Michael Danino on Indian Gentic studies

A powerful new tool 

In the 1980s, another powerful tool of inquiry came on the scene: genetics, with its growing ability to read the history contained in a human body’s three billion bits of information. In particular, techniques used in the identification of genetic markers have been fast improving, leading to a wide array of applications, from therapeutics to crime detection to genealogy. Let us first summarize the basic definitions relevant to our field. 

India’s case 

Since the 1990s, there have been numerous genetic studies of Indian populations, often reaching apparently divergent conclusions. There are three reasons for this: (1) the Indian region happens to be one of the most diverse and complex in the world, which makes it difficult to interpret the data; (2) early studies relied on too limited samples, of the order of a few dozens, when hundreds or ideally thousands of samples are required for some statistical reliability; (3) some of the early studies fell into the old trap of trying to equate linguistic groups with distinct ethnic entities — a relic of the nineteenth-century erroneous identification between language and race; as a result, a genetic connection between North Indians and Central Asians was automatically taken to confirm an Aryan invasion in the second millennium BCE, disregarding a number of alternative explanations. 

More recent studies, using larger samples and much refined methods of analysis, both at the conceptual level and in the laboratory, have reached very different conclusions (interestingly, some of their authors had earlier gone along with the old Aryan paradigm).