Faber 4

how did biology help change social views?

The impact of the Modern Synthesis (of Darwinian evolution and Mendelian genetics):

different concepts of race

A. Essentialist concept--entirely a social idea, not a biological idea
B. Population--this could be what population biology tells you, depending on what characteristic you focus on (but skin color does not tell you much about how closely related population groups are)
C. If you look at genetic diversity, there is no separation of what we call races

Dobzhansky argued that races could be defined only by gene frequencies, not by appearance, and were always shifting and mixing

A present-day way of visualizing this (more on African ancestry--in this system it only shows up if less than about 200 years ago):

sample ancestry

23andme also tells me my overall DNA is a bit less than 4% Neanderthal (putting me in the 91st percentile for Neanderthal variants)
Note that we are learning what we thought were different species were not so separate--humans and Neanderthals interbred--though one scientific theory is that they differences were enough that male hybrids were infertile while females were fertile

Dobzhansky saw it as theoretically possible that races would be different enough that interbreeding would lead to disharmonies, but he saw no credible evidence of that (note footnote 9 on pages 64-65)

A different way of thinking about race mixing

Dobzhansky argued (in opposition to Montagu) that the term race should still be used, but the public should be educated on its scientific meaning

But he also argued against Carleton Coon