Bonobos were able to communicate complex messages and use tools

said Itai Roffman from the University of Haifa who participated in the study of these great apes as part of his doctoral thesis.

For the first time, two bonobo chimpanzees have shown the ability to make and use stone tools in a sophisticated way, similar to the way primitive man used stone tools about 2.6 million years ago - according to a new study by the university, in collaboration with researchers from the USA*, published in the prestigious journal PNAS. "This is the first time that someone other than humans has reached such a technological level," said Itai Roffman, whose current research is part of his doctoral thesis. Watch the interview with Roffman on the academic channel.

Today, the cultural diversity of chimpanzees living in the wild is already recognized in science, for example - which ones pick with sharp sticks, crack nuts with hammer stones and anvil, and dig with wooden tools to obtain water and tubers. In his doctoral thesis, under the guidance of Prof. Avitar Nebo and Prof. Avraham Ronan, Roffman, an evolutionary anthropologist, tries to examine whether chimpanzees are able to show traits similar to those of the first primitive human species.

In the current experiment, the researchers worked with Kanzi and Pan-Benisha, two famous bonobos, who grew up around humans and learned to communicate with them in computerized sign language and English, at such a level that they were conversational and used sentences of 3-4 words.

In 1991 they were taught to make and use a simple flint tool, with which they cut a rope or a piece of leather to open an artificial box that contained food. Now Roffman presented them with new challenges that simulate natural situations, requiring the application of survival strategies used by our ancestors. In this experiment, food was placed in a small chamber dug in the center of a log, which was cut along its length and then glued, and the chimpanzees were asked to develop ways to obtain the food, when in the field where they were, various types of stones, deer antlers and branched branches were placed. According to Roffman, this challenge was like extracting the breast from a large animal bone. Likewise, the chimpanzees were asked to reach for food that was hidden deep in rocky soil, similar to the situation in nature.

In the first phase, the two bonobos made their stone tools, with their preferred raw material being flint. While holding two flint stones in their hands, they strongly hit stone with stone and created two types of tools according to the task before them. Kenzi showed the most impressive abilities in making tools for "heavy work" and tools for "light work" - tools like an ax and a wedge or tools like a drill and a carver, respectively. "These two types of stone tools are parallel in their shape and use to the two types of tools described for the first primitive man. In the task in which he had to crack the log, in order to reach the 'demon', he first threw it on stones, and then began to work on it with the help of the 'heavy' and 'light' tools while using them correctly along the glued groove of the log, in order to weaken and open it. For example, in the 'axe' he struck vigorous blows along the groove and in the 'drill' he used rotary movements while pressing on the groove of the log," noted Roffman. Also in the second task, the two chimpanzees adapted the work tools to the terrain conditions: they used their hands to dig in soft soil, branches to dig in muddy soil and their stone tools to dig in hard soil.

In these attempts, Kanzi and Pan-Benisha demonstrated high technological abilities, such that in fact only the primitive man has displayed until now. When Ruffman compared the marks of the grooves on the logs to the marks found on the fossilized bones of the beech from 2.6 million years ago - which the ancient man made when he wanted to get to the skeleton - he saw that they were almost completely identical.

Early man's ability to use stone tools for various purposes is considered the most important cognitive breakthrough in his technological development. The current findings indicate that this ability probably already existed in the last common ancestor of early humans and chimpanzees. "These findings may shed additional light on the evolutionary development of the primitive man," Roffman added, "and I assume that among these chimpanzee-bonobo family, who grew up alongside the human family - if they continue on this path - we will be able to see a continuation of impressive cognitive development in the future."

Roffman plans in the next two months to set up an expedition to study chimpanzees living in northwest Africa in a semi-arid environment in a rocky habitat similar in characteristics to that of the great African rift, where the various early human species split. In this resource-poor area, chimpanzees must employ survival and adaptation strategies to obtain water, food, and shelter. The findings of the current study support their potential both from being a sibling species to the primitive human family, and from their very existence there in extreme conditions, which should bring this potential to light. "It is very interesting to study these chimpanzees, who have lived for hundreds of years in close proximity and peace with native tribes, and maintain a human-chimpanzee interaction that is important to document in the wild," Roffman concluded.

*Prof. Sue Savage-Rumba and Ms. Elizabeth Robert-Pugh, of the Bonobo Chimpanzee Sanctuary in Des Moines, Iowa

**Doctoral student at the Authority for Advanced Studies and the International Center for Advanced Studies in Evolution, at the University of Haifa. Roffman is an Adams Fellow, on behalf of the Israel National Academy of Sciences.