Editing Human evolution (section)

=== Evidence from the fossil record ===
[[File:Homo habilis-KNM ER 1813.jpg|thumb|upright|Replica of fossil skull of ''[[H.&nbsp;habilis]]''. Fossil number KNM ER 1813, found at [[Koobi Fora]], Kenya.]]
[[File:Homo ergaster.jpg|thumb|upright|Replica of fossil skull of ''[[H.&nbsp;ergaster]]'' (African ''H.&nbsp;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.<ref>{{cite journal |last=Begun |first=David R. |date=October 2010 |title=Miocene Hominids and the Origins of the African Apes and Humans |journal=Annual Review of Anthropology |volume=39 |pages=67–84 |doi=10.1146/annurev.anthro.012809.105047 |issn=0084-6570}}</ref> The earliest fossils that have been proposed as members of the hominin lineage are ''Sahelanthropus tchadensis'' dating from {{mya|7}}, ''Orrorin tugenensis'' dating from {{mya|5.7}}, and ''Ardipithecus kadabba'' dating to {{mya|5.6}}. 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 {{mya|4}} and diverged into [[Paranthropus|robust]] (also called ''[[Paranthropus]]'') and [[Australopithecus|gracile]] branches, one of which (possibly ''[[Australopithecus garhi|A. garhi]]'') probably went on to become ancestors of the genus ''Homo''. The australopithecine species that is best represented in the fossil record is ''Australopithecus afarensis'' with more than 100 fossil individuals represented, found from Northern Ethiopia (such as the famous "Lucy"), to Kenya, and South Africa. Fossils of robust australopithecines such as ''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 {{Mya|2.8}}.<ref name="autogenerated1" /> ''H.&nbsp;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.&nbsp;habilis'' fossils, to be a separate species, while others consider them to be part of ''H.&nbsp;habilis''—simply representing intraspecies variation, or perhaps even [[sexual dimorphism]]. The brains of these early hominins were about the same size as that of a chimpanzee, and their main adaptation was bipedalism as an adaptation to terrestrial living.

During the next million years, a process of encephalization began and, by the arrival (about {{Mya|1.9}}) of ''H.&nbsp;erectus'' in the fossil record, cranial capacity had doubled. ''H.&nbsp;erectus'' were the first of the hominins to emigrate from Africa, and, from {{Mya|1.8|1.3}}, this species spread through Africa, Asia, and Europe. One population of ''H.&nbsp;erectus'', also sometimes classified as separate species ''H.&nbsp;ergaster'', remained in Africa and evolved into ''H.&nbsp;sapiens''. It is believed that ''H.&nbsp;erectus'' and ''H.&nbsp;ergaster'' were the first to use fire and complex tools. In Eurasia, ''H.&nbsp;erectus'' evolved into species such as ''[[H.&nbsp;antecessor]]'', ''[[H.&nbsp;heidelbergensis]]'' and ''[[H.&nbsp;neanderthalensis]]''. The earliest fossils of anatomically modern humans are from the Middle Paleolithic, about 300–200,000 years ago such as the Herto and [[Omo remains]] of Ethiopia, [[Jebel Irhoud]] remains of Morocco, and Florisbad remains of South Africa; [[Skhul and Qafzeh hominins|later fossils]] from the [[Skhul Cave]] in Israel and Southern Europe begin around 90,000 years ago ({{Mya|0.09}}).

As modern humans spread out from Africa, they encountered other hominins such as ''H.&nbsp;neanderthalensis'' and the Denisovans, who may have evolved from populations of ''H.&nbsp;erectus'' that had left Africa around {{mya|2}}. 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.{{sfn|Wood|2009|pp=[https://link.springer.com/chapter/10.1007%2F978-1-4020-9980-9_3#page-1 17–27]}}<ref name="NYT-01302012">{{cite news |last=Mitchell |first=Alanna |date=January 30, 2012 |title=DNA Turning Human Story Into a Tell-All |url= https://www.nytimes.com/2012/01/31/science/gains-in-dna-are-speeding-research-into-human-origins.html |archive-url= https://ghostarchive.org/archive/20220101/https://www.nytimes.com/2012/01/31/science/gains-in-dna-are-speeding-research-into-human-origins.html |archive-date=January 1, 2022 |url-access=limited |newspaper=The New York Times |access-date=February 13, 2012}}{{cbignore}}</ref>

This migration out of Africa is estimated to have begun about 70–50,000 years [[Before Present|BP]] and modern humans subsequently spread globally, replacing earlier hominins either through competition or hybridization. They inhabited Eurasia and Oceania by 40,000 years BP, and the Americas by at least 14,500 years BP.<ref>{{cite journal |last=Wood |first=Bernard A. |date=December 1996 |title=Human evolution |journal=BioEssays |volume=18 |issue=12 |pages=945–954 |doi=10.1002/bies.950181204 |issn=0265-9247 |pmid=8976151 |s2cid=221464189}}</ref>