Orrorin

Main article: History of mankind. Main dates

The name of the genus Orrorin is translated from the local language as "First Man." The remains of orrorins were found in Kenya. They lay between two layers of volcanic ash, thanks to which they date relatively accurately: between 5.8 and 6.1 million years ago, in the Miocene era.

Orrorin could not completely straighten the lower limbs in the hip joint. Nevertheless, he is the owner of a number of very progressive anatomical features: an elongated femoral neck with anteroposterior flattening, the spherical shape of its head.

Judging by the remains of animals and plants of the same era, orrorins lived in dry evergreen forests, and not in savannah, as many theories of human evolution predicted. Therefore, erect monkeys apparently first appeared in forests, and did not evolve from four-legged ones that entered open spaces. Perhaps straight flow was an element of adaptation to life on trees. Modern orangutans use all four limbs to move only along thick knots, while they either cling to thinner branches from below or walk along them on the hind limbs, preparing the front to cling to other branches higher or balancing for stability. Such tactics allow them to approach fruits located far from the trunk, or jump from one tree to another. Unlike them, the ancestors of modern chimpanzees and gorillas specialized in climbing vertical trunks and lianas, which is due to their crank-like and slash-like gait on the ground.