Why is infanticide so common in nature? Morality aside, isn’t it horribly inefficient?

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I was watching a nature documentary where a crab produced several dozen babies, and then turned around and started eating them. If she needed the nutrients so badly, why not just have fewer kids? From a thermodynamic standpoint that would preserve more calories.

I’ve also seen footage of birds brooding, laying, and then hatching multiple eggs, only to push half of the chicks out of the nest. That’s such a huge investment of time and energy. Why not just lay fewer eggs?

In other situations it is more understandable: A male lion might kill another male’s offspring to make room for his own. Cuckoos push other baby birds out of the nest so they can be adopted by the parents. But many cases of infanticide in the wild just seem time-consuming and wasteful.

In: Biology

14 Answers

Anonymous 0 Comments

What you’re describing is a type of ‘maternal output’ called ‘R’ selection.

It’s the opposite of K selection.

Basically, the larger the number of offspring, the less care the mother has to invest, as there is a better chance enough will survive to continue the reproduction of the species.

K selection is a lower number of offspring per birth/pregnancy, which means the maternal output has to be a much higher standard, because you only have 1 or 2 babies to make it to sexual maturity, you need to do more work to ensure at least one of them makes it.

Source: Wildlife Biologist

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