• Question: Why is it that girls dont have facial hair but boys do?

    Asked by the arch bishop of banter to Chris, Josh, Rebecca, Rob, Susan on 16 Jun 2015.
    • Photo: Susan Cartwright

      Susan Cartwright answered on 16 Jun 2015:

      Testosterone, the male hormone, stimulates body hair growth. This is is why younger boys don’t have more body and facial hair – they haven’t hit puberty yet, and are not producing high levels of testosterone.

      How much facial hair men have is also controlled by genetic factors – white men tend to be much hairier than east Asian men, for example.

      Why humans evolved this difference between men and women is a different question. The fact that the level of difference is not the same for all peoples suggests that it’s not that the extra body hair is actually useful. It’s probably sexual selection, i.e. women preferred to mate with men with more facial hair, and so genes which gave men more facial hair were favoured.

    • Photo: Josh Meyers

      Josh Meyers answered on 16 Jun 2015:

      Boys and girls are different! They have different DNA. DNA is made up of 23 pairs of chromosomes. The 23rd pair are known as the sex chromosomes; in women these are XX and in men XY.

      This difference causes a difference in development during puberty. Boys produce the hormone testosterone which causes beard growth and voice deepening among other characteristics. Girls produce oestrogen which causes the growth of breasts and initiates the menstrual cycle. These hormonal differences are what make boys and girls different.

      Did you know that beard hair is the fastest growing hair on the human body. If the average man never cut his beard in his life, it would grow to be 30 feet long (9 meters).

    • Photo: Rebecca Dewey

      Rebecca Dewey answered on 18 Jun 2015:

      Facial (and bodily) hair acts to extend the touch sensation past the skin for the length of the hair. Maybe through evolution it was useful for males to be able to feel things on their faces, like the direction of the wind, or if the weather was about to change. I don’t know though!

Comments