That struck me too. What is he talking about?
For example, there's a movement now to reconstruct how English was actually pronounced in Shakespeare's time, and they're actually putting on plays in what they call "original pronunciation."
It sounds like the way movie pirates talk -- "war" for example is "waaahr", like the pirates' "aaarrrr!" One of the ways to try to reconstruct the pronunciation is to take old poems, like Shakespeare's sonnets, and assume that the words really do rhyme, where they don't rhyme in today's language. (I noticed the lack of rhymes when I was a kid, and wondered why. Apparently it's due to pronunciation changes.)
Anyway, the original pronunciation experts say the modern upper class British pronunciation only dates from the last 200 or 250 years. In Shakespeare's time there was no "upper class" pronunciation.
But if that's true, it would seem that "lower-class" eveolutionary genetic distinctions, if any, could hardly go back much more than say 250 years.
It was when the English language moved its vowels.
(ducking)
A couple of thoughts on this - I have heard that the English spoke in Appalachia (among the most heavily accented and that may all be being lost due to TV, etc.) is close to the English spoken in Shakespeare’s time. I have no idea if this is true, but I’ve heard it many times.
It does make sense to think the words in a poem would rhyme, I will say that!
Another thing, I watched that movie “gangs of new york” which takes place in the mid-1800s. I complained to my friend about the characters “noo yawk” accents, but she told me that it was actually historically accurate that the new york accent we know and love was actually that old.
How anyone knows this in the era before recording I have no clue!
Here's a review that I think makes a lot more sense than the book does.
http://www.firstthings.com/article/2007/09/001-economics-as-eugenics
Historically, rich people always had more surviving children than poor people. Rich people never starved, always had good clothing, and got better medical care. (To the extent there was any such thing.)
So it's likely that rich people throughout history have generally been more successful at reproducing their genes. Especially because upper-class men have generally had a lot more children than those borne by their wives.
For obvious reasons, there is no effective firewall between the two -- no matter how properly the social niceties are observed in choices of marriage partners, there are too many opportunities for hanky-panky between the gentry and the hired help.
See this Youtube video on Shakespeare: Original pronunciation:
https://www.youtube.com/watch?v=gPlpphT7n9s