Cannibalism: A Perfectly Natural History

Content Warning: This section contains references to animal death.

Schutt believes that news reports have sensationalized claims that climate change is forcing polar bears into cannibalism. Headlines suggest that melting Arctic ice and food shortages have driven polar bears to consume each other. As a zoologist, Schutt investigates whether polar bear cannibalism is truly increasing and if humans are responsible. Polar bears, among the world’s largest carnivores, are uniquely adapted to a strict meat-based diet, primarily feeding on ringed and bearded seals. Unlike their more omnivorous bear relatives, polar bears have “re-evolved” (63) sharp carnassial teeth, which are specialized for cutting meat. While cannibalism is documented in at least 14 carnivore species—including lions, leopards, and sea lions—it usually occurs due to food scarcity, competition, or reproductive strategies.

Male lions, for example, kill and eat cubs sired by other males to ensure that females can mate sooner. In contrast, spotted hyenas have evolved a defense against male-inflicted infanticide: Females produce higher levels of testosterone, making them larger, stronger, and dominant over males. This hormonal shift also leads to the development of “pseudopenises” (65), through which they urinate, mate, and give birth, often with significant risk.

Reports of increasing cannibalism among polar bears gained traction after a 2006 study by Arctic researcher Stephen Amstrup.