Are Honey Badgers Immune to Snake Venom? What We Know

The short answer: resistant, not immune

The honey badger regularly hunts venomous snakes. In southern Africa it digs out and eats Cape cobras, puff adders and even the black mamba, and snakes can form a large part of its diet in the hot, wet season. To do this safely, an animal needs more than courage.

Scientists describe the honey badger as venom-resistant rather than immune. Resistance means the venom has a weaker effect than it would on a typical mammal; immunity would mean no effect at all. Badgers bitten by snakes can show symptoms, collapse and recover, or occasionally die.

What the 2015 study found

The key research is a 2015 paper by Danielle Drabeck, Antony Dean and Sharon Jansa of the University of Minnesota, published in the journal Toxicon with the playful title “Why the honey badger don’t care”. The team compared the DNA sequences of a muscle protein, the nicotinic acetylcholine receptor, across many mammals.

This receptor sits where nerves meet muscles. Normally the nerve releases a chemical messenger, acetylcholine, which binds to the receptor and makes the muscle contract. Many cobra and mamba venoms contain alpha-neurotoxins, small proteins that lock onto the same receptor and block the signal, so the muscles, including those used for breathing, are paralyzed.

The researchers found that the honey badger has a different amino acid at a key position in the toxin-binding site. A positively charged amino acid has replaced the uncharged one found in most mammals, and this is expected to repel and weaken the binding of alpha-neurotoxins. For a general overview of how these toxins act, see how does snake venom work?

The same trick in hedgehogs, pigs and mongooses

The most striking result was that the honey badger is not alone. Hedgehogs and pigs have independently evolved functionally equivalent changes at the same spot in the receptor. Mongooses, famous snake killers, have different changes at the same sites that add sugar chains to the receptor, which are thought to block the toxin physically.

The authors concluded that resistance to alpha-neurotoxins has evolved at least four separate times in mammals, through two different biochemical routes. This is a textbook example of convergent evolution, where unrelated animals arrive at a similar solution to the same problem.

A 2022 follow-up study by Drabeck and colleagues found further independent cases of this kind of resistance among African mammals, including five within the feliform carnivores, the group that contains cats, mongooses, hyenas and civets.

The limits of the resistance

The receptor change protects only against alpha-neurotoxins. Snake venoms are complex cocktails, and many contain other toxins that damage tissue, blood vessels or blood clotting. Puff adder venom, for example, mainly destroys tissue and disrupts blood rather than paralyzing muscles, so the receptor mutation would do little against it.

The 2015 study was also based on gene sequences rather than on experiments with live honey badgers, so how strongly the change protects a real badger has not been measured. Other factors may help, such as the thick, loose skin that keeps many fangs from reaching muscle. Whether honey badgers also carry venom-neutralizing proteins in their blood, as opossums do, is unknown.

What happens when a honey badger is bitten?

Field researchers and wildlife filmmakers have recorded honey badgers that were bitten while killing a snake, became limp or unconscious, and then recovered after a few hours and carried on. Such cases are probably the origin of the “immune” story, but they actually show the opposite: the venom clearly affected the animal.

How a bite turns out depends on the snake species, how much venom was injected and where the badger was bitten. Bites to the face and nose, where the skin is thinner, are probably the most dangerous. Honey badgers also reduce the risk by attacking quickly and biting the snake near the head.

Why it matters

Venom resistance is a striking example of an evolutionary arms race. Snakes evolve toxins that work on their prey and predators; some of those animals evolve receptors that the toxins cannot grip; and in turn, venoms may evolve new tricks. Studying these natural resistance mechanisms helps scientists understand how toxins work, and people also cannot rely on any such protection: anyone bitten by a snake should seek emergency medical help immediately by calling 911 (US), 112 (EU) or 999 (UK).