The Oldowan Gorge choppers are the oldest artefacts, made about 2.5 million years ago. These are just the oldest ones that we have identified; it is likely that there were older stone tools, but these have not yet been recognised. As our chimpansee cousins also make tools, it is likely that tool making has been with us since our most recent common ancestor, 7 million years ago, or longer. If you want to limit 'human' to only 'anatomically modern humans', that is 100.000 years ago or so, though the boundaries are a bit fuzzy.

The oldest known human artefacts are a collection of 2.6-2.5 million year old stone tools from Gona in Ethiopia. At some point we'll probably turn up something slightly older, but at this point it's unlikely to push back the date more than a few hundred thousand years. The tools from Gona therefore represent our ancestors' earliest efforts at shaping stone into useful forms. Which is not to say they didn't experiment with wood, bone or other organic materials earlier – they almost certainly did – but ephemeral artefacts like that would never survive so long.

The Gona assemblage is typical of the Oldowan – archaeologists' term for the earliest phase of stone tool technology. Humans used this same simple, rough and ready toolkit of all-purpose tools for over a million years. They took a large pebble and struck off flakes until one side had a cutting edge: a "chopper". These were used for slicing up plants, chopping wood and butchering animals. They also opportunistically used the smaller flakes produced by the reduction process for finer tasks, like scraping out animal skins or boring holes. This was the foundation for more sophisticated lithic industries; eventually our ancestors figured out how to use more controlled flaking to shape the original stone "core" into bifacial handaxes, and at the same time produce flakes with more predictable, useful forms. By the end of the Stone Age – some 2.6 million years after the tools at Gona were made – they'd mostly dispensed with the core tools altogether, and instead were producing tiny, razor-sharp flakes that could be set into sophisticated cutting tools.