In the 1960s, Louis and Mary Leakey found fossils at Olduvai Gorge in Tanzania that differed from Australopithecus: larger brained, with a different dental pattern. They named them Homo habilis — "handy human". The species lived in East and South Africa roughly 2.4–1.65 million years ago and is among the earliest known members of the genus Homo.

The name comes from the oldest consistent stone-tool industry found near the fossils — the Oldowan. Oldowan tools are plain pebbles flaked on one or two surfaces, but the principle is large: striking one stone against another in a deliberate way to shape it combines abstract planning with physical skill, a cognitive step. Habilis probably used these tools to scrape meat and crack bone for marrow; the move to higher-energy food from scavenged carcasses may have fuelled hominin brain expansion.

The boundaries of the species are debated. Some palaeoanthropologists split the Olduvai material into more than one species; others argue Habilis is closer to Australopithecus than to Homo. What is clear is that the tools and fossils of this window mark the beginning of a line that, within roughly two million years, would lead to Homo erectus — the first human to leave Africa.