Is it evolutionarily advantageous to be a cannibal?

12 September 2010

Question

Is it evolutionarily advantageous to be a cannibal?

Answer

Dave - I guess it depends what you are and how many diseases you've got that are going around. The big disadvantage to being a cannibal, evolutionarily, is that if you're eating something of your own species, it can get all the same diseases that you can. And therefore: you eat them and then you get all of their diseases and then you die. Chris - Yeah, that's exactly what happened to the Fore people in New Guinea who developed a disease called Kuru, which was a prion disease - a bit like Mad Cow Disease but it was a human equivalent. And because it was a ritual for the women in the tribe to eat the brains of a dead relative when they buried them, there was an excess of women affected by this terrible neurological condition that came on all of a sudden. The actual word means "he who trembleth" in the native language because people got this BSE-like disease and they all died. It was first identified as a cannibalistically-transmitted tendency many years ago which means it's interesting that people went and did almost the same experiment with cows and then were really surprised when BSE came along.

So I would say that actually, from an evolutionary point of view, it is not advantageous to be a cannibal, at least not for humans, and so that probably explains why the practice is so rare. Dave - Although I guess in some other species, especially if you're a very small animal which is quite short-lived and disease isn't so much of an issue, if you're really, really hungry then cannibalism is better than dying of starvation. So things like locusts will eat each other quite happily if they're hungry. Chris - So there you go, David Whorly 94: if you are going to be short-lived then it's probably okay for you to be a cannibal - you may benefit from the increased nutritional benefits of eating your compatriots. Muscle has got lots of iron in it and lots of protein which will help you to build your own muscles up. But you could, if you're going to live a long time, succumb to all kinds of nasty diseases so it will be disadvantageous.

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