Johannesburg - Two researchers have provided video proof that certain apes can swim, the University of the Witwatersrand said on Wednesday.
“For many years, zoos have used water moats to confine chimpanzees, gorillas or orangutans. When apes ventured into deep water, they often drowned,” it said in a statement.
“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.”
It said the apes used a kind of breaststroke, as opposed to the dog-paddle most terrestrial mammals used.
Renato Bender, who is working on a PhD in human evolution at the university, and Nicole Bender, who works at the Institute of Social and Preventive Medicine at the University of Bern, Switzerland, as an evolutionary physician and epidemiologist, provided the video.
It was based on their study of a chimpanzee and an orangutan in the United States. The primates were raised and cared for by humans and had learned to swim and dive.
“We were extremely surprised when the chimp Cooper dived repeatedly into a swimming pool in Missouri and seemed to feel very comfortable,” said Bender.
“It was very surprising behaviour for an animal that is thought to be very afraid of water.”
Several weeks later, Cooper began to swim. The orangutan Suryia, who was filmed in a private zoo in South Carolina, can swim freely up to 12 metres.
“The behaviour of the great apes in water has been largely neglected in anthropology. That's one of the reasons why swimming in apes was never before scientifically described, although these animals have otherwise been studied very thoroughly,” Nicole said.
“We did find other well-documented cases of swimming and diving apes, but Cooper and Suryia are the only ones we were able to film. We still do not know when the ancestors of humans began to swim and dive regularly.”
Most mammals use the dog-paddle instinctively. Humans and apes, on the other hand, must learn to swim.
The university said 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. They lost the instinct to swim,” it said.
“Humans, who are closely related to the apes, also do not swim instinctively. But unlike apes, humans are attracted to water and can learn to swim and to dive.” - Sapa