I think the existing categories reflect cultural knowledge that some things are correlated. (Such knowledge could be obsolete, of course.)
For example, people often want to spend more time with people they enjoy having sex with. So in theory, you could have an arrangement like “have sex with whomever you want, but keep doing 50% of care for our children”, but in practice it seems that people who find an exciting sexual partner start neglecting their other duties, such as their children from other relations.
This is further complicated by human propensity for lying and rationalization. The person who finds a new exciting partner will not come to you and say openly “hey, childcare is suddenly very unappealing to me, could we make a different mutually satisfying arrangement?” Instead, they will probably just start spending less time/attention on children while denying that they are doing so, or they will suddenly “notice” that the children are already grown up and actually need much less of their time/attention.
Shortly: If your partner finds a different sexual partner, popular wisdom predicts that your children will probably be neglected, so the traditional way to prevent it is to restrict each other’s sexual freedom.
Similar with buying a house: you probably intended to live there together, but now your partner may be more interested in living together with their new sexual partner.
Now of course, despite best effort, things happen that ruin our plans. But that is not a reason to actively invite plan-ruining things into your life. (That is, if you care about your plans.)
For example, people often want to spend more time with people they enjoy having sex with. So in theory, you could have an arrangement like “have sex with whomever you want, but keep doing 50% of care for our children”, but in practice it seems that people who find an exciting sexual partner start neglecting their other duties, such as their children from other relations.
You say “people”. That would make sense as an explanation for why females don’t want their mates to have sex with others. But for why males don’t want their mates to have sex with others, I think there’s a much stronger reaction, due to what I think is a much stronger effect of “If my mate has unrestricted sex with others, then the children she gives birth to might not be mine, so I might end up spending my life providing for what turned out to be zero biological children”.
Googling for “jealousy in the animal kingdom”, a result says:
In response to romantic rivals, male titi monkeys are known to become aggressive, place themselves between their mates and potential rivals, and occasionally physically restrain their mates to keep them from moving toward intruder males. For the research, published in October 2017 in the journal Frontiers in Ecology and Evolution, the scientists had male titi monkeys watch their mates interact with stranger males for 30 minutes and watch stranger females interact with stranger males for the same amount of time.
When observing their mates, the monkeys experienced increased levels of the hormones testosterone (associated with mate-related aggression and competition) and cortisol (an indication of social stress). Additionally, brain scans revealed the primates had heightened activity in an area of the brain associated with social exclusion in humans (the cingulate cortex) and another area associated with aggressive behavior (the lateral septum).
And if you wonder whether humans have inherited this, I’ll refer to my comment that mentions stats on violence (including murder) motivated by jealousy.
That part is made obsolete today by modern knowledge about reproduction, contraceptives, and paternity testing. The “they might go off with their lover and neglect me and our children” part is kind of addressed by family court today, although that comes with a huge dose of inefficiency, pain, and uncertainty; in practice you tend to just end up with single mothers raising their kids, maybe with some amount of child support; luckily modern civilization is so rich that the problems from such outcomes are usually psychological, rather than “kid starves to death”. In theory, one could draw up a contract in advance; I don’t know how well pre-nups tend to work.
I think the existing categories reflect cultural knowledge that some things are correlated. (Such knowledge could be obsolete, of course.)
For example, people often want to spend more time with people they enjoy having sex with. So in theory, you could have an arrangement like “have sex with whomever you want, but keep doing 50% of care for our children”, but in practice it seems that people who find an exciting sexual partner start neglecting their other duties, such as their children from other relations.
This is further complicated by human propensity for lying and rationalization. The person who finds a new exciting partner will not come to you and say openly “hey, childcare is suddenly very unappealing to me, could we make a different mutually satisfying arrangement?” Instead, they will probably just start spending less time/attention on children while denying that they are doing so, or they will suddenly “notice” that the children are already grown up and actually need much less of their time/attention.
Shortly: If your partner finds a different sexual partner, popular wisdom predicts that your children will probably be neglected, so the traditional way to prevent it is to restrict each other’s sexual freedom.
Similar with buying a house: you probably intended to live there together, but now your partner may be more interested in living together with their new sexual partner.
Now of course, despite best effort, things happen that ruin our plans. But that is not a reason to actively invite plan-ruining things into your life. (That is, if you care about your plans.)
You say “people”. That would make sense as an explanation for why females don’t want their mates to have sex with others. But for why males don’t want their mates to have sex with others, I think there’s a much stronger reaction, due to what I think is a much stronger effect of “If my mate has unrestricted sex with others, then the children she gives birth to might not be mine, so I might end up spending my life providing for what turned out to be zero biological children”.
Googling for “jealousy in the animal kingdom”, a result says:
And if you wonder whether humans have inherited this, I’ll refer to my comment that mentions stats on violence (including murder) motivated by jealousy.
That part is made obsolete today by modern knowledge about reproduction, contraceptives, and paternity testing. The “they might go off with their lover and neglect me and our children” part is kind of addressed by family court today, although that comes with a huge dose of inefficiency, pain, and uncertainty; in practice you tend to just end up with single mothers raising their kids, maybe with some amount of child support; luckily modern civilization is so rich that the problems from such outcomes are usually psychological, rather than “kid starves to death”. In theory, one could draw up a contract in advance; I don’t know how well pre-nups tend to work.