Experienced stone tool makers cannot figure out how a prehistoric tool was made just by looking at the finished product.

Prehistoric technology required direct social teaching because reverse-engineering a complex stone tool is almost impossible from the object alone. Anthropologists used to think that early humans could simply find a clever tool and copy it through trial and error. Experiments with modern knappers show that without being shown the specific technique, even experts fail to reproduce new designs. This means the spread of technology in the Palaeolithic era depended on deep social bonds and intentional instruction. Ancient innovation was a social achievement rather than just a series of individual inventions.