• Question: why are people black and white? why not blue

    Asked by tomwilson1997 to Christine, Edd, Jess, Nicolas, Zara on 17 Jun 2011.
    • Photo: Edward Codling

      Edward Codling answered on 17 Jun 2011:

      Blue people would be cool – just like in Avatar!

      The colour we are is due to the pigment in our skin. Some people have darker pigments than others and hence appear to have darker skin, while other people have light skin. The theory is that darker skin pigments help people deal with direct sunlight better – this is why (typically) people from Africa would have darker skin than those from Scandinavia. However, as people move around so much now and people of different colours are marrying and having children more than would have happened in the past it seems likely that we will all end up a ‘mid-brown’ colour in a few hundred years!

      We aren’t blue simply because the pigments in human skin aren’t that colour – melanin is the important pigment that gives us our colour: http://en.wikipedia.org/wiki/Melanin

      Something I am interested in is how animal coat patterns form – this is down to pigments as well. I actually teach my 3rd year students the maths of how pattern formation occurs – there is a great article here http://www.psy.cmu.edu/~rakison/murray.doc (it is probably best to look at the pictures first – the text is quite detailed)

    • Photo: Jessica Chu

      Jessica Chu answered on 17 Jun 2011:

      There is a chemical in the skin called melanin. This gives the skin colour. There are varied amounts of melanin in peoples skin which makes us all different shades of brown. People who originate from very hot places like subsaharan africa are exposed to a lot of sun and thus their skin produces more melanin to protect them from the suns rays. This makes them very dark brown coloured. People who originate in southern european countries have more sun exposure than those in northern european countries, so those in northern european countries have lighter skin.
      So we arent blue because the melanin is brown!

    • Photo: Zara Gladman

      Zara Gladman answered on 17 Jun 2011:

      Edd and Jess have already given great answers so no need for me to say much more 😀

      Melanin, the pigment mentioned already – affects eye colour as well as skin colour! Brown eyes contain more melanin than blue eyes.

      I just did a bit of reading on this, and turns out there are a few ‘blue’ humans out there!

      The “Tuareg” people are nomads in the Sahara who are also known as the Blue Men of the Sahara. This is because they wear blue robes – and because their skin may be tinged blue from the indigo dye used to colour the robes.

      I also came across an old story about a family called the ‘Blue Fugates’, who lived on the hills of Kentucky in the 1800s and were blue because of a blood disorder called ‘Methemoglobinemia’. This is a genetic disease and sufferers have a higher than normal amount of methemoglobin (a type of protein) in the blood. This means that blood is less able to carry oxygen around the body. More info here: http://en.wikipedia.org/wiki/Methemoglobinemia

      I don’t know if the story is true or not. There’s information here that suggests that yes, it is true – but that the family weren’t bright blue, the skin was only slightly blueish : https://php.radford.edu/~geog-web/GeogBlog/?p=68 – so not quite a smurf or Avatar character!!

      PS can’t resist posting this awful song from the 90s: http://www.youtube.com/watch?v=68ugkg9RePc

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