Niemitz: "The evolution of the upright posture and gait—a review and a new synthesis" (2010)

The German biologist Carsten Niemitz has argued for a number of years that early hominids evolved their ability to walk on two legs not in order to walk on land, but to wade in shallow water. This paper reiterates this claim and collects a number of interesting observations in favor of it.

Nietmitz himself calls his hypothesis the "Amphibische Generalistentheorie" (p. 250). He explicitly contrasts it with Elaine Morgan's "Aquatic Ape Hypothesis" (pp. 249-50) which, admittedly, sometimes has been a little vague on whether it hypothesized a swimming ancestor of Homo Sapiens, or a wading one (i.e., a metaphorical dolphin, or a metaphorical hippopotamus?).

There are especially two aspects of his paper that I found quite striking. The first is his very nice collection of observations of wading among apes. (For further illustration, see also the footage on  YouTube of bonobos walking on two legs in water.) The other is the interesting observation that human beings seem to be insulated in a quite different way from apes, with much less body heat escaping through the fat on the thighs.