Swimming Apes Caught on Camera for First Time Yielding Surprising Discovery

For the first time, researchers have captured video footage of apes swimming and diving, showing that rather than the typical dog-paddle used by most terrestrial mammals, these animals opt instead for a kind of breaststroke.

Apes' aversion to deep water as well as their tendency to drown in it have both been cited as a significant difference between them and humans -- a distinction that may be absolute, the new study shows.

Led by Renato Bender, a PhD student in human evolution at the School of Anatomical Sciences at Wits University, and Nicole Bender, an evolutionary physician and epidemiologist at the University of Bern, the study included a chimpanzee and an orangutan who were raised and cared for by humans and, in the process, taught to swim and dive.

To prevent the chimp named Cooper from drowning, the researchers stretched two ropes over the deepest part of the pool and watched as he comfortably dove into the water, picking up objects on the bottom of the pool.

Just a few weeks later, Cooper began swimming on the surface of the water.

Meanwhile, the orangutan Suryia, located at a private zoo in South Carolina, is capable of swimming up to 12 meters.

What the researchers found in observing both is that while each used a leg movement similar to the "frog kick," Cooper moved his hind legs in a synchronous manner, Suryia moved them alternatively.

Still, this swimming style, scientist hypothesize, is born out of something innate and represents the result of an ancient adaptation to life among the trees.

For most mammals, swimming is instinctive. For apes and humans, however, it's a behavior that must be taught. And since the apes' tree-dwelling ancestors spent less time moving across the ground, it's likely they developed alternative strategies for crossing rivers, wading in an upright position, and ultimately losing their instinct for swimming.

Humans, on the other hand, while also not instinctive swimmers, are attracted to water.

"The behavior of the great apes in water has been largely neglected in anthropology," Nicole Bender said. "That's one of the reasons why swimming in apes was never before scientifically described, although these animals have otherwise been studied very thoroughly."

And while Cooper and Suryia are the only ones the researchers were able to capture on film, the scientists said there are many other well-documented cases of apes who both swim and dive.

However, much remains a mystery.

"We still do not know when the ancestors of humans began to swim and dive regularly," she explained.