Filial cannibalism, which occurs when a parent eats its own offspring, has been documented in fish, insects and even domestic animals. And different species do it for different reasons.
Animals eating their own young, a behavior known as filial or brood cannibalism, may sound shocking or surprising, but it is surprisingly common throughout the animal kingdom.
Scientists have already documented this phenomenon in more than 1,500 speciesmainly in fish and insects, but also in familiar domestic animals such as cats and dogs.
Although it seems to go against the basic instinct of ensuring the survival of offspring, researchers say that eating babies can actually, in some cases, increase reproductive success of parents in the long term, explains .
According to behavioral ecologist Aneesh Bosefrom the Swedish University of Agricultural Sciences, filial cannibalism is “embedded in the reproductive strategies” of many species.
Not all animals are equally likely to eat their young: the behavior is rare in slow-breeding specieslike elephants or whales, which invest a lot in raising just one or two offspring over a long period.
In contrast, species that produce large quantities of offspring at one time, like many fish, insects and spiders, are more prone to partial brood cannibalism, in which only a few babies are consumed.
For these prolific breeders, sacrifice some offspring can, paradoxically, help the rest survive. When food is scarce, parents may eat part of the litter to reduce competition, ensuring that the babies that remain have better nutrition.
A classic example is one about scavenger beetlespublished 1987 in Behavioral Ecology and Sociobiologywhich concluded that these insects consumed some larvae so that the survivors would have resources enough to prosper.
In mammals like cats, dogs and pigsfemales can sometimes eat young stillborn or sick to recover the energy spent on reproduction, reduce the risk of disease or avoid attracting predators.
Genetic interests and parental conflict
O cannibalism filialIt always has to do with food. In some species, parents can target offspring that are not genetically yours.
For example, male bluegills (Lepomis macrochirus) can understand whether the newly hatched larvae are their biological descendantsdetecting chemical signals. When they identify unrelated offspring, they are more likely to eat them — a strategy that favors their own genetic success, but which can generate conflict with the femalewhich is related to all descendants.
In many species of fish, this tension translates into behavior in which the females guard eggs closelywhile males patrol looking for potential threats — or a snack.
Sometimes parents consume the entire litter. This drastic measure is more common in animals that can reproduce quicklyand, like rodents and rabbits.
If a litter is unusually small or if environmental conditions are threatening, the mother can eat all the babies to conserve energy and increase the likelihood of producing a larger, healthier litter later when circumstances are better.
Eating one’s own offspring may seem macabrebut science is revealing this behavior as a pragmatic strategy shaped by evolution — which, for many animals, can mean the difference between success and failure reproductive.
