Just as the threat of predation leads to the evolution of behavioral systems, so too does the threat of parasitic attack. In certain species of leafcutter

Personality styles vary widely across cultures, as Volume 1 of this work attests. On average, New Zealanders report higher extraversion than Nigerians; Chileans report higher openness to experience than Chinese (e.g., McCrae et al., 2005). Similarly, when comparing small-scale societies, the Wolof tend to be more self-restrained than the Warrau; the Aztec more restrained than the Amahuaca (Barry, Josephson, Lauer, & Marshall, 1976). But why does this variation exist? Is it simply stochastic noise, or ethnographic dazzle? Or do these cultural differences reflect real, adaptive responses to differing ecological and social demands between cultures? In this chapter, we focus on one specific ecological variable—the threat posed by infectious disease—and its implications for cultural variation in personality.