Lewontin came to that conclusion by examining exclusively blood type alleles, which was kind of asinine because they have no apparent geographic distribution pattern at all. Other genetic markers tell a much clearer story, as the principal component analysis shows. It couldn't really be any more obvious - the PCA makes a map. You can literally see each of the continents represented in a projection of genetic data.

Something like 30-50% of all human genetic variants are shared across continents. It's hardly asinine to say that a significant proportion of genetic variation is shared with everyone. Depending where you are talking about, ~20% of variation is unique to a given continent.

I don't think PCA plots really tell us much beyond there being distinct genetic clusters? One could do a PCA only on people with european ancestry, or people living in a small town, and there would be plenty of interesting structure to look at.

https://www.nature.com/articles/nature15393

If the difference was 70 or 80% would they even be the same species?

  "One could do a PCA only on people with european ancestry, or people living in a small town"

That would be extremely interesting. Maybe a way to do polygenic risk scores for traits like IQ.

WTF, no. In what universe was this ever true? 40 - 60 are the prime earning years, and always have been, except for maybe mercenaries and pirates.