In the Roger Scruton on altruism thread, some commenters have expressed confusion over the evolutionary explanation of altruism in ants. If workers and soldiers leave no offspring, then how does their altruistic behavior get selected for?
The answer is simple but somewhat counterintuitive. The genes for altruistic behavior are present in both the workers/soldiers and in their parents. Self-sacrificing behavior in the workers and soldiers is bad for their copies of these genes, but it promotes the survival and proliferation of the copies contained in the queen and in her store of sperm. As long as there is a net reproductive benefit to the genes, such altruistic behaviors can be maintained in the population.
Selfish genes, altruistic individuals.
Let’s dedicate this thread to a discussion of other counterintuitive evolutionary truths. Here are some of my favorites:
1. The classic example of sickle-cell trait in humans. Why is a disease-causing mutation maintained in a human population? Shouldn’t selection eliminate the mutants? Not in this case, because only the unfortunate folks who have two copies of the allele get the disease. People with one copy of the allele don’t get the disease, but they do receive a benefit: improved resistance to malaria. In effect, the people with the disease are paying for the improved health of the people with only one copy of the mutation.
(Kinda makes you wonder why the Designer did it that way, doesn’t it?)
2. In utero cannibalism in sharks:
Shark embryos cannibalize their littermates in the womb, with the largest embryo eating all but one of its siblings.
Now, researchers know why: It’s part of a struggle for paternity in utero, where babies of different fathers compete to be born.
The researchers, who detailed their findings today (April 30) in the journal Biology Letters, analyzed shark embryos found in sand tiger sharks (Carcharias taurus) at various stages of gestation and found that the later in pregnancy, the more likely the remaining shark embryos had just one father.
(Kinda makes you wonder why the Designer did it that way, doesn’t it?)
3. Genetic conflict between parents and offspring. Here’s a great example from a 1993 paper by David Haig:
Pregnancy has commonly been viewed as a cooperative interaction between a mother and her fetus. The effects of natural selection on genes expressed in fetuses, however, may be opposed by the effects of natural selection on genes expressed in mothers. In this sense, a genetic conflict can be said to exist between maternal and fetal genes. Fetal genes will be selected to increase the transfer of nutrients to their fetus, and maternal genes will be selected to limit transfers in excess of some maternal optimum. Thus a process of evolutionary escalation is predicted in which fetal actions are opposed by maternal countermeasures. The phenomenon of genomic imprinting means that a similar conflict exists within fetal cells between genes that are expressed when maternally derived, and genes that are expressed when paternally derived.
(Kinda makes you wonder why the Designer did it that way, doesn’t it?)
Can readers think of other counterintuitive evolutionary truths?
Addendum
4. Mutant organism loses its innate capacity to reproduce and becomes a great evolutionary success. Can anyone guess which organism(s) I’m thinking of?
Does anyone else other than Keith think this statement is an incorrect general summary of what happens with ants? Because at the moment, I see no reason to change it. Perhaps “germ-line” would have been a better choice than “genome” but…
Not really:
The genomes of the various casts do not differ significantly. There are no separate worker or queen genomes. The difference is in development, guided by environmental factors.
Well indeed! It’s selection and variation feeding back on each other in a reiterative ratchet. All biology is evolution when you get close. 🙂
That’s not what I meant. Of course the same set of genes (or very similar) reside in every cell (unless there are enucleated ant cells like erythrocytes in humans – I don’t know about this.) in every ant body. Evo-devo and how precisely eggs develop as queens, workers or soldiers is a whole subject on its own, I’m sure. And haploid males?
Alan, your desperation is showing.
keiths, paraphrasing Scruton:
Alan:
Alan:
Your answer was “Well, no”. The correct answer would have been “Well, yes”, because as Joe has kindly confirmed, the behavior does require a genetic explanation.
You got it wrong, Alan. You’ve made this into a huge deal, but it was just a mistake, and nobody is surprised that you and walto got it wrong.
You are human just like the rest of us.
Okiedokie, I misunderstood. Although in that case I’m not sure what you did mean. Could you explain?
Different mode of reproduction, no heterozygosity, but still essentially the same genes.
Again, thank you for your assessment which has been noted. Sorry that I disagree but I do. Impasse.
No, I declared victory on this issue long ago. I win, you all lose. Muhahah.
You are displaying a complete inability to acknowledge an obvious mistake. That’s pitiful, Alan.
I understand that all sterile workers carry a full set of chromosomes similar almost identical) to the queen. As Zachriel pointed out it is possible, under certain circumstances for a worker to become fertile and start laying eggs.
Again, thank you for your assessment which has been noted. I think you are incorrect, however. Might I just ask again about what it is you’d like to achieve when you post and comment here. I have asked a couple of times already but perhaps you missed it.
I’m not sure fertile is the right word here, since I’m not sure such eggs could ever lead to offspring, but okay. What I don’t understand is your statement
The copies that reside in workers are dead ends genetically speaking. They, except in particular circumstances, will not be passed on.
In honey bees, I believe, if a queen dies, it is possible for a worker to become fertile and lay eggs. But as she will not have mated, the eggs can only hatch as haploid drones.
ETA haploid
Alan,
Your eagerness to change the subject has been noted.
If you think I am incorrect, perhaps you can explain how “Well, no” is actually the correct response to an assertion that ant behavior requires a genetic explanation.
You are claiming that the behavior doesn’t require a genetic explanation. As I wrote earlier:
Yes, that’s been established – it’s a given. But what is the point you’re trying to make with this statement? I’m not sure how it’s relevant to the discussion: after all, it’s about the preservation of copies that can get replicated in offspring.
Frankly, it was a stylistic irrelevance, which is why i withdrew those two words. Don’t worry and please continue to be exercised over them. Your indignation has been noted and for such inconvenience, I apologise.
I note that you would rather not discuss what you hope to achieve when you post and comment here. I’m sorry I pressed you and I shall just have to continue wondering.
Now would be a good time for you, Keiths, to finally admit that the statement in your OP that “Self-sacrificing behavior in the workers and soldiers is bad for their copies of these genes,”
is wrong.
Self-sacrificing behavior in sterile actors (ants, skin cells, XY females) has ZERO effect on their copies…
Pot, kettle.
I tend to be a bit stream-of-consciousness. I may have misunderstood you. I must be up early doing stuff before the heat kicks in tomorrow and it’s past midnight here.
That’s not exactly true. After all, reproductive altruism is one of the most significant forms of altruism discussed here. Workers can be said to make a great “sacrifice” in the sense that they relinquish any and all chance at producing offspring in order to help others reproduce. Look up the wiki articles on eusociality: they mention reproductive altruism.
Here too. For some reason I am watching Japan – Greece. When I should really be hitting the sack.
keiths:
Alan:
“Well, no” expresses disagreement. It is not a “stylistic irrelevance.” Why are you refusing to take responsibility for your own comment?
In that context, an answer of “Well, no” is different from an answer of “No”. That’s a subtlety of language that you seem to miss.
DNA_Jock,
Gralgrathor is right about altruism. You should be a little more careful with your accusations.
Neil,
🙂
I’ll hazard a guess here.
I think keiths is standing up for truth, justice and the American way. And I think he is actually being quite honest and straightforward, as best he sees it.
I’m pretty sure that he does not understand why there’s problem. He does not answer your question that I quoted above, because he does not understand what it is about.
But environmental factors like chemical signalling will determine how an individual ant will develop and what behaviour it will display: what genetically programmed developments and behaviours are “triggered”.
I take it that was Alan’s point. You’ve got exactly the same genetic material in two ants–one becomes a soldier, one doesn’t. We conclude, therefore, that there are other factors than genetic factors in that differentiation. So, depending on what “genetic explanation” means, we can say either that altruism IS entirely genetically explained or we can say, altruism IS NOT entirely genetically explained. It’s a quibble, certainly, but it seems to me what Alan and keit have been arguing about for the last few days. And it’s silly (not to say immature) to keep insisting “I’m right! I’m right!” about a dispute of that nature.
As I said earlier, I disagree with this medicalization of keit’s obnoxiousness. Plus I think some people might even find it a little more insulting than when I call him a prick.
I understand your point – yet I cannot help but mention the fact that the production of chemical signalling as well as the responsiveness to it are, of course, genetically “programmed” – and so “genetically explained”.
But yes, “genetically explained” is a bit of a vague term. Perhaps we should be speaking of “explanations in terms of selection”, ie. the differential reproductive success of genes.
Workers can lay unfertilized eggs that lead to fully fertile, haploid males. However, the colony polices for cheaters.
Helanterä & Sundström, “Worker reproduction in Formica ants”, 2007.
Okay I feel slightly more kindly towards keiths.
I wrote:
to which you replied:
No. It is exactly true. You are correct about eusociality, but that does not affect the accuracy of my statement, nor the inaccuracy of keiths’s. You and keiths are failing to read for comprehension.
Choosing to not reproduce could be considered altruistic (certainly for some posters here 😉 ) [consider the creation of fruiting bodies in slime molds], but IF YOU ARE ALREADY STERILE then whatever behavior you indulge in, it has ZERO effect on the evolutionary fate of YOUR COPIES of your genes. As I said originally, your half-sibs (or other kin) may benefit.
I would have thought that was obvious from my examples, e.g. my skin cells’ sacrifice to save my daughters’ lives.
So keiths, I am very careful in my accusations.
Ah, thanks. Frequent successful worker reproduction could have some interesting consequences in the population dynamics of the colony and the species. Too bad I can only read the abstract.
1) You’re saying nothing new there: copies that aren’t replicated aren’t replicated. But what it’s about is their copies in other bodies that do get replicated. That’s what drives selection, in the case of altruism. The gene is the same, no matter in what body it resides.
2) Reproductive altruism is a real term, describing a real phenomenon. It doesn’t matter that it’s programmed, stimulated chemically, enforced by policing: spending ones energy at tasks other than reproducing is a behaviour, and when that behaviour aids the reproduction of ones genes through other channels (ie. the queen), it is, according to biological definitions, a case of altruism. And yes, the behaviour of worker does affect the chances of worker-genes getting propagated – through the queen.
Gralgrathor,
Thank you for agreeing with me. Perhaps you can get keiths to see the error in the OP: “Self-sacrificing behavior in the workers and soldiers is bad for their copies of these genes,”
[emphasis in original]
I didn’t. I felt that your statement was either indicative of a misunderstanding of the models under consideration, or irrelevant to them. I sought to correct this.
This statement, from the OP, is actually a correct description of the situation. The copies inside worker bodies aren’t replicated. But the important thing is that copies of the same genes do get replicated through the queen. And that the reproductive rate for these genes is increased by the behaviour that these genes code for in workers.
So much for insect ‘utopia’. It’s cooperation and competition all the way down.
http://www.jstor.org/stable/10.1086/518185
walto,
The question is not whether the altruistic behavior is “entirely genetically explained”. It isn’t, of course. At the very least you have to invoke biology, physics, and chemistry too.
The actual question was whether the altruistic behavior requires a genetic explanation, and the answer is clearly “yes”. Alan got it wrong:
keiths, paraphrasing Scruton:
Alan:
You and Alan got it wrong, walto. You’re human like the rest of us.
Zachriel:
Yes — even inside cells! From Haig’s abstract:
The selfish gene hypothesis is a very important one.
Thanks again!
One of my all-time favorite Denyse O’Leary quotes:
keiths,
“entirely genetically explained”. It isn’t, of course. At the very least you have to invoke biology, physics, and chemistry too.
The actual question was whether the altruistic behavior requires a genetic explanation, and the answer is clearly “yes”.
Aha, it isn’t (of course!) entirely genetically explained” but it requires a genetic explanation and “clearly has one.” Thanks for your careful clarification.
As I said above, what you’ve meant by genetic explanation in your posts on this matter has been “partial (or incomplete) genetic explanation,” since you (FINALLY!!) concede in the post I’ve quoted here that soldier ant altruism is not entirely explicable by genetics (which is precisely what Alan and Joe said in only slightly different terms).
However, I really think you and Alan should continue to fight about this for several more days. It’s crucial that he get exactly where you are on this issue and use precisely the same terminology.
Gralgrathor,
Please pay attention what I actually wrote rather than whatever misunderstandings you think I am suffering from, and take note of the various examples I offered. You might then realize that I am pointing to the germline / soma distinction, which you have accurately described as “The copies inside worker bodies aren’t replicated.”
Therefore the statement “Self-sacrificing behavior in the workers and soldiers is bad for their copies of these genes,” is wrong. [Emphasis in the original]
Of course its “irrelevant to the models under consideration”, and not “the important thing”. It’s a picayune point. keiths was wrong (and before you start citing Helanterä & Sundström, read the first paragraph of the OP), and he resists admitting it.
Another picayune point: they are not actually the same copies as those in the queen, they are very very closely related. Somatic mutations occur.
In slime molds, the self-sacrificing behavior of stalk cells IS bad for their copies of genes-for-making-fruiting-bodies, because they are NOT sterile. Making them even more interesting than ants…
Used to have a pet slime mold, but it ran away.
http://zachriel.blogspot.com/2006/02/come-home-little-physarum.html
Zachriel,
Cute.
I had not kept up with the research, but I guess chimera formation is less likely in the wild, reducing the need for ‘cheater detection mechanisms’…
Very interesting little buggers.
Zachriel:
DNA_Jock:
They’re amazing:
How Brainless Slime Molds Redefine Intelligence
Slime mold mimics Canadian highway network
Computing with slime: Logical circuits built using living slime molds
walto,
Your tap dancing notwithstanding, the issue is straightforward:
1. I asserted that the ant behavior requires a genetic explanation.
2. Alan disagreed.
3. You joined Alan.
4. Joe confirmed that the ant behavior requires a genetic explanation.
You and Alan got this one wrong.
Wow. I had no idea there were so many distinct kinds of intragenomic conflict:
Intragenomic conflict
Challenge for those who are curious about evolution:
Read through as many of these comments as possible (as painful as it might be) and then try to come up with a reasonable account of how you think these circumstances came to be, via hapless poor sampling of a random purposeless replicator.
And if one thinks that although they themselves don’t really have a good answer to this, but certainly those in the know do, just read a bit more of these comments and try to convince yourself that there is ANYONE at all who knows what the hell they are talking about!
“Um, well, its genetic, but not really genetic, its altruistic, but not really altruistic, its, the behavior is programmed in the genes, but its not really in the genes, its in the chemical signaling, but the signaling is part of the genetics, but we don’t know where the signaling comes from, and you see we understand it completely, except for all the parts we have no explanation for, but look, Joe has it all figured out,so just trust him, because we have already decided long ago that it just has to have a Darwinian explanation…..Oh, who the fuck knows, its just true. Or not true if that explains that there is no God. Which ones explains that again…dam”
Phoodoo’s comment is a classic muddy-the-waters strategy. No one actually has to “trust” me — there are empirical observations and mathematical theory and computer simulations, all showing ways altruistic behaviors can evolve. Phoodoo should come back after mastering Hamilton’s 1963 condition for the evolution of altruism by kin sekection.
You’ll have to explain to me how it is wrong, DNA, since I cannot see how reproductive altruism can be good for the physical copies of genes in the body of the one displaying the reproductive altruism.
I’m afraid you’re going to have to spell things out for me. Tell me exactly what phrase in the OP you disagree with and exactly why.
More… or less? Anyway, because of the reproductive strategy of the organisms in the slime mold, the dynamic’s completely different. There is no comparison. So I’ll stick to ants for now. We’ll do slime molds in another OP.
Edit: ah, Jock, I think I see what your point is now. You don’t see reproductive altruism as a behaviour. But, as I already pointed out: it is considered a form of altruism by biologists studying such phenomena as eusociality, and I see no reason to deviate from their definitions. Displaying reproductive altruism is bad for ones genes. Displaying additional altruistic behaviour on top of that can be bad for ones life-expectancy, etc, although because of the reproductive altruism it can no longer affect the odds of your physical copies of your genes getting replicated. But again, that’s irrelevant, except insofar as it affects the chances of other copies of the same genes getting replicated. So, /Edit.
That’s been done and done, ‘doo. You can find links to such accounts in the relevant wikipedia articles.