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Gli ultimi tweet di @johnhawks
14 apr 2023 · John Hawks. @johnhawks. “The most marvellous aspect of the problem raised by the recognition of the Neanderthal man as a distinct type is his apparently sudden disappearance…. A more virile form extinguished him.”—Arthur Keith (1920) ALT. 12:17 PM · Apr 14, 2023. ·.
18 mar 2022 · John Hawks. @johnhawks. Today's great apes, including chimpanzees and bonobos, two species of gorillas, and three species of orangutans, are a small surviving remnant of the diversity of apes that once existed. Each evolved in ways that helped them survive, just as our ancestors did. 10:04 AM · Mar 18, 2022·TweetDeck. Retweets. 65. Likes.
- Our Growing Population
- Finding Selection in The Genome
- Linkage Disequilibrium and Selection
- Testing Acceleration
- How Much acceleration?
- What Is All This Selection for?
- Conclusion
- References
Human populations have been growing rapidly during the last 50,000 years or so. That increase began around the time of the Upper Paleolithic, as documented by archaeological evidence. There was a later massive increase during the Neolithic. This agricultural transition actually was quite heterogeneous: earlier in West Asia and China, later in Europ...
Now, it comes to a problem of how we can see recent mutations that have been selected. A genome scan is based on things that vary, not things that are fixed. So we are looking at some window of frequencies. In our study, that was a window from around 22 to 78 percent. Before we go too far, it is important to point out that an adaptive gene will be ...
Now, I need to say a few words about how we find these genes when we scan the genome. The International HapMap consists of a list of over 3 million single nucleotide polymorphisms (SNPs) taken from a sample of people with ancestry in Northern Europe, West Africa, and East Asia. When we look at a sample of a long stretch of DNA from several people, ...
At this point, we have a theory that predicts acceleration of new adaptive variants, and we have data that appear to show a very fast recent rate. But we haven't yet directly tested the hypothesis of acceleration. We chose a null hypothesis approach. After all, the rate of change looks like it has been very high recently, but what it if were always...
Down at the bottom of the graph, you see the predicted number of selected variants over our window, under the hypothesis of population growth—roughly the demographic growth that really happened to humans. And here you see, that there are many, many fewer of these predicted, and in fact over the long course of human evolution, the rate would have be...
We know something about the functional categories of genes inferred to be under selection; we are studying this now. We expect it will keep us busy for some time. In a general view, they illustrate the idea that changing cultures and ecologies have been important in changing the pattern of selection. For example, many of the selected genes are invo...
I hope that this essay gives an introduction to the work we have done. This was based on a presentation about the research I gave earlier this year. There are many missing ends, and I'll be adding more information over the next several days about ways of testing for selection, as well as some of the more surprising implications of our research. I'v...
Hawks, J., Wang, E. T., Cochran, G. M., Harpending, H. C., & Moyzis, R. K. (2007). Recent acceleration of human adaptive evolution. Proceedings of the National Academy of Sciences, 104(52), 20753–20758. https://doi.org/10.1073/pnas.0707650104
Gli ultimi tweet di @johnhawks
11 mag 2022 · John Hawks Twitter. I'm a paleoanthropologist exploring the world of ancient humans and our fossil relatives.
