For many years, zoos have used water moats to confine chimpanzees, gorillas and orangutans. When apes ventured into deep water, they often drowned. Some argued that this indicated a definitive difference between humans and apes: people enjoy the water and are able to learn to swim, while apes prefer to stay on dry land.

But it turned out that this distinction is not absolute. Renato Bender, who was working on a PhD in human evolution at the School of Anatomical Sciences at the University of the Witwatersrand (Wits University), and Nicole Bender, who worked as an evolutionary physician and epidemiologist at the Institute of Social and Preventive Medicine at the University of Bern, have studied a chimpanzee and an orangutan in the US. These primates were raised and cared for by humans and have learnt to swim and to dive. Their findings have been published online on 30 July 2013, in The American Journal of Physical Anthropology.

Perhaps this ability to learn to like water and learn to swim, requires zoos to reconsider the common approach to confine these Great Apes in outdoor enclosures by water-filled moats. Although, until now gorillas in zoos broke out of their enclosure by jumping the surrounding - apparently too small - water-filled moats, but swimming across the moat to escape has not been documented yet. The researchers were extremely surprised when the chimp Cooper dived repeatedly into a swimming pool in Missouri and seemed to feel very comfortable. To prevent the chimp from drowning, the researchers stretched two ropes over the deepest part of the pool. Cooper became immediately interested in the ropes and, after a few minutes, he started diving into the two-meter-deep water to pick up objects on the bottom of the pool. Some weeks later, Cooper began to swim on the surface of the water.

Watch Cooper the chimp repeatedly made full submersions in deep water holding on to one or two ropes, often trying to grasp with one foot or one hand objects placed 2 m deep on the floor of the pool. He also is covering his eyes during the dives.

(Source: Wits University media release, 14.08.2013)