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I'm not suggesting they're the same thing at all. They're just the best approximation I could quickly find any decent statistics for. What were these higher ra

• bzbarsky 10y ago
  > What were these higher rates you refer to? I don't have exact numbers, and no one does that I've seen. Due to social disapproval people tended to keep such activities somewhat hidden. That said, genetic analysis of African-American populations shows a significantly higher percentage of European-origin genes than can be accounted for by marriage rates, yes? > Were they as high as would be expected if humans 'enthusiastically' interbred What rates would you expect? To make this more specific and avoid questions of lack opportunity vs lack of enthusiasm, what rate of slaveowners having children with at least one of their slaves would you expect under the "enthusiastic" hypothesis? (There's the complicating factor that in that situation at least one of the parties here might or might not have taken measures to avoid pregnancy even if sexual intercourse did occur; it's not clear to me how to account for that.)
  • jimmyk 10y ago
    >That said, genetic analysis of African-American populations shows a significantly higher percentage of European-origin genes than can be accounted for by marriage rates, yes? Yes, and a much lower percentage of European genes than you'd expect if there were no preference one way or the other for interracial breeding, and a much much lower percentage than you'd expect if humans enthusiastically interbred. >What rates would you expect? To make this more specific and avoid questions of lack opportunity vs lack of enthusiasm, what rate of slaveowners having children with at least one of their slaves would you expect under the "enthusiastic" hypothesis? In the early 1800's, blacks were about 20% of the population, and whites were most of the rest. If there were no preference one way or the other, we'd expect 20% of children of white women to be fathered by black men, and 80% of children of black women to be fathered by white men. If the actual rates are lower than that, then some kind of self-segregation is happening. Pointing out that slavery or other social institutions limited the rate of interbreeding is not an argument in favor of the idea that humans enthusiastically interbreed. If when living in close proximity they tend to set up systems that limit interbreeding, that is evidence that they don't enthusiastically interbreed. >(There's the complicating factor that in that situation at least one of the parties here might or might not have taken measures to avoid pregnancy even if sexual intercourse did occur; it's not clear to me how to account for that.) We don't have to account for that because we're discussing rates of interracial breeding, not rates of interracial sex.
    • bzbarsky 10y ago
      > blacks were about 20% of the population, and whites were most of the rest Yes, but this ignores the geographic inhomogeneity of both populations. For example, in Boston blacks were a much smaller fraction than 20%. Obviously if you're white and you live in a village in which everyone else is white too, your chances of having kids with someone who is not white are pretty low. This is why I suggested the more specific metric. > then some kind of self-segregation is happening. You're assuming either homogenous population distribution or a lot more population mobility than was happening at the time, I think. That is, you can conclude there is segregation in mating, but the extent to which it's _self_-segregation is a much harder question. Also, there were non-racial and non-geographic sources of segregation, like class/income. Note the comments in the wikipedia link below about black/Irish couples being a thing because the Irish were very poor. I'm pretty sure it's possible to account for these effects and discover that there were still racial self-segregation effects, but they will not be nearly as large as a naive 80-20 calculation like yours would suggest. They would, I expect, be larger than the (also existing!) self-segregation effects amongst white people of different ethnicities. An interesting thought experiment here is what you would expect to happen if you drop two (cis, straight) people of opposite gender but different races on a deserted island for a few years and how this compares to what happens when members of different subspecies are placed in proximity to each other with no other available mating partners. I don't know the answer to the latter, unfortunately. > Pointing out that slavery or other social institutions limited the rate of interbreeding I'm not doing that, precisely for the reasons you describe. I'm suggesting that limiting to my specific scenario removes issues of access due to population distribution effects and asks a specific question: given a white male who has the option of having children with black females (yes, the "enthusiasm" is very not symmetric here), what is the chance he will do so? Yes, this ignores the white-female-black-male case (though according to https://en.wikipedia.org/wiki/Mulatto#Antebellum_era https://en.wikipedia.org/wiki/Mulatto#Antebellum_era claims this was also going on; I'd have to look up numbers on "free people of color in the 1790–1810 censuses in the Upper South" to have an idea of how common it was). > We don't have to account for that because we're discussing rates of interracial breeding Well, we're discussing level of enthusiasm. Which as I said above was probably not symmetric, for reasons not necessarily related to race per se. I expect male white masters of female white indentured workers were also more enthusiastic about having kids than the workers were.
• bzbarsky 10y ago
  OK, here's one sort of relevant statistic. 1910 census at http://www2.census.gov/prod2/decennial/documents/36894832v1.zip http://www2.census.gov/prod2/decennial/documents/36894832v1.... and you want 36894832v1ch02.pdf in there, page 5 in the PDF (which is page 129 of the actual census document). I got there via https://www.census.gov/prod/www/decennial.html https://www.census.gov/prod/www/decennial.html if you want to look up other years. According to that document, in 1890 (I chose that year because the document actually clearly describes the classification criteria for that year, unlike other years it mentions), the "Negro population" was 7.5 million, of which 1.1 million were "Mulatto" and 6.3 million were "Black" (there are some rounding errors here; see document for more exact numbers). The definition used in that census was that "Mulatto" only included people with at least one white grandparent; this would obviously include the ones with a white parent as well. This doesn't directly tell you anything about interbreeding rates per se because there may have been systematic differences in the numbers of children different types of couples had. But it does indicate that even in the 19th century a fair number of children who had at least one black parent also had a white parent. Somewhere between 1/14 and 1/7, if I'm running the numbers right (the former corresponds to a "mulatto" having one "white" grandparent and three "black" ones, while the latter corresponds to having a "white" parent and a "black" parent).
  • jimmyk 10y ago
    1/7 to 1/14 is incredibly low for a race that had been in close proximity to another for over a hundred years. If there were no preference, or if there were a positive preference for interbreeding, you'd expect by that time nearly all descendants of the initial minority race to trace most of their ancestry back to the majority race. That 6/7 to 13/14 of the members of the race can trace back the vast majority of their heritage to the initial minority race is proof that not much interbreeding was taking place.