The second theory is similar and is known as "evolutionary neuroandrogenic (ENA) theory of male aggression".   Testosterone and other androgens have evolved to masculinize a brain in order to be competitive even to the point of risking harm to the person and others. By doing so, individuals with masculinized brains as a result of pre-natal and adult life testosterone and androgens enhance their resource acquiring abilities in order to survive, attract and copulate with mates as much as possible.  The masculinization of the brain is not just mediated by testosterone levels at the adult stage, but also testosterone exposure in the womb as a fetus. Higher pre-natal testosterone indicated by a low digit ratio as well as adult testosterone levels increased risk of fouls or aggression among male players in a soccer game.  Studies have also found higher pre-natal testosterone or lower digit ratio to be correlated with higher aggression in males.     
APPENDIX 1: Concerns About Attributing Cancer Causation to Emotions Some readers may raise the objection that attributing cancer causation to emotions could place an extra burden on the cancer patient: namely blaming the individual for causing their condition (this point was raised by one of the clinicians at ITM). For each individual cancer patient, blaming their cancer on any particular cause is probably of no value. Whether the cancer is blamed on an environmental chemical introduced by a reckless corporation, or on a high fat diet, on smoking, or on an inherited gene, the treatment of the cancer is not significantly altered; it is not possible to go back and undue the damage. Therefore, to become involved in the matter of placing blame for any individual case is a futile effort. Indeed, no matter what is blamed, the process of placing blame may simply stimulate more emotional distress (., anger and over-thinking) that impairs the healing process.