July 2, 2009

Chimpanzees Construct Tool After Video Demonstration

According to a recent study, chimpanzees are capable of building their own tools after watching demonstration videos.

The report, which appears in the Royal Society journal Proceedings B, says the animals were shown footage of a trained chimp constructing a tool with two components for a food reward.

When the chimps were given the same components after viewing the footage, they could build the tool and use it to obtain a treat.

According to the researchers, this demonstrates how powerful social learning is in primates.

"With video, we can control exactly how much information the animals see, so we can understand exactly how much information they need to work out how to do the task," said Dr. Elizabeth Price, of the University of St Andrews in Scotland, and lead researcher in the study.

Dr. Price and her team put the animals into five groups for testing.

One group was shown the entire demonstration video, which showed the chimp constructing a tool from a rod and tube.  Then the chimp used this tool to retrieve a grape that was outside of its cage.

Each of the other groups was shown progressively less of the video.  The final group was only shown the chimp eating the grape.

Researchers then setup the scenario for the test subjects.

"Those chimps that saw the full demonstration learned better how to construct the necessary tool (to reach the food)," Dr. Price told BBC News.

"The fact that they can learn how to build a better tool for a particular task is very exciting. This type of behavior is very rare in the wild, and it's an essential part of human tool use."

According to Dr. Price, a number of the chimps who did not view the entire demonstration were also able to construct the tool on their own.

"What was interesting about this group was that, when we presented them with the grape at different distances from the cage, they made the appropriate tool to reach it," Dr. Price said.

This group was also capable of switching between the unmodified tube and rod, or the constructed tool, depending upon how far away the grape was.  The animals didn't just copy the demonstration.

"Those that had been shown the full demonstration, and had socially learned to make the longer tool, continued to make it even when the grape was so close that it was more awkward to use," said Dr Price.

"It could be that social learning is such a strong force for the chimps that they apply a blanket rule of 'go with what you've seen' (rather than work out what's most appropriate for the task)."

The researchers are now planning to test young children with the same methods to see how much they rely on social learning.

The scientists are still unsure why tool-building is not seen more commonly in the wild.

"We've shown that they're clever enough, so there must be something else at play," said Dr Price.

"It may be that when chimpanzees reach an age at which they are... capable of performing these higher level techniques, they may be too old to have access to sufficiently tolerant demonstrators."


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