Hairanimals have lost much of their hair through evolution, and some animals, such as the elephant and the whale, have none at all.
In humans, hair grows mostly on the head, and the amount of body hair is different from race to race. Orientals and native North Americans have the least amount of body hair, while Caucasians tend to have the most.
Head hair has been of interest for hundreds of thousands of years. Among both men and women, styling and coloring of hair has been a way to find personal satisfaction. It has also been, at some times in history, a way to show importance and prestige. There have been, and still are times and places the amount of head hair is controlled by law, for example, by not allowing men to wear beards.
Men usually lose their hair as they grow older. This is known as baldness, and doctors call it "male pattern baldness". Its name comes from the fact that hair loss almost always follows the same pattern. It begins by hair falling first from the front and sides of the head, and thinning from the top of the head, usually until it is all gone. After a while, all that may be left is a fringe of hair running above the ears and around the lower back of the head. Even though it is unusual for women to go bald, many women suffer from thinning hair as they grow old, and the pattern of thinning is the same as it is for men.
People have tried to find cures for hair loss for thousands of years. In an effort to get their hair back, men have tried such "cures" as having their heads packed in chicken manure or rat intestines. It is only in the last decade or so that some treatments have been developed which work. Some doctors do hair transplants, where they take tiny plugs of hair from areas like the back of the neck and plant them in the bald spots on the head. Some drugs will cause hair to grow, but this hair is very delicate and will fall out in a short time if the drug is stopped.