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Belmont Club

Memory and Survival

May 30th, 2010 - 5:34 am

There’s a video on YouTube showing a father shielding his child from an out of control car careening from the street into a shop. The father turns and interposes his body between and the baby he is carrying just as the vehicle smashes the through the window. The entire event happens so quickly the action seems entirely instinctive; and it is behavior familiar to us. Tolkien, in the Two Towers, describes Sam’s charge on Shelob in defense of the fallen Frodo as driven by nature. “No onslaught more fierce was ever seen in the savage world of beasts, where some desperate small creature armed with little teeth, alone, will spring upon a tower of horn and hide that stands above its fallen mate.”  If so, nature must have a reason for it.  Perhaps a species consisting of individuals capable of placing something above their own personal survival enjoys an advantage over that which does not. Darwin dealt with the problem of ‘altruism’ in his Descent of Man.

The idea that group selection might explain the evolution of altruism was first broached by Darwin himself. In The Descent of Man (1871), Darwin discussed the origin of altruistic and self-sacrificial behaviour among humans. Such behaviour is obviously disadvantageous at the individual level, as Darwin realized: “he who was ready to sacrifice his life, as many a savage has been, rather than betray his comrades, would often leave no offspring to inherit his noble nature” Darwin then argued that self-sarcrificial behaviour, though disadvantageous for the individual ‘savage’, might be beneficial at the group level: “a tribe including many members who…were always ready to give aid to each other and sacrifice themselves for the common good, would be victorious over most other tribes; and this would be natural selection” Darwin’s suggestion is that the altruistic behaviour in question may have evolved by a process of between-group selection. …

The major weakness of group selection as an explanation of altruism, according to the consensus that emerged in the 1960s, was a problem that Dawkins (1976) called ‘subversion from within’; see also Maynard Smith 1964. Even if altruism is advantageous at the group level, within any group altruists are liable to be exploited by selfish ‘free-riders’ who refrain from behaving altruistically. These free-riders will have an obvious fitness advantage: they benefit from the altruism of others, but do not incur any of the costs. So even if a group is composed exclusively of altruists, all behaving nicely towards each other, it only takes a single selfish mutant to bring an end to this happy idyll. By virtue of its relative fitness advantage within the group, the selfish mutant will out-reproduce the altruists, hence selfishness will eventually swamp altruism. Since the generation time of individual organisms is likely to be much shorter than that of groups, the probability that a selfish mutant will arise and spread is very high, according to this line of argument. ‘Subversion from within’ is generally regarded as a major stumbling block for group-selectionist theories of the evolution of altruism.

But Martin Nowak, a mathematician and biologist at Harvard University, argues that membership in a society capable of altruism can provide a greater survival advantage over the long run than becoming a ‘selfish mutant’. Using game theory and the concept of the Prisoner’s Dilemma, he maintains that a group capable of cooperation provides a better better long term prospects. In the classic Prisoner’s Dilemma “two people might not cooperate even if it is in both their best interests to do so”. But in “the iterated prisoners dilemma (IPD) … of … N step[s] … (with N fixed) in which participants have to choose their mutual strategy again and again, and have memory of their previous encounters … greedy strategies tended to do very poorly in the long run while more altruistic strategies did better, as judged purely by self-interest.”

Interestingly the success of the IPD is contingent on the existence of memory, which in the human context is an awareness of history. History allows members of a society to understand their individual existence and well-being is somehow inseparable from that of the group.  Therefore from the viewpoint of IPD models, acts of group memory, like Memorial Day, are not simply events held for ceremonial purposes but are sources that are vital to the group’s — and the individual’s existence. Without that history — without that memory — then individuals will eventually forget the benefit derived from the altruism of their forebears and become susceptible to the preachings of the ‘selfish mutant’.  In a society without traditions the “free riders” may gain ascendancy and even suppress history to aid their increase. Gradually they may destroy a society’s capacity for mutual altruism and take it over for themselves. Yet even so their victory may be short-lived. Within their mutation lie the seeds of their own downfall. For “if the pathogen’s virulence kills the host and interferes with its own transmission to a new host, virulence will be selected against.” Eventually they kill the host and then themselves die.

It may take a while, but the demise  eventually happens. And then the survivors gradually rediscover the benefits of thinking in terms larger than themselves and begin to act on that basis. And then the words, “truly, I tell you, unless a grain of wheat falls into the earth and dies, it remains just a single grain; but if it dies, it bears much fruit” will become comprehensible again.

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