I'm not so sure that's really the case; it's more that for many animals there simply isn't any pressure to evolve (or retain) this trait.
It's not like the natural selection process has a feature list it can tick off. It operates with zero foresight and an incredibly dumb principle: whatever helps procreation.
Cows are not dying due to tetrodotoxin poisoning in significant numbers, as far as I know, so there is no reason for them to evolve resistance to it. The same applies to most animals, including the snakes outside that area.
Your dog can synthesise their own vitamin C and will never develop scurvy. Most animals can do this – humans and some other primates are the exception. An ancestor lost the trait for vitamin C synthesis by chance, and because these primates were living in trees eating lots of fruit with vitamin C, evolution simply didn't notice. There is no disadvantage to being able to synthesise vitamin C, and no advantage in dropping the trait. It didn't affect procreation (at the time). Now we're all stuck with it.
Now, maybe all of this does have a cost for the snakes. But it's far from a given that there is one.
You are assuming there is but one cause for development and/or loss of resistance.
There may not be much pressure to develop resistance to tetrodotoxin for most species. Simultaneously there might be a higher metabolic cost to retaining it for some species but not for others. It is also possible that resistance with low cost is very rarely lost which is why we carry resistance to toxins we don't often see but population bottlenecks in ancestral lines can cause loss of a trait to propagate - even by accident. And much like Vitamin C loss if it doesn't matter the loss sticks. We should not forget that there are multiple resistance mechanisms as well: an immune system generally primed to fight certain common causes of mortality can, entirely by accident, also be primed to recognize and destroy certain proteins conferring resistance to some toxins and not others.
I have barely scratched the surface above. The random walk of evolution and its constant hoarding tendencies should make everyone skeptical simplistic mechanisms of action as well as "just so" explanations of evolutionary history.
FWIW most things are multi-causal. I previously made the same argument about house prices. People who claim it is caused by foreign money, low interest rates, restrictive zoning, etc all want their pet theory to be The One True Reason. In reality the market is complex and many of the proposed causes are merely contributing factors.
People can handle significantly more of a wide range of plant toxins like theobromine and caffeine (both found in chocolate) which harm more pure predators like dogs in very low doses, but where rare for out imitate ancestors.
Cattle, deer etc however can handle many of those at much higher doses.
Is that because resistance to those toxins was strongly selected for in humans, or because the source of those toxins did not strongly select for effectiveness in humans?
The fact that guinea pigs, fruit bats, and passerines (almost half of all bird species!) also have a mutated GULO gene suggests that there is in fact some pressure to get rid of it as soon as it is bioavailable from diet.
So why did the trait of that mutant primate spread throughout the entire population? There should instead be a mixture of those who can and those who can’t synthesize vitamin C.
(Indeed, one should perhaps not so blithely assume that there was sufficient fruit for everyone and so C didn’t matter… for it is precisely the ability to survive in times of drought and scarcity that drive evolution, and there id no reason to suspect a population that could synthesize their own vitamin C was less fit than a population that couldn’t. The issue of vitamin C is far from simple…)
> There should instead be a mixture of those who can and those who can’t synthesize vitamin C.
Probably was for a long time. All of this happened about 60 millions years ago. It's been a while.
Synthesizing vitamin C takes energy, energy that could be used for other biological processes. It's also possible excess vitamin C has some minor deleterious effect. For example, it's an antioxidant, and these render immune cells somewhat less effective against certain threats (which they use oxidizing chemicals to destroy). It's been found larger doses of the ACE vitamins causes increased growth of lung cancer, probably due to reduced immune attack.
Some have argued against this idea, though, although I'm not convinced by the argument (see if you can spot the problem.)
Has anybody modeled what percent of a population has to die from something for the protective gene to become widespread?
Whenever a species winds up isolated in a cave, it loses eyesight really quickly in evolutionary terms because making and maintaining an eye is so metabolically expensive. So, while the mutations are random, any of them that can save the energy of developing vision get selected for very quickly.
So, even though the mutations are random, it really looks like "cause-and-effect" from the outside: get isolated in cave->lose vision; get exposed to outside light again->regain vision.
By the same token, changes that aren't very expensive metabolically will have very weak "cause-and-effect" because there is no particular pressure to carry the mutations forward or clean them up.
Turns out, it's the water-lily.
https://crookedtimber.org/2025/03/14/occasional-paper-the-in...
>Newts with weaker poison? They get eaten. Snakes with less resistance? Have trouble finding newts they can choke down, and don’t get to steal their poison. So the arms race continues.
How does a snake know that the Newt has weaker/strong poison? Is it leaving some Newts along and eating others, or is it eating any Newt it runs across? Does a strong-poison newt survive snake consumption attempts?
> And it explains why the newts keep evolving to be more toxic: the snake may want to eat newts generally, but if an individual newt packs enough of a wallop, the snake may just retch it up and go after a different one. Newts with weaker poison? They get eaten. Snakes with less resistance? Have trouble finding newts they can choke down, and don’t get to steal their poison. So the arms race continues.
That's got to be an extremely weak effect. No snake gets an individual benefit from eating the newts. They get a collective benefit, that predators recognize the species as poisonous, in which all snakes, poisonous and delicious alike, share equally.
The problem is large enough that actually-poisonous animals routinely have delicious mimics of entirely different species who free-ride off of the work the originals do to be poisonous.
You can't explain why snakes apparently need to avoid sending a dishonest signal with a theory that predicts that mimics don't exist.
> Successful predation of the rough-skinned newt by the common garter snake is made possible by the ability of individuals in a common garter snake population to gauge whether the newt's level of toxin is too high to feed on. T. sirtalis assays toxin levels of the rough-skinned newt and decides whether or not the levels are manageable by partially swallowing the newt, and either swallowing or releasing the newt.
Second-order effects are so cool
This might be a total tangent, but every time I see “newts”, I think about how Karel Capek actually coined the word robot in his 1920 play R.U.R., and then later gave us War with the Newts...really smart amphibians. Thanks for sharing.
[0]https://www.discovermagazine.com/planet-earth/a-beautiful-we...
> It’s so toxic that the poison from a single newt can easily kill several adult humans. You could literally die from licking this newt, just once.
TBF there is one death reported in Oregon from someone eating an entire newt in 1979, but they aren’t as bad as the article would have you believe. Many of us have handled these newts. There would be a lot more dead people if licking is all it took.
> A 29-year-old man drank approximately 150 mL of whiskey at about 11 AM July 9, 1979. At 6 PM he swallowed a 20-cm newt on a dare. Within ten minutes he complained of tingling of the lips. During the next two hours he began complaining of numbness and weakness and stated that he thought he was going to die. He refused to be transported to a hospital and was left alone for 15 minutes and then experienced cardiopulmonary arrest
It's great in german - 3 syllables for 3 letters, but english/french, it's NINE syllables for 3 letters. I always thought it should have been web.domain.org.
Kind of absurd to use multiple syllables for a single letter if you think about it.
> I always thought it should have been web.domain.org.
It should have just been "domain.org" - the web part is already specified in the protocol. And if you are concerned about domains only having a single IP that could have been (and for many protocols has been) solved with SRV records.
Thanks for the taking the time to find out for the rest of us.
They swarm all over the PNW, in season. Don't step on them if you can help it. They're not death newts. I'd be a dead commenter if they were death newts.
They swarm all over the trails in spring, and then they're gone for the rest of the season. That's my recollection of it.
I don't live there anymore, maybe they have evolved into these dangerous death newts. One can hope.
But this doesn't seem as immediate as the newt's defense where it's on the skin and thus causes potential predators to spit them out or even to seize up - meaning that at least some attacked newts survive the encounter. Eating the liver means the snake is dead. And since it's going to be impossible to tell if a particular snake is immune (and is thus potentially toxic) how would this deter predators? (Especially given the limited range of snakes with this immunity and the probability that there are predators of the snakes that don't necessarily have this same limited range - ravens, raptors, etc.)
And higher predators (like mammals) also have food preferences. They don't always eat stuff indiscriminately, so predators that don't _like_ snakes will preferentially survive. Eventually, this can get established as a genetic trait.
Or as a behavioral one, if parents don't teach cubs to hunt snakes.
Maybe the predator's carcass next to a half eaten garter snake is meant to serve as a lesson to other potential predators.
Or perhaps the aim is not to deter but to simply take one natural predator down with them for the good of their species.
I used to keep native snakes and lizards (and inadvertently breed them!), and couldn’t keep newts because I wasn’t sophisticated enough to create the right environments for them. This is one species I kept (and killed, unfortunately). I’ve learned to do it far better since then, but haven’t tried keeping newts again. They’re beautiful little creatures.
I do think the article plays up their toxicity some. There's only one reported human fatality I could find, from some dipshit who ate one on a dare. If you handle them gently and don't stuff your entire hand in your mouth immediately after, I suspect you're fine.
Perhaps interesting; https://pubmed.ncbi.nlm.nih.gov/34816428/ (Still need to read it)
I am not aware of any species besides humans that do this, though.
Though I remain a tiny bit disappointed that it wasn’t about some arcane royalty arrangement for the band “The Death Newts”.
I can already think of uses of this word jokingly in a people context
After preparing dinner, one girl got very ill, as did I, while other people who ate the dinner were fine. I was so worried I'd mis-identified some mushrooms.
But turns out she had handled one of these newts and the bacteria had transferred to the mushrooms she picked. I contacted it from washing the mushrooms. I threw up several times that night.
In hindsight, had we not washed the mushrooms as thoroughly as we did, things could have gone much worse.
Leafy greens also have very low calories per pound. We eat them for the nutrients not for the calories. Because of mushrooms and wild greens, I buy very little vegetables, all I need is relatively cheap (per calorie) foods to go with the wild stuff.
There is also risk of food poisoning with food from restaurants or the store.. not to mention the chronic poisoning of eating food grown with excessive pesticides etc.
For the most part the abundant edible mushrooms look very different from the dangerous ones. But yes you do need to know ID thoroughly if you go for certain species.
That said not everyone lives where edible mushrooms are abundant, I'm not trying to suggest everyone should do it.
All the significant calories comes from the oil or butter they're cooked in.
I'm not sure it was ever about avoiding starvation, but rather just a different flavor to eat sometimes. When you're always eating the same local ingredients, food can get boring pretty quick. It's the same appeal of spices -- you got a new flavor!
The calorific value of a meal is one of the least important aspects - you might as well complain that the mushrooms don’t come in sufficiently varied colours to make it worthwhile.
It’s not about the calories. It’s about the experience - the taste, the texture, the satisfaction of knowing you did it yourself.
Calls to poisen control concerning mushrooms: 8,294 Of those calls, 4862 were of unknown origin, only like 3-400 are confirmed dangerous wild grown mushrooms, 2k+ are psylocibin. 3-400 is probably <1% of the amount of people who forage, so its a lot safer than driving a car I'm guessing.
(This was a quick scan)
https://piper.filecamp.com/uniq/dPhtQdu6eCQnIQ5R.pdf [page 174-175]
Makes me wonder if a) these toxicity stories are exaggerated, b) it's really regionally specific, c) toxicity has radically increased in the past ~40 years since I was playing with newts, or d) we got dumb lucky.
I loved this article. I didn't know anything about the newt / snake interaction; I wonder if my dad did.
