According to most studies including this one http://www.menstuff.org/issues/byissue/infidelitystats.html more men cheat on their spouses than women. Is there an evolutionary explanation for this? The most commonly seen sociological explanation is that females have an incentive to stay faithful to one strong male in the group to ensure the successful growth of the next generation but one flaw with this argument is that this does not explain why the male would not care about the offspring's future and be loyal to the mother to ensure that offspring is safe and healthy.
Let's assume that in the beginning all males and all females are monogamous and then by genetic mutation (evolution) one of the males genes becomes a cheater and starts to have multiple partners. The cheater male gene then spreads in the population as a cheater male can have 100s of children while a monogamous male gene can only have 10 to 12 children if they stay with the same women for their entire life. What about cheating female genes ?
What is the evolutionary advantage of having multiple partners for a male that the female doesn't have? If a human male has 10 partners in an year then it possible for the male to have 10 children in a year provided the group can provide for the healthy growth all the children while a female can have only one offspring no matter how many partners she has so there is no incentive for the females of the human species to take the additional risk of finding multiple mates when it doesn't provide them more children. Cheater genes may die of due to additional risk taken by the cheater woman.
Natural selection from such a behavior will result in a population which becomes increasing has more and more polygamous males and monogamous females but this does not happen in reality and why?
An opposing force for this polygamous behavior of men could be the death of children who do not get enough care from the fathers and there by resulting in the decline of the polygamous genes. Polygamous genes would only survive only when the father has only few children so that the family or human group can support new born kids. This two opposing forces would then should find a balance where the polygamous genes remains polygamous but at the same time the degree of polygamy or number of partners is limited so that the survival of the children is sustainable.
If similar natural selection of genes where to take place in woman then woman would then become a serial monogamist because although woman doesn't have any incentive to have multiple partners at any one time they will have more children if they continuously have partners when first partners no longer mates with them and provides children. The serial monogamous gene can only survive if the number of children created as the result of the serial monogamy is limited so that the human group tribe can support the growth or survival of the children produced as the result of serial monogamy.