Help..there's a 12 year ols involved..

[Mazzerkhan]

I was wondering if some of you could help me. Child (12) and I were disscussing benefical mutations in skin colour and skin melanin content tonight. We talked about how darker skin protected in hotter climates from uv damage and lighter skins being avantageous to Vit D production in darker (northern climates)..then she asked the question I couldn't answer.."Mum why are we ginger?". (I have been waiting for this..). Any way my question is do any of you know what the genetic avantages to being ginger are or are we just a random mutation? if we are just random are there any theories as to why it became so prevalent in the UK/Irish poplulations? Please be aware that I am actually looking for serious answers..god made you that way won't cut it. (I have also heard EVERY ginger joke ever.. so don't bother...) If the answer is "nobody knows" cool. PS I also told child about the neanderthal theories which she found amusing, but think it was because I said the words..inter breeding. But is there really any validity in that hypothesis? Any help or links would be appreciated..

 

[Aught3]

It sounds like you have done a pretty good job so far describing the theory about melanin and population distribution.

In order too explain 'ginger' colouration you will need to separate two different types of melanin. Eumelanin is the type people usually mean when they talk about skin pigmentation. It is responsible for very dark skin tones and tans in lighter skinned people. Pheomelanin is responsible for the red colouring and is found in very high levels in red hair. It also makes lips red.

Shoot, gotta go, update later.
Ok, back.

Scientists don't even agree what happened in terms of eumelanin evolution. Last I read there was some evidence for positive selection in some genes (which fits with the vit D theory) while other genes show only neutral genetic drift (which fits with the reduction in UV rays due to latitude). Since the production of eumelanin and pheomelanin are closely tied together, and they have similar roles; it seems to be sensible to assume they both decreased together.

Why has pheomelanin been retained to a high level in Gaelic (correct word?) populations? Unfortunately, I think we know enter the realm of speculation. Founder effect could have done it or possibly it was just genetic drift (which is much less interesting). Unless evidence of positive selection can be found in the pheomelanin genes it seems like attributing its retention to natural selection would be a bit of a stretch.

I'll go have a bit of a trawl through the literature, and post if I find anything interesting.

 

[Mazzerkhan]

thanks for that. I am a chemist and my biological knowledge (2 modules as part of my degree 15 years ago) is now not enough for a 12 year old.. whislt one one level (mine) thats quiet depressing on another its quite inspiring..any hoo if any of you can point me in the right direction like Aught3 I will be eternally (joke) in your debt..