Darwin Was Right About How Evolution Can Affect Whole Group
Evolutionary biologists at McGill University have discovered molecular signals that can maintain social harmony in ants by putting constraints on their fertility. Dr. Ehab Abouheif, of McGill’s Department of Biology, and post-doctoral researcher, Dr. Abderrahman Khila, have discovered how evolution has tinkered with the genes of colonizing insects like ants to keep them from fighting amongst themselves over who gets to reproduce.
“We’ve discovered a really elegant developmental mechanism, which we call ‘reproductive constraint,’ that challenges the classic paradigm that behaviour, such as policing, is the only way to enforce harmony and squash selfish behaviour in ant societies,” said Abouheif, McGill’s Canada Research Chair in Evolutionary Developmental Biology.
It’s unfortunate that group selectionism is gaining some traction once again. It almost never makes any sense and simply acts as a way of taking the easy explanation over the difficult answer.
This study found that evolution has changed the genetic make-up of ants to the point where social harmony is achieved through “reproductive constraint”. In other words, some worker ants have less or no fertility level relative to others because of particular gene regulations. Big deal. This doesn’t point to any group selectionism.
What makes far more sense is that ants which promote social harmony are more successful on average. Instead of looking toward the goal-oriented ideas of group selectionism, it’s more reasonably to view this as individual genes promoting their own fitness. That is, most ants in a colony, if not all, are going to share a high degree of genes. It isn’t that the vehicle for these genes – the organism, in this case, the ant – is important. The survival of the gene itself is important. With more harmony comes, perhaps, more reproduction and more success. And what’s being reproduced are a high number of shared genes.
Think of it this way. My brother and I share 50% of our genes. If I help him to reproduce, I have roughly 25% of my genes surviving to the next generation. Of course, if I simply reproduce on my own, that’s 50% of my genes that will be passed on. But if I’m fighting with my brother over the same woman, we decrease our reproduction odds. It may just benefit me on the level of the gene to help him reproduce at my own expense. Having assistance will help his odds (even if this assistance is passive, as in not fighting him). This will give 25% of my genes a better chance of surviving than the 50% of genes I ‘own’ have when there is conflict.
Rather than showing the notion of group selectionism to be valid (though it remains plausible), this research offers some interesting evidence which favors natural selection occurring at the level of the gene
Filed under: Evolution, News | Tagged: Canada Research Chair in Evolutionary Developmental Biology, darwin, Dr. Abderrahman Khila, Evolution, group selection, McGill University, natural selection, reproductive constraint, Richard Dawkins, sciencedaily.com, selfish gene, the selfish gene |
For the Sake of Science 
In particular, “…the classic paradigm that behaviour, such as policing, is the only way to enforce harmony and squash selfish behaviour in ant societies…” is absurd. Where is this general ‘paradigm’ (a red flag for me anymore – anybody trying to upset paradigms is pulling somebody’s leg) written? Nothing I’ve read in the literature of eusocial insects suggests that each individual ant is craving reproduction and that only physical ‘policing’ keeps them all in line and working together. Intellectual tripe.
I’ve seen no reports that ants are selfish, or that guards hope to be queens someday…
Matt
“What makes far more sense is that ant colonies which promote social harmony as [are?] more successful on average. Instead of looking toward the goal-oriented ideas of group selectionism, …”
I don’t understand the derisive attitude I often see towards group selection. I realize that more evidence would need to accumulate for it to be generally accepted, but as a hypothesis I’m not sure how someone (not referring to you) can reject a priori the idea that selection might act on several levels at the same time.
In the above quote you speculated that ant colonies, not individual ants, might be more successful on average if they promote social harmony. How is that different from “group selectionism”? And is your phrase “goal-oriented ideas” a slam? In the real world it would seem that mutation and selection acting on one or many levels only appear goal-oriented after the fact, so group selection would not be any different from gene selection in that regard.
You are correct in pointing out an error in language on my part. I’ve updated and corrected this mistake.
Group selectionism, while it is a viable hypothesis, does seem to lend itself to goals, which makes little sense for a natural process.
Without group selection there would be no evolution.
The process began when when molecules first came together in groups to perform those functions we now consider to be characteristics of life.
At this point they were acted on by natural selection.
No group, no evolution.
I think that’s a bit of a redefinition of what is meant by group selection. There’s a discussion between Richard Dawkins and PZ Myers available on YouTube where this is one topic.
It may be a little variation, but I think it is a significant matter.
It’s important to always have in the back of the mind the initial starting point of the process of evolution to avoid confusion over what later became more complex.
We have to keep in mind that it was natural selection that formed those first organisms, the “survival machine” metaphor is misleading. As Dawkins said, genes have no foresight, they do not plan ahead, genes just are.
Such entities cannot build anything, it was chance groupings of these entities that were selected.
Group selection as it is traditionally defined would necessitate, I think, some actual foresight – if the fishing supply gets low, everyone cuts back. There would seem to need to be an acknowledgement beforehand that the fishing supply may become low and that every organism in the species needs to cooperate.
Of course, this leads to the next problem. There isn’t much in the way to block the introduction of a cheater into the population, at least not without anti-cheater foresight, wouldn’t you agree?
Forgive me for being hazy on this one, but I think the problem of cheaters was resolved recently, maybe by Wilson and Wilson, and was shown to not be a problem at all.
As you concede Mike, the arguments against group selection are not strong, and I think it would be wise to abandon what you refer to as “group selection as it is traditionally defined.” Much of that defining has been done by those opposed to the concept, with obvious results. The definition or description given by Dawkins in TSG for example, was simply incorrect.
The main objection to group selection seems to be that it is not as “provable” as gene selection, but selection at the level of genes has two obvious flaws.
The first is that evolution and natural selection are intimately tied to reproduction, yet genes do not reproduce. The entity that reproduces is a group of genes, and what that entity produces is another group of genes.
The second flaw of gene selection is related to the first. It is not genes that are selected, it is groups of genes. An organism survives and reproduces if its combination of characteristics allows it to do so. A characteristic of speed for example, will not be passed on if the organism that houses it is stupid or blind or impaired in some significant way.
When looked at this way, its clear that natural selection is group selection, which is why traditional ideas about group selection should be abandoned.