Patriotic fervour and suicide bombing are examples of memes which are "to die for" - memes which have the potential to kill.
A common complaint about the possibility of necrotrophic memes is: "but surely the hosts would evolve defenses".
Peter Turchin expresses this complaint - in connection with deaths of volunteers in warfare - as follows:
Yes, “memes made me do it” is one possible response from Richard Dawkins and his followers. It’s a variant of what might be called the “great deception” hypothesis, e.g. Marxist explanations how people are fooled to fight and die for the sake of the ruling class’ interests. The problem is that fighting in war has very significant fitness consequences (roughly one-quarter of male deaths in small-scale societies is due to warfare). So by the “selfish gene” logic such fierce selection should result in the evolution of very effective resistance to such lethal memes.There are a number of reasons why, in fact, such defenses do not arise that frequently in practice:
- Rapid cultural evolution - As with lethal diseases, deleterious memes typically have a shorter generation time and evolve more quickly than their hosts.
- Greater investment - Most lethal memes are memetically engineered by powerful agents. The memes responsible for the obesity epidemic are engineered by large corporations. The memes responsible for patriotic fervour are engineered by governments. The memes responsible for suicide bombing are the products of powerful and ancient religions. However, all these types of meme target individuals - who cannot afford comparable expenditure on defenses.
- Frequency-dependent selection - Memes that kill humans are not that common.
- Antagonistic pleiotropy - An "obey authority meme" might be useful most of the time - except when the authority happens to be sending you off to war.
- Only one chance - Fatal memes sometimes offer restricted opportunities to learn about their hazards. If they kill their hosts reliably, then conventional trial-and-error learning mechanisms may offer relatively little protection against them.
- Embryological tangles - Some of the memetic immune system is probably innate. That component has difficulty in identifying specific memes, since it must work through embryology. A "obey authority meme" might be generally positive while an "obey the general" meme might be generally negative - but it may be difficult to distinguish between them for a system which must manipulate its products via the tangles of embryology.