In the last post I suggested that although low heart rates might have an influence on violent crime, other biological measures needed to be considered.
Quick as a flash, reader East Coast came up with a relevant reference, and lest this languish in the comment columns I thought I would highlight the main findings, which are at the end of the abstract.
The genetic and environmental basis of a well-replicated association between antisocial behavior (ASB) and resting heart rate was investigated in a longitudinal twin study, based on two measurements between the ages of 9 and 14 years. ASB was defined as a broad continuum of externalizing behavior problems, assessed at each occasion through a composite measure based on parent ratings of trait aggression, delinquent behaviors, and psychopathic traits in their children. Parent ratings of ASB significantly decreased across age from childhood to early adolescence, although latent growth models indicated significant variation and twin similarity in the growth patterns, which were explained almost entirely by genetic influences. Resting heart rate at age 9–10 years old was inversely related to levels of ASB but not change patterns of ASB across age or occasions. Biometrical analyses indicated significant genetic influences on heart rate during childhood, as well as ASB throughout development from age 9 to 14. Both level and slope variation were significantly influenced by genetic factors. Of importance, the low resting heart rate and ASB association was significantly and entirely explained by their genetic covariation, although the heritable component of heart rate explained only a small portion (1–4%) of the substantial genetic variance in ASB. Although the effect size is small, children with low resting heart rate appear to be genetically predisposed toward externalizing behavior problems as early as age 9 years old
Prof Joe Murray, lead author of the heart rate paper I reviewed has sent in some further material:
Childhood behaviour problems predict crime and violence in late adolescence: Brazilian and British birth cohort studies
Crime and violence in Brazil: Systematic review of time trends, prevalence rates and risk factors
Additionally, Prof Murray says “Yes, it was the gap in knowledge about offenders identified in the 2013 review that motivates work in this in the Pelotas cohorts” so we may get better details about the ethnic composition of offenders in due course.