Key Points
- Chimpanzees and ancient hominins use similar methods to select tools.
- Chimps select nut-cracking tools based on their mechanical properties, not their appearance.
- Hard stones are used as hammers and softer ones as anvils. Young chimps often mimic the tool choices of older group members.
- The findings suggest shared cognitive traits between chimps and early humans.
An international research team has uncovered striking similarities between how modern chimpanzees select tools and the methods used by ancient human ancestors. Published in the Journal of Human Evolution, the study examined the decision-making process chimpanzees use to choose stones for cracking nuts and compared its findings to evidence of ancient hominin tool use.
Archaeological evidence shows that Oldowan hominins, who lived around 2.5 million years ago, were the earliest known tool users. These ancestors selected rocks with intention and precision to serve as choppers, scrapers, and cutting implements. Research suggests that tool-making knowledge may have been passed down through generations, reflecting an understanding of material properties and functionality.
Curious about whether modern chimpanzees exhibit similar behaviors, the researchers conducted a detailed study of the tool selection processes among wild chimps. Chimps crack nuts by using two tools: a hammer and an anvil. The hammer strikes a nut placed on the anvil, breaking it open. Chimps select hammers for their weight and shape, ensuring effective strikes, while anvils are chosen for their stability, resistance to damage, and ability to hold the nut securely.
Researchers provided chimpanzees with pre-measured rocks to understand these choices and evaluated factors like hardness, elasticity, rebound potential, size, weight, and shape. They observed that chimps consistently selected stones based on mechanical properties rather than visual appearance. Harder stones were preferred for hammers due to their durability, while softer stones were chosen as anvils to minimize nut displacement.
The study also revealed that young chimps often used tools previously utilized by older chimps, indicating that tool selection may be a learned behavior passed down within groups. This intergenerational transfer of knowledge mirrors the learning processes hypothesized for ancient hominins.
The researchers concluded that ancient hominins and modern chimpanzees display comparable strategies when choosing tools. This highlights shared cognitive and behavioral traits that may date back to a common ancestor.
