Dysgenic:
Dysgenics (also known as cacogenics) is the decrease in prevalence of traits deemed to be either socially desirable or well adapted to their environment due to selective pressure disfavoring the reproduction of those traits. [Wikipedia]
Noted in “Slightly Against Underpopulation Worries,” Scott Alexander, Astral Codex Ten:
The claim isn’t that fewer people will have PhDs in the future: colleges will certainly solve that by increasing access to education and/or dumbing down requirements. It’s a dysgenic argument where we assume at any given time the people with higher degrees have on average higher genetic intelligence levels. If they’re reproducing less, the genetic intelligence level of the population will decrease.
Which is decidedly simplistic.