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?
Joe seems to be saying it’s all of the genes responsible for the behavior.
Anything unique to the dying individual (or cell) is irrelevant.
petrushka:
Alan:
Petrushka,
That’s what dialogue is for. If you think I got it wrong, then give us your paraphrase of your statement:
This is all true (though I can’t be absolutely certain), as far as I am concerned.
Oh the irony!
What irony? We’re having a dialogue right now.
petrushka,
Right. This is exactly why I’ve been stressing that your focus on “unique mutations” is misplaced.
From an earlier comment:
I should point out that the analogy is not perfect. The genetic identity between all cells in a single body is total, so there’s a different dynamic. But, for the purposes of this discussion, the analogy is good enough, I guess.
The daily sacrifice of your skin cells does affect the propagation rate of the genes (meaning the template for all copies of it) that produce that behaviour. Which is what it’s about. But whatever the meaning of the word altruism is in the context of this discussion, I’m sure everybody agrees with me that we should draw the line at the singular organism (a sterile worker ant, for instance).
Which ones? What the biological explanations might be for individual examples of apparent altruism are still under observation; Blood sharing in vampire bats is still not clear. There are observations and there are hypotheses. It’s not settled yet.
Nope. It’s a label for a possibly unrelated group of behaviours across species. Ant altruism might make sense when looking at suicidal behaviour in ants. But to talk of altruism as a coherent property is as meaningful as talking about “junk” DNA.
It’s the observation, experiment and analysis that’s important. The label is handy for filing a library book. Ant altruism is an observed phenomenon. We can live with it as everyone (almost, not sure about you) understands that ant altruism implies nothing about sacrifice or laying down one’s life for ones companions.
I’m not focusing on unique. Just the reverse.
Cancer?
Perhaps worth repeating:
Yes. I don’t understand the point.
Indeed. Anything unique to the dying individual has never been the subject of this discussion. It’s about alleles (in the ideal sense, meaning all copies of the allele, no matter what body they occupy), and how successful they are in producing more copies of themselves.
I think we should be careful about reification. Handy labels should not persuade us to misleading anthropomorphisms.
Indeed, cancer cells have a different genetic makeup. Which is why they do not work well with the rest of the body. For the purposes of this discussion, you could consider them different organisms.
Anthropomorphisms? In what way?
Sure. But unless you are a germ-line cell, or perhaps a HeLa cell”, your genes die with you
Yes, that’s been my reading of your posts from the start of this strange argument.
Gralgrathor,
In this case “altruism”. I’m very doubtful that genuine altruism happens much amongst humans, let alone simpler organisms.
Let’s narrow the field a little. Let’s say that we’re talking about kin-altruism. Which is pretty well-defined in biology, and has a known evolutionary explanation.
Alan,
You said you trusted Joe’s opinion. Joe has confirmed that self-sacrificing ant behavior has a genetic explanation.
He is right. You are wrong.
But in this context, altruism means no more than behaviour that produces the effect of reducing ones own life-expectancy/reproductive chances/etc, while promoting those of another individual who is likely carrying some of your genes (and Darwin willing, the ones that cause the altruistic behaviour).
The French tell me they always know a Brit from how often they say thank-you and sorry. So excuse me for saying sorry again, it must be in the genes, for not walking away. I’m on record here as admitting several errors that I can remember and if I genuinely thought I was in error on the biology, I would say so.
No, they don’t. That’s the whole point of the evolutionary explanation of kin-altruism: your genes survive in the kin that you helped survive and propagate.
We gotta go back to ants here, because I don’t feel comfortable with the body/skin analogy. Despite what I said before, I feel as though I’m overlooking some fundamental difference in dynamics that affects the analogy.
The key is the reproductive element. Once chloroplasts and mitochondria threw in their lot with host cells, their destiny was forever linked.
Count the anthropomorphisms! 🙂
There’s no need to be too cautious. Anybody who knows anything about population genetics and the “gene’s eye view” on evolution as Hamilton and Dawkins held knows that we’re talking about effects, not intentions.
Well, you seem to be able to draw different inferences from what has been written than anyone else who has commented.. I regret to inform you that your declaration is not convincing. Sorry! But thank you for the comment.
Gralgrathor,
Experience on “Intelligent Design” websites has taught me I ought to be careful with language. And possibly experience elsewhere! 😉 We’re in the middle of a heat-wave here at the moment so I’m a bit lethargic but I will try to skim through “Selfish Gene” and “Extended Phenotype” again. Just flicking to the index, I see there are references to altruism.
Alan,
Not at all. Who (besides you) disagrees that there is a genetic explanation for self-sacrificing behavior in ants?
Joe was very clear:
Actually, The Selfish Gene is almost entirely about altruistic behaviour and how it could evolve.
The really bizarre thing is that Alan himself withdrew his statement about the necessity of genetic explanations at one point.
If he has been right all along, as he claims, one can only wonder why he chose to withdraw his statement.
Alan?
Does it help if I clarify by saying “that particular set or copy of genes resident in a sterile worker ant”. Because I agree with what you say.
I know. I just think that it’s a point worth making and repeating, because it’s that that the whole evolutionary explanation for kin-altruism is about: the preservation of copies of ones own genes in other bodies.
What? “Well, no”? Believe it or not, I was trying to find common ground with you. I don’t have a “side” or a “position”. I enjoy an argument but the best outcome is if everyone learns something new. Your motivation, I don’t understand. I’ve asked a couple of times what it is you want to achieve by contributing here. I’m still genuinely interested.
The problem is not the paraphrasing.
It seems reasonable to assume that keiths’ paraphrase is an attempt to present his understanding of what you wrote. So the problem you see in the paraphrase is really a consequence of a problem in understanding. It is made worse by the fact that keiths does not realize that he has a problem in understanding.
And where have I disagreed with the biology as outlined by Joe? You seem not to grasp the possibility that you are misreading what is being written.
Alan:
You know the answer perfectly well.
For the nth time, from an earlier comment:
Gralgrathor,
Believe it or not, Alan really is disputing that.
I say that the self-sacrificing behavior of soldier ants requires a genetic explanation, and Alan disagrees:
keiths, paraphrasing Scruton:
Alan:
I have no idea what non-genetic explanation Alan has in mind. Cultural? Older ants teaching their younger siblings to be good workers and soldiers?
He also disputes that the behavior of workers and soldiers directly influences the queen’s reproductive success:
keiths:
Alan:
Alan,
As my comment above demonstrates, you denied that the self-sacrificing behavior of ants has a genetic explanation, and you gave bad reasons for that denial.
You made some mistakes. It isn’t the end of the world. Why is this such a big deal for you? You’ve been fighting, literally for weeks, to avoid admitting your mistakes.
You even brought the issue back up a week after the original discussion ended!
Please take a serious look at why it is so hard for you to acknowledge mistakes. Or better yet, just give it a try. You’ll see that it isn’t nearly as bad as you’re making it out to be.
Alan really is not disputing that. Keiths seems to know what I think whether I tell him differently or not. This is not what I consider an honest way of proceeding.
It’s right there in the quote, Alan.
Are you going to argue that “Well, no” means “Well, yes”?
Take responsibility for what you wrote.
Ditto.
I’m tempted to riposte but I don’t have Walto’s energy.
Let me just ask you again. What are you trying to achieve here? This is a question I’ve asked a few times already and I’m still genuinely interested.
Well, maybe! Let me ask you again. What’s your goal in posting and commenting here? What are you trying to achieve?
Of course explaining how forms of altruism could evolve in species that are already eusocial is easy. And while useful as a model, such explanations don’t actually describe a real-life situation. In reality, reproductive altruism is part of eusociality, and an explanation for the evolution of the structure of an ant colony will have to explain how this particular form of altruism, the eusocial colony, evolved. That’s where it gets a bit tricky.
I don’t know much about the science, but I think the phrase “genetic explanation” isn’t terribly useful. Is there such an explanation for someone’s being fluent in German? How about for keit’s personality on the web? Yes and no. I believe what Joe did was explain to what extent the soldier ant’s altruism can be said to be genetically explained and to what extent additional causal explanations are necessary.
That was my (admittedly pretty ignorant) take on Alan’s remarks. In any case I didn’t see any contradiction between his views on the matter and Joe’s that wasn’t produced by keit’s purposeful misconstrual of “genetic explanation” to mean something like “being to some extent a result of the passing along of genetic information.” Nobody ever doubted that here, I don’t think–and I include Gregory.
Again, I could be mistaken–this is not an area I’ve studied, but I’m very familiar with fallacious arguments and intentional misrepresentations.
Gralgrathor,
On reading that paper on the cladistics of ants and their relationship in particular to mud-dauber wasps, I wondered whether ants evolved first and then evolved eusociality or eusocial insects evolved to become ants. I don’t think there is such a thing as a solitary ant species living today.
That was indeed my point. The explanation is the explanation. Calling it “genetic” adds (nor detracts) nothing. The quality of the explanation is not strained…
No, I don’t think so.
In other words, all of the ant’s behaviour is explained by the ant genome. 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”.
So, to summarize, I think Joe would confirm that the general rule is that genes are ultimately responsible, but that the path by which genome leads to behaviour may vary.
Alan,
You asked:
I showed you exactly where.
You suddenly seem eager to change the subject, but let’s stick to one thing at a time.
keiths, paraphrasing Scruton:
Alan:
Your answer was “Well, no”, and you gave a bad reason in support of it.
Unlike you, Joe knows that the behavior does have a genetic explanation.
How is that not a complete disagreement?
Whose genes seems to be at issue. Worker genes (there are epigenetic aspects – for example, queen larvae in bees get more royal jelly) result in the development of worker ants but the copies in the workers aren’t passed on. The worker phenotype contributes to the colony extended phenotype and the survival or not of this phenotype is a prerequisite for the posibility of new colonies being established by daughter queens from the “mother” colony. The germ-line passes exclusively through the queen and her daughter queens. (caveat Zachriel’s example)
We might as well argue whether ant behavior was shaped by selection. And try to differentiate this from the genome being shaped by selection.