglia, Mike; Stokes, Stephen et al. "Searching for traces of the Southern Dispersal". Leverhulme Centre for Human Evolutionary Studies. Cambridge, UK: University of Cambridge. Archived from the original on 2012-05-10. Retrieved 2015-04-21. 
  45. ^ Macaulay, Vincent; Hill, Catherine; Achilli, Alessandro et al. (May 13, 2005). "Single, Rapid Coastal Settlement of Asia Revealed by Analysis of Complete Mitochondrial Genomes". Science (Washington, D.C.: American Association for the Advancement of Science) 308 (5724): 1034–1036. Bibcode:2005Sci...308.1034M. doi:10.1126/science.1109792. ISSN 0036-8075. PMID 15890885. 
  46. ^ Boyd & Silk 2003
  47. ^ Brues & Snow 1965, pp. 1–39
  48. ^ Brunet, Michel; Guy, Franck; Pilbeam, David et al. (July 11, 2002). "A new hominid from the Upper Miocene of Chad, Central Africa". Nature (London: Nature Publishing Group) 418 (6894): 145–151. doi:10.1038/nature00879. ISSN 0028-0836. PMID 12110880. 
  49. ^ a b c Srivastava 2009, p. 87
  50. ^ a b Curry 2008, pp. 106–109
  51. ^ "Study Identifies Energy Efficiency As Reason For Evolution Of Upright Walking". ScienceDaily (Rockville, MD: ScienceDaily, LLC). July 17, 2007. Retrieved 2015-04-09. 
  52. ^ 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. (Washington, D.C.: National Academy of Sciences) 104 (30): 12265–12269. doi:10.1073/pnas.0703267104. ISSN 0027-8424. PMC 1941460. PMID 17636134. 
  53. ^ Aiello & Dean 1990
  54. ^ Kondo 1985
  55. ^ Strickberger 2000, pp. 475–476
  56. ^ Trevathan 2011, p. 20
  57. ^ Wayman, Erin (August 19, 2013). "Killer whales, grandmas and what men want: Evolutionary biologists consider menopause". Science News (Washington, D.C.: Society for Science & the Public). ISSN 0036-8423. Retrieved 2015-04-24. 
  58. ^ a b Schoenemann, P. Thomas (October 2006). "Evolution of the Size and Functional Areas of the Human Brain". Annual Review of Anthropology (Palo Alto, CA: Annual Reviews) 35: 379–406. doi:10.1146/annurev.anthro.35.081705.123210. ISSN 0084-6570. 
  59. ^ 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 (Philadelphia, PA: Lippincott Williams & Wilkins) 60 (3): 555–562. doi:10.1227/01.NEU.0000249284.54137.32. ISSN 0148-396X. PMID 17327801. 
  60. ^ Bruner, Emiliano (December 2007). "Cranial shape and size variation in human evolution: structural and functional perspectives". Child's Nervous System (Heidelberg: Springer-Verlag) 23 (12): 1357–1365. doi:10.1007/s00381-007-0434-2. ISSN 0256-7040. PMID 17680251. CiteSeerX: 10.1.1.391.288. 
  61. ^ Potts, Richard (October 2012). "Evolution and Environmental Change in Early Human Prehistory". Annual Review of Anthropology (Palo Alto, CA: Annual Reviews) 41: 151–167. doi:10.1146/annurev-anthro-092611-145754. ISSN 0084-6570. 
  62. ^ a b Leonard, William R.; Snodgrass, J. Josh; Robertson, Marcia L. (August 2007). "Effects of brain evolution on human nutrition and metabolism". Annual Review of Nutrition (Palo Alto, CA: Annual Reviews) 27: 311–327. doi:10.1146/annurev.nutr.27.061406.093659. ISSN 0199-9885. PMID 17439362. 
  63. ^ McBroom, Patricia (June 14, 1999). "Meat-eating was essential for human evolution, says UC Berkeley anthropologist specializing in diet" (Press release). Berkeley, CA: University of California, Berkeley. Retrieved 2015-04-25. 
  64. ^ Mann, Neil (September 2007). "Meat in the human diet: An anthropological perspective". Nutrition & Dietetics (Hoboken, NJ: Wiley-Blackwell) 64 (Supplement s4): S102–S107. doi:10.1111/j.1747-0080.2007.00194.x. ISSN 1747-0080. Retrieved 2012-01-31. 
  65. ^ 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. (Washington, D.C.: National Academy of Sciences) 108 (35): 14555–14559. doi:10.1073/pnas.1107806108. ISSN 0027-8424. PMC 3167533. PMID 21873223. 
  66. ^ Bown & Rose 1987
  67. ^ Barton, Robert A.; Venditti, Chris (October 20, 2014). "Rapid Evolution of the Cerebellum in Humans and Other Great Apes". Current Biology (Cambridge, MA: Cell Press) 24 (20): 2440–2444. doi:10.1016/j.cub.2014.08.056. ISSN 0960-9822. 
  68. ^ Starowicz-Filip, Anna; Milczarek, Olga; Kwiatkowski, Stanisław et al. (2013). "Cerebellar cognitive affective syndrome CCAS – a case report" (PDF). Archives of Psychiatry and Psychotherapy (Kraków, Poland: Polish Psychiatric Association) 3: 57–64. OCLC 220954272. 
  69. ^ 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 (Oxford, UK: Published by Oxford University Press on behalf of the Guarantors of Brain). doi:10.1093/brain/awu239. ISSN 1460-2156. PMID 25149410. 
  70. ^ Weaver, Anne H. (March 8, 2005). "Reciprocal evolution of the cerebellum and neocortex in fossil humans". Proc. Natl. Acad. Sci. U.S.A. (Washington, D.C.: National Academy of Sciences) 102 (10): 3576–3580. doi:10.1073/pnas.0500692102. ISSN 0027-8424. PMC 553338. PMID 15731345. 
  71. ^ Stanford, Allen & Antón 2009
  72. ^ a b Wood, Bernard A.; Richmond, Brian G. (July 2000). "Human evolution: taxonomy and paleobiology". Journal of Anatomy (Hoboken, NJ: Wiley-Blackwell on behalf of the Anatomical Society of Great Britain and Ireland) 197 (1): 19–60. doi:10.1046/j.1469-7580.2000.19710019.x. ISSN 1469-7580. PMC 1468107. PMID 10999270. 
  73. ^ Ajit, Varki; Nelson, David L. (October 2007). "Genomic Comparisons of Humans and Chimpanzees" (PDF). Annual Review of Anthropology (Palo Alto, CA: Annual Reviews) 36: 191–209. doi:10.1146/annurev.anthro.36.081406.094339. ISSN 0084-6570. Retrieved 2015-04-26. 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%. 
  74. ^ Sayers, Ken; Raghanti, Mary Ann; Lovejoy, C. Owen (October 2012). "Human Evolution and the Chimpanzee Referential Doctrine". Annual Review of Anthropology (Palo Alto, CA: Annual Reviews) 41: 119–138. doi:10.1146/annurev-anthro-092611-145815. ISSN 0084-6570. 
  75. ^ Ruvolo, Maryellen (October 1997). "Genetic Diversity in Hominoid Primates". Annual Review of Anthropology (Palo Alto, CA: Annual Reviews) 26: 515–540. doi:10.1146/annurev.anthro.26.1.515. ISSN 0084-6570. 
  76. ^ Ruvolo, Maryellen (March 1997). "Molecular Phylogeny of the Hominoids: Inferences from Multiple Independent DNA Sequence Data Sets" (PDF). Molecular Biology and Evolution (Oxford, UK: Oxford University Press on behalf of the Society for Molecular Biology and Evolution) 14 (3): 248–265. doi:10.1093/oxfordjournals.molbev.a025761. ISSN 0737-4038. PMID 9066793. 
  77. ^ Patterson N, Richter DJ, Gnerre S, Lander ES, Reich D (June 2006). "Genetic evidence for complex speciation of humans and chimpanzees". Nature 441 (7097): 1103–8. doi:10.1038/nature04789. PMID 16710306.
  78. ^ Begun, David R. (October 2010). "Miocene Hominids and the Origins of the African Apes and Humans". Annual Review of Anthropology (Palo Alto, CA: Annual Reviews) 39: 67–84. doi:10.1146/annurev.anthro.012809.105047. ISSN 0084-6570. 
  79. ^ Wood 2009, pp. 17–27
  80. ^ Mitchell, Alanna (January 30, 2012). "DNA Turning Human Story Into a Tell-All". The New York Times. Retrieved 2012-02-13. 
  81. ^ Wood, Bernard A. (December 1996). "Human evolution". BioEssays (Hoboken, NJ: John Wiley & Sons) 18 (12): 945–954. doi:10.1002/bies.950181204. ISSN 0265-9247. PMID 8976151. 
  82. ^ Maxwell 1984, p. 296
  83. ^ Rose, Kenneth D. (1994). "The earliest primates". Evolutionary Anthropology: Issues, News, and Reviews (Hoboken, NJ: John Wiley & Sons) 3 (5): 159–173. doi:10.1002/evan.1360030505. ISSN 1060-1538. 
  84. ^ Kordos, László; Begun, David R. (January 2001). "Primates from Rudabánya: allocation of specimens to individuals, sex and age categories". Journal of Human Evolution (Amsterdam, the Netherlands: Elsevier) 40 (1): 17–39. doi:10.1006/jhev.2000.0437. ISSN 0047-2484. PMID 11139358. 
  85. ^ Cameron 2004, p. 76
  86. ^ Wallace 2004, p. 240
  87. ^ 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 (London: Nature Publishing Group) 466 (7304): 360–364. Bibcode:2010Natur.466..360Z. doi:10.1038/nature09094. ISSN 0028-0836. PMID 20631798. 
  88. ^ "Figure 5. Temporal and Geographical Distribution of Hominid Populations Redrawn from Stringer (2003)" (edited from source), in Reed, David L.; Smith, Vincent S.; Hammond, Shaless L. et al. (November 2004). "Genetic Analysis of Lice Supports Direct Contact between Modern and Archaic Humans". PLOS Biology (San Francisco, CA: PLOS) 2 (11): e340. doi:10.1371/journal.pbio.0020340. ISSN 1545-7885. PMC 521174. PMID 15502871. 
  89. ^ Strait, David S.; Grine, Frederick E.; Moniz, Marc A. (January 1997). "A reappraisal of early hominid phylogeny". Journal of Human Evolution (Amsterdam, the Netherlands: Elsevier) 32 (1): 17–82. doi:10.1006/jhev.1996.0097. ISSN 0047-2484. PMID 9034954. 
  90. ^ a b Bryson 2004, pp. 522–543
  91. ^ Walker 2007, pp. 3–10
  92. ^ Ungar & Teaford 2002
  93. ^ Bogin 1997, pp. 96–142
  94. ^ Barnicot, Nigel A. (April–June 2005). "Human nutrition: Evolutionary perspectives". Integrative Physiological & Behavioral Science (New York: Springer US) 40 (2): 114–117. doi:10.1007/BF02734246. ISSN 1932-4502. PMID 17393680. 
  95. ^ "The new batch - 150,000 years ago". BBC - Science & Nature - The evolution of man (London: BBC). Archived from the original on 2006-01-18. Retrieved 2015-04-28. 
  96. ^ Whitehouse, David (June 9, 2003). "When humans faced extinction". BBC News (London: BBC). Retrieved 2007-01-05. 
  97. ^ Wood, Bernard; Collard, Mark (1999). "The changing face of Genus Homo". Evolutionary Anthropology: Issues, News, and Reviews (Hoboken, NJ: John Wiley & Sons) 8 (6): 195–207. doi:10.1002/(SICI)1520-6505(1999)8:6<195::AID-EVAN1>3.0.CO;2-2. ISSN 1060-1538. 
  98. ^ Viegas, Jennifer (May 21, 2010). "Toothy Tree-Swinger May Be Earliest Human". Discovery News (Silver Spring, MD: Discovery Communications, LLC.). Retrieved 2015-04-28. 
  99. ^ Wood, Bernard A. (January 1999). "‘Homo rudolfensis’ Alexeev, 1986—fact or phantom?". Journal of Human Evolution (Amsterdam, the Netherlands: Elsevier) 36 (1): 115–118. doi:10.1006/jhev.1998.0246. ISSN 0047-2484. PMID 9924136. 
  100. ^ 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) (Elsevier on behalf of the French Academy of Sciences) 1 (4): 243–253. doi:10.1016/S1631-0683(02)00032-5. ISSN 1631-0683. 
  101. ^ 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 (New York: Wiley-Liss) 288A (11): 1146–1157. doi:10.1002/ar.a.20379. ISSN 1552-4884. PMID 17031841. 
  102. ^ 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. 
  103. ^ Spoor, Fred; Wood, Bernard A.; Zonneveld, Frans (June 23, 1994). "Implications of early hominid labyrinthine morphology for evolution of human bipedal locomotion". Nature (London: Nature Publishing Group) 369 (6482): 645–648. Bibcode:1994Natur.369..645S. doi:10.1038/369645a0. ISSN 0028-0836. PMID 8208290. 
  104. ^ 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 (Washington, D.C.: American Association for the Advancement of Science) 276 (5317): 1392–1395. doi:10.1126/science.276.5317.1392. ISSN 0036-8075. PMID 9162001. 
  105. ^ Carbonell, Eudald; Bermúdez de Castro, José María; Parés, Josep M. et al. (March 27, 2008). "The first hominin of Europe". Nature (London: Nature Publishing Group) 452 (7186): 465–469. Bibcode:2008Natur.452..465C. doi:10.1038/nature06815. ISSN 0028-0836. PMID 18368116. 
  106. ^ 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. (Washington, D.C.: National Academy of Sciences) 98 (17): 10011–10016. Bibcode:2001PNAS...9810011M. doi:10.1073/pnas.151259998. ISSN 0027-8424. PMC 55569. PMID 11504953. 
  107. ^ 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 (Amsterdam, the Netherlands: Elsevier) 44 (4): 479–495. doi:10.1016/S0047-2484(03)00029-0. ISSN 0047-2484. PMID 12727464. 
  108. ^ Semaw, Sileshi; Toth, Nicholas; Schick, Kathy et al. (March 27, 2006). "Scientists discover hominid cranium in Ethiopia" (Press release). Bloomington, IN: Indiana University. Retrieved 2006-11-26. 
  109. ^ Harvati, Katerina (January 2003). "The Neanderthal taxonomic position: models of intra- and inter-specific craniofacial variation". Journal of Human Evolution (Amsterdam, the Netherlands: Elsevier) 44 (1): 107–132. doi:10.1016/S0047-2484(02)00208-7. ISSN 0047-2484. PMID 12604307. 
  110. ^ 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.  edit
  111. ^ Krings, Matthias; Stone, Anne; Schmitz, Ralf W. et al. (July 11, 1997). "Neandertal DNA sequences and the origin of modern humans". Cell (Cambridge, MA: Cell Press) 90 (1): 19–30. doi:10.1016/S0092-8674(00)80310-4. ISSN 0092-8674. PMID 9230299. 
  112. ^ 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 (Cambridge, MA: Cell Press) 134 (3): 416–426. doi:10.1016/j.cell.2008.06.021. ISSN 0092-8674. PMC 2602844. PMID 18692465. 
  113. ^ Serre, David; Langaney, André; Chech, Mario et al. (March 2004). "No Evidence of Neandertal mtDNA Contribution to Early Modern Humans". PLOS Biology (San Francisco, CA: PLOS) 2 (3): e57. doi:10.1371/journal.pbio.0020057. ISSN 1545-7885. PMC 368159. PMID 15024415. 
  114. ^ a b Viegas, Jennifer (May 6, 2010). "Neanderthals, Humans Interbred, DNA Proves". Discovery News (Silver Spring, MD: Discovery Communications, LLC.). Retrieved 2015-04-30. 
  115. ^ Gutiérrez, Gabriel; Sánchez, Diego; Marín, Antonio (August 2002). "A Reanalysis of the Ancient Mitochondrial DNA Sequences Recovered from Neandertal Bones". Molecular Biology and Evolution (Oxford, UK: Oxford University Press on behalf of the Society for Molecular Biology and Evolution) 19 (8): 1359–1366. doi:10.1093/oxfordjournals.molbev.a004197. ISSN 0737-4038. PMID 12140248. 
  116. ^ Hebsgaard, Martin B.; Wiuf, Carsten; Gilbert, M. Thomas et al. (January 2007). "Evaluating Neanderthal Genetics and Phylogeny". Journal of Molecular Evolution (New York: Springer US) 64 (1): 50–60. doi:10.1007/s00239-006-0017-y. ISSN 0022-2844. PMID 17146600. 
  117. ^ Mellars, Paul; French, Jennifer C. (July 29, 2011). "Tenfold Population Increase in Western Europe at the Neandertal–to–Modern Human Transition Paul". Science (Washington, D.C.: American Association for the Advancement of Science) 333 (6042): 623–627. Bibcode:2011Sci...333..623M. doi:10.1126/science.1206930. ISSN 0036-8075. PMID 21798948. 
  118. ^ Brown, Terence A. (April 8, 2010). "Human evolution: Stranger from Siberia". Nature (London: Nature Publishing Group) 464 (7290): 838–839. Bibcode:2010Natur.464..838B. doi:10.1038/464838a. ISSN 0028-0836. PMID 20376137. 
  119. ^ a b 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 (London: Nature Publishing Group) 464 (7290): 894–897. Bibcode:2010Natur.464..894K. doi:10.1038/nature08976. ISSN 0028-0836. PMID 20336068. 
  120. ^ Katsnelson, Alla (March 24, 2010). "New hominin found via mtDNA". The Nutshell (Blog) (Philadelphia, PA: The Scientist). ISSN 0890-3670. Retrieved 2015-05-01. 
  121. ^ Bokma, Folmer; van den Brink, Valentijn; Stadler, Tanja (September 2012). "Unexpectedly many extinct hominins". Evolution (Hoboken, NJ: John Wiley & Sons for the Society for the Study of Evolution) 66 (9): 2969–2974. doi:10.1111/j.1558-5646.2012.01660.x. ISSN 0014-3820. PMID 22946817. 
  122. ^ 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 (Amsterdam, the Netherlands: Elsevier) 60 (2): 251–255. doi:10.1016/j.jhevol.2010.10.005. ISSN 0047-2484. PMID 21129766. 
  123. ^ 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 (London: Nature Publishing Group) 431 (7012): 1055–1061. Bibcode:2004Natur.431.1055B. doi:10.1038/nature02999. ISSN 0028-0836. PMID 15514638. 
  124. ^ Argue, Debbie; Donlon, Denise; Groves, Colin et al. (October 2006). "Homo floresiensis: Microcephalic, pygmoid, Australopithecus, or Homo?". Journal of Human Evolution (Amsterdam, the Netherlands: Elsevier) 51 (4): 360–374. doi:10.1016/j.jhevol.2006.04.013. ISSN 0047-2484. PMID 16919706. 
  125. ^ a b 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 (New York: Wiley-Liss) 288A (11): 1123–1145. doi:10.1002/ar.a.20389. ISSN 1552-4884. PMID 17031806. 
  126. ^ Cusack, Sinéad (narrator) (February 3, 2000). "Supervolcanoes". Horizon. Series 36. Episode 08. Transcript. BBC2. 
  127. ^ Ambrose, Stanley H. (June 1998). "Late Pleistocene human population bottlenecks, volcanic winter, and differentiation of modern humans". Journal of Human Evolution (Amsterdam, the Netherlands: Elsevier) 34 (6): 623–651. doi:10.1006/jhev.1998.0219. ISSN 0047-2484. PMID 9650103. 
  128. ^ Schrenk, Friedemann; Kullmer, Ottmar; Bromage, Timothy (2007). "The Earliest Putative Homo Fossils". In Henke, Winfried; Tattersall, Ian. Handbook of Paleoanthropology 1. In collaboration with Thorolf Hardt. Berlin, Heidelberg: Springer. pp. 1611–1631. doi:10.1007/978-3-540-33761-4_52. ISBN 978-3-540-32474-4.  Confirmed H. habilis fossils are dated to between 2.1 and 1.5 million years ago. This date range overlaps with the emergence of Homo erectus. Wilford, John Noble (August 9, 2007). "Fossils in Kenya Challenge Linear Evolution". The New York Times. Retrieved 2015-05-04. 
    • DiMaggio, Erin N.; Campisano, Christopher J.; Rowan, John et al. (March 20, 2015). "Late Pliocene fossiliferous sedimentary record and the environmental context of early Homo from Afar, Ethiopia". Science (Washington, D.C.: American Association for the Advancement of Science) 347 (6228): 1355–1359. doi:10.1126/science.aaa1415. ISSN 0036-8075. PMID 25739409.  Hominins with "proto-Homo" traits may have lived as early as 2.8 million years ago, as suggested by a fossil jawbone classified as transitional between Australopithecus and Homo discovered in 2015.
  129. ^ Haviland, William A.; Walrath, Dana; Prins, Harald E. L.; McBride, Bunny (2007). Evolution and Prehistory: The Human Challenge (8th ed.). Belmont, CA: Thomson Wadsworth. p. 162. ISBN 978-0-495-38190-7. H. erectus may have appeared some 2 million years ago. Fossils dated to as much as 1.8 million years ago have been found both in Africa and in Southeast Asia, and the oldest fossils by a narrow margin (1.85 to 1.77 million years ago) were found in the Caucasus, so that it is unclear whether H. erectus emerged in Africa and migrated to Eurasia, or if, conversely, it evolved in Eurasia and migrated back to Africa.
  130. ^ Now also included in H. erectus are Peking Man (formerly Sinanthropus pekinensis) and Java Man (formerly Pithecanthropus erectus). H. erectus is now grouped into various subspecies, including Homo erectus erectus, Homo erectus yuanmouensis, Homo erectus lantianensis, Homo erectus nankinensis, Homo erectus pekinensis, Homo erectus palaeojavanicus, Homo erectus soloensis, Homo erectus tautavelensis, Homo erectus georgicus. The distinction from descendant species such as Homo ergaster, Homo floresiensis, Homo antecessor, Homo heidelbergensis and indeed Homo sapiens is not entirely clear.
  131. ^ Curnoe, Darren (June 2010). "A review of early Homo in southern Africa focusing on cranial, mandibular and dental remains, with the description of a new species (Homo gautengensis sp. nov.)". HOMO - Journal of Comparative Human Biology (Amsterdam, the Netherlands: Elsevier) 61 (3): 151–177. doi:10.1016/j.jchb.2010.04.002. ISSN 0018-442X. PMID 20466364.  A species proposed in 2010 based on the fossil remains of three individuals dated between 1.9 and 0.6 million years ago. The same fossils were also classified as H. habilis, H. ergaster or Australopithecus by other anthropologists.
  132. ^ Hazarika, Manjil (2007). "Homo erectus/ergaster and Out of Africa: Recent Developments in Paleoanthropology and Prehistoric Archaeology" (PDF). EAA Summer School eBook 1. European Anthropological Association. pp. 35–41. Retrieved 2015-05-04.  "Intensive Course in Biological Anthrpology, 1st Summer School of the European Anthropological Association, 16–30 June, 2007, Prague, Czech Republic"
  133. ^ The type fossil is Mauer 1, dated to ca. 0.6 million years ago. The transition from H. heidelbergensis to H. neanderthalensis at about 0.35 to 0.25 million years ago is largely conventional. Relevant examples are fossils found at Bilzingsleben (also classified as Homo erectus bilzingslebensis).
  134. ^ Bischoff, James L.; Shamp, Donald D.; Aramburu, Arantza et al. (March 2003). "The Sima de los Huesos Hominids Date to Beyond U/Th Equilibrium (>350 kyr) and Perhaps to 400–500 kyr: New Radiometric Dates". Journal of Archaeological Science (Amsterdam, the Netherlands: Elsevier) 30 (3): 275–280. doi:10.1006/jasc.2002.0834. ISSN 0305-4403.  The first humans with "proto-Neanderthal traits" lived in Eurasia as early as 0.6 to 0.35 million years ago (classified as H. heidelbergensis, also called a chronospecies because it represents a chronological grouping rather than being based on clear morphological distinctions from either H. erectus or H. neanderthalensis), with the first "true Neanderthals" appearing between 0.25 and 0.2 million years ago.
  135. ^ "Fossil Reanalysis Pushes Back Origin of Homo sapiens". Scientific American (Stuttgart: Georg von Holtzbrinck Publishing Group). February 17, 2005. ISSN 0036-8733. Retrieved 2015-05-04.  The oldest fossil remains of anatomically modern humans are the Omo remains, which date to 195,000 (±5,000) years ago and include two partial skulls as well as arm, leg, foot and pelvis bones.
  136. ^ Jabr, Ferris (July 18, 2012). "Does Thinking Really Hard Burn More Calories?". Scientific American (Stuttgart: Georg von Holtzbrinck Publishing Group). ISSN 0036-8733. Retrieved 2015-05-03. 
  137. ^ Gibbons, Ann (May 29, 1998). "Solving the Brain's Energy Crisis". Science (Washington, D.C.: American Association for the Advancement of Science) 280 (5368): 1345–1347. doi:10.1126/science.280.5368.1345. ISSN 0036-8075. PMID 9634409. 
  138. ^ Robinson 2008, p. 398
  139. ^ a b c Freeman & Herron 2007, pp. 786–788
  140. ^ 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. (Washington, D.C.: National Academy of Sciences) 111 (1): 121–124. doi:10.1073/pnas.1316014110. ISSN 0027-8424. PMC 3890866. PMID 24344276. 
  141. ^ a b Plummer, Thomas (2004). "Flaked stones and old bones: Biological and cultural evolution at the dawn of technology". American Journal of Physical Anthropology (Hoboken, NJ: John Wiley & Sons for the American Association of Physical Anthropologists). Supplement 39 (Yearbook of Physical Anthropology): 118–164. doi:10.1002/ajpa.20157. ISSN 0002-9483. PMID 15605391. 
  142. ^ Wong, Kate (April 15, 2015). "Archaeologists Take Wrong Turn, Find World’s Oldest Stone Tools". Scientific American (Blog) (Stuttgart: Georg von Holtzbrinck Publishing Group). ISSN 0036-8733. Retrieved 2015-05-03. 
  143. ^ Balter, Michael (April 14, 2015). "World's oldest stone tools discovered in Kenya". Science (News) (Washington, D.C.: American Association for the Advancement of Science). doi:10.1126/science.aab2487. ISSN 0036-8075. Retrieved 2015-05-03. 
  144. ^ Drake, Nadia (April 16, 2015). "Oldest Stone Tools Discovered in Kenya". National Geographic News (Washington, D.C.: National Geographic Society). Retrieved 2015-05-03. 
  145. ^ Diamond 1999, p. 39
  146. ^ Bar-Yosef, Ofer (October 2002). "The Upper Paleolithic Revolution". Annual Review of Anthropology (Palo Alto, CA: Annual Reviews) 31: 363–393. doi:10.1146/annurev.anthro.31.040402.085416. ISSN 0084-6570. 
  147. ^ Nowell, April (October 2010). "Defining Behavioral Modernity in the Context of Neandertal and Anatomically Modern Human Populations". Annual Review of Anthropology (Palo Alto, CA: Annual Reviews) 39: 437–452. doi:10.1146/annurev.anthro.012809.105113. ISSN 0084-6570. 
  148. ^ 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 (London: Royal Society) 366 (1567): 1060–1069. doi:10.1098/rstb.2010.0340. ISSN 0962-8436. PMC 3049097. PMID 21357228. 
  149. ^ Ambrose, Stanley H. (March 2, 2001). "Paleolithic Technology and Human Evolution". Science (Washington, D.C.: American Association for the Advancement of Science) 291 (5509): 1748–1753. Bibcode:2001Sci...291.1748A. doi:10.1126/science.1059487. ISSN 0036-8075. PMID 11249821. 
  150. ^ 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 2009-11-22. 
  151. ^ 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". The New England Journal of Medicine 361 (21): 2056–2065. doi:10.1056/NEJMoa0809716. PMID 19923577.  edit
  152. ^ 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.  edit
  153. ^ Cochran & Harpending 2009
  154. ^ Diamond 1999

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