Harvard's Edward O. Wilson tries to upend biology, again
boston.com
boston.com
I've often explained aspects of human society to my non-scientist friends in terms of group selection. (Short version: Humans who formed tribes out-competed the loners.)
On an unrelated note, I don't see how group selection and kin selection are mutually exclusive.
Kin selection: organism X helps organism Y because it improves the prospects for the part of X's DNA that Y also has. The more related X is to something, the more willing X is to sacrifice itself for it. The most extreme example is also the most familiar: each of your cells has DNA identical to each of your other cells (if all is well). So a cell is completely willing to kill itself for the "collective", even at the expense of its own ability to reproduce. A less extreme example is that of a woman declining to pursue kids of her own in order to help tend her sister's, which could be adaptive when, e.g., food is scarce.
Group selection: members of a particular group (e.g., a tribe) are willing to engage in altruistic actions (e.g., suicidal defense of said tribe pre-procreation) even though doing so maladaptive at the level of the individual's DNA. This kind of cooperation is adaptive for the group as a whole, but not in the least for the individual. Groups that encourage this kind of behavior will outcompete groups that don't, so groups are selected for this trait.
IIRC, the primary reason that group selection is thought to be wrong is that it (apparently) can't yield an Evolutionarily Stable Strategy (ESS) -- it will always be better for the persistence of any individual's DNA if that individual refuses to be altruistic.
I don't think that could be right, because the altruistic individuals altruism could include killing/punishing non-altruistic individuals. Shooting deserters comes to mind, as a real-life human example.
This sounds reasonable if you consider only one generation, or only the individual. But if you consider the whole group or species in the long run, the effect you see is exactly what you describe, i.e. groups that encourage this kind of behavior will outcompete groups that don't. So for a species to survive, it is much more important that the group survives than just an individual. If the individual survives, but it can't reproduce, then the species won't survive in the long term.
I think the important thing is to determine what behavior better represents reality, meaning what would explain the survival of current species on earth, not just try to confirm survival of the fittest for an individual.
"always will be better" seems to assume that group viability has no effect on individual survival.
While it's best to be the most selfish in the group, that doesn't imply that it's good enough. You need to also survive, and some groups help with that by having some altruism.
Group selection sounds more reasonable (by being more easily implementable at a sub-conscious level) to me.
* Though unlikely
Note that although the DNA is the genetic material, a selective pressure such as the threat of predation acts on organisms. Very rarely would selection act directly on the DNA. Rather, the correlation between carrying a snippet of DNA and not getting eaten causes that snippet to become overrepresented in the population over time.
I may misremember some of the details, but that's the gist. Your body basically generates antibodies via an evolutionary algorithm. Wikipedia has a good explanation. Keep an eye out for the word "selection": http://en.wikipedia.org/wiki/Somatic_hypermutation
Hey, look at that. Wikipedia also has this enlightening article: http://en.wikipedia.org/wiki/Unit_of_selection
This suggests that it takes a complex organism to fight disease. Once multicell organisms developed do you think an immune system was the first type of organized intelligence or that foreign invaders and parasites served as a catalyst to ever more complex systems?
As for the brain having some sort of monopoly on "organizing intelligent bahavior", that is a complex issue. I wouldn't say that the adaptive immune system necessarily possesses intelligence. It consists of many small and relatively simple components that interact to produce complex behavior. Realize that during somatic hypermutation, the immune system is not intelligently choosing which mutations to generate. It simply generates a random sample of all possible mutations and then sets up a simple selection process that produces a result that looks intelligent to us.
On the other hand, one could plausibly make a similar argument about the brain's intelligence being the product of the interaction of individual neurons. Many people believe that our brains are no less deterministic than a silicon-based computer. Complexity is complex.
Anyway, to give you another example, cancer cells are subject to greatly increased mutation rates, and mutations that result in faster growth or better recruitment of nutrient-supplying blood vessels (vascularization) will quickly become fixed in the tumor as the cells with that mutation overtake the growth of others. This also provides an example where selection at the cellular level is at conflict with selection at the organismal level. Within the tumor, selection favors faster-growing cancer cells, but these same cells are clearly the most detrimental to the organism as a whole.
I'll put a calendar reminder in 2 years from now to check back on how this one turned out :-)
Thanks for sharing! This is indirectly but wonderfully on topic for this site.
While some animals do exibit adoption, I don't think its nearly as common as altruism towards biological children. And group membership that requires altruism overwhelmingly seems to have genetic tie-in.
For this to happen across, say, two genetic lines, it seems you need the "cross-altruistic" genes to emerge more or less simultaneously in the two groups so they can cooperate. The probability for this to happen is smaller, so it's not surprising that it happens less often than kin-style altruism. But if this does happen (and apparently it does), then it means kin selection is not enough to explain altruism.
It seems to me that Wilson's theory is an elegant generalization of kin selection. I don't see the contradiction between them, although I'm not a biologist so quite likely I'm misunderstanding something.
This premise seems to be taken as fundamental dogma in the evolutionary theory community, but perhaps should be questioned. Here is my (layperson's) counterexample: a species might have a gene that switches between whether an individual is a drone or a reproducer over the course of their life; a switch like that could thrown early in the development based on ambient hormones or whatever. If the individual is not a reproducer, they don't spread their own genes but they help the hive or whatever.
I think there is an unexamined assumption guiding contemporary evolution, that ALL behavior must be explained by genes ALONE -- in the case above, lifetime behavior is determined by an environmental trigger, even though the set of possible behaviors is determined by genes. This dogma seems, well, silly and wrong.
(Throw in cultural behaviors with outcomes like longer life and more offspring, and the classical system completely falls apart.)
Genes that encode specific behaviors are just the simplest possible mechanism that works, and they do account for a vast number of phenomena. I think Occam's razor applies: If you suggest a more complicated mechanism, you should have some supporting evidence.
On the other hand, members of a herd are usually genetically related, so it is possible that kin selection can also explain this phenomenon.
Wilson isn't proposing they are mutually exclusive, he is saying they are both right but to differing degrees.
It's common in the sense that symbiotic relationships are common across ecosystems and probably a definitive element of what makes them a "system".
Stephen Gould took the idea further in his idea of "hierarchal evolution". Evolution isn't just happening on the genetic, individual, group, and species levels. It's happening at every level of organization.
My guess is that E. O. Wilson is probably right about ants, David Sloan Wilson is probably not right about group selection being like Daniel Dennett's universal acid, and Steven J. Gould was probably wrong in most of what he promoted.
its obvious - just compare 2 species of squirrels, one which demonstrate behavior described above and another which doesn't. Which species would survive over time better? Without making complicated statistical calculations, the Nature has already calculated the answer - we have the squirrel species of the first kind, and not of the second. It is also obvious why selfishness still exists - because altruistic traits seriously decrease the survivability chances of the individual specimen carrying the traits.
Some folks have done those complicated statistical calculations, and I believe the current consensus is that group selection is a pretty minimal effect, except in exceptional circumstances.
On the other hand, I'm not sure this is a great example. As a big scary potential predator I've scared away many a predator in my time, and y'know what? They don't cry out at all! They just run!
Does anyone have experience with screaming squirrels?
Evolution is a statistical macro process aggregating individual selection events. Thus the "defector" mutant squirrel have higher chances to survive, yet the (sub)species consisting of only such "defector" squirrels will lose to the (sub)species where statistically significant share of specimen demonstrate altruistic behavior.
People discussing evolution usually make 2 major mistakes :
- assigning explicit "species evolution/survival" level motivation to specific action of specific specimen
- directly extrapolating individual specimen events to the level of species, not paying attention to emergent higher-order system behavior
>Some folks have done those complicated statistical calculations,
such calculations is like law logic - can be bent both ways. Have any idea about chaotic dynamical systems and the effect even small perturbation can cause?
>Does anyone have experience with screaming squirrels?
if you hike in the SF Bay Area hills, you'll see the high social organization they exhibit, including "watch duty".
Edit: for illustration, as somewhat related in principle - recently "Schneier on security" posted http://www.schneier.com/blog/archives/2011/05/status_report_... about "dishonest minority" - their individual situation is better, yet the species consisting entirely of the "dishonest minority" type specimen would obviously lose.
Skimming through the supplemental information, it seems like they assume a Markov process where individuals adopt one of two strategies (with a preference towards adopting the strategy that their parent adopted), then look at which one is more likely to be dominant in the population.
In the case of kin selection in particular, the math is described by Hamilton's Rule, an inequality that must be satisfied in order for kin selection to explain a given altruistic interaction between individuals (http://en.wikipedia.org/wiki/W._D._Hamilton#Hamilton.27s_rul...).
Group altruism is stable and is a very strong attractor of population behavior. All that's required is that group members be able to recognize one another. http://people.brynmawr.edu/twong/models/pseudoaltruism.html Individuals born into such a group may learn this or it may be genetically inherited (instinctual), or both. Of course the distinction between learning and instinct is also a bit fuzzy.
http://en.wikipedia.org/wiki/The_Evolution_of_Cooperation
Axelrod showed that it is not necessary for individuals to share genes in order to cooperate to mutual benefit in an evolutionarily stable strategy.
For example, inter-species cooperation (as between dogs and humans) is almost certainly not a result of kin selection.
So even if Wilson is right and the theory of kin selection is flawed (I can't imagine how he could be right, but I haven't read the paper) that is not an indictment of Axelrod.