WEIT Chap8

What about us? Chap 8

Darwin firmly believed that humans evolved from other species, apelike creatures, in Africa. This statement created a lot of religious objections.It took fossils to finally convince the skeptics that humans had indeed evolved.

make a short introPierre.brawand 19 avril 2011 à 22:47 (CEST)

Fossil Ancestors

Complete fossil sequences don't exist. What we must look for is the general trend of the fossils over time, which clearly shows a change from apelike to humanlike features. The older possible hominin discovered is the "Sahelanthropus tchadensis", from the Central African desert of Chad, the region known as the Sahel. It dates from between six and seven million years ago, right when molecular evidence tells us that our lineage diverged from that of chimps. The discovery of this specie suggests that bipedal walking was one of the first evolutionary innovations to distinguish us from other apes. After "Sachelanthropus" we have the six-million-years-old fragments from a species, called "Orrorin tugenensis", which has a single leg bone that is an evidence of bipedality. Then, there's a two-million-years gap with no substantive hominin fossils. That is where crucial information about when be began to walk upright has still to be found. The fossils reappear, beginning about four million years ago and from them we see branches beginning to grow from the hominin tree.

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