Thursday, April 12, 2012

No, Really, Group Selection Doesn't Work

Group selection is kind of like the horror genre of movies: even if the movie was terrible, and even if the main villain gets killed off, you can bet there will be still be a dozen sequels. Like the last surviving virgin among a group of teenage campers, it's now on my agenda to kill this idea once again, because it seems the first couple dozen times it was killed, the killing just didn't stick. Now I have written about this group selection issue before, but only briefly. Since people seem to continue and actually take the idea seriously, it's time to explicitly go after the fundamental assumptions made by group selection models. Hopefully, this will put the metaphorical stake through the heart of this vampire, saving me time in future discussions as I can just link people here instead of rehashing the same points over and over again. It probably won't, as some people seem to like group selection for some currently unknown reason, but fingers crossed anyway.

                                        Friday the 13th, part 23: At this point, you might as well just watch the first movie again, because it's the same thing.

Recently, Jon Gotschall wrote an article for Psychology Today about how E.O. Wilson thinks the selfish gene metaphor is a giant mistake. As he didn't explicitly say this idea is nonsense - the proper response - I can only assume he is partially sympathetic to group selection. Et tu, Jon? There's one point from that article I'd like to tackle first, before moving onto other, larger matters. Jon writes the following:
In effect, this defined altruism-real and authentic selflessness--out of existence. On a planet ruled by selfish genes, “altruism” was just masked selfishness.
The first point is that I have no idea what Jon means when he's talking about "real" altruism. His comments there conflate proximate and ultimate explanations, which is a mistake frequently cautioned against in your typical introductory level evolutionary psychology course. No one is saying that other-regarding feelings don't exist at a proximate level; they clearly do. The goal is explain what the ultimate function of such feelings are. Parents genuinely tend to feel selfless and act altruistically towards their children. That feeling is quite genuine, and it happens to exist in no small part because that child carries half of that parent's genes. By acting altruistically towards their children, parents are helping their own genes reproduce; genes are benefiting copies of themselves that are found in other bodies. The ultimate explanation is not privileged over the proximate one in terms of which is "real". It makes no more sense to say what Jon did than for me to suggest that my desire to eat chocolate cake is really a reproductive desire, because, eventually, that desire had to be the result of an adaptation designed to increase my genetic fitness. Selfish genes really can create altruistic behavior, they just only do so when the benefits of being altruistic tend to outweigh the costs in the long run.

Speaking of benefits outweighing the costs, it might be helpful to take a theoretical step back and consider why an organism would have any interest in joining a group in the first place. Here are two possible answers: (1) An organism can benefit in some way by entering into a coalition with other organisms, achieving goals it otherwise could not, or (2) an organism joins a group in order to benefit that group, with no regard for its own interests. The former option seems rather plausible, representing cases like reciprocal altruism and mutualism, whereas the latter option does not appear very reasonable. Self-interest wins the day over selflessness when it comes to explaining why an organism would bother to join a group in the first place. Glad we've established that. However, to then go on to say that, once it has joined a coalition, an organism converts its selfish interests to selfless ones is to now, basically, endorse the second explanation. It doesn't matter to what extent you think an organism is designed to do that, by the way. Any extent is equally as problematic.

                                           If you want any hope of being a millionaire, you will need a final answer at some point: selfish, or selfless?

But organisms do sometimes seem to sometimes put their own interests aside to benefit members of their group, right? Well, that's going to depend on how you're conceptualizing their interests. Let's say I'm a member of a group that demands a monthly membership fee, and, for the sake of argument, this group totally isn't a pornography website. I would be better off if I could keep that monthly membership fee to myself, so I must be acting selflessly by giving it to the group. There's only one catch: if I opt to not pay that membership fee, there's a good chance I'll lose some or all of the benefits that the group provides, whatever form those benefits come in. Similarly, whether through withdrawal of social support or active punishment, groups can make leaving or not contributing costlier than staying and helping. Lacking some sort of punishment mechanism, cooperation tend to fall apart. The larger point there here is that if by not paying a cost, you end up paying an even larger cost, that's not exactly selfless behavior requiring some special explanation. 

Maybe that example isn't fair though; what about cases like when a soldier jumps on a grenade to save his fellow soldiers? Well, there are a couple of points to make about the grenade-like examples: first, grenades are obviously an environmental novelty. Humans just aren't adapted to an environment containing grenades and, I'm told, most of us don't make a habit of jumping into dangerous situations to help others, blind to the probably of injury to death. That said, if you had a population of soldiers, some of which had a heritable tendency to jump on grenades to save others, while other soldiers had no such tendency, if grenades kept getting thrown at them, you could imagine which type would tend to out-reproduce the other, all else being equal. A second vital point to make is that every single output of an cognitive adaptation need not be adaptive; so long as whatever module led to such a decision tended to be beneficial overall, it would still spread and be maintained throughout the population, despite occasional maladaptive outcomes. Sometimes a peacock's large tail spells doom for the bird who carries it as it is unable to escape from a predator, but that does mean, on the whole, any one bird would be better suited to just not bother growing their tail; it's vital for attracting a mate, and surviving means nothing absent reproduction.  

Now, onto the two major theoretical issues with group selection itself. The first is displayed by Jon in his article here:
Let’s run a quick thought experiment to see how biologists reached this conclusion. Imagine that long before people spread out of Africa there was a tribe called The Selfless People who lived on an isolated island off the African coast. The Selfless People were instinctive altruists, and their world was an Eden. 
The thought experiment is already getting ahead of itself in a big way. In this story, it's already assumed that a group of people exist with these kind of altruistic tendencies. Little mind is paid to how the members of this group came to have these tendencies in the first place, which is a rather major detail, especially because, as many note, within groups selfishness wins. Consider the following: in order to demonstrate group selection, you would need a trait that conferred group-level fitness benefits at individual-level fitness costs. If the trait benefited the individual bearer in any way, then it would spread through standard selection and there would be no need to invoke group-level selection. So, given that we're, by definition, talking about a trait that actively hinders itself getting spread in order to benefit others, how does that trait spread throughout the population resulting in a population of 'selfless people'? How do you manage to get from 1 to 2 by way of subtraction?

                                                                              Perhaps it's from all the good Karma you build up?

No model of group selection I've come across yet seems to deal with this very basic problem. Maybe there are accounts out there I haven't read that contain the answer to my question; maybe the accounts I have seen have an answer that I've just failed to understand. Maybe. Then again, maybe none of the accounts I read have actually provided a satisfying answer because they start with the assumption that the traits they're seeking to prove exists already exists in some substantial way. That kind of strikes me as cheating. Jon's thought experiment certainly makes that assumption. The frequently cited paper by Boyd and Richardson (1990) seems to make that assumption as well; people who act in favor of their group selflessly just kind of exist. That trait needs an explanation; simply assuming it into existence and figuring out the benefits from that point is not good enough. There's a chance that the trait could spread by drift, but drift has, to the best of my knowledge, never been successfully invoked to explain the existence of any complex adaption. Further, drift only really works when a trait is, more or less, reproductively neutral. A trait that is actively harmful would have a further hurdle to overcome.

Now positing an adaptation designed to deliver fitness benefits to others at fitness costs to oneself might seen anathema to natural selection, because it is, but the problems don't stop there. There's still another big issue looming: how we are to define the group itself; you know, the thing that's supposed to be receiving these benefits. Like many other concepts, what counts as a group - or a benefit to a group - can be fuzzy and is often arbitrary. Depending on what context I currently find myself in, I could be said to belong to an almost incalculably large number of potential groups, and throughout the course of my life I will enter and leave many explicitly and implicitly. Some classic experiments in psychology demonstrate just how readily group memberships can be created and defined. I would imagine that for group selection to be feasible, at the very least, group membership needs to be relatively stable; people should know who their "real" group is and act altruistically towards it, and not other groups. Accordingly, I'd imagine group membership should be a bit more difficult to just make up on the spot. People shouldn't just start classifying themselves into groups on the basis of being told, "you are now in this group" anymore than they should start thinking about a random woman as their mother because someone says, "this woman is now your mother" (nor would we expect this designated mother to start investing in this new person over her own child). That group membership is relatively easy to generate demonstrates, in my mind, the reality that group membership is a fuzzy and fluid concept, and, subsequently, not the kind of thing that can be subject to selection.    

Now perhaps, as Jon suggested, the selfless people will always win against the selfish people. It's an possible state of affairs, sure, but it's important to realize that it's an assumption being made, not a prediction being demonstrated. Such conditions can be artificially created in the lab, but whether they exist in the world, and, if they do, how frequently they appear, is another matter entirely. The more general point here is that group selection can work well in the world of theory, but that's because assumptions are made there that define it as working well. Using slightly tweaked sets of assumptions, selfless groups will always lose. They win when they are defined as winning, and lose when they are defined as losing. Using another set of assumptions, groups of people with psychic abilities win against groups without them. The key then, is to see how these states of affairs hold up in real life. If people don't have psychic abilities, or if psychic abilities are impossible for one reason or another, no number of assumptions will change that reality.     

Finally, the results of thought experiments like the foot-bridge dilemma seem to cut against the group selection hypothesis: purposely sacrificing one person's life to save the lives of five others is, in terms of the group, the better choice, yet people consistently reject this course of action (there, B=5, C=1). When someone jumps on a grenade, we praise them for it; when someone throws another person on a grenade, we condemn them, despite this outcome being better from the group perspective (worst case, you've kill a non-altruist who wouldn't jump on it anyway, best case, you helped an altruist act). Those outcomes conflict with group selection predictions, which, I'd think, should tend to favor more utilitarian calculations - the ones that are actually better for a group. I would think it should also predict Communism would work out better than it tends to, or that people would really love to pay their taxes. Then again, group selection doesn't seem to be plausible in the first place, so perhaps result like these shouldn't be terribly surprising. 

References: Boyd, R., & Richerson, P.J. (1990). Group selection among alternative evolutionary stable strategies. Journal of Theoretical Biology, 145, 331-342.

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