reply to post by Xtrozero
Well no doubt ardipithecus at ~ 5m years is very human-like, but even at the proconsulid level of ~ 20m years ago, they had some human-like traits.
Even 20 million years is nothing in geologic time.
Stone tools found at the bottom level of the cave — believed to be 2 million years old — show that human ancestors were in the cave earlier than ever thought before. Geological evidence indicates that these tools were left in the cave and not washed into the site from the outside world.
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The combination of stone tools indicating the presence of human ancestors and the dating of the level leads to the conclusion that human ancestors (hominids) were in the cave 2 million years ago. This is the earliest evidence for intentional cave occupation by human ancestors.
The Eastern African specimen: Homo habilis represents a pivotal phase in hominid evolution. Scientists have marked habilis as the beginning of the Homo line, where hominids are recognized as breaking off from the australopithecine classification. A large part in making the determination of where the beginning of the Homo line were to take place had much to do with the level of encephalization taking place in H. habilis, as it is with habilis that we begin to see strong movements toward a modern brain size. Homo habilis broke through into science in the early 1960's with the discovery of the OH 7 (the habilis type specimen) fossil at Olduvai Gorge, Tanzania by Louis Leakey and collegues. The existence of Homo habilis is currently dated to between 1.9 and 1.6 million years.
AL 666-1 Maxilla
~Found by William Kimball at Hadar
~Dated to 2.3 million years
There were a number of species of hominids in southern Africat 2 million years ago. The most likely candidate as the manufacturer of the stone tools found at Wonderwerk is Homo habilis. The oldest known stone tools from sites in Ethiopia date to 2.4 million years. The Wonderwerk Cave discoveries are those close in age to the very earliest known stone tools and similar in date to the bottom levels at Olduvai Gorge.
The main features of the transition from Australopithecines to H. habilis are the use of tools and an enlarged braincase (700cc) (Avers, 1989) (600 to 750 cc (Gore, 1997)). H. habilis could walk upright like modern humans, but could probably also climb trees to sleep, feed or escape predators. Their hand and foot had a combination of ancient and modern features, expected from an early ancestor. By the time that H. habilis arose, the foot still fell somewhere between that of a man and gorilla in its weight-bearing capabilities! Even the anklebone suggests their walking differed from the human striding gait. The robust lower legbones, the tibia and fibula showed that the adaptation to bipedalism was even less specialised at the knee joint. This bipedal, plantigrade primate thus had a different gait to modern humans, but not necessarily less efficient, and perhaps superior (see details on the australopithecine hip [2]). An adult female fossil representative of this species stood only 90 cm high, with hands hanging over the knees as in apes! These features of H. habilis are almost identical to those of A. afarensis , showing here that the primitive apelike characteristics served well in the niche of this creature in nature for a very long time.