Amazing amount of BS. The trans atlantic slave trade didn’t go on long enough to cause genetic shifts.
The American Eugenics movement of the 1920s - 30s was an attempt at selective human breeding. Thousands of mentally challenged/diseased people, criminals, alcohololics, as well as other “undesirables” (their opinion, not mine) were sterilized to prevent them from spreading their traits. Their ideas were then imported to pre-Nazi Germany, where they embraced and more enthusiastically executed than in the US.
Even if slaves weren’t people by law, they were still people and people aren’t so easily forced to breed. They may work for free and submit themselves to beatings and rape but a majority of women would not allow themselves to become slave factories for the benifit of their owners. Slave or not, women have great emotional attatchments to whomever comes out of them. I’m sure it was attempted and even achieved a few times but hardly as a common practice.
In re Pizzabrat’s assertion:
Oddly enough I think you can find ( I believe in Thorton or Curtin) support for the assertion in re negative natality which is difficult to explain by purely environmental terms. It’s been ages since I read the articles on this but there may be something to this.
In any case, I daresay that we’ve had substantive citations provided for the negative case and nothing but vague speculation for the positive case. As a GQ that rather decides it, no?
Added item, just in re the logic of it all: the folks who like to advance this idea (usually to “explain” supposed racial differences) in general utterly abstract away from the documented reality of black-white-Ameriindian mixing throughout the period of slavery and afterwards. Even were some large slave owners practicing eugenical breeding programs (and as noted, there is not a whit of good evidence for this, and fairly weak support for delibrate breeding per se) there are a whole bunch of other factors, such as the “miscenegenation” noted above which render the concept nonesensical.
I’m quite impressed by the way this potentially explosive issue has been handled here so far. But . . .
The attitudes of modern white conservatives is not really at issue here. The attitudes and actions of white (and black) slaveowners is at issue, and those people have been dead for a hundred years or more. If you have a problem with modern white conservatives, take it to the Pit, or to GD if you want to debate it.
bibliophage
moderator GQ
Yes. I think that does rather answer it. I thank you particularly for the comparison of the Middle Passage to other population-stressing events. That put it nicely in perspective.
Although I agree it’s probably BS, the reason is not because the slave trade “didn’t go on long enough.” The trans-Atlantic slave trade went on for 300+ years, or 15+ generations. Mortality rates on the Middle Passage are disputed, but they were certainly high enough to potentially have had a selective effect. More important problems than the length of time involved are the facts that (1) the bulk of the mortality was probably not due to having particular alleles of one (or a few linked) genes; (2) as Collounsbury has aptly pointed out, U.S. “African” Americans also have a very large admixture of European and Amerindian ancestry, which would confound selective effects due either to the Middle Passage or supposed “selective breeding.” There are several other problems as well, as the second link I provided discusses.
I see a wrinkle in this: while the trade did last a quite long time, the selective “effect” of the Middle Passage is what, 3 months long? Further, we have to be careful here, the demographics are quite whacky, per Curtin and others. E.g. the Carribbean, a major early destination had negative natural population growth over much of its history. Not enough women, oddly low birth rates etc. A biological black hole for most of those hundreds of years. Only towards the end, when it became more expensive to import than to try for natural regeneration do we apparently get self-reproducing populations. I think the story is largely the same in Brazil (but memory is hazy).
The same story for North America, the flow of slaves and above all those who have descendants are not evenly distributed over time, but bunched.
So, while data is sketchy I think we can say that as a coherent biological event (however odd and sketchy this statement is in re slavery) it did not last long enough. I believe (and I admit it has been years since looking at the quantative works on the issue) that the larger portion of slavery (as a function of demographics) is much less than 300 years.
All in all, however, I believe that we all agree that the data (historical, population and genetics) and plain logic don’t support the idea noted in the OP.
(As an aside, I think Colibri’s second link hits the main problems on this quite well, and above all is a fine refutation of the first link which simply demonstrates how poor historical knowledge and poor theorizing can lead one astray)
Collounsbury, the wrinkle you mention occurred to me also after I made my post. While selection for salt-retention might have been quite strong during the Middle Passage, that selection would have been absent once the slaves reached the New World. Presuming that the “normal” allele is favored in non-water-stressed conditions, gene frequencies would have reverted in a few generations to what they had been in the ancestral population in the absence of selection for the salt-retention allele(s).
On the other hand, the effect could have been significant if the newly imported slaves were important in contributing to the gene pool relative to the descendents of previously imported slaves. And your point on negative growth rates in the Caribbean suggests that this could have been true. However, I am not aware of any studies on the prevalence of hypertension in Caribbean populations.
An interesting study could be done on the “Bush Negroes” of Guyana, who are descended from escaped slaves but who live a traditional life-style similar to that of their West African forebears. Any comparisons between African Americans and West Africans is likely to be invalid because of too many confounding genetic, social, cultural, and economic factors.
Colibri, actually you raise some issues which I had not really thought well enough about previously. While as a practical matter I don’t think any of this is significant, it is intriguing.
True, and precisely my thinking but to attack myself, it occured to me in reading your message that much of the negative effect we can presume in re our hypothetical ‘water-stress/retention’ allele(s) are late in life effects.
Again I’m a doubter as I think structurally the Middle Passage as a biological stress is not coherent enough, long enough and different enough from other events (severe drought, e.g.) to really have a statistically significant impact.
But, getting back to attacking my own logic, if our allele(s) don’t have significant (i.e. pre-middle age) negative effects in re ability of pop to reproduce, then there’s no real selection against. Now here we’re in pure hypothetical land, but we do have a door for theoretically entertaining the idea.
I have a vague recollection that they are low. But I don’t recall where I saw that. So, I’ll offer the following as my best recollection of past reading but with the caveat that my recollection could wrong on key points. I recall reading in a critical article that neither new West African nor new Caribbean immigrants show elevated hypertension levels. (A wrinkle, I don’t recall if this was a relative --to AAms-- or absolute statement --gen. pop comp.)
Either way, the suggestion of the article was that AfAm hypertension can be explained via (a) poor health profiles in the community (i) diet (ii) social practice like smoking, drinking (iii) poverty (iv) possible role of social stress related to minority status.
Now, again, I’m throwing out the caveat that I can’t for the life of me recall where I read the article/study. I’m thinking it was around 96 or 97, so I guess that I’ve simply indicated that there is such studies out there to find but my own recollection feels shakey.
Mmm, yes.
Well, thanks for raising some interesting issues to think about.
Perhaps you’re looking at it the wrong way. It doesn’t matter how many generations were involved, or how carefully they were bred, or what selective pressures might have been at work during the Middle Passage. What we are talking about here is the Founder Effect. We’re not talking about modifications to the existing population of Africans. This is the creation of a new population in North & South American and the Caribbean, based on migrants from West Africa who survived the selective filter imposed by the slavers.
I propose that the Middle Passage was anything but selective.
There has been speculation in this thread that those who survived the M.P. had superior salt-retention ability or were “stronger” than the others.
The M.P. was not subtle. It imposed upon its (unwilling) participants the shock of dying from (but not limited to): lack of water, lack of food (two very different circumstances), bacterial infection, and heat stroke, among other things.
If all participants (slaves) were otherwise identical, then varying one factor (the amount of available water, for example) would tend to select for those people with a resistance to or affinity for the factor being varied.
However, there were a multitude of varied factors contributing to death during the M.P., I don’t think we can conclusively identify one, specifically, that was any more or less responsible than the others. It could be argued that those who survived the M.P. were not the salt-retentive, but rather those whose immune systems were most resistant to opportunistic infection. Those whose immune systems kept them “healthier” had less of a problem dealing with the lack of water than others. A “salt-retentive” who also had a bad infection might be worse off than a “non-retentive” who had a better immune system.
A pertinent, and equally horrible, example would be the recent WTC attack. While it could be argued that “the ability to run, fast” was a deciding factor in whether or not some of those involved lived or died, it can not be said that the attacks “selected” those who run fast for survival and “selected” the slow to die. There were a multitude of reasons people died in that attack, as well as during the M.P. We can identify one factor that may have played a role in whether or not a specific individual lived or died, however we can not broadly apply that to all participants in the situation. We can not say that “all salt-retentives had a better chance of surviving the M.P.” or “all those who run fast had a better chance of surviving the WTC” because the factors causing death were much more varied and numerous than those two factors.
So… yes, salt-retention did allow some slaves to survive the M.P., and the ability to run fast did allow some New Yorkers to survive the WTC attack. However, there were so many other factors contributing to the death toll of both these examples, it is not logical to conclude that one narrowly defined physical trait was a significantly contributing factor.