== Mankind in general is in an inbreeding depression... == 

 Man is not inbred in "isolated rural areas".  Man is inbred in all rural areas, thanks to the large families that were possible there.  Organisms (people) that inherit the genes for having a large families quickly end up engaged to their relatives.  Read that again until you understand it. 

 Nothing man does can be explained without the assumption of my heading.  The general rejection of hybrids, genius, and otherwise most able people by the majority can only be explained by the majority "desire" to pursue failure and their identical twin as a mate (directionally) on the real fact that this produces more children. 

 The human genome deteriorates noticably each passing year.  It is statistically measured.  The inbreed depression phenomenon is borne out by DNA analysis of populations. 

 The article shows inbred bias to not mention all this.