If their birth rate collapsed, it's just a natural response to all the CROWDING. Hell, they could STAND to lose a lot of people, get those prices down on those postage-stamp apartments. Instead of just paving and building over more farm or wildland.

Frankly, I think a certain concentration of same-species pheromones in the air triggers all kinds of societal weirdness in any/every species that isn't specifically eusocial (like certain bugs.) CROWDING ISN'T GOOD.

If their birth rate collapsed, it's just a natural response to all the CROWDING. Hell, they could STAND to lose a lot of people, get those prices down on those postage-stamp apartments. Instead of just paving and building over more farm or wildland.

Frankly, I think a certain concentration of same-species pheromones in the air triggers all kinds of societal weirdness in any/every species that isn't specifically eusocial. CROWDING ISN'T GOOD.