No need for either religion or imagination, Hellmut — see, Peter Singer.

You are now anathema in Utah, Hellmut. Consider yourself warned. :)

Hilarious post! Maybe it is the success of monogamy where the social element really comes into play – the costs of switching partners (re-dating, divorce, shared habitat and habits, etc.) being way too high.

Although there are all sort of configurations for functional families, it is probably safe to claim that monogamy is the modal or most common form.

In my opinion, the primary reason is not the cost of mating but the cost of child rearing.

Unlike turtles or amphibians that are precocious, humans are an altricious species, which means that our off-spring requires nurture rather than being self-reliant.

I am not aware of any other species that has to nurture its offspring as long as humans. Even in hunter and gatherer societies, it takes a dozen year before a male child approaches anything resembling self-reliance.

In post-industrial societies, it may take until the late twenties when a child acquires a post-graduate degree.

The altricious nature of human beings has far reaching implications. Once one considers our mammal nature, it becomes clear, for example, that libertarianism cannot account for the human condition.

(For example, it would be hard to argue that throwing children into the fires of Moloch is good for reproductive fitness of individuals, while it may be good for spreading the culture (it makes them committed believers or something).

Actually, it’s pretty easy to find a number of ways that smaller family size increases the fitness of offspring. The greater the parent per child ratio, the more care the child receives, which renders survival into adulthood more likely.

Once that is established, throwing babies into the fires of Moloch may function as pre-modern family size control.

Moloch worshipers would not be aware of that function but their offspring would nonetheless benefit from high parent children ratios.

There are other nasty considerations about relying on religious child sacrifice to breed and select for fitness.

I am not saying any of this is a good idea but with a little imagination, one can even imagine even infanticide beneficial.

That appears to be the problem with evolutionary social science. On a general level, pretty much anything can work. One has to establish a considerable degree of specificity before evolutionary considerations become falsifiable.