Stone tools are rocks that have been selected for use or intentionally altered. This technology appeared around 3.3 million years ago and became essential to hominins – all the living and extinct species that belong to the human lineage. Currently, we Homo sapiens are the only living hominin.

We are not the only living species to make and use stone tools, though – many other primates do – but the extent to which hominins modify them is unparalleled in the animal kingdom. Monkeys and other apes may hold a large stone in their hands to crack a nut on a flat, tablelike stone.

But most hominins don’t rely on stones collected as-is. They modify and shape them into useful tools for a variety of tasks, including cutting meat or plants, woodworking, scraping hide and even as projectiles.