A common reason behind the reason for hair lies with a male hormone called testosterone. In men testosterone has many uses which are commonly well know but generally the hormone works in line with other hormones to aid hair growth. However testosterone will not aid hair growth on you head meaning baldness seems inevitable, much to the disappointment of many. Testosterone as a hormone is grouped amongst other hormones as an androgen, a sex hormone generally found in men but can be found in women.
These hormones can be found in hair follicles and they cause hair to grow. Within men the amount of hair grown depends on the age of a man as male sex hormones are always present. In women however hair growth depends on how much testosterone their body is producing. Testosterone can have negative effects for females as they have multiple effects. Too much testosterone will cause facial hair to grow whilst thinning scalp hair which obviously can be a huge problem.
Body hair dates back to pre-evolution when primates were basically covered in hair and there was a reason for this. As everything was less developed in pre-historic times hair provided a source of warmth which was vital for survival. Without hair most primates would not have survived and society as we see it today would not be around.
Hair can also be a source of camouflage and for many mammals they can use their camouflage to hunt and hide. Having hair that order hair online before we evolved does not however explain why we have evolved with less and less hair.
There are many theories behind the reason why humans have evolved to have less hair but they all generally lead to the course of evolution. A common theory involves the idea that primates and aquatic-apes began hunting in shallow waters and fur became more of a hindrance rather than an asset which led to many generations generally being born without a coat of fur. A loss of fur was also paired with an idea of how hygiene concerns had a lot to do with our loss of fur. Apparently our pre-evolved counterparts disliked their fur as lice and parasites treated it as more of a farm to spread and breed. Increasing numbers of lice led to irritation for apes and in some extreme cases death became a consequence. Both of these generally explain why, as evolution went on, we lost our fur coats.
A loss of fur arose other problems especially went winter and the ice age set in. Before we lost out coats they were used as a source of warmth but without them we were more vulnerable to whatever nature threw at us. Neanderthals were the source of solving our temperature problem as they still had limited hair causing frost bite and other life threatening conditions. To solve a problem like extreme temperatures they Neanderthals began wearing animal skin to stay warm. Wearing animal skin is also thought to be the reason behind why we now wear clothes and since then we have obviously developed the clothes we now wear.