The hand becomes a tool
A long thumb and broad fingertips let a hominin hold a stone hard enough to strike it accurately.
- When
- —
- Duration
- 400 thousand years
- Known to
- ± 200 thousand years
- Era
- Early Pleistocene, Quaternary
Making a stone tool requires gripping a core firmly while striking it precisely, which demands a thumb long relative to the fingers, wide fingertips, and a wrist that can transmit force without collapsing. Hand bones from Olduvai and elsewhere show these features assembling through the Early Pleistocene, and a metacarpal from around 1.42 million years ago already shows the internal bone structure of a modern human hand under load. Climbing adaptations persist alongside them for a long time.