Evolution of Altruism

A few days ago I saw a TV news segment about a couple who adopted a Marine dog with PTSD. They did this to honor their son, the first Marine to receive the Congressional Medal of Honor since Vietnam. He died when he dove on a live grenade to save the other Marines in his squad.While this was an extreme example of heroism, such self-sacrificing behavior is common enough in our species to raise a challenge to the TOE. Kin selection doesn't explain such behavior, because non-kin are often the beneficiaries. Reciprocal altruism might explain it, but that seems to be a stretch when a young man who has not had an opportunity to reproduce sacrifices his life for others. Perhaps this behavior is evidence for group selection, but most evolutionary biologists seem to believe that group selection plays little, if any role, in evolution.Any thoughts?

Wow, my message really generated a lot of replies. I'll try to respond to each when I have time, but for the moment, I'd like to make a few general observations that address some of the most common themes in your replies.Is war a good model? Perhaps not. But I can think of instances of self-sacrificing behavior other than war. Firefighters and police officers put themselves in mortal danger to protect people they don't know. Yes, it's their job. But when faced with a life-threatening situation, why don't most firefighters and police officers say, "Take this job and shove it!"Does the ToE have to explain everything? No. But when a portion of the population engages in behavior that, on the face of it, appears to be highly maladaptive, it is reasonable to expect the ToE to give a satisfactory explanation.In our past, wasn't everybody in the tribe pretty much kin. This is a factual claim that requires evidence. Even if it is true, an unspoken assumption is that, in the last 10,000 years, we haven't adapted to our new social environment, in which many of our daily contacts are not close relatives. This claim also seems to be contradicted by research suggesting that we can recognize kin, even to the point that identical twins help nieces and nephews more than fraternal twins do.

Smoking is sometimes fatal, but it is probably new enough that we haven't had time to develop an instinctual fear or aversion to it. Fear of fire and violence comes naturally, however, and thus I think our tendency to sometimes overcome this fear to help others with no obvious benefit to ourselves requires an explanation.I don't think we need to explain game shows or Paris Hilton (at least not in the same way) because these passtimes are not as dangerous as firefighting, police work, or soldiering.

The ToE would have very little explanatory power if, every time apparently maladaptive behavior was observed, it was written off as "social evolution." Do you believe that the ToE can be used to explain the social behavior of non-human animals but cannot be used to explain human social behavior?

As a general rule the ToE, as I understand it, predicts that animals behave in their own genetic self-interest. On the face of it, self-sacrificing behavior would seem to falsify the TOE. Some instances of self-sacrificing behavior (e.g., by parents or siblings) have been explained in a manner consistent with the ToE. Other instances, I propose, have not been adequately explained. Perhaps good explanations will be found (or already exist). But to dismiss the evidence and say it needs no explanation strikes me as an unscientific position.

I've got to run. I'll come back to your other points later. But I'd like to reply to one point immediately, as it is so basic to the dicussion:There is no scientific controversy about the existence of altruistic behavior. It is defined as any behavior that reduces the individual's fitness while increasing the fitness of another individual.

Thank you for your detailed and thoughtful post, dwise1. If I understand your position, you are saying that the self-sacrificing human behavior I have described evolved through kin selection when Paleolithic humans lived in small bands in which all of the individuals were closely related.The members of such a band, however, could not have all been equally related. In addition to siblings, there were probably nieces and nephews, first cousins, second cousins, etc. An altruistic trait would increase in frequency if (assuming my math is correct) it caused the altruist to sacrifice his or her life to save the lives of more than two siblings, more than four nieces or nephews, more than eight first counsins, more than 16 second cousins, and so on.What's more, I doubt that each Paleolithic band formed a reproductively isolated population. There was probably immigration into the bands, further diluting the degree of relatedness.Thus I am skeptical that indiscriminate altruism could evolve by individual selection, even in a band of hunter-gatherers.An implied assumption of your argument is that human evolution essentially stopped 10,000 years ago. That we are Paleolithic creatures trying to cope in a modern social environment to which we are not adapted. I don't see any grounds for that assumption. The bill lengths of Darwin's finches have changed over a few generations in response to changes in the food supply. Why assume that human traits haven't changed over hundreds of generations?You also raise the interesting idea that military organizations basically trick soldiers into treating the members of the unit like biological brothers. That may be a plausible explanation for why the Marine dove on the grenade. But it cannot explain why a firefighter would enter a burning building to save someone he has never met.Edited by Stephen Push, : Corrected math error.

Before he was trained, he chose a profession that he knew would require such risks.And how would you explain the acts of civilians who risk their lives to save people? Such as some who stayed in the World Trade Center on 9-11 to help others.

I have no doubt that training plays a major role. But you can't train a pig to fly. And you can't train a misanthrope to be an altruist.Edited by Stephen Push, : Corrected typo.

I would say that humans tend to be diurnal by instinct but display a considerable amount of behavioral flexibility. They can switch to a nocturnal lifestyle when environmental conditions require, even though they suffer from some physiological problems as a result.I would say something similar about altruism. Humans display a considerable amount of behavioral flexibility, ranging from selfishness through limited cooperation to, in some situations, indiscriminate altruism.A fascinating species worthy of further study.

The nature-nuture controversy is SO 20th Century! Today we know that EVERYTHING is genetic AND environmental, especially with respect to the devlopmental environment (as in those diapers you changed).We may be selfish much of the time, but we are also capable of selflessness at times. Some posters in this thread have suggested extreme selflessness is a malfunction -- a psychosis or a result of too much testosterone. I think it is a cop-out to dismiss behaviors be don't understand as abnormal (although even if they are "abnormal," I still think they are worthy of study and explanation.)Evolution "designed" us with a capacity for indiscriminate altruism that is not seen throughout the animal kingdom. How did this capacity evolve? What developmental environments foster it? Under what environmental conditions is it expressed?Are these not valid scientific questions to ask?Edited by Stephen Push, : Corrected typo.

I think almost everyone is altruistic to some degree. Perhaps sacrificing one's life is just an extreme example of this trait, which is adaptive in its more moderate manifestations. Lots of traits are possessed to varying degrees, expressed only in certain circumstances, and absent altogether is some individuals. It's almost certainly not a single gene. The trait is probably affected by many genes, expressed to varying degrees in various situations, and enhanced or muted to a great extent by culture and learning. Cooperation could exist is the absence of altruism; every cooperative interaction could be a win-win scenario. Altruism requires that the altruist make a sacrifice, at least in the short run, although in the long run it may pay off, e.g., in the form of inclusive fitness or reciprocity. Altruism need not require detailed risk calculations. It could be nothing more than a compulsion to help others that, in some situations, overcomes self-protecting drives such as fear or hunger. [On second thought, I agree there would have to be some kind of risk calculation, but it need not be optimal. It just has to pay off on average.]Edited by Stephen Push, : Added last two sentences.

I know this is a brief summary from a secondary source, but I think it shows that there is scientific evidence behind these claims:We're Sorry - Scientific AmericanI'll try to post some primary sources as this discussion continues.

Some more literature on the evolution of altruism:Evolution of Altruism - Bibliography - PhilPapersThe nature of human altruism | Nature

In my admittedly limited review of the literature on the evolution of human altruism, I have so far come across several hypotheses. Many of these ideas have already been expressed by others in this thread, but I thought it might be helpful to summarize them. They are not all mutually exclusive.Some of these hypotheses concern morality and/or cooperation, but they are relevant to our discussion because they all attempt to explain human altruism. I am using the term morality here to distinguish the relevant behaviors from amoral forms of altruism, which are seen even in bacteria and yeast.1) Morality is a result of natural selection. This school of thought has generated at least two hypotheses:a) Morality evolved through individual selection, specifically kin selection and reciprocal altruism.b) Morality evolved though group selection.2) Morality is an exaptation (a new use for a structure or faculty that was selected for some other reason). According to this view, human intelligence evolved through natural selection because it facilitated tool use. Once intelligence reached a certain level, it was coopted by moral behavior. Specific moral codes are a result of cultural evolution.3) Morality evolved through a process of genetic-cultural co-evolution.In future posts I'll cite some specific references concerning each of these hypotheses.Did I miss any?