
Why some animals have venoms that are more lethal than they apparently need - JacobAldridge
http://www.bbc.com/earth/story/20160404-why-some-animals-have-venoms-so-lethal-they-cannot-use-them
======
dnautics
> "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.

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excalibur
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.

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elcapitan
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.

~~~
qrendel
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...](https://en.wikipedia.org/wiki/Genetic_drift#Time_to_fixation_or_loss)

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

~~~
abc_lisper
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.

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junto
> 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?

~~~
oppositelock
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.

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

------
taneq

        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.

~~~
masklinn
> 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.

~~~
TillE
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.

------
xg15
Why would you ever build a tank if you can already kill a human with a
handgun?

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

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vitno
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"

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

~~~
ars
"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.

~~~
dang
Ok, we'll use your suggestion. Thanks!

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

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

~~~
akavi
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?

~~~
gweinberg
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.

