Chimpanzees Are Behaving As Humans Did During Key Point of Evolution

A study of modern chimpanzees has uncovered behaviors that closely resemble those of our ancient human ancestors, providing insight into how our forebears may have used tools.

shows that the method used by a group of chimpanzees to pick stones for use as tools appears to be similar to the techniques recorded for Oldowan human ancestors.

This term refers to our early human ancestors that are linked to the Oldowan stone tool industry.

These Oldowan tools, dated to between 2.9/2.6 million and 1.7 million years ago, are among the first tools used by early hominins. In fact, there is evidence suggesting that tool use may have begun even earlier, more than 3 million years ago. However, the origins of this technology are still a topic of great debate.

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New studies suggest that using tools may be an ingrained trait among the primates that include gorillas, chimpanzees, orangutans, gibbons, bonobos, and humans. It is not especially surprising given the many examples we see today in the animal kingdom of using tools to adapt to one's surroundings, particularly among primates.

Humans and our closest relatives, chimpanzees, share the use of tools. Research suggests that chimps can consider factors like size and weight when choosing rocks to use as the right tools for a particular job.

This brings to mind studies of the Oldowan technology, which show that ancient human ancestors chose specific types of rocks for making tools based on their unique characteristics, such as their ability to break apart and withstand wear.

In a recent study, researchers aimed to analyze the patterns of stone tool choice for cracking nuts by wild chimpanzees in Bossou, Guinea—a West African country. This group of chimps is notable for their diverse tool-using behaviors, especially their unique use of movable rocks as hammers and anvils to crack open oil palm nuts.

"We've been fascinated by the origins of technology for many years, and I, along with study author Susana Carvalho, have been able to demonstrate that people over two million years ago were able to recognize the differences in various types of rock and select specific types of rock. But we've been puzzled as to how they were able to accomplish this," Braun said.

We wanted to study how they make decisions. Since we're aware that chimpanzees appear to understand rock properties, we were curious to see if their choices would be based on rocks they'd never encountered before.

To accomplish this, the team gathered rocks from western Kenya, where a diverse assortment of stones is readily available, and then transported them to Guinea and then out to the forest.

"We had already conducted thorough mechanical tests on these stones, which had given us a clear understanding of their distinct characteristics. Additionally, we were aware that some of them appeared similar in appearance, despite their varying mechanical properties," Braun stated.

The researchers arranged the stones randomly and waited to see which ones the chimpanzees would pick. Over a period of six weeks, the research team observed the chimps cracking nuts, noting each time they picked a stone and how frequently they used different ones.

We tracked how often they used specific rocks in comparison to how often those rocks were available. We began by analyzing the use of two rock types that are quite different, then gradually added more rocks to see if the chimpanzees could pick out subtler distinctions.

One of the major discoveries was that the chimps were able to identify certain qualities of the stones and use them for particular purposes. For instance, they used softer stones as anvils because if they used harder rocks, the nuts would slide off the anvils. Conversely, they used harder stones as hammers because this allowed them to crack nuts more effectively.

It became apparent that over the course of six weeks, the chimps had successfully determined the most effective rocks to use for each of the tasks involved in cracking open nuts.

"They would sometimes figure it out through trial and error, or sometimes they would identify a technique by looking at tools that other chimpanzees had already been using," Braun said.

The patterns of selection that the chimpanzees exhibited are very similar to those that scholars have observed in the archaeological record from early humans dating back more than 2 million years.

He believes that early humans may have also used trial and error to figure out which stones were most effective.

What would happen if early humans shared information about tools? If they combined knowledge from individual group members, they could quickly identify and use the most effective tools for specific tasks. Essentially, not every early human needed to comprehend the mechanical properties of tools themselves; just a few individuals could learn and share this knowledge, allowing the rest to determine the best options.

One of the truly human strengths is the ability to learn from others. It seems that chimpanzees also learn the essential details of using tools from one another, which might imply that some of the fundamental capabilities for using tools are also shared by our closest living relatives, the chimpanzees," he said.

The findings suggest that tools' use and learning from others' tool use may be characteristics of many types of primate groups.

People often think that tools set us apart from other animals, but the truth is, using tools and learning from others about how to use them is a common trait shared by many primates, including ourselves.

Do you have a question about human evolution? Let us know by sending an email to science@.

Reference

https://doi.org/10.1016/j.jhevol.2024.103625

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