Why did human beings evolve long hair on their head?

I can understand why many features have evolved in humans in order for them to survive. But why did human beings evolve the feature of having long hair on their head. Chimpanzees and gorillas didnt need it. And I see no need for it in humans. So why?Why did human beings evolve long hair on their head?
';Concerned'; makes an excellent point. I heard that theory as well. I've also heard it has something to do with sexual selection. There was a time in our ancestry, before the invention of the hair cut or salon, where we made a subconscious association between hair length and volume with longevity and health. A shiny, long-flowing mane usually meant that a person had darn good genes, and was associated with good health. So, natural selection probably went to work and men and women with longer hair got mates quicker until human beings started to get long hair as a whole species. Either one is plausible.Why did human beings evolve long hair on their head?
One problem with such questions is that we can never ';know'; why any given characteristic was selected for. Selection is inherently not a conscious process; it is an iterative, statistically driven one as devoid of thought or reasoning as the formation of icicles. Icicles are so regular and perfect that they must seem almost designed, yet we can watch one form in the course of a few hours.





Another problem is that there are actually multiple kinds of selection. As mentioned already, sexual selection can have as strong an effect on species traits as natural selection (retention of survival enhancing traits through iterative cycles of repetition ).





One frequently noted trait of the human species is that the ratio of penis length to body mass is much larger than nearly any other mammal. Similarly, birds of paradise and peacocks have such fantastically long feathers that it must almost certainly be a detriment to their survival, yet it has been demonstrated conclusively that the females absolutely favor mates with longer feathers. This could be, as also mentioned, that from a survival standpoint the possessor of such features has to overcome such inherent challenges that he (or she, as, for example, in the case of larger breasts) must be an otherwise genetically superior specimen to overcome this inherent impediment to survival. In the end we can only guess.
I read a theory that hair was a means of distinguishing between classes. People of higher social class had the time to groom (and grooming is seen in ';lower'; apes, like chimps). So good hair = health, vigour, wealth.





Pretty out there. But ultimately I'm confident we still have head hair because of *sexual selection* more so than other evolutionary forces like natural selection.





Bottom line is we really don't know.
I saw an interesting theory on that once. It suggested that there may have been a time when early humans spent most of their time in the water. Long hair would have floated on the surface, giving young children a handhold if they got separated from their parents and had to swim back to them.
humans lived in much colder climates, and since thermoregulation, and especially control of loss of heat through the scalp and neck, would be essential for survival in cold climates.
i'm going to side with ';runaway sexual selection';...you know, similar to how they explain why peacocks have long, bulky, but beautiful tail feathers.