Islam versus Europe

Enza wrote a post recently about the philosopher Peter Singer. Here's an extract from his book, "The Expanding Circle" in which he reflects on how altruistic behaviour might have evolved. It could almost be the history of Europe in a nutshell.

It may be that to explain how reciprocal altruism can get established, we need to allow a limited role for a form of group selection. Imagine that a species is divided into several isolated groups—perhaps they are monkeys whose terrain is divided by rivers which, except in rare droughts, are too swift to cross. Now suppose that reciprocal altruism somehow appears from time to time in each of these groups. Let us say that one monkey grooms another monkey, searching for disease-carrying parasites; when it has finished it presents its own back to be groomed. If the genes that make this behavior probable are rare mutations, in most cases the altruistic monkey would find its kindness unrewarded; the groomed monkey would simply move away. Grooming strangers would therefore bring no advantage, and since it leads the monkey to spend its time helping strangers instead of looking after itself, in time this behavior would be eliminated. This elimination may not be good for the group as a whole, but as we have seen, within the group it is individual rather than group selection that dominates.

Now suppose that in one of these isolated groups it just happens that a lot of monkeys have genes leading them to initiate grooming exchanges. (In a small, closely related group, kin altruism might bring this about.) Then, as we have seen, those who reciprocate could be better off than those who do not. They will groom and be groomed, remaining healthy while other members of the group succumb to the parasites. Thus in this particular isolated group, possessing the genes for reciprocal grooming will be a distinct advantage. In time, all the group would have them.

There is one final step. The reciprocal grooming group now has an advantage, as a group, over other groups who do not have any way of ridding themselves of parasites. If the parasites get really bad, the other groups may become extinct, and one dry summer the pressure of population growth in the recripocal grooming group will push some of its members across the rivers into the territories formerly occupied by the other groups. In this way group selection could have a limited role—limited because the required conditions would not often occur—in the spread of reciprocal altruism.

If we are prepared to allow group selection a role in the inception of reciprocal altruism, we can hardly deny that the survival of some groups rather than others can provide an evolutionary explanation for a more general tendency for altruistic behavior toward other members of a group. This is still quite distinct from the popular view of traits evolving because they help the species survive—groups are far smaller units than species, and come in and out of existence much more frequently, so group selection is more likely to be an effective counterweight to individual selection than is species selection. Nevertheless, a group would have to keep itself distinct from other groups for group altruism to work—otherwise more egoistically inclined outsiders would work their way into the group, taking advantage of the altruism of members of the group without offering anything in return. They would then outbreed the more altruistic members of the group and so begin to outnumber them, until the group would cease to be more altruistic than any other group of the same species. Although this would cost it its evolutionary advantage over other groups, there would be no mechanism for stopping this. If the group altruism had been essential to the group’s survival, the group would simply die out.

This suggests that group altruism would work best when coupled with a degree of hostility to outsiders, which would protect the altruism within the group from penetration and subversion from outside. Hostility to outsiders is, in fact, a very common phenomenon in social animals. Although there is a popular myth that human beings are the only animals who kill members of their own species, other species can be as unpleasant toward foreigners as we are. Many social animals, from ants through chickens to rats, will attack and often kill outsiders placed in their midst. In a series of experiments conducted on rhesus monkeys, it has been shown that introducing a strange rhesus monkey into an established group aroused much more aggression than either crowding the monkeys or reducing their food supply. Admittedly, keeping strangers away could just be a means of protecting one’s own food supply and that of one’s kin; but it could also be that this behavior serves the same role as geographical isolation in protecting the altruism of the group from debasement.