In the mountains of Oregon, there are newts with so much poison in their skin that each could kill a roomful of people. There are also snakes that eat those newts; they’re completely resistant to the toxins. The two are locked in an evolutionary arms race. As the newts become more toxic, the snakes become more resistant. One team of scientists has been studying this evolutionary conflict for five decades, and they’ve now shown that its seeds were planted 170 million years ago—before either snakes or newts even existed.
We know about this ancient conflict because of a young undergraduate student named Edmund “Butch” Brodie Jr. In the early 1960s, he heard a local legend about three hunters who were found dead at their campsite, with no sign of theft, struggle, or foul play. The only thing amiss at the scene was a dead roughskin newt, which the hunters had accidentally boiled in their coffee pot. These dark-backed amphibians have vibrant yellow-orange bellies, which they display to predators by arching their heads and tails over their backs—a clear sign that they’re poisonous. Perhaps those poisons killed the hunters.
Butch tested this idea by collecting newts, grinding up tiny amounts of their skin, and feeding the extracts to other animals. Everything died. The newts proved to be absurdly lethal. Another team of chemists showed that they carry tetrodotoxin (TTX)— the same poison found in the skins and livers of pufferfish. It’s ten thousand times more toxic than cyanide, and among the deadliest substances in nature. Each newt seemed to carry enough to kill any predator hundreds of times over. Why would they be so ludicrously toxic?