The Acheulean handaxe takes its name from Saint-Acheul, the town in France where it was first documented in the 19th century. It is a bifacial flaked tool, usually almond- or teardrop-shaped, with deliberate symmetry. Its difference from the Oldowan is not just craftsmanship but idea: the Oldowan aimed only at a sharp edge; in the Acheulean, the maker held the finished axe in mind and shaped the stone to fit that mental image.

Holding such a mental image is a major cognitive step. The maker turns the stone, plans how much to flake from each face, maintains symmetry. Modern experiments show that a good Acheulean handaxe takes years of practice to produce; the knowledge was likely transmitted across generations through teaching. This is one of the earliest signs of abstract communication — perhaps proto-language.

Acheulean tools first appeared roughly 1.7 million years ago in East Africa and spread over the next 1.5 million years to Europe, the Near East, India, and China. Homo erectus, and later Homo heidelbergensis, made them. Their functions: cutting meat, processing hides, working wood, digging. Sizes range from palm-sized to massive 30 cm pieces; some Acheulean axes were probably not made for practical use but for display or ritual — meaning that even at this early stage, technology served meaning, not only function.

The Acheulean dominated as the basic stone-tool type for nearly 1.5 million years, before giving way to the more varied and lighter Mousterian tools of the Neanderthals. No other technology in human history has remained stable for so long.