The cannibalistic trade-off: Why human cannibalism emerges
A PNAS study models cannibalism as a trade-off between nutritional gain and disease risk. Under severe food scarcity and low pathogen threat, cannibalism can become evolutionarily advantageous, explaining its sporadic historical emergence.
Background
- The article reports a PNAS study that uses a computational model to explore why human cannibalism has appeared across many cultures but never became a stable, long-term practice.
- Key prior context: archaeological and ethnographic records show cannibalism occurred in diverse settings—funerary rites, warfare, survival crises—but was typically sporadic or ritualized rather than a regular food source.
- The researchers model a "cannibalistic trade-off": eating conspecifics provides a short-term calorie boost but spreads prion diseases (like kuru, documented among the Fore people of Papua New Guinea), damages social cooperation, and triggers immune costs.
- The model suggests cannibalism only persists when protein is extremely scarce and population density is low, and even then it collapses once those conditions change—explaining why no society has made it a stable dietary mainstay.