 One question that has always fascinated human beings is how we really got where we are today. Who are our ancestors? Where did they come from? How did ancient human populations mix with each other to eventually form modern humans? Over the years, researchers have carried out several studies to uncover the answers to these questions. One recent study attempts to trace the ancestry of the people living in southern Central Asia, which of course includes India. 92 researchers from diverse fields and institutes collaborated for this study. They analyzed DNA samples from both ancient human populations as well as modern-day humans. They looked at different Asian countries from Iran to Tajikistan to South Asian countries. Since there were no samples from the Indus Valley civilization itself, the researchers studied the DNA of groups which were in cultural contact with the valley. These samples act as good proxies for the people of the Indus Valley civilization. Now we go to Prabir Purkayasta who will help us better understand the findings of the study. Welcome Prabir. So firstly, this map here is basically the key to the findings of the study. So before we start, before we really delve into the findings, can you just explain the larger picture this map shows to us? I think what we are seeing is unraveling some of the aspects of ancient migrations which earlier were not clear to us. Partly because the archaeological evidence, the linguistic evidence is rather difficult if the times are really 10,000 years, 8,000 years back. So what we are seeing is the ancient DNA which is deposited in bones which we are now able to extract. We are able to multiply that DNA much more so that we can study it, make copies of the DNA, study it at much more depth and length. We are able to see ancient migration patterns. We are also able to date them much better. So this study in fact shows that the picture we have had of ancient migrations is not a one set of migrations but really a series of migrations out of which two major ones except the ancient hunter-gatherer population which came out of Africa, spread across Eurasia and also other parts of the world. There are two other major migrations have taken place. One migration is of the farmers and that you see spread across Eurasia starting from what is called the fertile crescent which is the place where you have the Euphrates Tigris River, the Levant on one side and Iran on the other. So this is one part where you can see from farming you have led also to the expansion of farmers going to different places from Europe to Asia, different parts of Asia. This is one major migration. The second is of the pastoralists, the nomadic pastoralists who have really come from the Eurasian steppes, a little higher up between the Caspian Sea and the Black Sea. And then that migration overlays the earlier migration and it is these two migrations which have shaped largely the population of Eurasia. More Western Europe, Europe, Northern Europe and South Asia and Central Asia, of course also West Asia. But East Asia is really something which has not come into this picture as yet which I think still needs to be seen. So now let's focus on South Asia and Central Asia. So here there have been a lot of interesting theories in the past about where our languages came from, where agriculture came from, was it the Anatolian farmers or was it the Iranians or was it the steppes, people from the steppes. So does this study really give us some sort of conclusive answer as to where, how the Indus civilization really formed and how we got these things that we have today? Well, I don't think any answer is going to be a complete definitive answer. It's also going to raise a lot of other questions. But I think some things are clear. We would have expected that from fertile crescent where actually we have the start of farming in the world. Of course, this is not the only place where farming started. You have maize which starts in Americas. You have also rice which is not a part of this. So there are multiple places from which farming started. But when you look at wheat, barley, some of these crop, the ones which are in Europe and also in large parts of Asia, including South Asia, then we get one set of answers, which is that this is the fertile crescent from Anatolia to Iran. This is the place from which farming starts and wheat is really domesticated here, if you put it. There are various earlier varieties of wheat which are domesticated and this is the great Neolithic farmer-led revolution which leads to influx of the farmers. And this is also called what's called Demic expansion, demographic, geographic expansion, if you will, where the farmers travel with farming. It's not just cultural expansion that people pick up farming from others, hunter-gatherers become farmers. That's not the way it happens. The farmers also go. And it's a mixture of hunter-gatherers taken to farming and the farming population going that creates the new populations that we see. So this marker is very clear in this entire region, from Iran to South Asia, particularly what we will call, what would be called the Indus periphery in this paper because they don't have ancient DNA really from the Indus Valley civilization. Once we get the ancient DNA, we'll have much more definitive answers. They're conjecture and this conjecture seems to be fairly well brought thought out because it also looks at other ancient populations that existed in different parts, but also other parts of India. It seems that we have from the present genetic evidence to the ancient DNA evidence that we have a strong signature of Iranian farmers who came with wheat into North India, North-West India. We have also the first agriculture we see in India which is Mehergarh and that's just below the Bolan Pass. So it's clear connection to Iran is there and Iran, Zagros mountains are the place where originally near that area you have farming which comes across the Bolan Pass. So this makes a very convincing picture, bolstered, but other things we know which is archeological evidence. Now linguistic evidence is not possible at this age because you really talk of something which happened five to 7,000 years back. So there's no linguistic evidence that we can see unless we decipher the Indus Valley seals. But looking at the genetic signature, the archeological evidence, it's very clear the Neolithic farmers came from Iran into South Asia from of course North-West and then come down the Indus Valley and the Indus periphery signatures if you take what we see in the Sword Valley where they've got some ancient DNA which is about 1200 BC. So much later has steps influenced and you see what is called the B.A.M.C. area, so Bactria Magrania area. Then that area, it's very clear that this mixture is what probably is what we would also see if we went to the Indus Valley civilization. Interestingly, they have some South Asian flows into this area. So it was not just a one-way flow, it was two-way flow, but predominantly farmers coming into this area. Then of course there is trade, there are some Indus Valley artifacts we find in this region. So there is a back and forth flow, but that takes place after the initial expansion of farming which seems to have originated for Iran. And that's as I said, 5,000 to 7,000 years back. And this is the ancient migration about which we have not really had earlier too much of evidence. And earlier focus has been on languages mostly which then takes us to the Eurasian steppes. Well, that's the other migration, as you rightly said. Yes, we have focused really on Indo-European group of languages. And then there has been this debate, did it start from Anatolia, as you called the Anatolian hypothesis. That was the expectation that Indo-European languages spread with farming. That was one of the postulates made by Cavali Sforza, who was one of the pioneers of using statistical methods into this and also looking at genetic evidence. So very scanned genetic evidence and looking at blood groups, which as you know is a very crude indicator of genealogies if you will. But what was also argued that it would be very surprising if something else replaced this population because farming population may replace other populations is difficult to think of. And language being changed without large replacement of population was thought to be difficult. So there was this Anatolian hypothesis that language came really from Turkey and what is current modern Turkey, the Anatolian plateau and from there spread in different directions and that's in the European group of languages, the homeland of the Indo-European, proto-Indo-European language if you will. Now this has been clearly now shown, that's not true. The other hypothesis which is always there, in fact most of the historians, archeologists favored that evidence was that it comes from essentially what would be called the Eurasian steps. The areas I said earlier between the Caspian Sea and the Black Sea and this was some of the earlier Soviet historians and archeologists had postulated the what's called the Kuragan hypothesis which is also called the Yemeniya hypothesis because Yemeniya are what are called pit burials, people are buried in pits over there. So this is the origin of the Eurasian step people who then spread out with their language both across Central Asia and then down to South Asia and also to Europe. So this has been that origin which is overlaid on the earlier Neolithic farmers, the Indo-European group of languages. So proto-Indo-European group of languages really came most possibly with the horse and the chariot both of which would mean what I would call as war like dominance and therefore mobility being a very important part of war, therefore dominating to war and becoming the ruling classes if you will of a very large area carrying their language which is then the second migration we talked about which shapes the current population. As I said over two thirds of Eurasia, this is the population we see and also Central Asia and of course South Asia. Of course you will see a gradient of what would be called the South Indian ancestral South Indian population and the ancestral North Indian population. The gradient is because the mixing is really taking place from the North to South. If it takes from North to South obviously you will get that gradient and you will also see because India has a caste system endogamy and so on. So there are also upper caste groups which carry more of the Central Asian step signatures than other groups do. Of course the South Asian groups carry it as you go down, carry it less and less but it is not to be thought that the Central South Asian groups with the quote unquote original hunter gatherer population that very much a part of the Iranian influx as well and there is some evidence of the Iranian languages really are probably related to the original Iranian Neolithic farmers and that's the language groups that you get pushed down as the steps people come in. So this is the mixed picture but it's certainly a much clearer picture, more consistent with what the archaeological evidence, the linguistic evidence and what the historians have postulated based on what we think how societies evolve and that's very important. It's not that the genetic evidence is conclusive, it has to be taken in line with all the other evidences we have to have a coherent and meaningful picture of the past rather than fixing or getting fixated only on a specific view based on either genetics, archeology or linguistic evidence. You have to combine all of it and look at how societies could have evolved and then come to some conclusion. So if we look at the picture of Europe we see something very similar to what we've seen in Asia that there have also been two major migrations here of the agriculturists as well as of the pastoralists. So can you tell us about that? Yeah, I think the picture as you said is very, very similar. We have an initial expansion from the Anatolian plateau which is really a part of the fertile crescent, the northwest part if you will and from there you go to western Europe and you go to northern Europe. So that's a very easy path that you can see and it is of Neolithic farmers. It confirms the Demic expansion theory except that this Demic expansion does not take place with Indo-European language speakers or the Proto-Indo-European language speakers. It's really the Neolithic farmer. So that part of the thesis of Demic expansion is also confirmed here. The Neolithic farmers are the major first expansion and as the hunter-gatherer population comes in contact with them, they're absorbed into this, so mixtures start taking place. At some point they also adopt farming and there is also an explosion of their expansion. So you see all of this mixing, very similar to what you see in South Asia and Central Asia, very similar to that, particularly South Asia and Europe seem to follow a very similar pattern mainly because of agriculture. So you see that first part of it is relatively very, very similar. Then you have the next excursion, the next incursion if you will, of the Central Asian people which come from the Yemeni culture again and then you see that coming into what would be called the Corded Ware people who used a certain kind of pottery and you can see that there's a heavy incursion of the steps signature over there. There is a, you can see a significant step signature over there, also very close to the Central Asian steps that we are talking about which is really the region also above Black Sea. So that's not very far from what we are talking about. So it is not surprising to see that, that incursion as it were into Europe and then it spreads out. It spreads west, it spreads north and it also spreads to Southern Europe. So very very similar phenomena to what happens in South Asia as well. So it's interesting, the two thirds of Eurasia in that sense have a very common historical, you know, migrae, historical set of migrations which parallel each other. In fact, that even the timings are not very dissimilar. They may be give or take a thousand years so that's really not a very significant number in this context and it spreads slowly when it comes to the Neolithic farmers, spread faster when it comes to the steps people because they're mobile and you see therefore the whole picture of the Western Eurasian part including South Asia, Central Asia is actually very very similar in terms of what happens. So it's also very interesting look at the unity of human history if you will. Of course, this is not the Americas, this is not Eastern Asia, this is not Australia. So there are still a lot more to be explored but the picture that is emerging with agriculture, with the Indo-European group of language that we know, I think is a very fascinating one and it does for us. All of us who are interested in who we are, what we, where we came from, looking at it scientifically not mythologically that we all originated from some mythic creation of 2004 BC or from somewhere from Brahmahs, various parts of the body. If you don't take such mythological exercises but believe in looking at our own history, the sciences, I think the unity of the human civilization is very very important also to focus on. That we all came from Africa, then we have had this two major expansions which have taken place in Eurasia and this is what has shaped what we know the modern society to be or a major part of it. Of course as I said, let's not forget there is still East Asia, there is still Southeast Asia, there's still the Americas but we have a very broad picture of what this part of the world has seen. So thank you for being, for talking to us about this and for explaining this map to us and thank you for watching this clip.