Why are some people hairy?

Imagine a totalitarian world like the one in the 2014 movie, “The Giver” – free of suffering, pain and choices; the only requirement is that one should not be different. Thankfully, we don’t live in such a world. In this world everyone is different and unique, by choice or otherwise. And do you realize what one of the quickest (yet mostly ignored) way of recognizing someone is? By their hair, of course.

Did you know that one of the most noticeable differences in one’s hair is their hair pattern? Some have long hair, some have short hair, some have dark hair, and some have blond hair. But why so many differences? How did they come to be?

So… How where did all our hair go?

There are many theories about why we shed most of our hair. It is possible we shed hair to reduce the instances of lice infections, or as the Earth warmed over the last few thousand years, we shed hair to control body temperature (less hair on the body means more sweat which helps in cooling the body). It is possible that the reasons for changes in hair growth varied with geographical locations. Species in colder climates may have developed more hair than those in warmer climates. An outlandish theory even states that at some point in our evolution we became a semi-aquatic species and replaced body hair with body fat. Needless to say, paleontological evidence for such a species is still lacking.

What about hair growth?

In 2005, the International Journal of Dermatology published a study which studied 511 male and female volunteers. It found that the average rate of hair growth was 4 inches per year for Africans, 5 inches per year for Caucasians and 6 inches per year for Asians. Other studies show how hair density differs in different races. In fact, it has been noted that Asians have a much lower chance of balding than Africans and Caucasians, with Caucasians having the greatest chance. The period of hair growth also varies in different races – Asian hair can have a growth cycle of nine years, while African and Caucasian hair growth cycles vary between three to seven years.

So then is it all about genes?

It would be irresponsible to blame genetics alone for that receding hair line. Our bodies first produce vellus hair, which is difficult to see but very useful for our body’s temperature control. As the human body matures, hormones like testosterone convert the vellus hair to terminal hair, which is dark and is what’s responsible for forming beards in men. Some factors like malnutrition, ill-health or even genetics can affect this transition, by causing each follicle to react differently. These differences are the reason why a person who is balding does not go completely bald at once – it’s a slow process.

Studies have shown that stress can also adversely affect hair growth and can lead to premature balding. Extreme stress can stop hair growth and cause it to fall off. Some scientists believe that that UV exposure and heat also affect hair growth on a day – to – day basis.

Faulty follicle reaction can also lead to full facial hair growth and this condition is known as hypertrichosis. This condition is rare but there are living examples such as Fajardo Aceves Jesus Manuel of Mexico. In women, the availability of excess hormones during menopause causes a spurt of facial hair growth.

Regardless of all these theories and differences, it is important to note that modern technology has make it possible to control this hair growth as you deem fit. You have hair re-bonding for permanent hair growth, while processes like electrolysis give you permanent riddance of body hair.



Castro, B. (2014, January 27). How Fast Does Hair Grow? Retrieved November 21, 2015, from http://www.livescience.com/42868-how-fast-does-hair-grow.html

On why (some) humans have lost their body hair? Why are we the only hairless primate? (2007, June 9). Retrieved November 21, 2015, from http://anthropology.net/2007/06/08/on-why-some-humans-have-lost-their-body-hair-why-are-we-the-only-hairless-primate/

Why Testosterone Affects Body Hair Growth. (2013, February 17). Retrieved November 21, 2015, from http://www.todayifoundout.com/index.php/2013/02/why-testosterone-effects-body-hair-growth/

Why are some people hair-ier than others? (2008, July 24). Retrieved November 21, 2015, from http://skinbeautifulblog.com/2008/07/24/why-are-some-people-hair-ier-the-others/

Diversity of hair growth profiles. (n.d.). Retrieved November 21, 2015, from http://onlinelibrary.wiley.com/doi/10.1111/j.1365-4632.2005.02800.x/abstract

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