Do Males Vary More Across the Board? The Extended Bateman’s Principle Hypothesis

Abstract

In 1948, Bateman published a landmark paper bearing on the evolutionary variable of reproductive success (RS). Drawing on data regarding the life cycle of fruit flies, Bateman discovered that mating rates in various experiments all demonstrated higher variability in males than in females. Females were more likely to mate a moderate number of times while data from males were characterized by a clear variability in RS (with males likely to encounter low, moderate, high, or even extremely high levels of RS). This phenomenon, now known as Bateman's Principle, has shown to be generally operative across various species including our own (Brown, Laland, & Mulder, 2013;Brown, Laland, & Mulder, 2009). The current work aims to address whether this basic asymmetry in variability across the sexes generalizes to trait domains that bear on RS. In other words, do males, relative to females, show higher variability in measures of morphological traits (e.g., height), social-emotional traits (e.g., emotional intelligence), cognitive traits (e.g., short-term memory ability), and important life outcome variables (e.g., markers of physical and financial health)? To address this issue, our methods included an intensive examination of the literature on male/female differences across a broad array of human domains. The literature review presented here addresses this idea, often referred to as the variability hypothesis (see Feingold, 1992), across a broadreaching suite of physical and behavioral dimensions. Ultimately, our results and conclusions provide strong evidence for the variability hypothesis in humans.