Infanticide in Nature: Why Animals Hate Their Babies

Prairie dogs exemplify extreme infanticide behavior, killing young of close relatives to reduce food competition and increase resources available for their own offspring.

Males in many mammalian species (lions, langur monkeys) kill unrelated offspring to mate with mothers, “resetting” female reproductive status and enabling own offspring production.

Females in numerous species enter estrus (reproductive receptivity) or heat following offspring death, physiologically enabling male infanticide strategy by accelerating reproductive availability.

Females commit infanticide in species with extensive paternal care and limited male availability, killing competitors’ offspring to acquire male caregivers for their own reproduction.

Filial infanticide—parents killing own offspring—creates evolutionary paradox since “it can’t be beneficial to kill your own progeny at least not for reproductive fitness,” yet occurs across numerous species.

Females evolved multiple countermeasures “punishing infanticide as a viable fitness strategy,” including false estrus, Bruce effect, and paternal uncertainty through polyandry.

Social species evolved collective punishment mechanisms—social discouragement, coalition formation, exile, execution—deterring infanticide through reputational and physical costs.

Humans show “long long historical record of infanticide” including population control, unwanted pregnancy responses, sex selection, and sacrificial rituals, with modern manifestation in Cinderella effect—stepparents showing 10x higher child harm rates.