Sheldon's physiological theory:
People with certain body types are more likely to commit crimes - physical advantage.
Endomorphs - fat, lacking muscle, relaxed and socially outgoing.
Ectomorphs - thin, introverted, emotionally restraint.
Mesomorphs - muscular, strong, adventurous and aggressive.
4000 convicts - majority have mesomorph somatotypes and minority was ectomorphs.
Mesomorphs have physical advantage and a high pain threshold.