Ellis (this special edition) has advanced a comprehensive theoretical and empirical account of the possible cause(s) of ethnic differences in criminal behavior. In this response, we 1) assess the contribution of Ellis’ evolutionary neuroandrogenic (ENA) theory to explaining ethnic differences in criminal behavior; 2) highlight two traits related to lifehistory and ENA theory that are becoming increasingly important in the United States: self-control and general intelligence; 3) document the interplay between individual differences in self-control and general intelligence and cultural and economic changes (specifically, we investigate how self-control and general intelligence are becoming more important to success in modern technologically based societies); and 4) we illustrate how these trends are likely to continue and possibly accelerate. Therefore, understanding these trends has important implications for both scholars and policy makers. Specifically, understanding secular changes in criminal behavior requires possessing a basic outline of social changes that have occurred over the last fifty years and how these changes have intersected with human psychology.

Lee Ellis’ ENA theory

Ellis (2003, 2005, 2011) originally proposed ENA theory to account for sex and age variation in criminal behavior. The theory was later extended to account for universal gender differences in cognition and behavior (Ellis, 2011). In the target article, Ellis further extends ENA theory to account for ethnic differences in criminal behavior. The gist of ENA theory is that evolutionary pressures lead males and females to engage, on average, in different behaviors to maximize inclusive fitness (Buss, 1989). These sex-related differences selected for relatively more competitive males who are generally more concerned with dominance and status than females (Geary, 2010). The main proximate mechanism driving phenotypic and behavioral differences between males and females is differential exposure to androgens, with testosterone hypothesized to be a particularly important androgen. Previous research by Ellis and colleagues has demonstrated the parsimony and usefulness of ENA theory in accounting for criminal behavior and sex differences more broadly (Ellis, 2011; Ellis et al., 2015). However, in this target article, Ellis demonstrates the potential power of ENA theory to account for well-known ethnic group differences in criminal behavior. Ellis demonstrates specifically that androgen exposure is associated with criminality and that, with a few exceptions, androgen exposure generally varies ethnically in ways that match criminal behavior (higher levels of androgen exposure equate to a greater propensity for criminal behavior). Ellis, much to his credit, has also synthesized a vast corpus of literature related to ethnicity and hormonal exposure and, admirably, has pointed out weaknesses in the empirical literature as well as cases where ENA theory seems to be contradicted. Although we commend Ellis for the breadth of ENA theory and his ability to apply it to the controversial topic of ethnicity and crime, we do have a few criticisms of his piece before we expound our thoughts about general intelligence, self-control and social change. First, although Ellis provided clear evolutionary logic to account for sex differences in androgen exposure (e.g., building off parental investment theory), he did not supply similar evolutionary logic for differential ethnic group exposure to androgens. This is not fatal to ENA theory because it focuses on androgens which are a proximate cause of criminal behavior. However, Rushton (1985, 1988) provided a sweeping life-history theory of ethnic/racial differences in a variety of behaviors including those related to crime. Rushton’s life history framework seems consistent with Ellis’ ENA theory but there may be other evolutionary accounts that explain ethnic differences in criminal behavior and/or androgen exposure. Second, we believe that ENA theory is probably too parsimonious to explain fully the complexity of ethnic differences in criminality.