6 million years ago: earliest evidence of bipedalism.
Around 6 million years ago and after hundreds of thousands of years of drought in Africa, there was a sudden increase in temperature that produced widespread humid environments. The first evidence of a bipedal species dates from this period.
Orrorin tugenensis is a hominid about the size of a chimpanzee, found in Kapsomin, in the Rift Valley in Kenya, in the year 2000.
The remains found belong to five individuals, both males and females. From the shape of the hand and arm bones, it is possible to tell it was an arboreal species. In this sense, they were very similar to today’s apes.
However, the femur is not like an ape’s femur; it is more like the femur of a bipedal species. Also, the spine seems to have had an upright position. Their small teeth are more like human teeth. We know for sure that this species lived after the divergence of hominids and apes, but there is no certainty that it is a human ancestor.