Farmers have known and used hybridization in plants and animals for centuries in order to produce improved and stronger plants. The resulting hybrids are often more resistant to environmental factors and diseases. Could this be the case in mixed-race individuals as well? Dr Aarathi Prasad investigates in this programme if there are advantages to have parents from two different races.
Studying benefits of being mixed-race is very controversial. Just four decades ago inter-racial marriages were illegal and eugenics has claimed millions of lives throughout history of mankind. Even today right wing groups across the globe believe that mixing of races is against the 'natural order'. As a geneticist and mother of a mixed-race child, Dr Prasad presents a compelling argument for challenging the ideals of so-called 'racial purity'.
Populations are said to be 'pure breeding' when their offspring express consistent, replicable and predictable characteristics. To achieve this, a population must inbreed in order to increase the number of genes they have which are homozygous, meaning that the individual has inherited the same copy of a particular allele from both parents. But common sense shows us that inbreeding is detrimental to the species, argues Dr Prasad, pointing to the increased incidence of genetic conditions among the children of related individuals or small communities. The genes of more genetically diverse populations, on the other hand, show a higher percentage of 'heterozygotsity' (two different copies of each gene), duplicating the ability of them being able to adapt to fluctuating environmental factors, such changing climate and the spread of new viruses or infections. So, is it not fair to assume that being mixed-race would be beneficial? This line of reasoning forms the backbone of Dr Prasad's investigation into the potential advantages of being 'mixed-race'.
Throughout the course of this programme, Dr Prasad visits various experts in the field to try and gather evidence for her theory: Dr Mark Shriver, who studies human origins at Penn State University, has found that face symmetry, a trait believed to make people more attractive and therefore more successful in finding a mate, occurs more frequently among mixed-raced people; Professor Bill Amos at Cambridge University has carried out research to show that in humans, having genetic diversity can protect you against parasites and infectious diseases to such an extent that in Kenya, having low levels of diversity can lead to increased likelihood of death before the age of five.
Dr Prasad travels to Brazil, a country where mixed-raced children have been born since the colonization of the country around 500 years ago and account for 86 per cent of the population. Dr Gerome Breen of King's College London has been looking at the influence of genetic heritage on mixed and non-mixed people and how this can help individuals cope with post-traumatic stress. Brazil is a country of great inequality, with more affluent groups being more commonly of European ancestry, while those of mixed-race are more likely to live in the cities' slums. Despite the latter group being frequently exposed to violent crime and extreme poverty, Dr Breen has found that mixed-race people and affluent people experience the same levels of stress, suggesting that those of mixed-race are more likely to have healthy biological systems to enable them to cope with stress.
Although these preliminary results from renowned scientists provide a compelling case for the benefits of being of mixed-race, the difficulty of defining what is meant by 'race', both culturally and biologically, leaves questions over the scientific validity of these studies and indeed some of Dr Prasad's arguments. Race can be defined by a number of factors: by location, by physical characteristics, by cultural norms, and, more recently, by genetic makeup. But, since we all share the same ancestry, we all share a certain amount of genes, with research showing that 85 per cent of genetic variation occurs within local populations. If we further add the diversity occurring due to immigrations into the population, biologically race becomes an impossible concept.
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