Frowning is a peculiarly human habit, explained by the aquatic hypothesis as a response to the sun’s glare from the surface of the water. But, except in their faces, humans have largely lost the muscles which move their skin. Vestiges remain in phenomena like scalp hair standing on end through fear, and cold causing goose pimples, but we have nothing like the ability cows or horses have to shake off flies by vigorously twitching their skin. The skin muscles were lost along with hair because moving hair was their main function—no hair, no skin muscles—they had become redundant.
The retention of muscles to move the skin in the face is connected with visual communication. Animals floating upright at the water’s surface only had their faces exposed. Interpretation of subtle facial movements therefore took on special significance. The expression of emotions via facial expressions would have been especially important as social structure evolved.
A layer of fat underneath the skin is a much better insulator than fur for a warm-blooded water dweller. No primate has it—except man. It is another peculiarly human feature. Some other terrestrial animals store fat but rarely under their skin. Humans are born with a fat layer. Human babies are unusually rounded, and heavier than the babies of the great apes. A human baby is almost twice as heavy as a baby gorilla or chimpanzee though human adults are lighter. According to the aquatic theory, besides providing necessary insulation to the baby this fat was a vital aid to buoyancy.
Other mammals besides man have sweat glands which they use for excretion of wastes. Man is unusual in having exceptional numbers of them, and in using them as a way of keeping cool. Sweat cools by taking away body heat as latent heat of vaporization. It requires free access of air to the skin since air trapped near the skin soon becomes saturated in moisture. Further evaporation then stops and sweating no longer works. Hairiness stops sweating from being efficient as a cooling system. No great ape, other than man, sweats to keep cool. It would be inefficient if it did.
But for sweating to evolve as a means of keeping cool on dry or even arid grasslands is absurd—it drains the body of essential water and salts. And it would be suicidal for any ape to opt for a water cooling system where water is at a premium—on the dry grasslands. A man walking naked in the tropical sun at 100 degrees Fahrenheit (40 degrees Celsius) can lose up to 28 liters of fluid and an eighth of his body’s salt a day by sweating. For urination only one liter is needed. It is plain nonsense to postulate that the savannah ape first lost its hair to keep cool, then put on a subcutaneous layer of fat to keep warm and finally developed a life threatening system of sweating to keep cool again. The only way to make sense of such a ridiculous sequence is the aquatic hypothesis. The first two stages, hair loss and the evolution of a fat layer instead, were adaptations to living in water.
Sweating served two purposes. It was a way of ridding the body of surplus salt ingested while foraging in the sea. And it was a natural way of allowing a water ape to keep comfortable when out of the water by taking a little of its environment with it. The loss of large amounts of water would not matter if a water supply is always nearby, and so aquatic apes would not have willingly moved away from their water source. Their gradual re-adaptation to the land would have been by them staying close to rivers and lakes and moving inland only as their sophistication grew.
We have seen how close we are to the chimpanzees in terms of DNA. We are also similar in our thought processes. Chimpanzees have a wide range of emotions and have sufficiently mobile faces to show them. But when distressed they do not cry, simply because they cannot, despite their evolutionary closeness to humans. Only elephants and humans of land animals express tears. All other animals that weep are aquatic—and there is a lot of evidence that elephants were aquatic at some time long ago! It is a poignant sight to see a baby seal after its mother has been clubbed to death by a human with a baseball bat, weeping on the ice floes before it too has its skull crushed, killed to gratify human vanity.
Birds, particularly marine birds, have nasal glands behind their beaks to get rid of excess salt, but these birds also get a wet beak from the salt gland when they are excited or emotionally aroused. They are crying. Other marine creatures such as the marine turtles, marine iguanas and terrapins have similar glands. Crocodiles do cry crocodile tears but only the marine variety, not river crocodiles which do not have to cope with salty water. Many dinosaurs had spaces in their skulls in front of their eye sockets and these are thought to have housed similar salt glands. So it is possible that some dinosaurs also cried. The connection of tears with the salt gland and the sea seems obvious, even if its original use is no longer applicable. Only the idea of the aquatic ape can begin to explain a human’s ability to cry.
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