All Indians share about 50 percent of their genetic ancestry with the first migrators who came out of Africa about 65 thousand years says a book, Early Indians by Tony Joseph. His work is indeed fascinating as it works with the new science of population genetics. Here I try to present the main findings of genetic sciences enshrined in the book under our study. Indian population is born from four major pre-historic migrations.
The first being out of Africa is also the one that populated the world. This migration took the coastal migration route. When these migrators arrived in India, they did not find any other humans as they sought to settle down. No matter what our language, no matter our caste or religion, all Indians share 50 to 60 percent of their genes with these early Indians.
The second migration happened 9000 years ago that came through West Asia. This population was related to agriculture. It, therefore, relates to the beginning of agriculture. It also includes domestication of animals. India in Lahuradewa in Uttar Pradesh on the banks of Ganga , we have people experimenting with wild rice. We can find a first agricultural settlement in Balochistan which is under Pakistan today. This agriculturist mixed with earlier Indians and agriculture spread all round in the region.
It is from this population that we have the Harrapan civilization. Harrapan civilization flourished for about 700 years. Harrapans are ancestors of both north and south Indians. But their linguistic heritage seems to rest with the south Indians as north India was swept by Indo-European linguistic group ( early sankrit ). But their cultural heritage is across India both north, south, east, west. Harrapan declined because of a long drought and they left their cities and seem to have mixed with other Indians of that time.
The third migration occurred about 3500 years ago. This was result of agricultural expansion in China (East Asia) which resulted in the entry of austroasiatic linguistic families into India. It brought people speaking languages like mudari etc.
The fourth migration consists of Indo-European linguistic speakers who came to India about 3000 to 4000 years ago. They are known as Aryans. Between 2000 BCE and beginning of the common era, there was mixing of all Indians. This is genetically proved. Only one group of Indians seems to have escaped this mixing. They are Adamanites. At the end of the first century AD or CE, we find that there begins a kind of non-sharing of genes. Hence, this must be when endogamy became the way of life and we can say it was a time when caste system began to take shape.
These genetic studies show that Indian did not come from common genetic stock. We are a result of mixing several migrations. No one group of Indians share genetic purity . Hence, there lessons for us all Indians in this genetic findings especially those who essentialize and fix Indian-ness in the vedic age alone. We have the Harrapans as well as the early Indins whose influence and legacy cannot be kept aside.
There appears to be stark difference in cultural practices between the Harrapans and Aryans. Harrapans do not seem to have to much belief in God but have great respect to their women. The Aryans are profoundly religious. God Indra seem to share similarity with Greek God Zeus. Aryans appear to be patriarchal and steadily established endogamy. Although, they did have Goddesses like Saraswati, Usha etc. It seems that women were mainly confined to their homes. Hence, caste like system begin to show at the end of the first century CE .
Therefore, we have to agree in the light of population genetics, India and Indian civilization is a product of inward migrations. The out of India migration theory proposed by some right-wing scholars is not backed by genetics. If this was true, than we should be able to find the early Indian gene spreading out of India. There is no genetic spread in that direction but what we have is the opposite . The genetic direction is leading into India. Hence, there is no scientific foundation for out of India Aryan migration. What we find is a genetic bases for migration into India and great genetic mixing of the Aryans with other Indians of that time and great genetic freezing at a later time, particularly in the 1st century CE (caste formations)