• Question: why are there black and white people? why arnt we all one colour????

    Asked by brandonarcher1 to Amy, Karen, Sarah, Vijay, Will on 14 Jun 2012. This question was also asked by notarappershf, nilokoko.
    • Photo: Will Reynolds

      Will Reynolds answered on 14 Jun 2012:

      Hi brandon. Skin colour is determined by how much sunshine a region of the world gets. Dark skin helps to block out harmful UV radiation that comes from the sun, so people who are native to countries that are very hot usually have dark skin like Africa, Asia, South America and Australia. But in europe and north america people have lighter skin because there is much less sun and UV radiation. Recent research has shown that all humans originated from Africa, so would have all had dark skin, but the people who setlled in europe evolved lighter skin during an ice age where they had to shelter in caves and didn’t get much sun. We need sunlight to make vitamin D so having dark skin during an ice age would have been a disadvantage because they wouldnt have been able to make enough vitamin D to stay healthy and so evolved lighter skin. People with light skin living in hot countries have a high rate of skin cancer because they are exposed to too much UV radiation and people with dark skin living in europe sometimes have to have UV treatments to boost their vitamin D levels.

    • Photo: Sarah Martin

      Sarah Martin answered on 14 Jun 2012:

      Hi brandonarcher1!

      That is a great question!

      As Will has already pointed out, in order to survive life outside Africa, European ancestors evolved genes that reduce the production of melanin and make them look paler. Most however can increase their melanin levels slightly by getting a tan!

      Here’s a list of the genes that each make a little difference to our colour – there are quite a few!
      So, the TYR gene which helps produce melanin has a mutation in about half of all modern Europeans, so it doesn’t work very well.
      Same goes for the MATP gene, which helps transport melanin.
      One type of the SLC24A5 gene ensures only little melanin is made, and 99.9% of Europeans have this type, but hardly anyone anywhere else in Asia or Africa does. It’s the SLC24A5 gene that scientists think is the main reason why white people are white, and not black any more. But this difference only evolved in the last 10,000 years!
      Other genes tested in forensic science to check the ethnic origin of people is a gene called ASIP, which stops melanin production (they find it in 80% of Europeans, 75% of Asians and 20–25% of Africans) and a type of the gene KITLG, which slows melanin production down (found in 80% of Europeans and Asians and less than 10% of Africans).

      All clear? Thanks for the question!

      🙂 Sarah

    • Photo: Karen Reed

      Karen Reed answered on 16 Jun 2012:

      Well what more can I say – excellently answered by will and Sarah already!

      Brilliant question though 🙂

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