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.     
As an example, should you choose to run a cycle that includes both Dianabol and Anavar, you will need to be extremely careful when it comes to overlapping them. The two are both hepatotoxic, which means they will cause liver damage. You will need to consider this carefully when it comes to choosing cycle lengths. If you take Dianabol for four weeks at the beginning of your cycle, then make the switch to Anavar, you should limit your Anavar use to four weeks, as well. This reduces your entire cycle time to eight weeks, which helps to alleviate some of the risk of liver damage.