Aggressive-antisocial boys develop into physically strong young men

Abstract

Young men with superior upper-body strength typically show a greater proclivity for physical aggression than their weaker male counterparts. The traditional interpretation of this phenomenon is that young men calibrate their attitudes and behaviors to their physical formidability. Physical strength is thus viewed as a causal antecedent of aggressive behavior. The present study is the first to examine this phenomenon within a developmental framework. We capitalized on the fact that physical strength is a male secondary sex characteristic. In two longitudinal cohorts of children, we estimated adolescent change in upper-body strength using the slope parameter from a latent growth model. We found that males' antisocial tendencies temporally precede their physical formidability. Boys, but not girls, with greater antisocial tendencies in childhood attained larger increases in physical strength between the ages of 11 and 17. These results support sexual selection theory, indicating an adaptive congruence between male-typical behavioral dispositions and subsequent physical masculinization during puberty.

Keywords: adolescent development; aggression; antisocial behavior; physical strength.

Fig. 1

Path diagram of a latent growth model. Rectangles represent observed hand-grip strengths at the age-11, age-14, and age-17 assessments. Circles denote latent variables, and triangles represent the grand means of the intercept and slope parameters. Residual variances (RV) are time-specific, and represent variation unexplained by the growth model.

Fig. 2

Median split of male participants into high and low groups of antisociality at age 11. Observed hand-grip strength values are plotted at age 11 (bottom panel) and age 17 (top panel). The ranges of values on the y-axis (14-24 kg and 38-48 kg in the two panels, respectively) are deliberately truncated in order to allow for adequate resolution of the error bars, which represent 95% confidence intervals. Please note that grip strength approximately doubled between ages 11 and 17.

Fig. 2

Median split of male participants into high and low groups of antisociality at age 11. Observed hand-grip strength values are plotted at age 11 (bottom panel) and age 17 (top panel). The ranges of values on the y-axis (14-24 kg and 38-48 kg in the two panels, respectively) are deliberately truncated in order to allow for adequate resolution of the error bars, which represent 95% confidence intervals. Please note that grip strength approximately doubled between ages 11 and 17.