Girls under 12 can be wives too

If girls about 12-16 were the best to acquire as wives what about girls a bit younger say 9? A 9yo wife wouldn’t be ideal since she wouldn’t reach reproductive age for about 8 years but it can still work. Humans have long lifespans and as long as he’s not too old a man can afford to wait. Even if he does die before she reaches reproductive age he can still benefit through inclusive fitness since widows in primitive societies are usually passed on to their dead husband’s brothers or other close male relatives.

In primitive societies it’s quite common for men to marry girls of this age so although it’s sub-optimal the strategy definitely does work. We must expect men to have evolved adaptations for acquiring girls of this age such as finding them physically attractive and being susceptible to falling in love with them but to also be averse to having intercourse with them since they’re not physically ready for it.

As we go younger and younger there will be a point at which girls are too far away from the beginning of their reproductive lifespans and the probability of them surviving to reproductive age is too low for it to be worthwhile for a man to chase after them, assuming older females are available too. My estimate of this age is under about 7. I arrived at this estimate partly from gut feeling and the fact it’s uncommon for men in primitive societies to marry girls under the age of about 7.