Minstrel said:This is the basis of eugenics, which is, at best, highly controversial and many consider it to be a discredited psuedo-science. Hitler believed in eugenics, and tried to breed a "master race" using only the brightest and strongest (and white, of course, but that's a different matter).
However, I've read statistics that show that these traits tend to regress to the mean. Two brilliant parents will likely produce a less intelligent child, two great athletes will most likely produce a less athletically gifted child. On the flip side of this, two people less intelligent than the mean are most likely to produce a child more intelligent than themselves.
Therefore, it's not possible to breed a race of "super-athletes" and I doubt slavery had a noticeable effect on the fitness of the African-American population. Through regression to the mean, whatever advantages the original slaves had were likely down to normal levels after all the generations of slavery.
I don't think you can compare the mixing and matching that Hitler did (and for how long?) to slavery, which was FAR more harsh, and far longer. If I recall correctly, more Africans died en route to America than there are blacks in the US today. Don't quote me on that, but just showing its a significant amount of people.
As for the statistics, I guess the easiest way to put it is this. A man with 160 IQ has a child with a woman with an IQ of 180, their child has an IQ of 140 which is less than both children, a less intelligent child, as you have said.
A man with an IQ of 110 has a child with a woman with an IQ of 100. They have a child with an IQ of 120. It's greater than the parents, but still less overall than the offspring of the two extremely intelligent parents.
I think after many generations there would be regression, but it apparently shows that there is a higher percentage that does have some (I never said it was a great effect, as many have implied that I said) roots in slavery.
It may be very minimal, but that doesn't mean it is non existent.