Actually, there are cultures which foster intense distance running so I think even the genetics/distance running argument isn't a "slam dunk" - ie, to just act like the point is proven is a cheap, unsupported argument.
Aha, but what if those cultures persist over countless generations? The degree to which one fits into one's culture partially determines one's reproductive success. Wouldn't this weed out the genetically poor distance runners while advantaging the genetically good distance runners?
