Or it could just be a similar mutation to "disable" breeding when population density became high.
Also it may not be genetic but developmental, due to high hormone levels at certain stages of development caused by population\breeding stress on parents\mothers.
If this sort of "crowding" mechanism works in humans I think it would have to be because we've carried it from waaaaaay back in our evolutionary past.
I doubt very much that any of our genus (or close relatives) have had much crowding of population in the last 10 million years at least. That is until the last few 1,000.
Rats have been subject to this for a very long time I'm sure.