Why some animals have venoms that are more lethal than they apparently need | Hacker News Reader

Why some animals have venoms that are more lethal than they apparently need

bbc.com

97 pointsJacobAldridge40 comments

> "Protein synthesis requires a substantial energy investment, but this has not stopped the evolution of venoms containing thousands of peptides and proteins, at considerable cost to the animals in question."

This is eminently silly. Of course protein synthesis is energetically costly, but your cells are doing it anyway. There are a lot of wierd hormones that are proteins or proteogenic peptides, when an "inexpensive" small molecule might have been just fine too.

Energy utilization is hardly hyperoptimized; if so a lot of "junk DNA" might as well not be there.

I would think that the biggest evolutionary advantage of higher venom doses would be the speed with which the target is incapacitated. Sure it's enough venom to kill the creature 20 times over, but what Darwin cares about is that it stopped moving 10 seconds faster.

Besides the fact that the title is yet another misleading piece of click optimization, I would have expected that the evolutional reason for this is that there is a distant past in which snakes for example had way larger potential enemies than mice. As in "whale-sized sea predators". And then after those were gone, there was just no evolutional reason why the level of poison should go back, simply because it's not a disadvantage.

When an fitness advantage is removed from an allele, so that possessing it becomes completely neutral, the gene still tends to disappear slowly over time due to mutation and genetic drift. The formula for the average time to complete disappearance is given here: https://en.wikipedia.org/wiki/Genetic_drift#Time_to_fixation...

So, in that case, you would still expect for the potency of the venom to have declined over a long period of time.

You are right. This is the same reason, why island birds like dodo have lost their wings - there wasn't enough selection pressure for it.

That makes sense, thanks.

If true this to me directly contradicts evolution.

People seem to just be redefining evolution at will, without saying the original theory was wrong.

That said, even the wiki articles says genetic drift is controversial.

> This super-mouse has probably evolved its resistance to the viper bite because it is a key component of the snake's diet.

How does that work exactly?

Surely to evolve, you need to procreate, and then through mutations, we get some kind of increased defence.

In order to evolve some kind of anti-venom, presumably you need to get bitten, which I assume kills the mouse, and as everyone knows - dead mice don't procreate.

Is it maybe from a partial bite?

It's not a binary thing, and it's why mortality is measured with LD50 (lethal dose for 50% of exposed subjects). The actual distribution is a curve spanning a spectrum of venom resistance.

The snake eliminates more mice with lesser resistance than mice with greater resistance, and over time, the mice with higher resistance have more offspring.

This is more of an adaptation driven change than a random mutation driven one.

Summary: Animals have venoms so potent because some other animals are resistant to them. Most other animals are not.

    Why does a snake possess the capability to kill hundreds of thousands of mice with each bite?

Why not? If it doesn't cost anything significant then it won't be selected against.

"Furthermore, one experiment conducted with pit vipers demonstrated an 11% increase in metabolic activity following venom extraction, indicating a link between physical exertion and venom production."

The article points out in a few places that venom production does have significant costs.

So replenishing venom supplies may result in an increased metabolic load post-extraction, but that increase may not be so much when compared to another method of hunting. For example, it's probable that the heightened metabolic load associated with a python crushing/strangling its prey is a substantial increase from the animal's ~ergodic resting state.

If anyone has numbers on this, please link them!

Also, injections are probably not going to be clean and ideal. Having a toxin that does the job o(1000)-fold with a full delivery volume will still do the job with a tiny fraction of that in the event of a partial toxin delivery. This will still result in the death of the prey with a single, albeit flawed, attack.

> The article points out in a few places that venom production does have significant costs.

You are confusing venom production with the lethality of said venom.

Nowhere does it imply that making a very lethal venom costs more than making a less lethal one.

> Why not? If it doesn't cost anything significant then it won't be selected against.

Much of the point of the article is that it does have significant metabolic cost.

Significant metabolic costs that have proved for several thousands of years a compelling survival strategy. Nature is the ultimate field tester.

And yet it wasn't selected against. :)

Evolution and natural selection were probably not designed by an engineer. Or if it was, then they also probably designed the DC-3, which I have jumped out of when I was skydiving years ago. Exceptional longevity and reliability. https://en.wikipedia.org/wiki/Douglas_DC-3

Sure, but there's no guarantee that evolution produces optimal outcomes at any given point in time (eg, the present day). Too much is a lot safer than too little. As long as you're alive, you can always eat a bit more.

Why would you ever build a tank if you can already kill a human with a handgun?

What if you want to kill a LOT of humans that also want to kill you?

Much less evidence!

The title of this article is entirely misleading based upon what the content is.

This is actually an article that can be summed up as "LD50 results for venom are irrelevant, some animals (e.g. hedgehogs) have resistance to venom that could kill [insert large number] mice. That's why the venom is so potent"

That and the article asks the question 3 times and then immediately digress into yet another repetitive example of why the question is so important.

If someone can suggest a title that's 80 chars or less and accurately represents the article, we can change it.

The offender is the original article author, not the HN entry. The former goes on and on piling fluff until you want to hit him in the head with a hammer. Then you see the actual content can be summarized in a single phrase.

"Why do some animals have venoms that are more lethal than they apparently need"

The original title is really quite bunk "can not use them?" What? That's just wrong.

The whole article is kinda stupid anyway, the answer to the question is: So they can use them on animals that are resistant to the venom.

There isn't much else in the article, you may want to just kill the story as a waste of readers time.

Ok, we'll use your suggestion. Thanks!

The story has been flagged off the front page. We'll probably leave it at that.

The biggest problem with this title is not that it's inaccurate, it's that it's also misleading. I clicked on this article expecting to read about animals whose venom is so toxic that they would actually injure themselves if they tried to use it ("...so lethal they cannot use them").

I couldn't make it passed the misuse of "begs the question."

And from the Beeb of all broadcasters!

Shameful, really.

It bothers me too. The really bad news for American English is that the latest edition of Garner's Modern Usage rates this sense of "beg the question" at "Language Change Index: 4" which means "ubiquitous but..."

I find mixing up "beg the question" a very understandable, sensible mistake compared to "make it passed", tbh.

I had trouble making that make cense to.

This mini-thread might remind us that most of us make spelling, grammatical and usage errors, we usually understand anyway, and we should usually forgive and forget.

Said as an old person who makes more mistakes by the day, and cares less.

Blame the person who chose to translate "petition principii" so terribly.

No one in isolation would interpret the Modern English phrase "begs the question" as meaning "assumes the desired conclusion as a premise"; the natural, "naive" interpretation is that it's synonymous with "raises the question". So why blame the reader for the translator's mistake?

If you need a translation of "petitio princippi", maybe you can use "assumes the conclusion" or "takes $premise for granted" instead?

I agree that "begs the question" is an awkward way of saying "assumes the conclusion", but it is also an awkward way of saying "raises the question". As the Mad Hatter sagely observed, one should say what one means.

I find the "wrong" usage very intuitive and vivid, while the "correct" usage is very unclear in its relation to its meaning. According to wikipedia the "correct" usage stems from a mistranslation, so maybe it is about time to stop saying "beg the question", when you really mean that someone is "assuming a point or conclusion", although honestly, I have never encountered this usage.

I suppose that begs the question: does it even mean "to assume a point" anymore?

You should read more of my Hacker News comments inwhere I use the phrase correctly.

I lost you at "inwhere".

Heh. "passed". I get it.

It's not a misuse. It's the correct usage. The notion that "begging the question" being used as a piece of debating jargon, is the only possible use or arrangement of those words, is frankly bizarre.

I really wish this foolish "correction" would just go away.

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