David Reich: belief

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…We don't know. There are debates even about that. One example I've heard archaeologists I work with think about is the Comanche in the US Southwest. They were another horse-based, expanding group. They expanded dramatically in parallel to the Spanish expansion and alongside the US expansion, before encountering the militarized United States at some point. It’s local. There’s local bands of people expanding. They go on campaigns. They expand to certain areas. The Beaker people and the Corded Ware people were contemporary to ancient Sumer and a lot of the Egyptians we actually have written history from. It's not so ancient. They weren't writing, but they were contemporaries of these people not so far to their south. So we really don't know what was going on. We really don't know what was going on, but imagine if you were part of a community where there's a certain culture. We’re getting this from reconstructions from Indo-European myth. That’s probably the class of cultural shared knowledge these people were operating from because we think these people were the spreaders of Indo-European languages in this part of the world. At a certain age, males would band together and go on raiding parties and so on, and then maybe settle down later in life. You can imagine a process where, built into the culture, you have a process of expansion, exploitation. One thing that's really interesting that has actually emerged in the last few years—and was not really strong at the time that I wrote my book—was an understanding of the relationship between the Yamnaya and groups like the Corded Ware and the Beakers. The Yamnaya are these groups that thrived between about 5,300 and 4,600 years ago in the steppes north of the Black and Caspian Seas. They're probably the first people to domesticate the horse. That's arguable. They use the horse and the cart, which was newly invented, and the wheel to exploit the open steppe lands and be able to economically expand much more rapidly. They're the world's first extreme mobile pastoralists, but they can't get further than the steppe. They expand into Europe. They expand into the little island of the steppe that's in the Great Hungarian Plain in the Carpathian Basin, and they stop. They can't expand their way of life to the forested parts of Europe, which is most of Europe. Somehow, the ancestry of the Yamnaya gets absorbed by the Corded Ware group, and then later the Beaker group. That takes it further through Europe. But the Corded Ware group is quite different from the Yamnaya culturally. In fact, a lot of archaeologists think that they're so different, they can't be the same. They have some shared features, but the Corded Ware have many different traditions. One possibility is that the Yamnaya expanded and they encountered early Corded Ware. The Corded Ware learn some of the adaptations of the Yamnaya. Then they actually take Yamnaya women and absorb them into Corded Ware mostly male communities. ed and they encountered early Corded Ware. The Corded Ware learn some of the adaptations of the Yamnaya. Then they actually take Yamnaya women and absorb them into Corded Ware mostly male communities. They create a new community and that group expands. One of the mysteries of the Yamnaya expansion was that everybody had this cognitive bias to think this is very male driven. People have these Indo-European notions of male-centered mythologies and so on. This must be an extremely male-centered migration. You look at the genetic data. You look at the Y chromosomes, which track male migration, and the mitochondrial sequences, which are more sensitive to female migration. It looks like the steppe expansion from the east to west involves both sexes. Both males and females expand. People have found this confusing. There's been a lot of incredulity about this. Most people expect to see that it's an even movement of males and females, but it's quite clear that the bias is not so strong. We think the most likely explanation for what's happening now is that it actually is a male-biased process, but it's one that's interrupted. So the Yamnaya expansion is very male-biased. It expands to the edge of the range. They encounter the Corded Ware complex people. Then what happens is the Corded Ware complex people interact with the Yamnaya people and in fact the Yamnaya people actually lose out in that interaction. In fact, the Corded Ware males absorb and take Yamnaya females. They actually also take farmer females. You actually see these sites in early Corded Ware sites in Czechia, where both things are happening. Females from farmers and females from Yamnaya are being absorbed into the Corded Ware community. Then they expand further. So what you actually have is a two-step process. You have a male Yamnaya expansion, and then that ancestry from the steppe is carried further through females being absorbed into the Corded Ware. Then you have another male-driven expansion under the Corded Ware and so on. That brings both female and male Yamnaya lineages West, but not always with the Yamnaya ancestry being associated with the intuition that you would think it's domination. The same sort of parallel thing in another part of the world is what you see in remote Oceania in the Southwest Pacific. Look at Vanuatu, which are some of the first islands that people got to about 3,000 years ago in the Southwest Pacific. Moving to this other part of the world, if you look at New Guinea and Australia, people are there almost a little bit after 50,000 years ago. People are in the Solomon Islands and the Bismarck Archipelago to the east of New Guinea, maybe 35 to 40,000 years ago, and they stop. The Pacific has all these fertile places that are good places for people to live. It's completely empty of people until 3,000 years ago. Suddenly, these people from Taiwan go through the Philippines. They skirt the edge of New Guinea and the Bismarck Archipelago. They get to Vanuatu and Fiji and Tonga and New Caledonia and Samoa about 3,000 years ago, super rapidly in the guise of something called the Lapita cultural complex. inea and the Bismarck Archipelago. They get to Vanuatu and Fiji and Tonga and New Caledonia and Samoa about 3,000 years ago, super rapidly in the guise of something called the Lapita cultural complex. If you look at the DNA of the people from this, they're almost entirely East Asian in ancestry. They look like early Taiwanese people. Today people in Vanuatu and Fiji and Tonga and New Caledonia have only 10 percent of this DNA. So something else happened afterward. The first people are almost entirely East Asian via Taiwan and the Philippines. Then you look at later DNA from the same part and 2,500 years ago, 500 years after the initial arrival, there's mass movement of Papuans in a male-driven way from New Guinea and the Bismarck Archipelago into Vanuatu. You have people with overwhelmingly Papuan ancestry from New Guinea coming into Vanuatu. That's the origin of the ancestry that's overwhelmingly there in Vanuatu, New Caledonia today. So there's a two-step process. The initial step is East Asian ancestry and these people who invented outrigger canoe technology and long-distance sailing. Then the technology becomes adopted by Papuans, who are using this culture for the next few hundred years. We can see them trading back and forth between the Bismarck Archipelago and Vanuatu. By the end, this culture is carried out by Papuan ancestry. Males from this group then spread into New Caledonia and take local females. But the ancestry is flipped from the way that people have this cognitive bias that it should be. People think, “Oh, it should be the East Asian males somehow dominating the local females or something.” You see the reverse. This is what's going on. It's very complicated and subtle. When you actually see evidence of males and females behaving differently, it proves that there's socially asymmetric behavior of two groups as they interact. What it means is confusing. It could be female mate choice. It could be violence. It could be genocide. It could be different patterns of male and female dispersal, with groups who travel being of one sex or the other. We can look for clues in the genetic data. Certainly in concert with the archaeology, we can maybe figure out more.…

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