Vive la Différence

Variation is the driving force behind evolution and the reason why any species persists on this planet. Yet the science of human diversity is curtailed by controversial politics and outcries against racism. Some resistance comes from indigenous groups who feel they would be lab rats, but most comes from cautious government groups like the European Union, who at one point banned all research into human diversity. As a result gene studies were forced to obliterate the ethnic source of their samples.

Of course it is important to be sensitive to the threat of racism; historically human diversity science has led to eugenic groups, the sterilisation of ‘undesirables’ and most infamously, the hideous acts committed by the Nazis. However science is the only real route to defeating ignorance (listening Daily Mail?) and as gene trials have progressed it has become obvious that the main differences are ones we see – hair, skin colour and facial features. We might have just our mother’s eyes, but we all possess the genetic markers of one woman who lived in Africa 200, 000 years ago – Mitochondrial Eve.

Racial groups are simply pockets of random mutations, favoured or dispelled on exposure to the environment. A Channel 4 documentary picked four random men, representing each main ethnic background, and read their DNA. Men were chosen as the Y chromosome is passed, unchanged, directly from father to son. Any mutations in the Y chromosome will be passed to all male offspring, and then on to all their male descendents. It was found that the Caucasian and the African representatives shared a European great-grandfather, while a few hundred generations ago, existed a man who had founded the lineages of the European, African and Japanese men in question. Ultimately all 4 men possessed a mutation that had originally occurred in one man, several thousand generations ago.

The documentary also traced the stories of just a handful of genes within these ethnic groups. A gene for alcohol tolerance is absent in 50% of oriental descendents. Its been suggested the reason for this was the safety of drinking water. To overcome the dangers of waterborne disease, Eastern people boiled their water whilst Western groups fermented it. Avoiding gastrological infections enhanced survival and reproductive fitness, hence a gene for the degradation of alcohol became widespread in Western populations.

Other considerations were epicanthic folds and nose shape. Epicanthic folds are associated with oriental races but are found in South African populations; sure enough these stem from a common ancestor. Nose shape (also heavily subject to sexual preference and cultural measures of attraction) has been thought to reflect the temperature of the surrounding environment; longer noses are able to better warm the air before it is fully inhaled, improving the efficiency of Oxygen transfer, hence why Europeans may tend to have larger noses than more southerly populations.

Skin colour, the most controversial and identifiable feature of race, is the result of a conflict between producing enough vitamin D and protection from skin cancer. Populations living in sunny climes produce large quantities of melanin pigment to reduce UV penetration, which causes cancer. However sunlight is required for the production of Vitamin D, vital for bone metabolism. As our ancestors moved North, the weaker sun meant skin pigment had to be lost in order to prevent Vitamin D deficiency – a problem still occasionally seen in dark-skinned people living in Northern countries; our ancestors didn’t have cow’s milk or calcium supplements readily available.

Thus the study of human diversity provides much insight into why we appear different and traces how we spread out from one continent to populate the world. However there are very urgent reasons why gene studies should include information from as many ‘races’ as possible. The Human Genome, a compilation of ‘all human genes’ was actually only composed of about 20 individuals, all American. Most of our knowledge of genetics has stemmed from European or Oriental sampling. While groups bay to protect ethnic minorities, they are actually ensuring that these people may never benefit from genetic research. For example studies into the genetic causes of prostate cancer rely namely on samples from American and European backgrounds even though rates are 3x higher in African-American men. Causal genes found in the study may play less or no role in the African-American cancers, and thus these men’s ability to access screening and targeted treatment may be destroyed as a result.

Even if ethnic diversity is controversial as a source of academic interest, its medical applications are profound. Races do differ in prevalence of inherited disease, response to drugs and tendency to develop particular illness. Because it protects against malaria, one haemoglobin variant is common in Sub-Saharan African descendents, however it also increases the incidence of a potentially fatal blood disorder called sickle-cell anaemia. Many Europeans have an increased risk of skin cancer due to a melanin pigment variation associated with red hair. Certain isolated populations possess only one blood group as opposed to the A, B, AB or O varieties familiar in Western individuals.

Genetic research into population differences has found we are all more alike than we are different; all various compilations of genetic traits that make us better adapted to our environment. Unfortunately many of the differences we do perceive in our genetic information contribute to states of illness; isolating which genes are responsible and identifying risk are important avenues of medical research that will reduce morbidity and death. Pharmaceutical companies are currently driving large-scale trials to develop a new generation of genetically-tailored medicines. Once again, variation is all about survival.

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