Prehistory

7 Million B.C.T.

The earliest fossils that have been proposed as members of the hominin lineage -- the lineage of mankind -- are Sahelanthropus tchadensis.

5.7 Million B.C.T.

Orrorin tugenensis appeared.

5.6 Million B.C.T.

Ardipithecus kadabba appeared.

The Sahelanthropus tchadensis, Orrorin tugenensis, Ardipithecus kadabba 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 either of these species are ancestors of another branch of African apes, or that they represent a shared ancestor between hominins and other apes. However, the question of the relation 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 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 are best represented in the fossil record is Australopithecus afarensis with more than a 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 alternativelyParanthropus 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 members of the genus Homo are Homo habilis which evolved around 2.3 million years ago. Homo habilis is the first species for which we have positive evidence of use of stone tools. They developed the oldowan lithic technology, named after the Olduvai gorge where 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 with the arrival of Homo erectus in the fossil record, cranial capacity had doubled. Homo erectus were the first of the hominina to leave Africa, and these species spread through Africa, Asia, and Europe between 1.3 to 1.8 million years ago. 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 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 are 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 Skhul in Israel and Southern Europe begin around 90,000 years ago.

As modern humans spread out from Africa they encountered other hominins such as Homo neanderthalensis and the so-called Denisovans, who may have evolved from populations of Homo erectus that had left Africa already 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.^[61][62]

This migration out of Africa is estimated to have begun about 70,000 years BP and modern humans subsequently spread globally, replacing earlier hominins either through competition or hybridization. They inhabited Eurasia and Oceania by 40,000 years BP, and the Americas by at least 14,500 years BP.^[63]

3 Million B.C.T.

An upright walking australopithecine apeman appeared on the earth in the late Pliocene period and has thumb-opposed hands in place of forefeet, permitting him and his female counterpart to use tools.


1.75 Million B.C.T.

Anthropods used patterned tools.


1 Million B.C.T.

Australopithecine apeman became extinct as the human species became more developed. Homo erectus erectus was unique among primates in having a high proportion of meat relative to plant foods in his diet, but like other primates he was omnivorous, a scavenger who competed with hyenas and other scavengers while eluding leopards.