(This is not a casteist rant, though the first few paragraphs may sound like it is, the fact is that it isn’t.)
It’s kind of obvious isn’t it, there is a discernable difference between people of different castes. You wouldn’t expect an upper caste individual to look like someone born into a lower caste family would you. It is a simple observation, whether you wish to acknowledge it or not. Despite this, when in 2001, Bamshad et al. described genetic differences in Indian caste populations, many took up arms against the paper, describing it as the work of a western imperialist trying to fracture the foundations of Indian society. What Bamshad et al. described was that Indian caste populations differ with respect to the genetic distance they show from other contemporary world populations. Upper castes they found, show a closer affinity to European (particularly East-European) populations than to Asian ones, while for lower castes, this observations was reversed. What they proposed was nothing new or radical, history documents that the caste system was imposed by the Aryans (of European descent) on the Dravidian populations of India, with the Aryans putting themselves in higher positions and relegating the Dravidians to lower positions. The paper merely corroborated this view from a genetic standpoint. Dravidic tribal populations, which have limited interaction with other population groups, correspondingly showed the closest affinity to Asian populations.
Many denounced the paper as one promoting division in Indian society though I can’t really understand why. It was an honest attempt to understand the genetic structure of the Indian population, the significance of which I will discuss later. For all doubts raised as to the veracity of the paper; many Indian researchers also have independently achieved similar results (Majumder 2001; Basu et al. 2003 and Roychoudhury et al. 2000).
Bear with me now, while I digress for a moment; I was travelling by train a few years ago. Sitting in the compartment, I overheard a gentleman describing at length the ‘fact’ that lower castes were genetically inferior to upper castes. He was of the opinion that ‘superior’ genes ensured that upper caste individuals were more intelligent than their lower caste counterparts. Such thought is commonplace, we have numerous similar stereotypes, like the intelligent Tamilian or Jew and hardworking Japanese to name a few. People tend to ascribe such characteristics particularly those related with intelligence to genes. Unfortunately this view is a deterministic one and not really accurate. We may loosely describe traits such as height in terms of genes (or nature), such as a tall-gene. Complex traits such as intelligence on the other hand are much more difficult to explain genetically. First as these traits are typically controlled by a multitude of genes acting in concord and secondly as upbringing and environment (nurture) also contribute to these traits in no small part. Nature vs. nurture, the genetic chicken and egg conundrum has been debated for ages, the currently accepted view as described by Matt Ridley is Nature via Nurture. This implies that both genes and environment interact to develop particular characteristics in an individual. This is what I have to say for the point raised by my companion on the train and all others who think the same; Intelligence is too complex a trait to be attributed purely to the work of genes. As a consequence intelligence doesn’t exhibit simple inheritance patterns as for instance height, a not–so-complex trait. Intelligence depends heavily on environmental factors ranging from nutrition to social interaction. We don’t even know of a gene (or genes) for intelligence yet, we only have a number of prospective candidates. So to describe particular population groups as being genetically unintelligent is downright wrong since we don’t even know what constitutes genetic intelligence.
The question of genetic superiority though is an old one, some of its earliest proponents include Francis Galton (Darwin’s cousin) who preached eugenics. Eugenics basically proposed selective breeding of superior traits in humans like breeding cows that provide higher milk yields. Hitler practiced a sinister form of eugenics in attempting to breed his Aryan master race. Though eugenics has been scientifically denounced, its ideas live on in stereotypes such as those of our train-prophet.
I think it is these stereotypes that scare the people who criticized Bamshad et al. Caste is a major problem in India, particularly now when the reservation bill has polarized the country. People are worried that showing castes differ genetically, somehow will promote stereotyping of caste groups. Like I said earlier, this is a deterministic view i.e. it assumes genes are absolute determinants of the presence of traits in individuals. Additionally, it assumes that differences imply the superiority of one caste group over the other. It is a simple case of people projecting their worst fears on to the paper, they are merely assuming that the paper supports our commonly held stereotypes; while in reality it never approaches the subject.
Now, why would you ever need to study the genetics of Indian caste populations? It seems to hold more potential to raise trouble than do good. The reason is that genetics has a lot to offer to a number of other fields of study including pharmacology and history. Everyone knows that humans originated in Africa, that a small population of humans, about 200,000 years ago began their journey out of Africa and eventually populated the entire globe. Few know that this was proved genetically by Cann et al. (1987). India, has a diverse population, with four different linguistic groups spread across the country, all of which entered at different times, bringing with them their culture and most importantly their genes. Genetics has the potential to unravel the complex, intertwined histories of these groups. It may also prove invaluable in the relatively new field of pharmacogenomics, which involves individualised drug administration based on an individuals genes. Pharmacogenomics has the potential to revolutionise conventional drug development and administration, in the process reducing drug costs and increasing drug efficacy. Additionally it will allow us to identify and protect endangered tribal groups such as those indigenous to the Andaman Islands. Most importantly it will allow us to understand ourselves much better. We pride ourselves in our diversity, then why do we oppose studying it?
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References
Bamshad M J, Wooding S, Watkins W S, Ostler C T, Batzer M A & Jorde L B. Human population structure and inference of group membership. Am. J. Hum. Gen. 72: 578-589, 2003
Basu A, Mukherjee N, Roy S, Sengupta S, Banerjee S, Chakraborty M, Roy M, Roy B, Bhattacharyya N P, Roychoudhry S & Majumder P P. Ethnic India: A genomic view, with special reference to peopling and structure. Genome Res. 13:2277-2290, 2003
Majumder P P. Ethnic populations of India seen from an evolutionary perspective. J. Biosc. 26:533-545, 2001
Roychoudhury S, Roy S, Dey B, Chakraborty M, Roy M, Roy B, Ramesh A, Prabhakaran N, Usha Rani M V, Vishwanathan H, Mitra M, Sil S K & Majumder P P. Fundamental genomic unity of ethnic India is revealed by analysis of mitochondrial DNA. Current Science 79:1182-1192, 2000
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