Why do we have body hair?

Your eyelashes serve a purpose in that they prevent debris from entering your eyes. However, unlike the lashes, most body hair does not appear to serve any health function. According to theories of evolution, body hair is a remnant of our days as hairy apes.

Sexual Selection

"The absence of hair on the body is to a certain extent a secondary sexual character; for in all parts of the world women are less hairy than men. Therefore we may reasonably suspect that this is a character which has been gained through sexual selection." - Charles Darwin

The alteration of the body in attempts to make it more pleasing in order to attract a mate is universal. What differs across time and cultures is definitions of what is beautiful and what is done to the body to achieve the standard.

Looking at Darwin's quote, if women with less body hair represented the standard of beauty among our ancestors, then they were more likely to acquire a mate. In acquiring a mate, they would produce offspring who would have similar traits. If this cycle was repeated over enough generations, then both male and female offspring would have far less body hair than their ancestors. In addition, female offspring would have less hair than their male counterparts because secondary sexual characteristics, such as the growth of body hair, are sex-linked traits. Not all body hair growth differs between the sexes. The sexual difference occurs in the hair pattern, which is genetically determined, and the type of hair - vellus, which are fine hairs, and terminal, which are course hairs - but not in the number of hairs on the body. Hirsutism is an example, albeit rare, in which a woman would have excessive hair growth. It's a condition in which the body hair grows in a male pattern, especially the facial and chest hair.