Chimps 'pass on cultural traditions'

WILD CHIMPANZEES have a rich cultural tradition on a par with human societies, according to one of the most detailed investigations of ape behaviour. A combined evaluation of seven long-term field studies has found that chimpanzees pass on dozens of traditions to each other in an intricate display of cultural inheritance.

The research draws on the accumulated knowledge of 151 years of chimpanzee observations in the forests of central Africa and is the first to demonstrate such a vast array of traditions in a species other than mankind.

Although several examples of chimpanzee behaviour, such as drumming on trees, were shared by all groups of chimps in the study, the researchers identified 39 aspects of behaviours that had evolved separately and were passed on through the generations by teaching.

The scientists discounted the possibility that the cultural traits were genetically determined or moulded by the chimps' particular habitat, which could have explained why only certain chimps have learnt a particular behaviour.

A separate study found that chimpanzees were able to match the face of a male chimpanzee they had never met to his mother - although they could not match daughters to mothers, indicating the importance of knowing the status of male members of a troupe.

Andrew Whiten, professor of evolutionary and developmental psychology from the Scottish Primate Research Group at the University of St Andrews, said the research breaks new ground in showing the complex nature of chimpanzee behaviour. "It's giving us a big picture that hasn't been done before. What's significant is that humans and chimps have been around for millions of years yet until 40 years ago we had little knowledge of chimp behaviour," Professor Whiten said.

The latest research, published in the journal Nature, uses as an example the two ways in which wild chimpanzees "fish" for ants, using a branch stripped of its leaves. The chimps of the Gombe national park in Tanzania, observed by the renowned zoologist Jane Goodall, use a long branch to collect the ants and swipe them into a ball of food with a hand.

Chimps at other sites use shorter twigs and pick off the ants with their lips, a far less efficient method. "It seems the chimps of the Gombe have invented a smarter technique which they have passed on to each other," Professor Whiten said.

Another culturally inherited trait was nut-cracking, using stones or pieces of wood, which was common among a western group of chimps belonging to the verus subspecies. However, nut-cracking was not present in the eastern population of a group of the same subspecies that was separated from the western group by a wide river. "The fact that this behaviour terminates abruptly at the Sassandra-N'Zo river within the range of the verus subspecies shows that it is culturally, rather than genetically, transmitted," the researchers said.

Frans de Waal, a primatologist at the Yerkes Primate Research Center in Atlanta, Georgia, said the latest findings emphasise how chimpanzees keep inching closer to humanity. "The record is so impressive that it will be hard to keep these apes out of the cultural domain without once again moving the goalposts," he writes in Nature. "Biologically speaking humans have never been alone."

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