Snakes keep turning cannibal but why? Study reveals the surprising evolutionary pattern behind it

How Evolution Keeps Pushing Snakes Toward Cannibalism (Representative Image; Canva)

A review published on 02 Nov 2025 in Biological Reviews found that cannibalism in snakes has evolved independently at least 11 times. Analysing 503 cases across 207 species, researchers said the behaviour often emerges during food scarcity or environmental stress. The study identified higher reports within Colubridae, Viperidae and Elapidae families. Experts suggest cannibalism may improve ecological fitness, though some scientists remain cautious about linking it strongly to generalist diets.

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Scientists have found that cannibalism among snakes is far more common than previously believed, according to a review published on 02 Nov 2025 in the journal Biological Reviews. The analysis examined hundreds of documented cases worldwide and suggests the behaviour evolved independently many times across snake history.

Cannibalism recorded across snake evolutionary history

Researchers reviewed 503 documented cases worldwide. These cases involved 207 different snake species. Reports came from wild and captive settings. Snakes inhabit every continent except Antarctica. The review found cannibalism evolved at least 11 times. Scientists believe environmental stress often triggers behaviour. Limited food resources appear a major factor.

Lead author Bruna Falcão spoke to Live Science about the findings. She is a graduate biology student. She studies at the University of São Paulo. She said cannibalism benefits ecological fitness. She described the behaviour as strategic.

Snake families show different cannibalism patterns

The behaviour appeared common in several families. These included Colubridae, Viperidae and Elapidae. Colubridae accounted for 29% of reports. This is the largest snake family globally. Researchers linked cases to food scarcity. Viperidae represented 21% of reports recorded. Many of these occurred in captivity. Scientists suspect confinement increased stress levels.

Elapidae made up about 19% of reports. This family includes cobras known to eat snakes. Almost half the cannibal species had generalist diets. Researchers linked dietary flexibility to opportunism. However, biologist Xavier Glaudas expressed caution. He was not involved in research. He questioned strength of the generalist link.

What jaw structure and adaptation reveal

Jaw flexibility also influenced cannibal behaviour. Species lacking wide jaws showed no cases. Researchers examined evolutionary trees for patterns. They confirmed repeated independent evolution events. Glaudas called the review a welcome study. He said it clarifies behavioural correlations.

Examples include male Montpellier snake in France. These males consumed females outside mating season. Scientists linked this to food shortages.

Researchers believe many reports remain undiscovered. Older archives may hold further examples. Falcão said more evidence likely exists. She suggested snakes adapt opportunistically worldwide. Cannibalism may reflect ecological resilience.