Zombies and the Selfish Gene

            With Halloween fast approaching I thought I’d do something that was seasonally appropriate for this blog: Zombies! Well, specifically zombies and selfish gene theory.

            Zombies are currently in vogue. TV shows (e.g., Walking Dead), movies (e.g., Zombieland), and video games (e.g., Left for Dead) have shown that zombies are currently experiencing a Renaissance of popularity in the science fiction (SF) genre. SF is an interesting gauge of public concerns, especially SF of a distopian nature. Whether by intention or accident, such SF resonates with the public’s current fears. Invasion of the Body Snatchers (1956), depicting a situation where townsfolk were being systematically replaced by emotionless, conforming “pod people,” was viewed by many as representing the insidious creeping threat of communist ideals indoctrinating the average American. In the same way, zombie fiction reflects current worries. Early films, such as White Zombie (1932), or even later work like Hammer Horror Films’ The Plague of the Zombies (1966), focused on the mystical cause of zombification, typically linked to voodoo rituals or the like. However, post-millennial zombie fiction, for example, 28 Days Later (2002), The Zombie Survival Guide (2003), and Pride and Prejudice and Zombies (2009), have shifted to a biological, generally viral, vector for zombification.

Zombie art by Paul La Rue, author of the webcomic Exiles

            Once infected through an exchange of bodily fluids the “zombie phage” takes control of the human host, hijacking the behavioural control, and forcing the new zombie to seek out additional bodies to parasitize. The possible self-destruction of the zombie in the process of infecting others is of little concern to the controlling virus: all that matters is the selfish propagating of the virus into new bodies.

            Interestingly, the fictional zombie virus controlling the behaviours of a human host bears distinct similarities to an important concept in evolutionary psychology named the Selfish Gene Theory. In 1976 Richard Dawkins proposed that many aspects of human behaviour could be better understood if one hypothesized that the gene and not the individual person is the actual “unit” that evolutionary selection acts on. The ultimate goal, according to evolutionary theory, is for organisms to pass their genes on to the next generation. Naturally, as resources are finite this leads to behavioural competition between individuals to be reproductively successful.

            Dawkins took this a step further, arguing that the competition exists at the level of the genes themselves, instead of the level of the organism. He proposed that genes are “replicators” inhabiting a host “vehicle.” Replicator genes, barring mutation, copy themselves faithfully across generations. For all intents-and-purposes they are immortal. For example, the same gene that evolved to regulate the development of the dorsal and sides of worms millions of years ago is present in modern humans, fulfilling essentially the same role during our embryonic development. The vehicles inhabited by immortal genes are, however, ephemeral. Moreover, their short-lived bodies are, according to Selfish Gene Theory, expendable. The ultimate destruction of a zombie “vehicle” by shotgun blasts in a movie is acceptable to the viral “replicator” as long as the virus is passed to a new host before the original’s loss. In Dawkin’s view the aim of genes is to selfishly pass themselves to a new generation, thereby maintaining their immortal existence. As a consequence, genes will specifically drive their vehicle to perform behaviours, sometimes highly risky or dangerous ones, provided that such behaviours increase the chance of passing copies of the genes to the next generation. If the host vehicle’s efforts to propagate the genes results in its early destruction, so be it; vehicles are expendable.

            Dawkins’ Selfish Gene interpretation actually helps explain a variety of human behaviours. While such traits as altruism can be explained through this theory, given that I’m contextualizing my discussion with zombies, I’m going to take a less noble (although equally sacrificial) example. Consider that humans (generally males) will not uncommonly engage in high-risk sports (e.g., free climbing, base jumping, street racing, etc.). Competing in such activities may serve to demonstrate their physical fitness, one trait utilized by women in selecting males for mates. The cognitive understanding of the dangers involved in these activities, which may result in short- or long-term injuries or even death, is not as much of a deterrent to the behaviour as one might suspect. If the individual is the evolutionary level of selection, behaviours that lead to the early destruction of said individual should have been evolutionarily selected against long ago. But if Selfish Gene Theory is correct and it is the replicator genes that are in control of the expendable vehicle then the maintenance of such behaviours makes more sense.

            But isn’t it a bit of a stretch to suggest that our genes may be trying to kill us in the aim of reproducing? Well, besides fictional zombies there are real-life examples of parasites hijacking the nervous systems of host organisms, forcing their hosts to suicidal actions that only benefit the propagation of the parasite’s genes. For example, grasshoppers normally avoid jumping into ponds due to the risk of being trapped by the water’s surface tension and drowning. However, grasshoppers infected by horsehair worms are compulsively attracted to water and will hurl themselves into ponds. Once in the water the horsehair worm bursts out of its insect host to find other worms in the pond to mate with, thereby continuing its life cycle. (For more examples of parasites taking control of hosts nervous systems, please see Sapolsky, 2003).

            Lest you’re now feeling totally freaked out that tiny parasitic genes are whispering self-destructive commands to you, do keep in mind that Dawkins only viewed the idea of “conscious” genes actively controlling your every behaviour as a metaphor. Genes are just molecular sequences of codons on your DNA that, ultimately, code for protein synthesis. Genes aren’t intelligent, scheming, manipulators of your actions selfishly sacrificing your ephemeral existence for their own immortality. That being said, the Selfish Gene Theory does provide psychologists with some important insights into real-world “zombie-like” self-destructive behaviour often seen in people.

            Happy Halloween!

References

Dawkins, R. (1976). The selfish gene. New York City: Oxford University Press.

Sapolsky, R. (2003). Bugs in the brain. Scientific American, 288(3), 94-97.