Dwarkesh Patel: evaluation

Transcript context

…I’m a geneticist, and I work on human history and how ancient people relate to each other and people living today. We did an interview two years ago, which ended up being one of the most popular interviews I’ve ever done. I think people found it really compelling that there’s so much about human history we don’t know and are just learning about now as a result of the kinds of techniques your lab is using. You have a new preprint that’s very exciting, and I wanted to talk to you about it. Can you give me a little bit of context on what we’re talking about today? The dream was that when this ancient DNA field started, more than 16 or 17 years ago, we were going to learn a lot about biology —about how people’s biology changed over time— by getting DNA out of ancient human remains and tracking changes over time. And that dream has really not been realized since the beginning of this field. The field has been a big success with regard to learning about human history. It’s resulted in surprising findings about human migrations —people not being descended from the people who lived in the same place hundreds or thousands or tens of thousands of years before— and mixture being common in human history, and sex-biased processes being common. And there have been things that were not expected from archaeology. The field’s been a big success from that perspective, but what’s not been successful is learning about biology and biological change. One big reason has been that the sample sizes have been too small. When you have a single person’s DNA, it provides a tremendous amount of information about history. That’s because when you look at one person’s DNA, it’s not a single person. It’s many people. It’s your two parents, your four grandparents, your eight great-grandparents, 16 great-great-grandparents, and so on. Going back in time, thousands, tens of thousands, even hundreds of thousands of ancestors are contributing to people today. When you look at the DNA of a single person’s genome or a Neanderthal genome, you have effectively tens of thousands of ancestors all represented in your data. And you can position that individual exquisitely with respect to other people from whom you have data. But when you are interested in how a particular genetic variant—that affects something like your skin pigmentation, or your ability to digest cow’s milk into adulthood, or a behavioral trait—changes over time, a single person gives you only one sample, or maybe two samples: the one in their mother and the one in their father. To get a high-resolution picture of how the frequency changes over time, you need very big sample sizes, truly very large numbers of people. We just didn’t have that until the last few years. What motivates the study we’re talking about today, and the work that hopefully a number of groups will be doing in the coming years, is the fact that we now finally have those numbers. We can do something with the data to see how frequency changes over time.…

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