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.     
If an androgen-associated adverse reaction occurs, treatment should be interrupted and, after disappearance of the symptoms, be resumed at a lower dosage. Patients with latent or overt cardiac failure, renal dysfunction, hypertension, epilepsy or migraine (or a history of these conditions) should be monitored, since androgens may occasionally induce salt and fluid retention. Androgens should be used cautiously in pre-pubertal boys to avoid premature epiphyseal closure or precocious sexual development. A decrease in protein bound iodine (PBI) may occur,but this has no clinical significance. Treatment of male patients over the age of approximately 50 years with androgens should be preceded by a thorough examination of prostate and baseline measurement of prostate-specific antigen serum concentration.