Conventional wisdom that apes shy away from water has been challenged by two Swiss researchers who have made the first-ever video recordings of a chimpanzee and an orangutan swimming and diving in a swimming pool.This content was published on August 16, 2013 - 15:02
Not only do they swim, but the apes use a kind of breast stroke to do so, rather than the dog paddle favoured by other terrestrial mammals.
Normally, apes drown if they get into deep water – which is why zoos use ditches to confine them. But Cooper the chimpanzee and Suryia the orangutan were raised by humans in the United States and had learned to both swim and dive.
“We were astounded when Cooper the chimpanzee kept diving under the water in a swimming pool in Missouri, and seemed to be enjoying it,“ said Nicole Bender, an evolutionary physician and epidemiologist at the Institute of Social and Preventive Medicine at the University of Bern.
He started by diving to retrieve objects from the bottom of a pool two metres deep, after the researchers had stretched two ropes over the deepest part of the pool to ensure he did not drown. A few weeks later, he started to swim on the surface.
Suriya was able to swim freely for a distance of up to 12 metres.
Most mammals can swim instinctively, but both apes and humans have to learn the skill. However humans, unlike apes, are attracted to water.
Nicole Bender and her co-researcher Renato Bender, who is working on a PhD in human evolution at the School of Anatomical Sciences at Wits University in South Africa, surmise that the swimming style used by the apes could be an adaptation to life in trees.
“The tree-dwelling ancestors of apes had less opportunity to move on the ground. They thus developed alternative strategies to cross small rivers, wading in an upright position or using natural bridges,” said a media release issued by Wits University.
Cases of swimming and diving apes had already been documented, but they had never been filmed before.
The research is published in the current edition of the “American Journal of Physical Anthropology”.
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