According to Dieter Lukas and Elise Huchard in their research paper “The evolution of infanticide by males in mammalian societies” published in Nov. 14 issue of Science, many mammalian species practice infanticide. They studied the data on 260 species, from mice to mongoose and from bats to bears, and found in 119 of them adult males killed the young animals genetically unrelated to them. They wrote in their abstract: “Male mammals often kill conspecific offspring. The benefits of such infanticide to males, and its costs to females, probably vary across mammalian social and mating systems. We used comparative analyses to show that infanticide primarily evolves in social mammals in which reproduction is monopolized by a minority of males. It has not promoted social counterstrategies such as female gregariousness, pair living, or changes in group size and sex ratio, but is successfully prevented by female sexual promiscuity, a paternity dilution strategy. These findings indicate that infanticide is a consequence, rather than a cause, of contrasts in mammalian social systems affecting the intensity of sexual conflict.” So, infanticide is not a natural order of things for mammals, but rather a consequence of the social structure of polygyny where one male can monopolize a large number of females.
Granted that such a theory is merely an interpretation rather than a fact as Nietzsche would have said, I find the researchers’ study result rather fascinating. I’m inclined to think the same theory can be applied to human behaviors as well. I wonder if the killing of the young as well as its general extension, homicide, is more prevalent in polygynous societies.