As humans became more intelligent, their tools become more symmetrical. “They became standardized as a result of social norms and also utility. Eventually, over time, hand axes were made special to set them apart,” Lam said. “There was a trend to distinguish these common tools that had a standard shape.”
Examples of hand axes from about 250,000 to 700,000 years ago contain some of these special properties, such as being made of pink rock or rock embedded with fossils. Ancient humans also made large axes that stood out from the crowd.
Story: Jennifer Welsh, LiveScience | Photo: Pierre-Jean Texier, National Center of Scientific Research, France