Maybe different groups have different interests?
The Very Long War Between Snakes and Newts
The two have been locked in an evolutionary arms race since before they even existed.
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 were they be so ludicrously toxic?
Butch found a clue when he checked one of his traps and found a common garter snake devouring a newt. Overcoming his mild phobia of snakes, he collected some and found that they resisted amounts of tetrodotoxin that would kill far larger animals.
While Butch focused on the newts, his son, Edmund Brodie III, became fascinated by the snakes. Together, they showed that throughout western America, places with mildly toxic newts also had mildly resistant snakes. Meanwhile, hotspots with unusually lethal newts also had snakes that withstood staggering levels of tetrodotoxin. The two species were locked in a beautifully coordinated arms race of toxicity and resistance.
But what set off the starting pistol? How did the first snakes survive their encounters with the first newts? To find out, the team needed to understand how the snakes came to shrug off the poison.
Tetrodotoxin kills by corking molecular pores on the surface of nerve and muscle cells, which act as channels for sodium ions. If these ions can’t traverse the channels, muscles can’t contract and nerves can’t fire. Paralysis ensues, breathing ceases, and death follows. In 2005, the Brodies found that garter snakes avoid this fate by changing the shape of their sodium channels, so that tetrodotoxin no longer plugs them.
