英语时差：为什么同类相残不常见（上）

Have you ever wondered why cannibalism isn’t more popular? Just think about it: each animal is made of a complex variety of chemical ingredients. As an animal, we can either try to assemble these ingredients haphazardly, eating other animals and plants and hoping these assorted meals will add up to exactly what we need. Or we can get all our essential nutrients in one complete package by dining on our next-door neighbor! You might think that cannibalism would be a good long-term survival strategy. Indeed one study has shown that tadpoles that dine on tadpoles grow bigger than those who don’t. Why isn’t cannibalism more popular in the animal kingdom?