A recent study shed new light on the evolution of tool use, revealing striking similarities between modern chimpanzees and ancient human ancestors in their selection of stone tools. The results of the study were published in the journal Nature Human Behavior.
Researchers observed chimpanzees in the forests of Bossou, Guinea, noting that these primates use two tools to crack nuts: a hammer and an anvil, as reported by Phys.org. The hammer is held in the hand and brought down heavily onto a nut sitting atop the anvil, according to Scientias.
The chimpanzees prefer harder stones for hammers and softer stones for anvils, optimizing their efficiency in cracking hard-shelled nuts, reported Scientias. Harder stones require fewer strikes to crack a nut, enhancing the effectiveness of the chimpanzees' tool use, according to Phys.org.
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. This behavior reveals an intuitive understanding of material properties, even when they are not visible to the naked eye, according to SciencePost.
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, according to SciencePost.
Oldowan hominins were intentional in their selection of rocks for tool-making, reflecting an understanding of specific material properties, such as hardness and fracture resistance, as reported by Phys.org. These hominins used stones as choppers, scrapers, hand axes, and simple cutting implements, marking a key milestone in the technological history of hominids.
The oldest known use of stone tools dates back to about 2.5 million years ago, during which Oldowan hominins used stones as tools, while the earliest stone tools, known as Lomekwian tools, date back about 3.3 million years, well before the appearance of the genus Homo, according to SciencePost.
The study also showed that young chimpanzees learn by observing adults. Younger chimpanzees used the tools that had been used earlier by older chimpanzees, suggesting the possibility of learning and transmission of tool selection. This transfer of knowledge underscores the importance of social learning in primate culture.
"The ability to flexibly organize individual actions into sequences of tool use was likely key to the global success of humans," said Elliot Howard-Spink, the lead researcher from the Max Planck Institute for Animal Behavior, according to Correio Braziliense. "Our results suggest that fundamental aspects of human sequential behaviors may have evolved before the last common ancestor of humans and chimpanzees, and then may have been elaborated during the subsequent evolution of hominins," Howard-Spink stated, according to Correio Braziliense.
The researchers recorded the sequences of actions the primates performed, totaling about 8,260 acts for more than 300 fruits. Most chimpanzees organize actions in sequence, like humans do, revealing not only intelligence but also cultural innovation among chimpanzees.
The discovery raises an intriguing question: Were the cognitive mechanisms involved in tool selection fundamentally different between ancient hominids and non-human primates? Chimpanzees show that relatively simple processes, like individual and social learning, are sufficient to develop effective technology.
This article was written in collaboration with generative AI company Alchemiq