Yes, in humans, compared to other mammals, very little body hair. Scientists have put forward many theories about this.
1. * The theory of selection ovogo h2> The less body hair, the better it can be seen n * Italy. Charles Darwin himself believed that it attracts the attention of the opposite of a * and increases the possibility of successful reproductive and evolutionary development.
2. The theory of thermoregulation h2> Maybe the lack of hair in some way connected with the regulators of the human body, live in the tropical environment. At an early stage of development, people living within a 15 ° to the north or south of the equator. Therefore, the disappearance of hair could be the result of human adaptation to the hot climate, because, unlike most mammals, humans hunted during the day and not at night.
3. The theory of the brain to increase h2> According to this theory, the development of the human brain to its present form would be impossible in the presence of thick hair. The presence of additional brain cells, decreases the risk of primitive people sunstroke while running long distances.
4. Theory defective gene h2> Another theory is that one loses the scalp due to the presence of a defective gene and thus mutation. Probably, this mutation occurred at an early stage of development of hominids, as it affected all races.
5. The theory of protection from parasites h2> There is an assumption that the hairless man is much easier to get rid of parasites (lice, mites and so on. N.) Than hairy. The parasites are carriers of diseases and create discomfort.
6. Theory clothing h2> With the advent of clothes just eliminated the need for thick hair, to help people survive. Hair became irrelevant and eventually disappeared.
7. The aquatic ape theory h2> This is a very controversial theory is that the people came out of the water environment and the loss of the scalp for the same reason that whales, dolphins and manatees. Keep warm in the water helps the subcutaneous fat layer, not the hair.
Needless to say that each of these theories is subjected to serious criticism. For example, with respect to the theory of thermoregulation repeatedly emphasized that human skin, with its abundance of sweat glands perfectly copes with heat transfer - both with hair and without them. I wrote the late anthropologist Marvin Harris, of Columbia University, "we are cooled by water, which is released, our sweat glands. In humans, these glands 5 million - far more than any other mammal ».
As for the theory of defense against parasites, then, for example, Charles Darwin wrote: "Is [infected skin parasites] evil sufficient scale to cause baldness of the body - it is a moot point, since none of the pets that live in the tropics, as I know, I am not familiar with any specific means of protection from parasites ».
Which theory is correct, scientists still can not solve.