I have always been curious about the effects of mass-death on human genetics. Is large scale death from plague, war, or natural-disaster likely to have much effect on the genetics of cognitive architecture, or are outcomes generally too random? Is there evidence for what traits are selected for by these events?
Too random to have much effect, I should think. And at the same time, not awful enough to reduce the population to the point where drift would become important. Unless we’re talking asteroid impacts.
One can imagine exceptions. For example, if alleles that gave resistance to some deadly plague had negative side effects on intelligence, then you’d see an effect.
Note that negative side effects are much more likely than positive side effects.
I know of some neat anecdotal exceptions. Von Neumann got out of Germany in 1930, while the getting was good. When a friend said that Germany was oh-so-cultured and that there was nothing to worry about, Von Neumann didn’t believe it. He started quoting the Melian dialogue—pointed out that the Athenians had been pretty cultured. High intelligence helped save his life.
I’m also interested in Nanani’s question below, with a specific emphasis on human-caused mass death selecting for specific characteristics. For example, the Cambodian purges of intellectuals or the Communist purges of successful businesspeople. Are these too tenuous a proxy for genes to cause long-term change in alleles, or did the Cambodians and Communists do long-term harm to their genetic legacy?
Seconded, but with a request for contrast, if possible, with human-caused mass-death such as invasion by conquering hordes. What effect do such phenomena have at the genetic level wrt cognition, as opposed to cultural or lingustic transmission?
And what about human-caused mass death selecting for specific characteristics? For example, the Cambodian purges of intellectuals or the Communist purges of successful businesspeople. Are these too tenuous a proxy for genes to cause long-term change in alleles, or did the Cambodians and Communists do long-term harm to their genetic legacy?
Purges in Cambodia might have changed average genotypes because they hit such a high fraction of the population. Generally it’s hard to change things much in one generation, though—particularly because of loose correlations between genotypes and dreadful political fates. In the future dictators should be better at this. Now if Stalin had taken all the smartest people in the Soviet Union and forcibly paired them up, artificially inflating assortative mating for intelligence, you would have seen an effect. If you were a billionaire, you could maybe bribe people into something similar.
In AD175 Marcus Aurelius brought 5,500 Sarmatian heavy cavalry warriors to northern Britain where, after twenty years service, they “settled in a permanent military colony in Lancashire” which was “still mentioned almost 250 years later.” You remind us of the possibility that the colony could have influenced the legend of King Arthur, and go on to add something new: it also “could have introduced several thousand copies of that hypothetical allele into Lancashire” and that the average Englishman “might be mostly Sarmatian in a key gene or two.” I’m English, and intrigued! Are you able to expand on this? (Book pp. 146-148) I hope it is something good like increased unruliness (independence streak) and aggressiveness in battle and not something naff like Sarmatian lewdness...!!
I have always been curious about the effects of mass-death on human genetics. Is large scale death from plague, war, or natural-disaster likely to have much effect on the genetics of cognitive architecture, or are outcomes generally too random? Is there evidence for what traits are selected for by these events?
Too random to have much effect, I should think. And at the same time, not awful enough to reduce the population to the point where drift would become important. Unless we’re talking asteroid impacts.
One can imagine exceptions. For example, if alleles that gave resistance to some deadly plague had negative side effects on intelligence, then you’d see an effect. Note that negative side effects are much more likely than positive side effects.
I know of some neat anecdotal exceptions. Von Neumann got out of Germany in 1930, while the getting was good. When a friend said that Germany was oh-so-cultured and that there was nothing to worry about, Von Neumann didn’t believe it. He started quoting the Melian dialogue—pointed out that the Athenians had been pretty cultured. High intelligence helped save his life.
I’m also interested in Nanani’s question below, with a specific emphasis on human-caused mass death selecting for specific characteristics. For example, the Cambodian purges of intellectuals or the Communist purges of successful businesspeople. Are these too tenuous a proxy for genes to cause long-term change in alleles, or did the Cambodians and Communists do long-term harm to their genetic legacy?
Seconded, but with a request for contrast, if possible, with human-caused mass-death such as invasion by conquering hordes. What effect do such phenomena have at the genetic level wrt cognition, as opposed to cultural or lingustic transmission?
And what about human-caused mass death selecting for specific characteristics? For example, the Cambodian purges of intellectuals or the Communist purges of successful businesspeople. Are these too tenuous a proxy for genes to cause long-term change in alleles, or did the Cambodians and Communists do long-term harm to their genetic legacy?
Purges in Cambodia might have changed average genotypes because they hit such a high fraction of the population. Generally it’s hard to change things much in one generation, though—particularly because of loose correlations between genotypes and dreadful political fates. In the future dictators should be better at this. Now if Stalin had taken all the smartest people in the Soviet Union and forcibly paired them up, artificially inflating assortative mating for intelligence, you would have seen an effect. If you were a billionaire, you could maybe bribe people into something similar.
In AD175 Marcus Aurelius brought 5,500 Sarmatian heavy cavalry warriors to northern Britain where, after twenty years service, they “settled in a permanent military colony in Lancashire” which was “still mentioned almost 250 years later.” You remind us of the possibility that the colony could have influenced the legend of King Arthur, and go on to add something new: it also “could have introduced several thousand copies of that hypothetical allele into Lancashire” and that the average Englishman “might be mostly Sarmatian in a key gene or two.” I’m English, and intrigued! Are you able to expand on this? (Book pp. 146-148) I hope it is something good like increased unruliness (independence streak) and aggressiveness in battle and not something naff like Sarmatian lewdness...!!
I have no further knowledge or insight about that, but Greg might. I will call this question to his attention and we may see what he knows.
HCH