[foob]

> it works slowly over thousands of years

This isn't always the case; evolution can happen relatively quickly in response to rapid changes in the environment [1]. There are plenty of people alive today who have particularly strong urges to have children, and the widespread introduction of birth control creates a major selective pressure towards any heritable genes that produce or enhance those urges. The effects of this could be very significant over even a relatively small number of generations.

[1] - https://en.wikipedia.org/wiki/Punctuated_equilibrium