To paraphrase an old quip: Groups come and groups go; stupidity remains.
Before their culture was contaminated by the Masters of Violence (that's us), the Gebusi tribe of Papua New Guinea had settled into an interesting cultural routine. The tribe was small, consisting of only about 400 people. Whenever someone died of a sickness, the Gebusi were convinced it had to be a consequence of witchcraft, an action by a single sorcerer who had cast a spell that killed the victim with an illness. So who was the witch? Sooner or later an accuser came forward, the tribal elders met, evidence was presented, arguments followed, and without fail someone was condemned as the sorcerer who had caused the death of the last victim of sickness. The guaranteed sentence was death of the sorcerer, and within a short time he was ambushed and killed. No objections were raised by the community at large and only rarely by the accused sorcerer's family. After the killing of the alleged sorcerer, the men, women, and children of the tribe returned to the routine of their daily life.
I'm a great fan of cultural diversity and pluralism, but we do need some accounting here. It's obvious that the Gebusi, at least as they were before contact with the West, had perfected a fail-safe method of doubling their death rate, and it raises some interesting questions about how and why individuals and groups behave.
Some scientists (I am not one of them) believe that a set of rules found useful in describing the behavior of simple social animals (such as ants and hamsters) can be applied to human groups as well. They argue with almost religious fervor that their ideas derive from Charles Darwin, and that any attempt to refute their ideas is an heretical anti-evolution attack on Darwinism and the idea of natural selection. But an application of Darwinism is not Darwinism itself, and a critique of an application is not a critique of the theory from which the application derives. To close off attacks on applications of theory by accusations of heresy is a good way to destroy science.
So what about the Gebusi? Well, for one thing we have this little problem of fitness. If the behavior of the Gebusi can be explained by simple natural selection, how does the effective doubling of the death rate improve fitness? By reducing the drain on scarce resources? Not tenable, since both resources and land were plentiful. The problem of a fitness explanation remains. The general idea these days is that when we talk of "fitness" we are talking of the fitness of a particular group of genes, with any individual constituting a Dawkins "gene-carrier". Can we explain the behavior of Gebusi gene-carriers? Some people try. We're presented with the idea of "inclusive fitness" and in this case maybe a prediction that in the Gebusi tribe accusers will tend to accuse of sorcery distant relatives rather than close relatives and thus improve the replication chances for their own and closely related gene-sets. Unfortunately, the idea does not work, since careful field analysis shows that the Gebusi accusers were more likely to accuse close relatives rather than distant relatives -- thus increasing the extinction rate of their own gene-set compared to other gene-sets.
What about group selection rather than individual gene-set selection? It seems like a blind alley to explore the idea that doubling the group death rate increases the fitness of the group. But maybe someone can find an argument at the group selection level. I'm dubious, but I'm willing to listen.
Are the Gebusi (or any words that you read here) a refutation of Darwinism? Absolutely not. If anything is refuted, it's the application of simple Darwinism to the Gebusi. I say "simple" Darwinism because where is it written that the idea and applications of natural selection are to remain intact as proposed by Darwin or anyone alive today for the next -- let us say -- ten thousand years? Science is not religious dogma, and the notion that any ideas that we have today will remain unmodified in the far future seems to me to be ridiculous.
And this is particularly true of any ideas that we have about human behavior. We are complex organisms, and the ideas that we find useful to explain and predict our behavior will likely also be complex. Classical Darwinism appears to be too simple to explain and predict the behavior of real human groups. The biological nature of humanity (particularly the plasticity of the human brain in response to experience) may require some new rules added to classical natural selection.
In any case, aside from the Gebusi being an apparently difficult call for classical Darwinism, they present us with a cautionary tale. At this moment, people in the Middle East are killing each other with great zest. Mortars, rockets, suicide bombers, kill, kill, kill, all of it increasing the death rate of the human species. We can apply Darwinism and maybe analyze it as a question of group survival. But in the backs of our minds lurks the question: Is death necessary? Me, I'm thinking about the Gebusi. In their language, they had no word for any number greater than three. They were not exactly an advanced civilization, which is maybe one reason they could not figure out they were engaged in gradual suicide. As for us, we like to think of ourselves as an advanced civilization. Are you certain of that? As I look at Gaza, I do think that in the far future they will collect our skulls and call us Early Man.