Ultimate Causes, Proximate Mechanisms

Why does a soldier throw himself on a hand grenade to save the lives of a half-dozen unrelated fellow soldiers? Why does someone run into a burning building they happen to be passing to save a child they don't know? From a Darwinian perspective these seem to be enigmatic behaviors that would "select against" such individuals (or more properly, select against the heritable component of this behavior).

There are several possible explanations for this....

...The most important one might be that this sort of behavior doesn't really happen very often. It is so rare that it can be ignored and written off as irrelevant in the light of overwhelming evidence that humans usually act selfishly. There are billions of people in this world, but we can name the top altruists. We can't name all the selfish people.

But if we want to provide a hypothesis that could explain non-kin based altruism that should be kin-based altruism, there is one.

We don't need to explain altruism as kin-based. One person can do something "altruistic" for another person because they expect (and usually get) a return, like in that move that I haven't seen "Pay it forward" or that insurance company commercial that I've seen too many times (not the cavemen or the gecko, but the one where the lady stops the man from getting run over, etc.). More likely, such forms of reciprocal altruism are more direct. I scratch your back, and in the not too distant future, you scratch my back (not someone else's back).

We may also expect "altruistic acts" to occur as a means of showing off.

But the burning baby and hand grenade scenarios don't involve a payoff if, at the end, you are dead. So, these behaviors have to be either truly dumb from a Darwinian perspective, or something else.

This is where Ultimate vs. Proximate explanations or mechanisms for behavior come in. Simply put, an organism may be selected by Darwinian processes to tend towards a particular behavior, and in the context of this behavior's evolution, it makes sense to implement this behavior under certain conditions. But then the conditions change. When the conditions change, evolution may eventually cause a change in how this behavior works, but in the meantime the behavior becomes (at least some times) "inappropriate."

Since there is a difference between the ultimate (evolutionary) fitness-related reasons for the behaviors existence and the specific neurological or hormonal mechanism for the behavior's implementation, the former can make sense in the large view, and the latter often not make sense in the immediate instance.

In the so-called "environment of evolutionary adaptiveness" men are usually with other men who are their close relatives. In humans, it is more often than not the female who moves out of her natal (birth) group to join her new mate in his natal group. Thus, a given man is related to the other men in his group. The other men may include his father, uncles, brothers, and sons. Children in the group are all his children, his siblings children, or otherwise related. Thus, at any one moment in time, if you can give up your life to save every single person in you group, you might be doing something that makes sens in an evolutionary framework. At the very least, there should evolve a mechanism that allows for the option of suicidal altruism.

The guy in the army is not hanging around with his relatives. He is unrelated to his fellow soldiers. But in the evolution of this trait, there did not develop a mechanism to assess this degree of relatedness to group members. The degree of relatedness was an already extant, expected, reliable thing that made up part of the context in which suicidal altruism might evolve. Perhaps all it takes is a sense of "brotherhood" to cause a male's brain to shift into "might-have-to-die-to-save-genes" mode. Certanily, training, living, and fighting together could facilitate this sense of brotherhood among men in the military, and it is clear (and this has been studied) that there are training techniques and other aspects of military life that enhance this phenomenon.

Thus, evolved traits including behaviors always have to be understood ... explained ... at multiple levels. One way to do this is to separately consider the ultimate (evolved, fitness-related) and the proximate (mechanistic ... how does the trait actually work) levels as separate. (There are other levels but that is for another time.) The proximate mechanisms can be very powerful. Hunger and sex drive. Say no more.

This way of thinking helps to explain the very interesting behavior recently exhibited by a pair of gay flamingos. (Thanks to CMF for bringing this to my attention.) Gay flamingos may seem odd, but there are gay couples (both males and females) in all thus-far studies species of pair bonding birds.

Here's the story:

LONDON (AFP) - A pair of gay flamingos have adopted an abandoned chick, becoming parents after being together for six years, a British conservation organisation said Monday.

Carlos and Fernando had been desperate to start a family, even chasing other flamingos from their nests to take over their eggs at the Wildfowl and Wetlands Trust (WWT) in Slimbridge near Bristol.
But their egg-sitting prowess made them the top choice for taking an unhatched egg under their wings when one of the Greater Flamingo nests was abandoned.

The couple, together for six years, can feed chicks by producing milk in their throats.
Fernando and Carlos are a same sex couple who have been known to steal other flamingos' eggs by chasing them off their nest because they wanted to rear them themselves," said WWT spokeswoman Jane Waghorn.

"They were rather good at sitting on eggs and hatching them so last week, when a nest was abandoned, it seemed like a good idea to make them surrogate parents."
Gay flamingos are not uncommon, she added.

"If there aren't enough females or they don't hit it off with them, they will pair off with other males," she said.

Both male and female birds in pair bonding species tend to have strong nesting and off-spring care drives. These drives are hormonally driven (that's the proximate mechanism) and serve to enhance individual fitness by enhancing reproductive success (that's the ultimate explanation). It has been noted that gay male couples seem to do a much better job at raising young than heterosexual couples (and possibly gay female couples) in birds. I suspect there could be two reasons for this, if it is true. First, males may need extra doses of offspring care hormonally mediated drives in order to get them to do the right thing (instead of acting like guys). Second, they may be engaged in less intrasexual competition, and thus have more energy and time for offspring care.

(By the way, there is a famous pair of gay male eagles at the US National Zoo that has raised many offspring from eggs laid by hetero-birds.)

It probably helps that in Flamingos and many other birds, males can "lactate."


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Well, it might be helpful to look at the original Darwin on this.

Loosely paraphrased from "The Descent Of Man":

Why do people care about the sick and weak? We build hospices, we care for the poor. If you were a dog breeder and one of your dogs was weak and sickly you probably wouldn't let it survive to breed, so why do people?

Society is built on sympathy, on people "feeling for" each other. If we tried to shut that down we'd turn into a bunch of cold-hearted bastards and wipe ourselves out within a generation.

So Darwin was making a group selection argument?

Let's check on that. What's the original quote you're basing the paraphrase on.

But in the evolution of this trait, there did not develop a mechanism to assess this degree of relatedness to group members.

I can't go with that. It's been present in human history (notably in its negative sense) from when we started keeping any kind of records. The flip side is "xenophobia," or "racism," etc. We know that children imprint very early on the appearance of their caregivers, for instance.

Having been well outside the normal range in height growing up made that really obvious to me. On the one hand, I was excluded by the kids my own age and on the other always felt more comfortable with adults and older kids. Similarly, children are proverbially cruel to those who are different -- the handicapped, most obviously.

The development of spoken language just builds on the same mechanism by abstracting "this person thinks like me" in place of appearance. We've built social mechanisms to extend that to "people are like me" or "animals are like me," and in extremis, "everything is like me."

By D. C. Sessions (not verified) on 14 May 2009 #permalink

DC: You are not saying anything here that contradicts what I say in the paragraph you quote from. What you need to do is to consider kin recognition at the detailed level. You need to specify your argument a lot more.

You are not saying anything here that contradicts what I say in the paragraph you quote from.

Wouldn't dream of it -- more like elaboration.

By D. C. Sessions (not verified) on 14 May 2009 #permalink

Of course! But I think we can and should elaborate on the details. (Oh, and my assertion could be totally wrong .... so few people actually do ever throw themselves on the hand grenade... they could all be crazy people...)

BTW I'm sitting here on the side of the road in the northern twin cities, in the car, using a randomly chosen wireless network. It's called "lynksys" or something.

Heroic, hazardous, and potentially fatal actions may pay off as a personal style. The daredevil habit often brings admiration. As the saying goes: 'Women want to be with you; men want to be you'. If you earn the Metal of Honor and live, most don't, protocol demands that every uniformed service member, without regard to service or rank, salute you. You enter a room wearing the metal and generals are obliged to stand and render honors. Heady stuff for a private.

If things go too far wrong and you end up dead your reputation and the admiration outlives you. Throw yourself on a grenade and your a candidate for The Metal of Honor. Heroic action is a way of gaining status and avoiding anonymity.

Another side to this is that some people fear, and or loath, the idea of growing old. A friend watched his father die slowly of Alzheimer's. He found out he is genetically predisposed to the disease, and colon cancer. His desire to live to a 'ripe-old-age' is tarnished and his tolerance for risk increased. He has given up his car for a motorcycle. Taken up skydiving. Learned to scuba dive. Got divorced. Took up dating wild women. At work he volunteers for all the most hazardous jobs.

Irony is he is, by all accounts, having a ball.

Much of our present economic system seems to be intent on inducing feelings of inadequacy in consumers. Inadequacy that the system tells you can be corrected by buying the right car, or living in a bigger house, or wearing the right clothing. The disappointment felt after you get the stuff and find out your still the ugly duckling serves to reinforce the feeling of weakness.

It also shifts value away from what you are to what you do and, more specifically, how much money you make. Status, money and power are the brass ring. People are often willing to lean out very far, and risk extinction, to grab it.

To me this makes far more sense than the classic model of trading ones life to protect some greater percentage of your genetic identity.

It's called "lynksys" or something.

That's the router equivalent of "I'm soooooo drunk!"

By D. C. Sessions (not verified) on 14 May 2009 #permalink

Another explanation may be that humans didn't evolve with threats that were as certain to be fatal as a hand grenade. Passively watching a tiger or Neanderthal kill my friends would eventually lead to my own death. Facing a threat immediately with my tribe intact would offer a better chance for my own survival. A hand grenade can't be overpowered or frightened, so my normal response to a threat to the group is inappropriate.

By Terry Schubring (not verified) on 14 May 2009 #permalink

It seems to me as though it's somewhat analogous to the evolution of traits in certain butterflies that make them A) horribly unpleasant to consume and B) very brightly colored. Yet the bright colors surely increase the odds of a particular butterfly being spotted and eaten (or fatally wounded by the first bite, or injured in a way that makes its death likely later, or...) by a predator that hasn't figured out that "these things taste bad."

Greg, are paleolithic puns best appreciated when listening to oldies stations?

By D. C. Sessions (not verified) on 14 May 2009 #permalink

The paraphrased quote is in its original form here: http://www.uncommondescent.com/intelligent-design/a-complete-darwin-quo…

We civilised men, on the other hand, do our utmost to check the process of elimination; we build asylums for the imbecile, the maimed, and the sick; we institute poor-laws; and our medical men exert their utmost skill to save the life of every one to the last moment. There is reason to believe that vaccination has preserved thousands, who from a weak constitution would formerly have succumbed to small-pox. Thus the weak members of civilised societies propagate their kind. No one who has attended to the breeding of domestic animals will doubt that this must be highly injurious to the race of man. It is surprising how soon a want of care, or care wrongly directed, leads to the degeneration of a domestic race; but excepting in the case of man itself, hardly any one is so ignorant as to allow his worst animals to breed.

The aid which we feel impelled to give to the helpless is mainly an incidental result of the instinct of sympathy, which was originally acquired as part of the social instincts, but subsequently rendered, in the manner previously indicated, more tender and more widely diffused. Nor could we check our sympathy, even at the urging of hard reason, without deterioration in the noblest part of our nature. The surgeon may harden himself whilst performing an operation, for he knows that he is acting for the good of his patient; but if we were intentionally to neglect the weak and helpless, it could only be for a contingent benefit, with an overwhelming present evil.

I like the way Darwin undoes the prospect of eugenics with the very last phrase in this quote.

I don't see Darwin explicity stating that humans (as social primates) evolved a "do it for the group" instinct. Rather he postulates an "instinct of sympathy, which was originally acquired as part of the social instincts" To me that implies reduce aggression, increased sociality, increased social intelligence, etc. which is what we would expect individuals to benefit from in a social setting because of the multi-part game that a social milieu is, essentially. His is not (in this quote) an explicitly non-group selectionist argument, but it is not an explicit group selection argument either.

It is impossible, though, to really assess Darwin's group-selectionist orientation or lack thereof because in his day the concept was not clearly articulated.