Promiscuity: Difference between revisions

(Regarding the Himba tribe) some have noted that it seems implausible that a man would invest in his sister's children instead of his own unless the paternity certainty would be lower than 25% (as each child of his sister shares 25% of his genes) and that this seems unrealistically low.<ref>https://www.researchgate.net/publication/327455603_Kinship_Human_Evolutionary_and_Biosocial_Approaches_to</ref> Amongst the Himba, approximately 48% of children aren't sired by their father and 70% of mothers have children from men other than their husband. At first glance it seems that Himba men should invest into their wive's 'children' instead of their sister's children. If we do a probability tree assuming that their's a 50/50 chance that a Himba man's child is his and that he has two of 'his' children by his wife and that his sister has two children he has a 100% chance in investing to 0,5 times his amount of genes if his sister's children inherit's his property (each child has 0,25 times his genes; combined they would have 0,5 times his genes); if his wife's children inherit then he invests (on average) ((0.5 + 0.5) x 1/2 x 1/2) + ((0.5 + 0) x 1/2 x 1/2) + ((0 + 0.5) x 1/2 x 1/2) + ((0 + 0) x 1/2 x 1/2) = 0,5 times his genes as well. So it seems that it is no more advantageous for a Himba to invest into his sister's children rather than his own. But consider this: let's take 100 Himba couples and assume that they each have two children on average, this would give you a total of 200 children. We know that 48% of children are not sired by their 'father' meaning that, of the 200 children, 96 of them are illegitemate. We also know that at least 30% of Himba women are faithful and do not cuckold their husbands. If we exclude this group of women we'd deduct 60 children from the 200 children and are left with 140 children. This means that, of the men that are cuckolded by their wives, 96 out of the 140 children are illegitemate(or 24/35 to simplify). Ergo, we can calculate how many times his genes a cuckolded Himba man will invest into on average if he has 2 children. That is equal to ((0.5 +0.5) x 9/35 x 9/35) + ((0.5 + 0)) x 9/35 x 24/35) + ((0 + 0.5) x 24/35 x 9/35) + ((0 + 0) x 24/35 x 24/35) = 0,24 times their genes. In other words, for 70% of Himba men, it is twice as condusive to reproductive success to invest in the children of their sister rather than the children of their wives and to have children with the wives of other men. -->

==References==