Cockroaches evolve aversion to glucose

| 70 Comments

Not stated is whether they manage to lose weight, nor whether they still get cavities or develop diabetes. But a recent article in Science shows that cockroaches evolved an aversion to glucose after glucose was used for a number of years as a poisoned bait. That is, the cockroaches developed an aversion to the bait rather than a resistance to the poison. The Science article is kind of written in Greek

In response to the anthropogenic assault of toxic baits, populations of the German cockroach have rapidly evolved an adaptive behavioral aversion to glucose (a phagostimulant component of baits).

but The New York Times has a nice summary and notes, almost as a throw-away, that the result might have application to diseases, such as malaria, that are spread by mosquitoes.

Memo to potential trolls: Yes, yes, we know—they are still cockroaches!!

70 Comments

Memo to potential trolls: Yes, yes, we know—they are still cockroaches!!

True; but they no longer have any sugar daddies.

Mike Elzinga said:

Memo to potential trolls: Yes, yes, we know—they are still cockroaches!!

True; but they no longer have any sugar daddies.

LOL! I guess somebody had to do it.

“Memo to potential trolls: Yes, yes, we know—they are still cockroaches!!”

That’s a bit harsh don’t you think?

But they’re still insects! hexapods! arthropods! metazoa! eukaryotes!

Also any categories that should be between those.

Probably evolved an aversion to shoes, too.

The cockroaches I’ve seen play dead after a good clogging.

Glen Davidson

If cockroaches evolved, why is there still the Discovery Institute?

Got you, monkey-pants evilutionists!

Glen Davidson

Memo to self: stop sending candy to the Disco Tute. They won’t eat it.

So, putting insecticide on our skin could select for mosquitoes to have an aversion for landing on us? Is that the dumb possible application?

https://me.yahoo.com/a/JxVN0eQFqtmg[…]X_Zhn8#57cad said:

If cockroaches evolved, why is there still the Discovery Institute?

Got you, monkey-pants evilutionists!

Glen Davidson

They didn’t evolve from weasels.

OK, according to the NY Times article efforts to control mosquitoes that can carry malaria was stymied by selection for mosquitoes that do not rest on walls inside of homes, where pesticides are generally sprayed. The roaches can be another example of selection that just happens to avoid a pesticide. In this case it seems to be selection for roaches that detect glucose as a bitter substance. Interesting.

But they’re still bilaterians!

Sorry. Couldn’t resist.

DS said:

“Memo to potential trolls: Yes, yes, we know—they are still cockroaches!!”

That’s a bit harsh don’t you think?

Why?

glipsnort said:

DS said:

“Memo to potential trolls: Yes, yes, we know—they are still cockroaches!!”

That’s a bit harsh don’t you think?

Why?

Well the regular trolls might deserve it, but even the potential trolls?

They’re still eumetazoans.

“In response to the anthropogenic assault of toxic baits, populations of the German cockroach have rapidly evolved an adaptive behavioral aversion to glucose (a phagostimulant component of baits).”

Evolution (unintelligence) is assumed; the actual evidence could rightly be interpreted as being caused by invisible Intelligence. In fact, it is highly illogical to say an unguided and unintelligent process was responsible.

Ray Martinez said:

“In response to the anthropogenic assault of toxic baits, populations of the German cockroach have rapidly evolved an adaptive behavioral aversion to glucose (a phagostimulant component of baits).”

Evolution (unintelligence) is assumed; the actual evidence could rightly be interpreted as being caused by invisible Intelligence. In fact, it is highly illogical to say an unguided and unintelligent process was responsible.

Why should anyone interpret the evidence that way? Just because you say so?

Further comments by the Martinez troll will be sent to the bathroom wall. Please do not feed it (the troll, that is).

Martinez is still a cockroach, even on the bathroom wall.

Forgive me, but cockroaches have shown a capacity to learn. Trolls do not.

Ray learns.

Mainly misrepresentation, but it’s still a very minimal sort of learning.

Learning science, proper inference, etc., never. Heaven forbid, or at least his version of heaven forbids it.

Glen Davidson

Matt Young said:

Forgive me, but cockroaches have shown a capacity to learn. Trolls do not.

Agreed. Maybe we should try the glucose test on Ray.

Ray Martinez said:

In fact, it is highly illogical to say an unguided and unintelligent process was responsible.

It will become illogical when you show us some reasonable evidence for the existence and actions of the intelligent guide that explains the process better than the natural explanation we already have.

Ray Martinez said: it is highly illogical to say an unguided and unintelligent process was responsible.

Can anyone tell me why an intelligent, guiding agent would even care about the welfare of German cockroaches?

Sinjari said:

Ray Martinez said: it is highly illogical to say an unguided and unintelligent process was responsible.

Can anyone tell me why an intelligent, guiding agent would even care about the welfare of German cockroaches?

Don’t be silly man, it’s the cockroaches themselves. They were intelligent enough to figure out that they were being poisoned and that the glucose was being used as bait. They were then intelligent enough to sequence their own genome and determine the genes responsible for taste. They then genetically engineered themselves to taste bitter instead of sweet and presto, they now had an aversion to glucose. So you see, they will now avoid glucose, even though it is rarely associated with poison and is usually a good source of energy.

What they were apparently not intelligent enough to do was to just avoid the poison! What a shame.

DS said:

Sinjari said:

Ray Martinez said: it is highly illogical to say an unguided and unintelligent process was responsible.

Can anyone tell me why an intelligent, guiding agent would even care about the welfare of German cockroaches?

Don’t be silly man, it’s the cockroaches themselves. They were intelligent enough to figure out that they were being poisoned and that the glucose was being used as bait. They were then intelligent enough to sequence their own genome and determine the genes responsible for taste. They then genetically engineered themselves to taste bitter instead of sweet and presto, they now had an aversion to glucose. So you see, they will now avoid glucose, even though it is rarely associated with poison and is usually a good source of energy.

What they were apparently not intelligent enough to do was to just avoid the poison! What a shame.

That’s the Lamarckist explanation (also sometimes invoked by badly confused creationists in their effort to “say anything to contradict evolution”).

For a definitive ID explanation we have to go to a real expert, like Michael Behe.

Behe has made it clear that the Designer favors malaria parasites over humans. He has also noted that the bacterial flagellum, which increases the fitness of some pathogens, is magically designed by the Designer. Other authorities repeatedly assert that a deity rumored to be the same as Behe’s designer, wink, wink, is directly responsible for massive natural disasters.

Cockroaches are disgusting but massively less dangerous than malaria. They can cause a nasty allergy, and they are good “canary in a coal mine” indicators or unsanitary conditions that may harbor more dangerous threats, but in themselves, they aren’t especially threatening to human life.

So I would say, Sinjari, according to ID/creationists, favoring cockroaches is the least of it.

So I would say, why

Too many typos, point still stands.

Perhaps I wasn’t clear. My point was that what was observed was probably the least intelligent thing that you could do in response to poison. Whether cockroach or god, if you really did have any sort of actual “intelligence” you could certainly have come up with a better solution. Why not just avoid the poison, or make yourself immune to it, or find a way to metabolize it and get energy from it, or just eat the glucose and leave the poison, or use the poison to poison those who were trying to poison you, or avoid glucose without having it taste bitter, or choose one of a thousand simpler and better solutions?

On the other hand, what is observed is exactly the sort of thing that you would expect from random mutation and natural selection. And since that hypothesis explains all of the evidence, there is no need to invent any unseen forces and unlikely mechanisms for which there is absolutely no evidence. So Ray has once again been decapitated by Occum’s razor. That’s why he never provides any explanations, he just tries to ridicule evolution. If he ever did come right out an say what the fudge he’s talking about, everyone could see immediately that he was full of excrement.

DS said: On the other hand, what is observed is exactly the sort of thing that you would expect from random mutation and natural selection. And since that hypothesis explains all of the evidence, there is no need to invent any unseen forces and unlikely mechanisms for which there is absolutely no evidence.

Ah, but it all depends on your faith-based presuppositions. You are assuming – without evidence! – that we don’t live in a world ruled by invisible entities that miraculously guide us. [End creationism mode]

DS said:

Perhaps I wasn’t clear. My point was that what was observed was probably the least intelligent thing that you could do in response to poison. Whether cockroach or god, if you really did have any sort of actual “intelligence” you could certainly have come up with a better solution. Why not just avoid the poison, or make yourself immune to it, or find a way to metabolize it and get energy from it, or just eat the glucose and leave the poison, or use the poison to poison those who were trying to poison you, or avoid glucose without having it taste bitter, or choose one of a thousand simpler and better solutions?

On the other hand, what is observed is exactly the sort of thing that you would expect from random mutation and natural selection. And since that hypothesis explains all of the evidence, there is no need to invent any unseen forces and unlikely mechanisms for which there is absolutely no evidence. So Ray has once again been decapitated by Occum’s razor. That’s why he never provides any explanations, he just tries to ridicule evolution. If he ever did come right out an say what the fudge he’s talking about, everyone could see immediately that he was full of excrement.

Your point is clear and needless to say I agree with all of that.

I’m making what may be a subtle point. Lamarckism is wrong but still a lot less wrong than ID/creationism.

Under Lamarckism, which seems silly to those who have studied biology but is a common intuitive assumption, the cockroaches mysteriously “know” that they “need” to avoid glucose and somehow mutate their own genomes.

Under ID/creationism, the cockroaches don’t do it themselves. The post-modern right wing fundamentalist God “The designer” does everything. Which generates a whole new set of problems.

Then we are in complete agreement, which make you wise beyond my years. But why would anyone assume that cockroaches were intelligent in order to promote a religious agenda? Perhaps Ray is just going senile.

Marilyn said:

phhht said:

(There are lots of causes for mutations, but I’ve picked a random cosmic ray.)

Really.

Yes, I really did. So what?

Yes, I really did. So what?

Please, no bickering.

ksplawn said -

The genetic trait which re-wires a cockroach’s brain to sense glucose as bitter is one that already existed, even in wild-type populations. It’s a feature that was independently popping up in the background. It did not suddenly “evolve” or “adapt” just because people were putting out sweetened baits full of poison. Normally this type of taste perception was not an advantage for the cockroach, because it meant they’d pass over easy meals of high-energy foods loaded with glucose. Hence the relatively low rate of wild-type roaches with this reaction to glucose.

However, once there was a significant cost associated with the normal roaches that had a “sweet tooth,” like baited poisons, the mathematics of selection suddenly reversed. In human habitats, at least, it became an advantage to turn away glucose-rich foods because those were likely to kill you, removing your genetic load from the population. The roaches who already had the variant form of the genes for processing taste were suddenly being selected for instead of selected against, like their normal cousins. Thus, the frequency of their genetic traits in the population increased significantly. That’s the definition of evolution, and this is a great example of evolution through random mutation and (artificial?) selection.

This is likely to be about right but it may be a bit more complicated. Aversion to glucose might be related to a recessive allele. Under normal circumstances homozygotes might be selected against, but heterozygotes might not be. The heterozygotes might like glucose just a little less than cockroaches without the allele at all. The allele might or might not be linked to other alleles with significant effects.

Or, not mutually exclusively, there could be multiple genes involved. It doesn’t have to be a one gene effect. There could have been a spectrum of reaction to glucose in the naive population, ranging from rare individuals with aversion through varying degrees of attraction, based on an array of alleles.

Cockroaches have short generations and the poison is probably never perfectly effective. Numerous pathways to the glucose aversion point are possible. The only way to know what really happened is to do molecular genetic and neurobiological studies.

Phht said -

Both A and B like glucose. That means that both A and B have the allele, the genetic variant, for glucose attraction. The allele frequency in your population is 100%, because all (both) members of your population have the same allele.

Now suppose that A is pierced by a random cosmic ray which happens to alter his genome. (There are lots of causes for mutations, but I’ve picked a random cosmic ray.) Suppose that, due to the random cosmic ray, cockroach A now has the allele which disfavors glucose, while B remains unaffected. The allele frequency of the gene - that is, the ratio of the number of population members who have the allele to the total number of members of the population - has changed to 50%.

Suppose that A and B each produce ten offspring, giving us twenty-two members of our population. Suppose that five of the offspring of A inherit the mutated gene, and that no others do. The allele frequency in our population is now 6 (A plus his five offspring who got the mutant gene) divided by 22, or 27.27%.

At this point, natural selection comes into play. All sixteen of the roaches who like glucose eat of the poisoned motel and die, without leaving any progeny. The other roaches, who do not like glucose, eat other stuff and will, later on, reproduce. The size of the population is now six, and the frequency of the allele for disliking glucose is now 100% (the allele for liking glucose has a frequency of 0%.).

Notice that there is NO REASON WHATSOEVER to suppose that cockroaches exercise any sort of intentional behavior. Evolution explains what we actually observe WITHOUT ANY NEED for additional assumptions. Everything just works, and nobody needs gods or intelligent cockroaches or mysterious supernatural agents to explain it. Evolution works just fine without any of that stuff. Why drag it in if nobody needs it?

This is a model that incorporates mutation and natural selection, but it’s less likely than what ksplawn is saying. New mutations may or may not be involved. It’s highly unlikely that a one generational event like this occurred. It doesn’t have to be a one gene effect. This analysis ignores zygosity, or at best, assumes that a dominant allele is involved.

However, both of these models are within the realm of possibility, without invoking magic. Neither relies on supernatural or inexplicable events.

Matt Young said:

I may indeed be conflating Lamarckism with neo-Lamarckism, but I thought that more was involved than just need – the giraffe needed more than to be taller; it had to stretch its own neck if it was to pass its longer-neck trait to its descendants. Notice also that the Darwin quotation above,

…no amount of exercise, or habit, or volition, [my italics]…

uses the term “volition,” though that must have been written long after Lamarck’s time. Maybe someone more expert can shed some light on the chronology.

It does get semantic.

I use the term “Lamarckism” as I was taught to use it - if the environment directly produces a targeted mutation that humans would perceive an organism as “needing”, wanting”, or “striving for” (for its descendants, that is), that’s all Lamarckism to me. Whether some sort of conscious application of psychic powers by the short-necked giraffe ancestor is required is moot. However, I guess we could make the distinction, within Lamarckism, between conscious and unconscious targeting of the mutation. It’s still Lamarckism to me because the environmental situation leads to a targeted mutation - no selection necessary. It still all has the same problems I mentioned above. The “conscious” idea raises a big new problem - why aren’t we humans conscious of targeting our own genomes, if that’s how mutation works?

I have learned to recognize - and dislike - the term “neo-Lamarckism” as a very clumsy reference to a perfectly valid scientific observations. Some organisms have evolved DNA repair mechanisms which are less effective in a “stressful” environment. As far as I know, human DNA repair enzymes don’t have this characteristic, but some types of lake fish in Africa show this. It really only makes sense in organisms with vast numbers of offspring and high mortality of young offspring. A decently supported hypothesis is that when new predators or the like bring “stress” to the environment, a more diverse brood of young is more likely to contain rare individuals with new modifications that might be useful against the new stress. In a more stable environment, this tendency would be selected against. Because, in this model, the environment impacts on mutation rate in a meaningful way, this is sometimes, execrably in my opinion, but nevertheless, sometimes referred to as “neo-Lamarckism”.

Anyway, though, that’s just my personal understanding, and if the general meaning of the word slowly changes, so be it.

The roach article reminds me of a taste variation seen in humans. I am referring to the classic traits of being a ‘taster’ for the bitter chemical phenylthiocarbamide (PTC), which is a dominant allele. Homozygotes for a mutation (possibly for a particular taste receptor protein, but it could be something else) are ‘non-tasters’. They cannot taste this chemical. There are variations in what individuals in a population can taste or not taste, and these variations can have a genetic basis and so be subjected to natural selection. Of course the roach situation is especially interesting since it appears to result in a difference in an interpretation of what they taste. There are a variety of ordinary ways in which this could occur (in theory).

Of course the roach situation is especially interesting since it appears to result in a difference in an interpretation of what they taste. There are a variety of ordinary ways in which this could occur (in theory).

Meaning “interpretation” in the sense of “behavioral reaction to”, I presume.

It does get semantic.

I use the term “Lamarckism” as I was taught to use it - if the environment directly produces a targeted mutation that humans would perceive an organism as “needing”, wanting”, or “striving for” (for its descendants, that is), that’s all Lamarckism to me. Whether some sort of conscious application of psychic powers by the short-necked giraffe ancestor is required is moot. However, I guess we could make the distinction, within Lamarckism, between conscious and unconscious targeting of the mutation. It’s still Lamarckism to me because the environmental situation leads to a targeted mutation - no selection necessary.

I think the point is that the organism has to do something positive in order for the trait to “take.” That is why the giraffe’s neck gets longer with succeeding generations but the spaniel’s tail does not become bobbed.

Psychic powers are irrelevant (also nonexistent). All you have to think is that the somatic cells communicate acquired characteristics to the germ cells, as Darwin speculated. As far as I know, Lamarckism did not involve the supernatural.

harold said:

The “conscious” idea raises a big new problem - why aren’t we humans conscious of targeting our own genomes, if that’s how mutation works?

That’s always been my response. If the bacterium can “will” itself a flagellum, why can’t I will myself all sorts of better features? Certainly my “intelligence” is “better” in some sense than that of the bacterium. Certainly my imagination is. Ray’s never been able to answer that one.

I’m glad that Matt posted this subject. I really appreciate your explanation Phhht it has made the circumstances very clear so I can understand better. It is an important subject to me as there has been talk about insects been put into the human food chain so how poison affects these and rodents is a concern to me for any side effects that possibly would not be noticed in the near future.

I’m glad you found it helpful.

Be sure to note that the oversimplified example I gave does not correspond exactly to the situation of the cockroaches in the paper.

Marilyn said:

I’m glad that Matt posted this subject. I really appreciate your explanation Phhht it has made the circumstances very clear so I can understand better. It is an important subject to me as there has been talk about insects been put into the human food chain so how poison affects these and rodents is a concern to me for any side effects that possibly would not be noticed in the near future.

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This page contains a single entry by Matt Young published on May 24, 2013 8:50 AM.

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