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 you are interested in learning more about risk taking behaviour, dopamine and addictions why not try our second level module SDK228 The science of the mind: investigating mental health . This module covers addiction as one of its topics with a focus on the role of dopamine in producing risk taking behaviour. The module also covers other aspects of mental health including mood disorders like depression and anxiety, as well as dementias. SDK228 is part of our degree in Health Sciences (Q71) and our degree in Natural Sciences (Q64), as well as our Open Degree .