Large-Scale DNA Study Reveals Where People From India Originally Come From

The history of humanity is vast, and there are still dozens of angles that have not been approached scientifically. Studying human DNA is one of the many ways to understand past communities and societies, and looking at different cultures only adds to the collective knowledge that scientists have about the past.

India is a Blind Spot

India is one country that has, surprisingly, been left out of many studies regarding past cultures and humans. India is the most populous country in the world, with more than 1.4 billion residents on the subcontinent. It is closely followed by China as the most populous country, though India is significantly more densely populated.

The fact that it’s the most populous country makes the gap in knowledge surrounding Indian DNA a surprise. Genetic studies have often focused on other regions of the world, with notable focus being paid to Anglo-Saxon countries, as well as countries in Africa.

Humans Originate From Africa

This focus centers around the fact that humans are believed to have originated from Africa, with all other cultures and societies stemming from individuals who left the continent and settled elsewhere. The change in scenery accounts for many physical features that distinguish different cultures, including hair texture, skin and eye color, and social structures.

If it’s widely believed that humans originated from Africa, though, it still doesn’t explain the disregard for the subcontinent of India. Scientists have, up to this point, even been unsure exactly when humans immigrated from Africa to India, while other countries have a clearer timeline of movement.

A Study Seeking to Close the Knowledge Gap

A study that was recently published examining thousands of years of DNA seeks to close that knowledge gap in a big way. Scientists out of University of California Berkeley sequenced the DNA from more than 2700 people in India.

The study was wide-ranging, looking at individuals from most of the geographic regions in India, both rural and suburban. They looked at speakers of all the major languages in India, and the different tribal and caste groups in order to capture the diversity of the country.

Understanding Indian Genetic Code

This thoroughness as far as sampling goes is very important for the goal of the study, which was to understand the genetic code of India better. India has nine identified subcultures through the continent, and countless different microcultures among the different regions, tribes, and geographic areas.

Understanding the difference in genetic code between all these different types of people is crucial to understand Indian people as a whole. In a country as densely populated as India, it’s disingenuous and ignorant to consider the entirety of the population as one homogenous mass.

The Goals of the Study

Ultimately, the study sought to understand several key questions that, thus far, have gone unanswered in regards to the population of India. Among these questions is the question of when modern humans first arrived in India from Africa and whether they were part of the major mainland migration out of the continent.

It’s entirely possible that modern humans immigrated to India earlier than many other cultures, meaning that they could have left via a coastal route, rather than the mainland migration that many other cultures did.

Looking for Trace Evidence

Most importantly, the study sought to discover what trace evidence remained of now-extinct archaic humans in Indian populations. Traces of ancient populations such as Neanderthals and Denisovans linger in many cultures in these older parts of the world, and it tells an important story of these ancient peoples.

“These analyses provide a detailed view2 of the population history of india and underscore the value of expanding genomic surveys to diverse groups outside Europe,” the report reads. This emphasis on looking beyond white, Anglo-Saxon cultures clearly drove the study, as revealed with this preprint report.

Previous Research into Ancestry

Previous research into Indian populations has shown that most Indians derive their ancestry from three ancestral groups: descendents of ancient Iranian farmers, herders from the Eurasian steppe region, and indigenous South Asian hunter gatherers.

The first two groups are suspected to have moved to India from their respective regions between 5000 and 2000 BCE. This gives quite the genetic history of peoples in India, and that’s without considering the fact that the South Asian hunter gatherers are suspected to have been in the region for much longer than the other two groups.

Variability in Ancestry Revealed

The new study reveals significant variability in the ancestry of modern Indian individuals, even among those three clear groups. Patterns emerged with a wider scope of data, clarifying some long-asked questions regarding Indian genetics.

For instance, the proportion of individuals associated with Andamanese hunter-gatherers were highest in the south, and lowest in the north in India. Additionally, the proportion of individuals with these specific genes was higher among certain language and caste groups through the southern region.

The Interconnectedness of Ancient Cultures

The study points to this as a revelation as far as mixture events in Indian culture. “This highlights that the ancient admixture events are related to the spread of languages and the history of the traditional caste system in India.”

This helps to draw conclusions regarding other transitions, as well. For instance, modeling how ancient DNA extracted from Iranian groups could risen in present-day Indians, the researchers found that the most likely scenario behind the variation was an influx of farmers from Sarazm, an ancient agricultural hub.

Mixture Goes All Ways

Other archaeological studies have previously pointed to trade connections between Sarazm and South Asia, and this was not a one-way link. Indian DNA has been found in samples of modern-day Iranian individuals as well.

This cross pollination of genetic code reveals exactly how interconnected these ancient cultures were. “Societies were far more connected in deep time than most have given them credit for,” commented Mcihael Frachetti, an archaeologist at Washington University in St. Louis.

The Diversity of Ancient DNA in Indians

The most surprising discovery out of this study, though, regards the amount of genomes that portrayed a wide diversity of Neanderthal and Denisovan genes, compared to other sampled populations.

The study found that about 91$ of worldwide Neanderthal sequences can be seen in India, and approximately 51% of Denisovan sequences are unique to India. This helps researchers understand how India fit into the development of the greater worldwide population of modern humans.

The Central Question of Migration

Lastly, as far as the question regarding timeline of immigration out of Africa, the researchers discovered that most of the genetic variation in Indians stemmed from a single major migration out of Africa that occurred about 50,000 years ago.

There were, of course, earlier migrations of smaller communities out of Africa that made their way to the Indian subcontinent, but the results of the genome research revealed that these smaller migrations contributed little to the modern-day genetic code of Indians.

Further Questions to be Asked

The research reveals a fascinating new aspect of human genetics, closing a data gap that has been there for far too long. And while this is a great start to further understanding the diversity of ancient cultures, it is far from the end of the questions that need to be answered.

Scientists have their work cut out for them as far as genetic research goes, and only by asking questions going forward will any further knowledge be attained. Understanding our modern cultures requires looking far into the past, and doing so with open eyes and minds.