Venomous Shrew And Lizard: Harmless Digestive Enzyme Evolved Twice Into Dangerous Toxin In Two Unrelated Species

[Siddhartha]

ScienceDaily (Nov. 2, 2009) — Biologists have shown that independent but similar molecular changes turned a harmless digestive enzyme into a toxin in two unrelated species – a shrew and a lizard – giving each a venomous bite.

The work, described this week in the journal Current Biology by researchers at Harvard University, suggests that protein adaptation may be a highly predictable process, one that could eventually help discover other toxins across a wide array of species.

“Similar changes have occurred independently in a shrew and a lizard, causing both to be toxic,” says senior author Hopi E. Hoekstra, John L. Loeb Associate Professor of the Natural Sciences in Harvard’s Department of Organismic and Evolutionary Biology. “It’s remarkable that the same types of changes have independently promoted the same toxic end product.”

This finding shows how “easy” it is for evolution to occur at the molecular level. Both the shrew and the lizard have the same harmless digestive enzyme (kallikrein), and both have independently evolved slightly different toxic enzymes, both of which are slight variations of this digestive enzyme,

 

[reggieM]

This finding shows how “easy” it is for evolution to occur at the molecular level. Both the shrew and the lizard have the same harmless digestive enzyme (kallikrein), and both have independently evolved slightly different toxic enzymes, both of which are slight variations of this digestive enzyme,

One aspect that is not easy at all in either of these claims is the actual evolutionary path that both organisms took. Why did the venom not kill off both the shrew and the lizard? The article merely states that this improbable event happened twice in independent organisms. It does not explain the step-by-step path that caused a non-venonmous shrew or lizard to move to one that carries venom which is both deadly to prey and yet harmless to itself (and to it’s own progeny).
It does not explain how the venom first arose and what selective advantage a non-harmful version of the venom had.

 

[Bob_Crowley]

One aspect that is not easy at all in either of these claims is the actual evolutionary path that both organisms took. Why did the venom not kill off both the shrew and the lizard? The article merely states that this improbable event happened twice in independent organisms. It does not explain the step-by-step path that caused a non-venonmous shrew or lizard to move to one that carries venom which is both deadly to prey and yet harmless to itself (and to it’s own progeny).
It does not explain how the venom first arose and what selective advantage a non-harmful version of the venom had.

I’m also curious as to why snakes decided to stop using limbs and use venom or crushing instead. Was there some advantage to not using their one time limbs? Why did some decide to use venomous methods (along with special hollow or grooved fangs, and glands to make the poison) whereas others decided crushing their prey to death was good enough?

Was there some advantage for the Archer Fish to shoot down insects? That must have taken a bit of collateral development, along with the specially designed eyes that allow it to focus correctly through the water / air interface.

Evolutionists have got a lot of explaining to do. I find it easier to believe they were created as specific species.

And of course the whole web of life just hangs together, with everything keeping everything else in check, with Man as the chief exception. Very considerate of blind chance processes.

 

[wanstronian]

Evolutionism: Continuing research and discovery of clear evidence to support a scientific theory.
Anti-evolutionism: Denial of this evidence on petty and tenuous grounds, usually in favour of the “invisible man in the sky” hypothesis.

 

[reggieM]

The Darwinian bedtime story probably explains everything we need to know about snakes. They got rid of their legs because they wanted to live underground. But now they live above ground and they forgot to grow legs back to replace the ones they lost. Or, in another story (which is equally 100% true), snakes were originally fish that didn’t need legs. Then they came on the ground and grew legs like everybody else did. But then, they really wanted to go back in the water again - and also stay on the ground, so they got rid of the legs that they just grew.

As for the venom – that story must be even more interesting then the snake legs one. Venom has to be created which happens to be deadly to snake-prey, but not harmful to the snake. Then the snake has to have hollowed-out fangs to contain the venom and the organ to create it, muscles to pump it, and a brain to know that venom is the best weapon to use (rather than wrapping and crushing prey or just eating it without the venom).

This is supposed to happen in a step-by-step function with mutations creating harmless versions of the venom that have no survival advantage, and versions of hollow-fangs that don’t work and versions of venom-producing organs that produce no venom.

But natural selection supposedly kept all of these partially functional features, waiting around for the right mutations that would perfect them into the venom-producing machinery that we see in snakes now.

Snakes knew that in the future they’d need hollow-fangs so the snakes with partially hollow fangs that provided no survival advantage had a higher reproduction rate – because, of course, eventually fangs were going to mutate and become fully functional.

 

[wanstronian]

The Darwinian bedtime story probably explains everything we need to know about snakes. They got rid of their legs because they wanted to live underground. But now they live above ground and they forgot to grow legs back to replace the ones they lost. Or, in another story (which is equally 100% true), snakes were originally fish that didn’t need legs. Then they came on the ground and grew legs like everybody else did. But then, they really wanted to go back in the water again - and also stay on the ground, so they got rid of the legs that they just grew.

As for the venom – that story must be even more interesting then the snake legs one. Venom has to be created which happens to be deadly to snake-prey, but not harmful to the snake. Then the snake has to have hollowed-out fangs to contain the venom and the organ to create it, muscles to pump it, and a brain to know that venom is the best weapon to use (rather than wrapping and crushing prey or just eating it without the venom).

This is supposed to happen in a step-by-step function with mutations creating harmless versions of the venom that have no survival advantage, and versions of hollow-fangs that don’t work and versions of venom-producing organs that produce no venom.

But natural selection supposedly kept all of these partially functional features, waiting around for the right mutations that would perfect them into the venom-producing machinery that we see in snakes now.

Snakes knew that in the future they’d need hollow-fangs so the snakes with partially hollow fangs that provided no survival advantage had a higher reproduction rate – because, of course, eventually fangs were going to mutate and become fully functional.

Nothing worse than the uneducated man who is unaware of his lack of education. Actually, maybe one thing worse: that man trumpeting his misconceptions on a public forum, exposing his ignorance for all to see!

 

[reggieM]

Nothing worse than the uneducated man who is unaware of his lack of education. Actually, maybe one thing worse: that man trumpeting his misconceptions on a public forum, exposing his ignorance for all to see!

Agreed – that’s why evolutionary theory is such an embarrassment.

 

[wanstronian]

Agreed – that’s why evolutionary theory is such an embarrassment.

Your version of it certainly is. Luckily your version isn’t really evolution - it’s just a parody knocked up without knowledge of the facts, with the intent to make creationism sound like a more plausible explanation.

 

[reggieM]

Your version of it certainly is. Luckily your version isn’t really evolution - it’s just a parody knocked up without knowledge of the facts, with the intent to make creationism sound like a more plausible explanation.

There are the facts and then there are evolutionary speculations.
Probably the easiest argument that an evolutionist can offer is:

“You just don’t understand the theory”.

That usually works quite well because nothing more needs to be said.

If a person truly understood the theory, then he’d know that evolutionary speculations are correct.

If a person points to the illogic and contradiction of evolutionary claims – then obviously, he doesn’t understand the theory. If he did understand it, he’d know that everything fits together just fine.

When various aspects of evolutionary theory are falsified, then that’s not a problem either.

Usually, a theory attempts to explain what will be found in future discoveries of the data.

For evolution, the theory changes to adapt itself to the data as it is found.

It works like this:

Darwinian evolution is true. Therefore, everything we find in nature, necessarily fits the Darwinian model. If it doesn’t appear to fit, we claim that it is “possible” that it evolved in this or that way. If enough things don’t fit that some, more honest, scientists get nervous – we say that Darwinian methods also include genetic drift, horizontal gene transfer and self-organization.

If that doesn’t work on occasion, we say that the non-fitting data is an “anomaly” and not worth pursuing.

It’s an amazing system and it’s a marvel how scientists have gotten away with this for so long.

 

[wanstronian]

There are the facts and then there are evolutionary speculations.
Probably the easiest argument that an evolutionist can offer is:

“You just don’t understand the theory”.

That usually works quite well because nothing more needs to be said.

If a person truly understood the theory, then he’d know that evolutionary speculations are correct.

If a person points to the illogic and contradiction of evolutionary claims – then obviously, he doesn’t understand the theory. If he did understand it, he’d know that everything fits together just fine.

When various aspects of evolutionary theory are falsified, then that’s not a problem either.

Usually, a theory attempts to explain what will be found in future discoveries of the data.

For evolution, the theory changes to adapt itself to the data as it is found.

It works like this:

Darwinian evolution is true. Therefore, everything we find in nature, necessarily fits the Darwinian model. If it doesn’t appear to fit, we claim that it is “possible” that it evolved in this or that way. If enough things don’t fit that some, more honest, scientists get nervous – we say that Darwinian methods also include genetic drift, horizontal gene transfer and self-organization.

If that doesn’t work on occasion, we say that the non-fitting data is an “anomaly” and not worth pursuing.

It’s an amazing system and it’s a marvel how scientists have gotten away with this for so long.

Although not as long as Christians have been getting away with saying, “God did it.”

 

[redneck22]

Agreed – that’s why evolutionary theory is such an embarrassment.

Do you ever notice how ALL the examples of “Evolution in action” show the same creature reproducing the same creature, just as the book of Genesis says they would. Snakes produce snakes, shrews produce shrews.

 

[edwest2]

Your version of it certainly is. Luckily your version isn’t really evolution - it’s just a parody knocked up without knowledge of the facts, with the intent to make creationism sound like a more plausible explanation.

Your response clearly shows that a power struggle is going on between true knowledge and an invention of men. Creationism and ID must be removed from the public mind as not the least bit likely, or, in the more confrontational case, ID must be called religion.

In the New York Times article written by Cardinal Schoenborn, titled “Finding Design In Nature,” he writes that the immanent design in nature is actual design.

Chemicals to man is ludicrous. Life cannot spring from non-life. On a Catholic forum, the Catholic answer should be given: man was willed. He is not an accident.

Evolution is a terrible storytelling device. As a professional writer, I understand how fictional stories are put together. It is amazing the the underlying premise that something happened is given as gospel, but the explanations that follow can run the gamut of anything and everything, get dicredited, drastically revised, partly overturned, and in the end, it’s like nothing happened. Science is not the whole answer. And finally, I am convinced that the constant, almost daily recitations about evolution here have no other goal than to convince the unwary that science is a god. To be listened to without question (or only questioned by those who understand-accept it). Here are the facts, we are told.

For Catholics, the information provided by science is not sufficient.

Peace,
Ed

 

[wanstronian]

Do you ever notice how ALL the examples of “Evolution in action” show the same creature reproducing the same creature, just as the book of Genesis says they would. Snakes produce snakes, shrews produce shrews.

Do you suppose that a shrew should produce something vastly different to itself if evolution is true? If so, you clearly do not understand evolution.

 

[wanstronian]

Your response clearly shows that a power struggle is going on between true knowledge and an invention of men.

That seems to be true. In the absence of any evidence, God appears to fall into the latter category while science is working towards the former.

Creationism and ID must be removed from the public mind as not the least bit likely, or, in the more confrontational case, ID must be called religion.

How likely is something to be true, when there is no evidence for its truth? I don’t think creationism et al should be ignored, but it should be represented accurately - along the lines of “some people believe this but there is no evidence to support it.” This is nothing more than the reality.

In the New York Times article written by Cardinal Schoenborn, titled “Finding Design In Nature,” he writes that the immanent design in nature is actual design.

What does that opinion prove? Am I missing your point?

Chemicals to man is ludicrous.

Quite right - in a single step the idea is ludicrous. However, nobody except theist parodists are claiming this to be the case.

Life cannot spring from non-life.

This is an assertion on your part, it has not been proven to be impossible. Various experiments, as discussed on this forum, have reproduced the beginnings of such a process. Just because we haven’t been able to bung some chemicals in a test tube and get a recognisable life form out, that doesn’t make it impossible. We have no real idea of the mix of chemicals and environmental conditions that would have existed originally. It’s necessarily trial and error. On a proportional basis, there is infintely more evidence in support of abiogenesis than there is for Creation.

On a Catholic forum, the Catholic answer should be given: man was willed. He is not an accident.

Why? The forum is open to atheist and theists alike. Why should we all conform to Catholic doctrine? Wouldn’t this just be a self-confirming waste of bandwidth?

Evolution is a terrible storytelling device.

But it’s not telling a story. It’s explaining a process, to the best of its ability.

As a professional writer, I understand how fictional stories are put together. It is amazing the the underlying premise that something happened is given as gospel, but the explanations that follow can run the gamut of anything and everything, get dicredited, drastically revised, partly overturned, and in the end, it’s like nothing happened. Science is not the whole answer.

Indeed. And it likely never will be. But at least it’s getting there, slowly and surely.

And finally, I am convinced that the constant, almost daily recitations about evolution here have no other goal than to convince the unwary that science is a god.

That’s an understandable point of view from someone who apparently needs some form of God in their lives. To the rest of us, science is simply the best way to test and understand our environment.

To be listened to without question (or only questioned by those who understand-accept it). Here are the facts, we are told.

No, that’s exactly the point. Unlike religious doctrine, science thrives on being questioned. That’s its raison d’etre. That’s why scientific theories have changed and evolved over time as new evidence comes to light. Contrast this to religious doctrine which has remained dogmatically static throughout the centuries, despite having not a jot of evidence in support of it (maybe that’s why it’s remained static: no evidence = no reason to change the hypothesis).

For Catholics, the information provided by science is not sufficient.

It doesn’t answer everything to the nth degree, no. I fail to understand how Catholics can rationally reject an explanation for which the evidence is incomplete, in favour of an answer for which the evidence is non-existent.

 

[Fran65]

You are confounding Catholicism with Creationism. The two are not the same and are not even necessarily linked.

 

[ipwnuathalo]

Wait, wait…can we go back to the original post for just one brief moment?

I want to understand the original article. I read it. Seems pretty reasonable, but I’d say the reasonableness is dependent upon actually understanding the biochem, not only of the proposed pathway, but ALSO of the necessary biochemical modifications that the animal has to have to be concurrently immune to its own poison.

If there’s a modification pathway that allows the digestive enzyme to gradually become poisonous through a series of multiple modifications, then the concurrent defensive modification has a chance to develop. If not, no. These are the sorts of things I’d like to know.

I’d say that unless someone can answer such questions (I certainly cannot) then they have no idea whether the proposed evolutionary event is a reasonable proposal or not. If you don’t know whether you are posting reasonable stuff or not, should one post it?

 

[Havard]

Evolutionism: Continuing research and discovery of clear evidence to support a scientific theory.
Anti-evolutionism: Denial of this evidence on petty and tenuous grounds, usually in favour of the “invisible man in the sky” hypothesis.

“Sometimes the way people understand things is by rewriting them in their own terms, and then saying ‘Oh, well what a crazy idea that is.’ And of course if they haven’t done justice to them in their own terms, then it is pretty crazy.” - American philosopher and noted atheist Daniel Dennett.

 

[reggieM]

Seems pretty reasonable, but I’d say the reasonableness is dependent upon actually understanding the biochem, not only of the proposed pathway, but ALSO of the necessary biochemical modifications that the animal has to have to be concurrently immune to its own poison.

That seems to be a reasonable comment. You don’t know the answer but you think the answer should explain these various things. I can add others like, what is the mathematical probability that both creatures would independently develop the same venom and use it for the same purpose? We can then look at that number and determine if it’s reasonably probable. Then we look, not only at the biochemical pathway that incrementally created the venom (from a non-venom state, to a non-harmful-to-anyone venom, to a harmful-to-prey-only venom) – on a trial-and-error basis (the errors happened to kill proto-snakes and shrews – so where was the selective advantage?), BUT we have to look at the pathway for storing and distributing the venom – as well as the mental and psychological changes that took place changing the previous method of food-gathering to the new one.
We could look at non-venomous shrews and lizards and ask how they survived without the need for venom … and more.

If there’s a modification pathway that allows the digestive enzyme to gradually become poisonous through a series of multiple modifications, then the concurrent defensive modification has a chance to develop. If not, no. These are the sorts of things I’d like to know.

It can gradually become poisonous but unless it has value as a non-harmful poison, it will not have selective advantage and will not survive for future generations.

So, we have the possiblity that the non-harmful venom, perhaps, “irritated” the lizard’s prey enough to make it easier to catch them. Thus, the venom persisted. The exact same ‘explanation’ would be needed for the shrew. A non-harmful intermediate venom was preserved and used for some reason. Then, when it became strong enough it was used to poison victims. But evolution cannot just hang on to something for its future value. It has to contribute something in the non-perfected state.

I’d say that unless someone can answer such questions (I certainly cannot) then they have no idea whether the proposed evolutionary event is a reasonable proposal or not. If you don’t know whether you are posting reasonable stuff or not, should one post it?

The great thing about evolutionary theory is that what is considered “reasonable” is based on what one considers “possible”. And the great thing about that is what is considered “possible” is limited only by the extent of one’s imagination.

If someone cannot answer questions about how this venom could have evolved in two, unrelated species – then this is a problem for the evolutionists who make their claims here on CAF on a daily basis.

The questions about whether evolution could do this or not are certainly reasonable – whether they’re informed at a level of advanced microbiology or not. In just the same way, you outlined some questions that need to be answered.

The claim is that these features evolved by Darwinian processes. Even more, the same feature evolved twice in non-related organisms. How probable is that? Why should one believe this claim without some solid answers to the questions posed?

If evolutionists say nothing or offer inconsistent and unpersuasive arguments – do their claims deserve assent merely because they’re evolutionary scientists and therefore cannot be wrong?

 

[ipwnuathalo]

But evolution cannot just hang on to something for its future value. It has to contribute something in the non-perfected state.

Sidebar - I wish those two sentences could be made to flash in bold neon letters in every thread that contains the word “evolution”.

 

[wanstronian]

You are confounding Catholicism with Creationism. The two are not the same and are not even necessarily linked.

You’re quite right, however I was responding to Ed who spoke specifically about Catholics not believing in Evolution. I’m not aware of any alternative to evolution that doesn’t fall into my category of having no supporting evidence?