Microkhan by Brendan I. Koerner

(Cross-posted to/from PLoS Blogs)

All the recent chatter over the dangers of professional football compelled me to look up one of my favorite snippets of Greek mythology: the tale of Achilles’ choice, from Book Nine of the Iliad. For those who have only foggy memories of high-school English, the story goes like this: the gods of Olympus gave Achilles the option of leaving Troy alive, in which case he would live to a ripe old age and die in anonymity. If he stayed in Troy, by contrast, he would be killed in battle, but his name would be renowned for all eternity. The fact that you’re reading these words makes clear which fate Achilles selected; the parallel with debilitated former football players is tough to miss.

Leo Tolstoy explored similar philosophical terrain in The Two Brothers, a brief parable about siblings who choose very different paths through life. One is a stand-in for Achilles, a risk taker who prefers the peaks-and-valleys model of existence; the other is content to live in peace. The former brother gets the last word in the story, which suggests that Tolstoy’s sympathies, like those of Homer, lay with the bold.

And that makes sense for men of letters, who typically need strong characters in order to create drama. (Okay, maybe not Arthur Miller, but you get the point.) But should populations at large similarly favor risk takers? While bold individuals certainly play a key role in advancing any species’ fortunes, no population can afford to have too many members bent on glory at all costs. There has to be a balance between those with a predisposition to sally forth, and those who hang back in the rear and provide stability. What, then, is the optimal ratio between the two types?

There are some clues to be found in one of my favorite papers of recent vintage: “Effects of group size and personality on social foraging: the distribution of sheep across patches” from Behavioral Ecology. The paper describes an experiment in which researchers split their ovine subjects into two groups: one consisting of sheep notable for their boldness, the other of meeker compatriots. (The personality determinations were made based on how the sheep responded to various inanimate objects.) They then observed the animals’ grazing habits over time, in order to discern how temperament might affects the sheep’s’ willingness to wander toward new patches of grass.

It came as no surprise that the bold sheep were more willing to break away from their groups in order to exploit fresh turf. But as the researchers noted, this doesn’t mean that risk-taking individuals are necessarily more valuable to a population’s survival than their meeker counterparts; it is the interplay between these two personality types that creates a population with the best long-term odds of success:

Our results demonstrate that individual variability can also promote behavioral plasticity at the level of groups within populations. It is possible that much of the variation in the spatial organization of groups may depend on fairly small phenotypic differences between a few individuals. Different personality types may also act as complementary forces at the scale of the flock or herd, with bold individuals contributing to the spread of the group and their ability to explore new resource sites and shy animals contributing to the maintenance of group cohesion.

The question then becomes, What is the ideal ratio between shy and bold individuals? Perhaps someday we’ll be able to get a better sense of the answer by evaluating the distribution of so-called risk-taking genes—though, to be honest, I remain deeply skeptical of such methods, which strike me as too dismissive of nurture’s role. Or maybe there is wisdom to be gleaned from the realm of military science, which has long been fascinated with the concept of the tooth-to-tail ratio—that is, the correct proportion of combat to support troops.

Above all, I’m curious about the role that narratives play in shaping the bold-to-shy balance. The Iliad’s commendation of Achilles’ choice or Sports Illustrated’s frequent paeans to gridiron heroes reinforce the notion that it’s always more noble to opt for glory over comfort. Does this suggest that humans are too predisposed toward meekness, so that we require cultural encouragement to develop a sufficient number of risk takers to sustain the species? If so, one might argue that storytelling has been more integral to our collective success than opposable thumbs.