From Scientific American:
Occasionally in science there are theories that refuse to die despite the overwhelming evidence against them. The “aquatic ape hypothesis” is one of these, now championed by Sir David Attenborough in his recent BBC Radio 4 series The Waterside Ape.
The hypothesis suggests that everything from walking upright to our lack of hair, from holding our breath to eating shellfish could be because an aquatic phase in our ancestry. Since the theory was first suggested more than 55 years ago, huge advances have been made in the study of human evolution and our story is much more interesting and complicated than suggested by the catch-all aquatic ape hypothesis.
In 1960, marine biologist Alister Hardy published an article in New Scientist, titled: Was man more aquatic in the past? He re-told the familiar tale of the evolution of land animals from ancient fish, and then considered the return of various groups of reptiles, birds and mammals to an aquatic existence: ichthyosaurs and plesiosaurs, crocodiles, sea-snakes, penguins, whales, dolphins and porpoises, manatees and dugongs, and seals—as well as polar bears, otters and water voles, who hunt in water. Then he suggested that many of the unique characteristics of humans and their ancestors, marking them out as different from the other apes, could be explained as adaptations to spending time in water.
Hardy put forward all sorts of features which could be explained as “aquatic adaptations”: our swimming ability—and our enjoyment of it; loss of body hair, as well as an arrangement of body hair that he supposed may have reduced resistance in the water; curvy bodies; and the layer of fat under our skin. He even suggested that our ability to walk upright may have developed through wading, with the water helping to support body weight.
For Hardy, this aquatic phase would have occupied the …