From Michael Weatherill
Adrian Barnett reports an association between varying levels of melanin in skin and the balance between contradictory requirements for protection and synthesis in the skin. These, he notes, vary seasonally in regions away from the equator. He also notes that the number of melanin reservoirs does not vary greatly with skin colour.
These observations, taken together, would suggest that in temperate regions skin colour should vary seasonally. Tanning fits with this theory, but not perfectly. The time lag is great, and the range of the change is small compared with the observed regional variation in skin colour.
St Andrews, Fife, UK
