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?
For years, biologists have suspected that the answer has to do with disease. Many diseases are species-specific, infecting only animals of the same species. Perhaps the risks of catching a species-specific disease by eating your same-species neighbor outweigh the benefits of such a nutritionally complete meal. A study of so-called tiger salamanders has explored this theory.
Tiger salamanders are interesting because if they grow up in over-crowded conditions, they can change into so-called cannibal morphs, or big salamanders with extra-wide mouths, perfect for munching other salamanders. The study found that cannibal salamanders were likely to die earlier than their non-cannibal peers, precisely because of the risks of catching a disease from their dinner. What's more, cannibal morphs showed a marked preference for dining on salamanders of a different species, rather than dining on their own.
What's the moral? Don't eat your neighbor. It's hazardous to your health.