Homo ergaster, also called "African Homo erectus", is an extinct chronospecies of Homo which lived in eastern and southern Africa during the early Pleistocene, between 1.8 million and 1.3 million years ago.
There is still disagreement on the subject of the classification and ancestry of H. ergaster. However, it is now widely accepted as the direct ancestor of Asian Homo erectus, Homo neanderthalensis, Homo heidelbergensis, and hence Homo sapiens.
It is one of the earliest members of the genus Homo, possibly ancestral to, or sharing a common ancestor with, Homo erectus. Some paleoanthropologists consider H. ergaster is just the African variety of H. erectus. There are Asian fossils of H. erectus, which was the first human species to spread from Africa.
The name ergaster means "workman", in reference to the Acheulean hand axe industry developed by the species. The species' period in eastern and southern Africa coincided with the first part of the Pleistocene, the cooling of the global climate and the start of the ice ages. These events would have shrunk the rainforests in Africa, and expanded the savannahs and open forests to which ergaster was well suited.