Modern humans found to be fittest ever at survival, by far

[bemildred]

5. Wiki says:

7 Ma Sahelanthropus tchadensis

Hominina speciate from the ancestors of the chimpanzees. The latest common ancestor lived around the time of Sahelanthropus tchadensis, ca. 7 Ma [4]; S. tchadensis is sometimes claimed to be the last common ancestor of humans and chimpanzees, but this is disputed. The earliest known human ancestor post-dating the separation of the human and the chimpanzee lines is Orrorin tugenensis (Millennium Man, Kenya; ca. 6 Ma). Both chimpanzees and humans have a larynx that repositions during the first two years of life to a spot between the pharynx and the lungs, indicating that the common ancestors have this feature, a precursor of speech.

http://en.wikipedia.org/wiki/Timeline_of_human_evolution#Primates

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So maybe they were not chimps yet, but they had left us behind. Anyway, it explains the number.