16 The Burden of Locomotion in Water: Could the Aquatic Ape Have Overcome It?
Joseph Ghesquiere and Helene Bunkens (7 pages)

SUMMARY

Special adaptations for buoyancy locomotion, and thermoregulation are typical of any aquatic mammal  A hypothetical aquatic human ancestor must have lost such qualities in later stages of our phylogeny for present-day humans are poor survivors in water. Protagonists of the Aquatic Ape Theory assume the cradle of mankind to have been located in a warm climate on an African coast. The humans least subjected to ecological pressures, and hence most resembling those ancestors would be those living nowadays in that area: black Africans. However, though their exercise capacity appears to equal that of other humans, their swimming performance is relatively poor. Their buoyancy is less, they are less streamlined and their thin subcutaneous adipose layer is less suitable for insulating the body. Of all the diverse present-day humans, black Africans seem the least well suited for an aquatic way of life.

INTRODUCTION
Buoyancy, locomotion and thermoregulation in water would be key factors of a putative aquatic ape. Of all terrestrial animals humans are amongst the poorest survivors in water. If AAT were true we must assume that we have lost our ability since that time.
It is generally accepted that we evolved in Africa, if AAT was true we'd expect to find the best swimmers were black Africans.

WADING IN WATER
Study of people in water (up to arm pits). Wading is far more expensive than walking.

SWIMMING
Black Africans appear to be less adapted to swimming than other human groups, for instance having less buoyancy.

   COUNTER-ARGUMENTS
They do make a good point about black Africans being relatively poor swimmers and, if true, it is a challenge to the AAH to explain that observation.

However their wading experiment can easily be criticised because they only tested wading at very deep depths. It would have been more efficient and quicker to swim at such depths. The point about wading is that it is most efficient at shallow depths and it is a plausible model for how bipedalism might have begun.

The African swimming problem is more difficult. I explain it like this: If the Danakil depression was the cradle of humanity and the human diaspora began when the inland see last began to dry up around 150,000 ya then the first groups to leave would probably have been the ancestors of the black African races. They would have had longest to become more adapted to hot, dry climates and terrestrial life. Assuming the molecular data is correct and that all other humans came out of Africa relatively later on - perhaps after another 70,000 years by the gradually drying inland sea then they - also submitted perhaps to a coastal exodus - would naturally be the better swimmers.