While not in so flippant a tone, I agree with V. Cannibalism isn’t a physical issue at all, beyond the nutritional value and potential contamination of human flesh. At this point in our social progression, the fact that we have such a strong taboo against cannibalism is almost entirely the function of tradition and moral reckoning.
Were cannibalism a legal practice, the biggest physical obstacle would be the quality of the likely sources of meat: Most people who die due so because of age, sickness, or trauma. None of these potential sources would compare in quality to prime, healthy humans slaughtered especially for their meat. And, on the reasonable premise that we would never condone the slaughter of human beings for their meat, we are then left to the second-rate pickings of the deceased. We’d be, in effect, scavengers. I don’t know how healthy it would be to consume this meat—scientific studies would be in order.
Furthermore, there is the risk that, were cannibalism accepted in regions marred by lawlessness, people would slaughter one another simply to eat. Goodness knows we don’t need yet another reason to kill each other. But the reason this potential concern doesn’t carry much logical gravity is that we assume in parallel that the world will gravitate toward lawfulness, and it is therefore in the context of the rule of law that we would most prudently decide these issues.
Were the quality, purity, and social ramifications not an issue, however, cannibalism could certainly have a practical use. We waste exorbitant amounts of land and money in the outmoded tradition of burying our dead in petite boxes. Human flesh is at the top of the food chain, and the top of the industrial chain. Every human being represents an incredible investment of resources. Consuming our own flesh would probably be one of the better returns we could get on this expensive venture known as humanity. And, as postulated by Robert Heinlein, cannibalism could even evolve into a practice as dearly head as our current methods of dealing with the dead.
To put it briefly, I’ve got nothing against cannibalism. If I lived in a culture where people ate human meat, then I’d probably eat it too. But cannibalism is so deeply rooted in our social psyche as something unnatural and monstrous, and the need to legalize cannibalism and incorporate it into our way of life is so comparatively small, that the matter is and likely shall remain one of purely academic interest.