Except that 20s-30s men are competing directly against other, college aged men. And maybe that’s enough.
Edit-another pet theory is a changing climate. Cultures in drier climates tend to be more sexually conservative. A large portion of the US has been in drought conditions for decades
You seem to be misunderstanding this thread. The OP was referring to sex imbalance as a matter of chromosomal sex, as in more men than women in countries like India / China.
Edit-another pet theory is a changing climate. Cultures in drier climates tend to be more sexually conservative. A large portion of the US has been in drought conditions for decades