Science

While Certain Primates Avoid the Water, A Chimp and An Orangutan Swim Against the Current

If apes could talk, they might tell you about their fear of water. Of course spoken language is one of the things that separate humans from their closest living relatives. And until recently, swimming and diving was thought to be another one of those defining characteristics. But last month, a couple (literally) of researchers countered claims that apes are physically incapable of swimming by providing the first rigorously documented account of deliberate swimming in two different hominoid species.

Renato Bender, a doctoral candidate at Wits University in South Africa, and his wife, Nicole Bender, published their findings online in the American Journal of Physical Anthropology on July 30.

Their investigation began when Renato Bender was preparing to study how humans and apes interact with water, Nicole Bender told National Geographic. “When we did a literature search, we didn’t find anything. So we started to ask around to other people and what they knew,” she said.

Those conversations led the Benders to a seven-year-old male orangutan named Suryia, who resides at The Institute of Greatly Endangered and Rare Species in Myrtle Beach, S.C. When they came to observe Suryia in August 2010, he was already a seasoned swimmer. He had been exposed to water from an early age, taking daily baths at seven months and getting regular swimming and diving lessons at three years, according to the Benders’ research report.

Suryia’s owners told the Benders about another ape who also had this unusual desire to be in the water. His name is Cooper, a chimpanzee, and he was raised by humans in Malden, Mo. Like Suryia, Cooper’s relationship with water began in the bathtub. At four years old, he started dunking his head under the water, first in the tub and later in a swimming pool.

And so the Benders had their research subjects. Interestingly, these two apes were both born in 2003 and were similar in size at the time of observation, Suryia at just over 83 pounds and Cooper at about 79 pounds.

They observed Suryia and Cooper on separate occasions. Renato Bender took pictures and video in the water and Nicole Bender filmed from the edge of the pool. What they saw was shocking. Most mammals can swim instinctively by initiating a doggy-paddle stroke. These apes, however, displayed limb movements akin to the human breaststroke. Both swam from the shallow end to the deep end of the pool. Cooper liked to dive down and retrieve objects from the bottom of the pool, holding his breath for as long as 15 seconds.

This peculiar swimming behavior raised some interesting questions, which the scientists addressed in their paper. Why do these apes swim more like humans than most other mammals? For millions of years, apes were primarily forest dwellers (many still are, while some, like chimpanzees and humans, have ventured out onto open plains). When you spend most of your days swinging from trees, you lose what the Benders call the “fixed rhythmic action patterns” associated with moving around on four limbs on solid ground. This is also associated with the innate, doggy-paddle, running-through-water swimming that many mammals are capable of.

The researchers predict that throughout hominoid evolution, apes became increasingly poor swimmers and avoided bodies of water. In the process, they may have developed “non-swimming strategies” when their environment forced them to interact with water.

The researchers suggest their observations will pave the way for future studies of apes’ interaction with water, an understudied field in anthropology with a history of sloppy science. They are currently working on a forthcoming paper about swimming behavior in four chimpanzees and an orangutan, according to their website.

“This issue is becoming more and more the focus of research. There is still much to explore,” Renato Bender said in a statement.

(Video courtesy of Myrtle Beach Safari)

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