Question: I'm a ginger. I've heard that being ginger is a mutation. Do you know if this is true? Also, why do we get itches, and what are freckles. I understand these are nothing to do with antibiotics, but it's still biology.

Robert Hampson answered on 17 Nov 2014:

Ginger hair is the rarest hair colour in humans but is found most commonly among the people of the British Isles especially Scotland and Ireland. It is caused by having two genes containing a mutation in the MC1R gene. These are recessive genes which is why you must have a two copies, one from both your mother and your father. If you do not have two copies, the other gene becomes dominant and you don’t end up with ginger hair. Freckles are also associated with ginger hair because the gene prevents the normal mechanism of tanning on exposure to strong UV light. Freckles are like a replacement mechanism for defence against the sun’s UV light.

It seems that in colder climates with less sunlight, being ginger can be a genetic advantage. It allows the skin to make more vitamin D reducing the risks for diseases like rickets. However, in hotter climates, it is a distinct disadvantage as sun burn is more likely as is skin cancer.

Itches are distinctly harder to explain as we don’t really know how they work definitievely. It is something to do with the release of histamine. So, for example, if you scratch yourself somewhere, it causes the release of histamine in the skin, this semi triggers nerves in the area, which cause the effect called an itch. The most effective way of getting rid of an itch is in fact not scratching it. Itches and scratching maybe be a behavioural and biological evolutionary response to some of our healing processes. Sometimes rubbing/scratching an area, for example, can help release natural painkilling chemicals.