Origins

The previous article ended with Homo erectus, a human species that had already changed the shape of our evolutionary story. By about 1.9 million years ago, Homo erectus had appeared in Africa. It had a body much more like ours than the earlier australopithecines: long legs, shorter arms, and a build suited to walking and traveling over long distances. Over time, populations attributed to Homo erectus spread into parts of western and eastern Asia. ...

For many years, human evolution was commonly pictured as a fairly simple progression: one ancient form gradually becoming another until modern humans appeared. That picture was useful, but it was too simple. Today, the fossil record looks much more like a branching tree than a ladder. Different hominin species appeared, overlapped, disappeared, and sometimes lived in the same regions at roughly the same time. In some periods, several distinct human relatives may have been sharing Africa together. ...