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> We can reject some ideas (like innate genetic susceptibility) on the basis of scanty evidence This is an article about genetic selection due to the plague in

> We can reject some ideas (like innate genetic susceptibility) on the basis of scanty evidence This is an article about genetic selection due to the plague in Europe. Lol.

AlotOfReading 4y ago
The idea I'm talking about here is an older one that virgin soil epidemics devastated American populations because they were innately susceptible to them, often as a result of genetic homogeneity or something. That's not supported by decades of research into those kinds of questions. This article is talking about selective pressure as a result of epidemics, which is absolutely a thing.
- chrisco255 4y ago
  Selective pressure impacts genetics though, so doesn't it come full circle to the same argument?
  - AlotOfReading 4y ago
    No, it's best to think of them as unrelated. On one hand, you have an argument that "virgin soil" epidemics in the columbian exchange were deadly because Native Americans had no genetic diversity (not true) and thus effectively no differential susceptibility. That's a complex narrative causally linking many different processes and observations over centuries. On the other, you have a statement that disease can cause selective pressure. The only relationship is that they're both about genetics and disease.
    - inglor_cz 4y ago
      "Native Americans had no genetic diversity (not true)" That feels a bit like a strawman. Few people would claim that Native Americans had no genetic diversity. But the claim that they had less genetic diversity than Old World populations is plausible. After all, there was a massive population bottleneck/founder effort in their relatively recent history. The groups of people who walked across the Beringia and settled the Americas had to be small-ish, with their total size not exceeding several tens of thousands. Siberia is, until today, very sparsely populated. Compared to the Old World, the New World population squeezed through a population bottleneck of perhaps 0,1-0,5 per cent of the total human population of that time. It then started diversifying again, but genetic drift is a longish process.
      - AlotOfReading 4y ago
        I've seen it (incorrectly) described before that native Americans were practically clones from a genetic perspective, so it's a relatively mild strawman. Founder effects did reduce genetic diversity of native Americans and it takes a long time to rebuild that. We actually use this to track historical migrations. It's also worth pointing out that a very similar process affected everyone outside Africa. That's why the sharpest dropoff in genetic diversity is between Africa and everywhere else. Not all diversity is equal or generates at the same rate either and the highest diversity genes tend to be the ones related to disease resistance /immune system functioning. Native Americans actually have several new alleles here that apparently evolved independently in the new world. When you talk about specific things like the MHC, they're still quite diverse and not too far off from similar European populations.

> We can reject some ideas (like innate genetic susceptibility) on the basis of scanty evidence This is an article about genetic selection due to the plague in Europe. Lol.

AlotOfReading 4y ago

The idea I'm talking about here is an older one that virgin soil epidemics devastated American populations because they were innately susceptible to them, often as a result of genetic homogeneity or something. That's not supported by decades of research into those kinds of questions. This article is talking about selective pressure as a result of epidemics, which is absolutely a thing.

chrisco255 4y ago
Selective pressure impacts genetics though, so doesn't it come full circle to the same argument?
- AlotOfReading 4y ago
  No, it's best to think of them as unrelated. On one hand, you have an argument that "virgin soil" epidemics in the columbian exchange were deadly because Native Americans had no genetic diversity (not true) and thus effectively no differential susceptibility. That's a complex narrative causally linking many different processes and observations over centuries. On the other, you have a statement that disease can cause selective pressure. The only relationship is that they're both about genetics and disease.
  - inglor_cz 4y ago
    "Native Americans had no genetic diversity (not true)" That feels a bit like a strawman. Few people would claim that Native Americans had no genetic diversity. But the claim that they had less genetic diversity than Old World populations is plausible. After all, there was a massive population bottleneck/founder effort in their relatively recent history. The groups of people who walked across the Beringia and settled the Americas had to be small-ish, with their total size not exceeding several tens of thousands. Siberia is, until today, very sparsely populated. Compared to the Old World, the New World population squeezed through a population bottleneck of perhaps 0,1-0,5 per cent of the total human population of that time. It then started diversifying again, but genetic drift is a longish process.
    - AlotOfReading 4y ago
      I've seen it (incorrectly) described before that native Americans were practically clones from a genetic perspective, so it's a relatively mild strawman. Founder effects did reduce genetic diversity of native Americans and it takes a long time to rebuild that. We actually use this to track historical migrations. It's also worth pointing out that a very similar process affected everyone outside Africa. That's why the sharpest dropoff in genetic diversity is between Africa and everywhere else. Not all diversity is equal or generates at the same rate either and the highest diversity genes tend to be the ones related to disease resistance /immune system functioning. Native Americans actually have several new alleles here that apparently evolved independently in the new world. When you talk about specific things like the MHC, they're still quite diverse and not too far off from similar European populations.