Brussels, 23 Feb 2006
Researchers from the Max Planck institute in Germany and Cambridge University in the UK have filmed chimpanzees (pan troglodytes) employing the most sophisticated tool use yet seen in the species.
The footage was presented at the annual meeting of the American Association for the Advancement of Science in St Louis, US, as part of a press briefing by Andrew Whiten, professor of evolutionary and developmental psychology and Wardlaw Professor of Psychology at the University of St. Andrews.
Chimpanzees share 96 per cent of their genetic make-up with humans. Tool use was initially thought to be a wholly human attribute, but several animals have been found to employ tools, including many species of bird using gravity to either drop stones onto fragile shelled food such as eggs, or drop harder objects to the ground to crack them.
New Caledonian crows were found to be adept at manufacturing, selecting and using simple tools in 2003, including sticks that could be used as a shovel to reach inaccessible food. Otters have been observed using stones to crack nuts, while chimpanzees have been found to display more complex forms of tool use.
In the late 1950s, Jane Goodall observed chimpanzees carefully stripping twigs which were then inserted into termite mounds. Termites would cling to the twig, which the chimpanzee would remove to eat the termites - evidently a delicacy. What was most surprising about this behaviour was that the chimpanzee would be quiet and focused, in sharp contrast to the animal's normal behaviour - lively and noisy.
More astounding was the discovery that chimpanzees might spy a particular twig, carefully strip it and then carry it around in anticipation or expectation of finding another termite mound, demonstrating careful planning. Researchers in the late 1970s found highly specialised tool use in Ivory Coast chimpanzees, systematically looking for the right kind of surface and stone for cracking particular kinds of nut.
Professor Whiten is examining the cultural spread of behaviour amongst primate groups, and how this may give clues to the spread of human culture. In Africa, trends observed in different chimp groups will be unique to that group. 'In far west Africa, chimps use stones and branches to crack nuts. That's really important to them. But chimps don't do that in east Africa. And even more important, in west Africa they don't do it on the east side of a major river.'
Some females were even observed climbing trees with makeshift hammers to save going up and down the tree. The problem for researchers wanting to see what the chimpanzees get up to has always been that they are frightened of humans, and will run away at the slightest sound.
The use of hidden camera techniques has proved extremely fruitful. The current study looked at a group of chimpanzees based in the Goualougo Triangle in the Nouable-Ndoki national park in Congo. 39 different tool-using behaviours have so far been identified, which are passed down through the generations.
'The chimp is using a toolkit', said Professor Whiten. The chimps first took a robust stick which they trimmed and used to dig into the termite nest. They used the stick to dig a hole some 30 cm deep, and then use a thin stick, chewed at the end, to fish for the termites inside. Other chimps can be seen awaiting their turn to fish for termites.
The observations have shown that the chimpanzees can easily learn from one another. In captivity, Professor Whiten found that once a new skill is learned, the behaviour rapidly spreads amongst the chimp population. 'To our surprise we even found evidence of conformity to local cultural norms. Chimpanzees who managed to discover the technique predominantly used by the other group later tended to return to the fold, and go along with what most members of their group preferred to do,' he said.
These complex cultural behaviours have a great deal of overlap with the way human cultures spread and develop, and show once again how much we share with our primate cousins. As Professor Whiten observes, 'Our culture didn't come out of nowhere'.