Why do we have hair?
Sounds a simple question, but this dead material which sprouts out of the top of our heads holds
more fascination to us than how our hearts work or even how our brains work!
There is no definitive answer but there are very solid theories as to why we have it and why we lost it; When we were primates we did not have language and so needed a way in communicating with each other, hair along with facial expressions and gestures made up a primitive sign language which we can still see (and feel) when cats and dogs become aggressive they show their hackles (a ridge of hair which runs down their spine) today, goose bumps are the remnants of that indicator, everyone must have said at some point that the hairs have gone up at the back of their neck!
Protection must have been the initial reason though…protection from the cold and from U.V light.
So why did we lose it?…we are called the hairless ape, if it was so important to keep warm why loose most of our fur coat?
Scientists believe now that it was down to the way we hunted (rather than the story of humans inventing clothes and so loosing hair after that).
We are not the fastest of hunters, but we can travel great distances because of 2 things, our up-right stance and our cooling system.
We have specially adapted sweat glands called ‘eccrine’ glands which allow us to sweat whilst running, walking (doing any strenuous thing really), apart from horses (who can sweat allot whilst they run) most other cooling systems in animals are very poor…they have to pant to get rid of heat.
So the animal would run off when they saw us coming, but we would then track it down and chase it again, and again, and again until the poor creatures died of heat exhaustion as much as they did the flint spears through their carcass.
This specialty developed to such an extent that the body shed hair to cool quicker, leaving the top of the head, underarms and genitals covered in hair.
The scalp hair was initially left for U.V protection from the sun and the hair around the genitals is used to help maintain constant temperature of our vital reproductive organs, as for our under arm hair…something’s are a mystery even to me!
The more interesting question though is why do we have elongated highly pigmented scalp hair?
….I’ll save that for another blog!