• Question: why are peoples skin colour different?

    Asked by whdavandbeat to Blanka, Emma, Mike, Cees on 3 Jul 2012. This question was also asked by whmichandbeale.
    • Photo: Emma Trantham

      Emma Trantham answered on 3 Jul 2012:

      All of us (well everyone except someone who is albino) has a black pigment in their skin called melanin. If we have more melanin in our skin then our skin is darker.

      Melanin’s main purpose is to protect our skin from some of the harmful rays that the sun produces.

      I think the theory is that all humans originated in Africa. Obviously in Africa the sun is very strong so all humans would have had lots of melanin in their skin making them very dark-skinned.

      As some tribes migrated north (e.g. to Europe) they would have been exposed to less sunlight. This would have meant that not only did they need as much melanin to protect their skins from the sun, but actually the melanin would have been a bad thing because it would have prevented enough sunlight getting to their skin for them to make Vitamin D.

      So those tribes that moved northwards developed fewer and fewer melanocytes and got paler and paler skin.

      The colour of our skin now depends on our ancestors – were they tribes that stayed in Africa for a long time or were they tribes that moved into less sunny places?