notes on its blog that the idea that the gene for red hair could soon become "totally extinct" is just a hoax. [The disappearing redhead gene is a variant of the old disappearing blonde gene
urban legend.] Nevertheless, Marie Claire does warn that global warming could cause "a dramatic increase in people born with auburn hair."
It's getting this from The Daily Record
, which in turn is getting it from a Dr. Alistair Moffat who works at a genetic testing company. Moffat's reasoning is that "red hair in Scotland, Ireland and the north of England is adaptation to the climate. We do not get enough sun and have to get all the vitamin D we can. If it was to get less cloudy and there was more sun, there would be fewer people carrying the gene."
Moffat seems to be assuming that rising temperatures and more sunshine will make people with red hair less able to reproduce than their non-red counterparts. Presumably this will happen because Gingers will die from skin cancer before they're able to produce babies.
But of course, all this won't happen right away. We'll only see the disappearance of redheads "within a few centuries."
This all sounds like an attempt to offer some sort of hazy scientific justification in support of the disappearing redhead/blonde gene urban legend. Honestly, I think the bigger danger is that global warming will cause the human race itself to go extinct within a few centuries, rather than just redheads specifically.
Dr. Moffatt is apparent proof that too much sun is bad for you.
First of all: is the larger share of red hair in the northern British Isles the result of selection on red hair because of the environment (climate)? Or is it the result of a founder population effect? i.e. that the founding population initially was small and contained a rare trait (redheads) by chance that got genetically dominant because of this founder effect and the continued genetic isolation of an island.
Second: even if it is climate that selected on redheads, this does not mean that changing climate will make them disappear. First of all, the genes are well-entrenched in the N-British population. Given the significant percentage of the gene pool they represent, they will survive in the gene pool even if no clear positive selection continues to work on them. They will only disappear if some clearly negative selection criterion will start to work on them. Mere climate change will not necessarily do that. For at least some time (if not by definition, as I will argue), redheads will continue to benefit from their increased capability of producing vitamin D compared to non-redheads. Even in a very sunny climate, at 53-54 North latitude the amount of sunlight per day is limited compared to lower latitudes (especially in winter). Someone with fair skin will *always* be in an advantageous position so far North. It is not likely that negative effects will truely matter, certainly as modern people wear clothes, use sunlotion and do not work outside all day. It is unlikely anyway that an increase in skincancer or someting like that will kill off redheads before they can reproduce (and that is what matters), rather than when they are 40. 54 North is not Australia: half of the year the sun is extremely low in the sky and only shines for an extremely short period of the day at this latitude, and climate change will not change that. An increased capability to produce vitamin D will stay advantageous under these conditions.
In other words: the positive selection factor (a better vitamin D production capability) will stay and continue to be beneficial. Negative selection factors appear negligible. Ad to that a potential additional positive selection factor in that positive sexual selection on redheads could be present in the N-British culture, and it is clear that redheads will not disappear.
For more information see: http://www.ucl.ac.uk/mace-lab/genetic-ancestry