^BHuman evolution. ^b Illustration showing stages in the evolution of humans. At left, ^Iproconsul^i (23-15 million years ago) is depicted hypothetically as an African ape with both primitive and advanced features. From it ^IAustralopithecus^i ^Iafarensis^i (>4- 2.5 Myr BP) evolved and displayed a bipedal, upright gait walking on two legs. ^IHomo^i ^Ihabilis^i (2.5 Myr BP) was truly human (“homo”) resembling ^IAustralopithecus^i but also used stone tools. About 1.5 Myr BP ^IHomo erectus^i (at centre) appeared in Africa, used fire, wooden tools, and migrated from Africa into Eurasia. ^IHomo^i ^Ineanderthalensis^i (200,000 years BP) lived in Europe and Middle East and was closely related to modern humans (right).