Bonobos can be just as handy as chimpanzees. In fact, bonobos’ tool-using abilities look a lot like those of early humans, suggesting that observing them could teach anthropologists about how our own ancestors evolved such skills. Until now, bonobos have been more renowned for their free and easy sex lives than their abilities with tools. They have never been seen to forage using tools in the wild, although only a handful of wild populations have been studied because of political instability in the Democratic Republic of the Congo, where they live.
As for those in captivity, Itai Roffman of Haifa University in Israel and his colleagues previously observed one captive bonobo, called Kanzi, using stone tools to crack open a log and extract food. However, it was possible that Kanzi was a lone genius, raised by humans and taught sign language, as well as once being shown how to use tools.
To find out if other captive bonobos shared Kanzi’s aptitude, Roffman’s team looked to animals at a zoo in Germany and a bonobo sanctuary in Iowa. The team gave them a series of problems that required tools to solve – for example, showing the bonobos that food was buried under rocks, then leaving a tray of potential aids such as sticks and antlers nearby.
Two of eight zoo animals and four of seven in the sanctuary made use of the tools – in some cases almost immediately. The bonobos used sticks, rocks and antlers to dig, and also used long sticks as levers to move larger rocks out of the way (see video above). Some used different tools in sequence.
In another task, three of the sanctuary animals used rocks as hammers to smash long bones and expose food hidden in the marrow cavity. Another cracked them neatly open lengthwise, a technique previously thought to be unique to the human lineage.
One bonobo even sharpened a stick with her teeth to fashion a spear – something chimpanzees do to hunt bushbabies – then jabbed it at Roffman, whom she may have regarded as an intruder.
The study shows that bonobos are capable of a wide range of tool use that puts them at least on a par with chimps, says Roffman. Their foraging techniques resemble those used by the earliest Stone-Age humans of the Oldowan culture. “When you give them the raw materials, they use them in correct and context-specific strategies,” Roffman says.
However, captive bonobos, unlike their wild cousins, have plenty of time to experiment, says Francesco d’Errico of the University of Bordeaux in France.
The captive animals’ actions may bear little resemblance to what happens in the wild. Still, says d’Errico, it shows the potential is there and the skill may even come and go as needed. Roffman suspects that once researchers study bonobos in the southern part of their range, where food is harder to get, they may find that tool use is common.
If so, tool use in great apes may be older than we thought, reaching back at least 5 million years to the common ancestor of chimps, bonobos and humans.
From New Scientist Life online.