The aquatic ape hypothesis (or aquatic ape theory as it is frequently called) holds that some hominid ancestors of humans spent a significant time in a semi-aquatic setting, living on the African seacoast and gathering most of their food from the seashore and shallow offshore waters, before returning to a more land-based existence.
This is a minority position not widely held in biology. The conventional view of human evolution is that humans evolved on the savannas of Africa.
The theory was originally suggested by Alister Hardy. Elaine Morgan studied and promoted it, producing books on the subject including The Aquatic Ape and The Scars of Evolution.
Here follows a list of aquatic ape arguments and counter-arguments from savannah theorists:
- Nakedness: Of the hundreds of primate species, humans are the only species in which hair does not cover almost the entire body. The only environments known to give rise to naked mammals are aquatic and subterranean. Other naked mammals are totally subterranean (naked mole rat), swim (whale, dolphin, walrus and manatee), wallow (hippopotamus, pig and tapir) or seek mud and water regularly (rhinoceros and elephant).
- Sceptics counter that human hair is drastically different from all of the other species. They also find the comparison to truly aquatic mammals (cetaceans, sirenians, etc.) to be highly flawed, as these animals have evolved characteristics over a far longer period than humans. Also, humans sweat more per unit surface area than any other mammal, making them particularly effective at remaining active during the heat of the day. A layer of fur would reduce the effectiveness of this; human sweat may be seen as an analogue of the water-seeking behaviors of the animals mentioned.
- Sceptics counter that human hair is drastically different from all of the other species. They also find the comparison to truly aquatic mammals (cetaceans, sirenians, etc.) to be highly flawed, as these animals have evolved characteristics over a far longer period than humans. Also, humans sweat more per unit surface area than any other mammal, making them particularly effective at remaining active during the heat of the day. A layer of fur would reduce the effectiveness of this; human sweat may be seen as an analogue of the water-seeking behaviors of the animals mentioned.
- Bipedalism: Humans are the only surviving bipedal mammal. Although it gives us the ability to use tools whilst walking or running, it directly causes the following problems: back problems, varicose veins, hemorrhoids, hernias and problems with childbirth. Since evolution works in small steps, it is hard to see how bipedalism could have evolved on the savanna: the mass of the torso makes bipedalism inherently unstable. Water, however, supports the body.
- On the other hand, no aquatic mammal is bipedal either. Those animals that are temporarily bipedal (such as kangaroos and primates) use their upright state for locomotion, feeding and sentry behaviour. All useful for terrestrial life. Furthermore, for standing in shallow water, it is useful to have lower legs substantially longer than upper legs, as is common in wading birds. Human legs do not fit this pattern.
- On the other hand, no aquatic mammal is bipedal either. Those animals that are temporarily bipedal (such as kangaroos and primates) use their upright state for locomotion, feeding and sentry behaviour. All useful for terrestrial life. Furthermore, for standing in shallow water, it is useful to have lower legs substantially longer than upper legs, as is common in wading birds. Human legs do not fit this pattern.
- Breathing: With the exception of humans, land mammals have no conscious control over their breathing. The voluntary control humans have over their respiratory system is similar to that of aquatic mammals which inhale as much air as they need for a dive, then return to the surface for air.
- The ability to moderate breathing, to a lesser degree of control, is seen in many other animals, including other apes and dogs.
- The ability to moderate breathing, to a lesser degree of control, is seen in many other animals, including other apes and dogs.
- Fat: Humans have ten times as much fat in our bodies as is normal in an animal of our size. We are by far the fattest primates. Mammals which hibernate have seasonal fat: aquatic mammals, like humans, retain fat throughout the year.
- Fat is also very important in developing and maintaining the brain, which is a very expensive organ in terms of energy requirements.
- Fat is also very important in developing and maintaining the brain, which is a very expensive organ in terms of energy requirements.
One difficulty in evaluating this theory is that the places it suggests fossils might be found are mostly below sea level at the present epoch.
The skepticism with which the aquatic ape hypothesis has been received by most scientists is often cited by those who claim to be victims of a close-minded scientific elite (for example creationists and feminists).
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