Great apes usually avoid deep water for fear of unseen predators that might be lurking there, but anecdotal evidence shows that they will go for a dip if they feel safe enough. (Agencies)
Cooper the chimpanzee and Suryia the orangutan, raised respectively in Missouri and South Carolina, have taught themselves to swim in a swimming pool.
Both the apes instinctively opted for a version of breaststroke to keep afloat, that is, they moved their limbs out sideways from their bodies, roughly parallel to the water's surface, according to a footage taken by Renato Bender at the University of the Witwatersrand in Johannesburg, South Africa.
Suryia's limbs moved mostly alternately but Cooper often kicked with both hind limbs simultaneously, more like human breaststroke, said Bender.
This behaviour is unusual because almost all other four-limbed mammals use doggy paddle, with their limbs moving vertically through the water directly beneath their body. Bender believes apes prefer breaststroke due to our tree-swinging past.
Our shoulders and those of other apes have joints that can move in all directions instead of in just one plane, like the shoulders of most other mammals. That might make breaststroke the natural choice, said Bender.
Great apes usually avoid deep water for fear of unseen predators that might be lurking there, but anecdotal evidence shows that they will go for a dip if they feel safe enough.