/sci/ - Science & Math

>>11501698
Alright fuck I guess I'll give you somewhat of an answer since everyone else here is fucking retarded.

In some cases it is hyped-up mate guarding. You mentioned this in your second paragraph but incorrectly, I'm not aware of a species where low-ranking males protect females in exchange for sex outside of estrus; in species with defined ovulatory/estrus periods, sex rarely occurs at all outside of them. But mate-guarding does occur, either by physical presence (big chimp scares away little chimps while female is fertile) or other cool ways (like leaving a copulatory plug in the females vagina so no one else can put it in). Monogamy is an exaggerated version of this where the male gains entire (well close enough) access to a female for either a breeding season or sometimes a lifetime.

Another reason this can happen is if offspring care necessitates two parents. For example, in many species of songbirds, if one parent dies or leaves, the chicks die too, because they are too much work for a single bird mom. So if you are a male bird, you need to stick around and raise your kids because if you don't you won't pass your genes along at all.

Other stuff can happen too but these are two examples of selection pressures for it, and both have probably occurred in humans btw