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Apes ‘ape’ more rationally than humans

When we describe someone ‘aping’ someone else, it implies they are mindlessly copying them. This does apes a disservice, according to a recent study by scientists from the University of St Andrews. In fact, it’s the young members of our own species who are more likely to ‘ape’ their elders without too much thought.

The study, published online in the science journal Animal Cognition by Dr Victoria Horner and Professor Andrew Whiten, was conducted in the Ngamba Island Chimpanzee Sanctuary, Uganda. The team then conducted a similar study with pre-school children, for comparison.

The Sanctuary occupies a 100-acre island in Lake Victoria and is home to dozens of young chimpanzees, orphaned mainly because their mothers were victims of the current popularity of ‘bushmeat’ in Africa.

A series of studies conducted on Ngamba by St Andrews primatologists in recent years, supported by the Biotechnology and Biological Sciences Research Council (BBSRC) is seen as one way of helping stimulate their minds, substituting for the challenges of life in the wild.

In the new study, the young chimps were divided into two groups. Each individual chimp then took part in a behavioural experiment in which Dr Horner, a familiar play partner for them, used a stick to retrieve a food morsel from an artificial mound. This idea was modelled on wild chimpanzees’ predilection for fishing from termite mounds in this way. In this case, the ‘mound’ was an opaque box with covered holes in the top and in one side. Dr Horner, acting in the role of the youngster’s mother, used the stick to remove a cover over the top hole, then stabbed the stick into it firmly several times. The cover on the lower hole was then removed and the stick was probed into this to retrieve a food morsel. The mound was then baited with food again and the chimp got its turn.

What would you do, if you were the chimp? The scientists predicted you would do something different than if you were in the other group, who saw a demonstration with a box that was identical except for being totally transparent, apart from the tunnel holding the food reward. In this case, when the stick was stabbed in the top hole, the observer could see that all it did was to ineffectually batter against a false ceiling above the food tunnel. Horner and Whiten thought that in this case any ‘rational imitator’ would omit the stabbing in the top of the box. By contrast, when the box is opaque, not being able to see the stabbing action is irrelevant might lead an observer to copy the whole routine, just to be safe.

What Horner and Whiten found was that the young chimpanzees did indeed act in this more intelligent way. They were significantly more likely to omit the top, stabbing action if they were in the group that saw the actions done with the ‘giveaway’ transparent box.

“This tells us several important things about how the chimpanzee mind is working in this kind of social learning situation, which is probably very important to youngsters observing their mothers using tools in the wild” says Dr Horner. “Most importantly, it suggests that apes like these do not merely ape in a mindless way, but rather more rationally, imitating selectively on the basis of a certain level of understanding of which events can and can’t plausibly cause others. That’s quite sophisticated”.

What surprised the researchers a little more was how young, pre- school children responded to the same experiences. In contrast to the chimpanzees, they typically copied all the actions, including the irrelevant ones performed on the transparent box. “They were not just doing this to please me” say Horner, “because they would do this even if I left the room and they thought they were not being watched”.

Whiten says they suspect this is simply underlining what an intensely cultural species we are. “The chimpanzees are demonstrating an adaptive ability to pick up aspects of ape-level material culture like simple tool use, but children need to acquire culture on a vastly greater scale. It looks as if, at the age of 3 to 4 years old in particular, they operate a kind of rule of thumb, that if an adult is doing something that has a useful outcome, then it’s a good idea to copy all they do, even if some of it doesn’t, on the face of it, make too much sense. Chimpanzees, at least in the kind of task we set them, may be more discriminating!”

But he also suggested there could be an explanation that saves humans’ self-respect – “One alternative is that the children are actually more tuned into the psychology of the individual they are watching and assume that someone repeating an action like this really intends it, so it’s worth copying”.

The team is now following this up with more detailed studies with young children, supported by a grant from the Economic and Social Sciences Research Council (ESRC). ENDS

NOTE TO EDITORS

Dr Victoria Horner available for interview – (in USA, 5 hr time difference) – email vhorner@rmy.emory.edu or telephone 001-404-727-9071/001-770-414-6002.

Issued by Beattie Media On behalf of the University of St Andrews For more information, please contact Claire Grainger, Press Officer – 01334 462530, 07730 415 015 or cg24@st-andrews.ac.uk; Ref: press releases/apesape View the latest University news at http://www.st-andrews.ac.uk

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