There are different sorts of red hair. Some people seem to have what we call “strawberry blonde”, some bright red and some auburn. As far as we know, the genetics underlying these differences are fairly similar, in that changes in the gene referred to above, seem to be important for all sorts of red hair. However, if you have bright red hair it seems you are much more likely to carry two different copies of the gene than if you are a strawberry blonde. We are, however, not completely certain about some of the details in this particular aspect of the work.
There are some other puzzles about red hair. Some men might have red beards but dark coloured hair. This is not entirely surprising as in many mammals the front of the body is a slightly different colour to the back. In some animals, the molecular basis of this is clearly understood, as in these animals, they produce a different protein that seems to have the opposite effects to the red hair gene mentioned above. In man, we don't think this is the case, but we also observed that people who do have red beards are more likely to carry at least one different copy of the red hair gene.
Another puzzle is why hair colour changes so much during life. Most people are aware that hair colour tends to be lighter at birth and gets darker, particularly during adolescence and puberty. Apart from saying that the cells that produce melanin become more active at this period we don't understand why this is. Similarly, of course, we don't really understand greying and lightening of the hair in old age. People with red hair often have different coloured hair at different times of their life. It seems that it is more likely to be red in childhood or in early adult life, than in later life.
One medical importance of red hair is that individuals with red hair are, on average, more likely to burn in the sun and they are at an increased risk of skin cancer. The sensible advice seems to remain that since it is painful and uncomfortable to burn repeatedly in the sun, it is sensible to alter your behaviour such that you don't suffer the discomfort! On the other hand the risks of skin cancer should also be put in context. For instance if you have red hair, the medical risks don't compare with the far greater and much more serious risks from smoking and drinking large amounts of alcohol or being very grossly overweight.
We don't know with certainty when the first “red heads” walked the earth but, based on our own research, our guess is around twenty thousand years ago. In evolutionary terms, this is relatively recent, and although we can't be certain, the explanations for the development of red hair generally fall into two groups. The first, is that there may have been some advantage to having red hair and pale skin. One reason for this is that you make vitamin D in your skin, and therefore you are less likely to get rickets (vitamin D protects you against rickets) if you have pale skin and there is not much sunlight around. An alternative explanation, which some of our own work supports, is that it may have just been due to chance in that, to state it simply, nature may have been fairly indifferent to hair colour in areas of the earth without high sunshine. Diversity may rule!
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