Monday, February 28, 2011

Living In The Wrong Skin

My ‘outlaws’ (Figures 17.1, 17.2 and 17.3) love southern Spain – as well they might. They flew in to Málaga Airport on the 8th, keenly anticipating a blast of warm sunshine, which they stood no current chance of experiencing back home in North Wales. Among other benefits, they were keen to get a decent tan (Figure 17.4), before returning home to make their friends’ skins turn slightly green (with envy).

Figure 17.1: Eighty degrees and sunny in Andalucía

Copyright 2011 Paul Spradbery

Figure 17.2: Main Street, Gibraltar

Copyright 2011 Paul Spradbery

Figure 17.3: Winter sun in Southern Europe

Copyright 2011 Paul Spradbery

Skin tone is determined principally by a pigment called melanin. Brown-black in colour, the higher the concentration in a person’s skin, the darker the skin appears. Darwinian natural selection has produced an impressive spectrum of skin colours among human populations. Those of equatorial origin have the darkest skin, whereas the lightest is, generally, prevalent on those from polar regions. It is easy to understand how this has come about. Ultraviolet (UV) light from the sun catalyses the synthesis of vitamin D from cholesterol in the skin, but can also cause DNA mutations and subsequent malignant disease. More UV means more vitamin D but more DNA damage. The relationship between skin colour and climate is, therefore, crucial to human health.

Native populations are well adapted to the environments of their ancestral homelands. The evolutionary process has seen to that. For example, the dark-skinned inhabitants of sub-Saharan Africa are adequately equipped to withstand strong and persistent sunshine. On the other hand, those living near the poles, where sunlight is weak and sporadic, have very little pigmentation, and thus dermal penetration by UV (and, in turn, vitamin D synthesis) is enhanced.

Since the advent of long-haul travel, particularly by air, inter- and transcontinental human migration has reached unprecedented levels. As a result, there are, today, millions of people around the world ‘living in the wrong skin’. By that I mean ‘living in an environment with skin colour detrimental with respect to climate’.

Discrepancies between optimal and actual skin tone can lead to compromised health, often serious or possibly fatal. On the one hand, it is the collective misfortune of many Asians living in Northern Europe to have significantly higher incidence of vitamin D deficiency diseases, including rickets, than do their white neighbours. In short, their skin is too dark to absorb sufficient UV. (Moreover, women who, for cultural reasons, are compelled to clothe themselves from head to toe, regardless of the weather, are further hastening the problem.) Still, relatively few of them experience skin maligancy.

Conversely, Caucasian migrants to, for example, Australia have no difficulty in absorbing enough UV to synthesize their vitamin D requirements. They are, however, at relatively high risk of contracting skin cancer. In the UK, cancer risk to Caucasians is much lower. Sadly, public health advice often lacks any sense of proportion. It is now commonplace for British children to go to school armed with sun-block compounds. I read, only last month, of a (Caucasian British) schoolgirl whose mother had insisted on her using ‘Factor 50’ lotion. Consequently, the poor girl contracted rickets.

I am not for a moment suggesting that substantial longitudinal migration by humans is either wrong or should somehow be prohibited (although I am sure there will be some tedious, swivel-eyed PC zealots out there straining to force such sentiments into my mouth and back out again). It ought simply to be acknowledged that if an individual’s skin tone is not appropriate to his or her (UV) environment, then the potential for subsequent illness or disease becomes too serious to be ignored. No one should suffer as a result of political correctness.

The ‘outlaws’ returned to a damp and cloudy Britain, relaxed and conspicuously tanned – if only for a short while.

Figure 17.4: Sorted for vitamin D!

Copyright 2011 Paul Spradbery

Copyright 2011 Paul Spradbery

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