A recent paper has concluded that prevention of infanticide was the most likely precursor to monogamous mating systems in some primate species. Another paper suggested a different possibility in mammals more generally, namely that under certain ecological conditions females are so dispersed that the best strategy for a male is to remain close to a rare female when he finds her. This prevents other males from mating with her, and increases the chances of successfully passing on his genes.
I’m still sorting through what all this means, and wonder if the search for broad patterns oversimplifies things too much. As Peter Gray put it: “It’s all so confusing, if lead researchers can’t seem to find similar evolutionary grounds behind social monogamy.” Anyway, if prevention of infanticide really was the key to jump-starting monogamy (at least in some primate species), it makes me think of its downstream consequences. This reminds me of the parable of the Zen Master and the Little Boy.