Pre-Historic Migrations in India – Tracing the DNAs

What is the issue?

• A recent genetic research on pre-historic samples has revalidated the politically sensitive ‘Aryan Migration Theory’.  
• But additionally, the current paper has also stressed the irrevocable genetic inter-connectedness of all modern-day individuals.     

What is the study about?

• A recent study titled ‘The Genomic Formation of South and Central Asia’ has published its analysed on the contented Aryan migration theory.
• While term “Aryan” has been consciously avoided, it has claimed that there was indeed some kind of migration into India in around the 2000 BCE.
• “Ancient DNA” from 612 individuals in Central and South Asia were observed and a population influx into the region was claimed to be perceptible.
• Significantly, the timing of this influx is said to perfectly coincide with the terminal phase of the “Indus Valley Civilisation” (IVC).
• The study states that Steppe pastoralists around the “Volga and Don Rivers” in Russia moved towards India and came in contact with IVC populations.
• Indications at multiple sites highlight that the migrants mixed with the southern population and produced a distinctive mixture of ancestry.

What were the various population mixes that were deciphered?

• The research proceeds with the understanding that that present-day South Asians have descended from a mixture of two highly divergent populations, namely - Ancestral North Indians (ANI) and Ancestral South Indians (ASI).
• With that viewpoint, it has worked to trace the complex genetic mixing that took place in various ways to create the ANI and ASI. 
• The study has claimed to have deciphered 3 separate population groups that intermixed to form ANI and ASI. They are:

• Ancient Ancestral South Indians (AASI) – They were the South Indian hunter-gatherers. Ex: Onge (indigenous Andamanese people) 
• Iranian Agriculturalists - Pastoralists who lived near the ‘Zagros Mountains’ around 8000 BCE and had know the Indian subcontinent.
• Steppe Pastoralists - Loosely referred to as the ‘Aryans’, these people are said to have inhabited the vast Central Asia grasslands.

• The study has asserted that the initial IVC folks were a mix of the indigenous AASI population and the Iranian Agriculturalist population.

• Later, the Steppe pastoralists (Central Asians) are said to have moved southwards and mixed with the IVC population.
• Further, the people from IVC are said to have moved further south to merge with the indigenous AASI to form the Ancestral South Indians (ASI).
• During the same time, the mixture between the Steppe people and the Indus Valley people is said to have create Ancestral North Indians (ANI).
• Later, the ANI and ASI continued to mix with each other to create almost the entire ancestry of South Asian population (except some secluded groups).

What are the significant pointers?

• Castist Bias - A strong connection had also been found between the Steppe pastoralists and the priestly castes (brahmins), and cultures of North India.
• 10 out of 140 current Indian population groups that were studied were found to have a higher amount of Steppe ancestry than Indus Valley ancestry.
• Signfincant among these were the ‘Brahmin-Tiwari’ and ‘Brahmin-UP’ groups and Bhumihars - all being the traditional custodians of early sanskritic texts.
• More importantly, the general enrichment in Steppe ancestry was distinctive of the north Indian populations and was not found in south Indian groups.
• Conclusions - It can be hence be stated that, the ANI are related to Europeans, central Asians, Near Easterners, and people of the Caucasus.
• Contrarily, the ASI descend from populations that are not related to any present-day populations outside India.
• While ANI and ASI were very distinct in their origins, they are said to have mixed dramatically in India over the centuries.
• Resultly, everyone in mainland India today is a mix, albeit in different proportions of ancestry with other populations.
• Therefore, no Indian can claim to be genetically pure and any such conception is a fallacy driven by socio-political situations.  

What is the essence of the research?

• The current study is the 1^st to have co-analysed ancient individuals and the present day individuals and is claimed to be path-breaking by the researchers.
• Essentially, the study shows that there are no “pure” people anywhere — except perhaps in some very isolated and remote places like Andamans.
• We are all mixed and almost all parts of the world have seen repeated mass migrations that have deeply impacted their demography.
• Hence, the genetic studies should be liberating in a way because it should make us aware that we are all interconnected.

What are some of the criticism that rose against the study?

• The study makes the assumption that there was a possible migration and then proceeds to establish the evidence gathers into this assumption. 
• While this is indeed one of the standard research methodologies, some have claimed that analysising migratory trends by this method is faulty.
• Additioanlly, the study worked with genetic data from the pherepheral cites of the IVC as data from regions like Harappa are yet to be released.
• But the DNA at sites like Harappan are likely to have formed the core of IVC, and not having analysed them is a big drawback. 
• The study is silent about the pre-IVC population in the Indus valley, and seems to be assuming a near absence of humans in the region before 3000 BCE.
• Also, the influence of Mesolithic and Neolithic populations in the Indian sub-continent seems to the genetic pool hasn’t been probed sufficiently. 

How has DNA analysis techniques aided in revealing pre-history?

• Improvements in the DNA anylitical techniques have greatly aided the decipherment of historic migrations not just in India but around the world. 
• Recently, it was established that Europe went through two major mass migrations that changed their demography.  
• Also, the Americas before the Europen arrival in the 15^th century is said have been populated by four distinct migrations form Asia.
• On these lines, the findings about South Asia are just one part of the series of prehistory revelations that has been ushered in by DNA research.

Source: Indian Express