Humans are among the few mammals that have evolved to be nearly completely hairless - this now being something we go out of our way to achieve.
It seems strange that we find fluffy, furry animals cute and attractive and yet are disgusted by the few that are bald. The naked mole rat for example, can cause instant repulsion.
However, in our species particularly in women, we consider smooth hair free skin to be desirable; resulting in desperately shaving, waxing or any other extraordinary measures we can come up with to remove our body hair.
A constant battle some might say. This may not be something we really think about or consider, but when compared to our closest ancestor the chimpanzee, who are covered in dense fur, this seems unusual.
Perhaps our lack of hair could have been advantageous in our evolution and success as a species?
Why did it disappear?
There are a number of theories behind our distinct baldness as a species. One leading hypothesis suggests it may help to prevent overheating, allowing us to venture into hotter climates such as the African Savanna.
“We lost most of our hair and increased the number of eccrine sweat glands on our body and became prodigiously good sweaters” said Nina Jablonski, Professor of Anthropology at Pennsylvania State University.
Bare skin allows rapid cooling from sweat glands, whereas being covered in hair traps moisture resulting in less evaporation to cool us down.
However, the loss of hair also resulted in the loss of UV protection from the Sun (obviously there was no such thing as sun cream millions of years ago). So, we needed to adapt. “Dark skin pigmentation to protect against sun damage would have almost certainly evolved at the same time as body hair was lost” said Professor Jablonski.
The gene MC1R specifies a protein that produces two types of pigmentation in the skin; eumelanin which protects against the sun’s UV rays and pheomelanin which doesn’t. The first being brown/black in colour and the latter, red/brown in colour.
Studies have shown that in African populations, the protein that protects from sunlight demonstrates an invariant quality. Whereas in other locations such as Europe, we saw variant mutations of the gene. Due to the cooler climate, this led to a survival disadvantage, as it would on someone living in an extremely hot climate.
Good bye pests!
Another possible survival benefit a lack of hair produced – less of those irritating and sometimes harmful parasites! These troublesome creatures are not only annoying, they can carry harmful viruses, bacteria and diseases such as malaria and Lyme disease, which can prove fatal.
All from one tiny little bug. Dense fur provides an ideal cosy home for them to thrive in and reproduce, surviving off their hosts and debilitating their health. Therefore, less fur means less parasites!
This then leads onto the modern concept of hairlessness being an attractive trait. Ever wondered why we ever began shaving our body hair and why we see smooth, sleek skin as appealing on humans, but not on other mammals? No doubt some women have thought about why on earth shaven legs even became a thing.
Charles Darwin’s explanation for the evolution of hair loss was sexual selection. He theorised that our ancestors with the least amount of hair were seen to be healthier and fitter, for the reasons mentioned before. Consequently, individuals with less hair were seen as more attractive and more likely to be selected as mates to reproduce and pass on their hairless genes.
So why do females generally have less hair than males?
There is no definitive scientific explanation for this, but it has been put forward that females are more concerned with other features males possess, such as strength and social status. Hair on males, such as a large beard, could have been more of a flashy show to get themselves noticed and signify superiority - similar to a lion’s mane.
Males on the other hand were apparently more concerned with a female’s ability to nurture and raise offspring, as they bare the higher parental investment. Smooth hairless skin can therefore be seen as an advertisement of their health. Perhaps that’s not what men think today when they see nice smooth legs, but these ideals originated from somewhere.
Whatever the reasons may be, we have evolved to be a funny looking bunch. Being the most dominant species, you would have thought we'd have something magnificent to show for it. Perhaps in the form of extravagant, vibrant plumage or fantastically coloured thick fur, as opposed to tufts of hair under our armpits, a dense coverage on our heads, strips of hair above our eyes and thick coarse hair around our genitals.