A recent study reveals striking similarities between modern chimpanzees and ancient human ancestors in their selection of stone tools. Researchers observed chimpanzees in the forests of Bossou, Guinea, noting that these primates use two tools to crack nuts: a hammer and an anvil. The chimpanzees prefer harder stones for hammers and softer stones for anvils, optimizing their efficiency in cracking hard-shelled nuts. By closely watching how chimpanzees chose rocks as their tools and how well the tools they chose worked as intended, researchers found that the chimpanzees chose their rocks based on their mechanical properties rather than how they looked. The researchers contend that the results of their observations suggest that ancient hominins and modern chimpanzees share some similar techniques when choosing stones for use as tools.