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Friday, August 30, 2013

Can apes swim?

It is often assumed that, apart from humans, great apes cannot swim. Many zoos use moats to contain captive chimpanzees and other primates, and it generally works well. It is true that chimpanzees tend to have very low buoyancy (that is, they sink), making drowning a grave risk for them. And indeed, even humans generally require some amount of instruction before they can fend off the dangers of drowning. But is it universally true that apes cannot swim? Renato Bender and Nicole Bender of the University of Witwatersrand, South Africa say no. 

Cooper, a male chimpanzee and Suryia, a male orangutan, were both raised in a human environment where they were exposed to swimming pools. You can see footage of the swimming primates below.

A couple of things about this. Suryia was specifically trained to swim, and both animals were given many opportunities to become used to deep water. Ropes strung across the deep end of a pool gave Cooper a safe way to full submerge himself without risking drowning. Finally, it’s only a sample size of two. In other words, these behaviors probably don’t say much if anything about inherent or wild primate behaviors or abilities.

That said Cooper and Suryia do both seem quite comfortable in the water, indicating that there’s no reason wild primates should necessarily have an aversion to deep water. Clearly, they can learn to compensate for low buoyancy by purposeful swimming. Perhaps this is something that zoo keepers should consider in the future.

A. Suryia swimming, view from above. The most characteristic elements are the high range of limb movements, especially from the hind limbs, and the lateral component of hind and front limbs. 
B. Suryia swimming, view from the side. The action of the hands and feet during the stroke is shown. Suryia keeps his eyes open under water. 

Bender R, & Bender N (2013). Brief communication: Swimming and diving behavior in apes (Pan troglodytes and Pongo pygmaeus): First documented report. American journal of physical anthropology PMID: 23900964.

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