We, or at least some of us, most definitely have such traits.
Holding newborn babies tend to have a quite obvious and equally instant hormonal effect on a lot of people. For some people, even a few such encounters may be enough to induce baby fever.
And there are other factors at play, too, that are also inheritable. Factors like impulse control, introversion / shyness, ambitiousness drive and tendency to magical /religious thinking may all affect the number of offspring one way or the other.
So all that is needed is a few generation of strong selection pressure for such traits, and we're back to overpopulation again being a much bigger threat than population collapse.
Holding newborn babies tend to have a quite obvious and equally instant hormonal effect on a lot of people. For some people, even a few such encounters may be enough to induce baby fever.
And there are other factors at play, too, that are also inheritable. Factors like impulse control, introversion / shyness, ambitiousness drive and tendency to magical /religious thinking may all affect the number of offspring one way or the other.
So all that is needed is a few generation of strong selection pressure for such traits, and we're back to overpopulation again being a much bigger threat than population collapse.