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 would rather try to increase testosterone naturally, you could try a natural testosterone booster. These Test for sale products contain ingredients designed to boost the production of testosterone in your body rather than introduce more. Often, they contain a compound known as tribulus terrestris ; men around the world have used it for generations to improve libido. Although there are only limited scientific studies and the results are inconclusive, millions of men across generations cannot be wrong. Today, the most positive testosterone booster reviews focus on compounds that contain this popular ingredient.
The partition coefficient of the ester in question is important because is effects how long the drug itself stays in the system. If the testosterone transfers too quickly from the oil to the blood, the result is a sudden spike in testosterone which then rapidly drops once the dose has been used up. In the example of free testosterone injected into the muscle from a water suspension (as in Aquiviron, mentioned above), the testosterone is essentially immediately available to the bloodstream due to its low partition coefficient, and thus there is an immediate spike of testosterone which is used up quickly in the body.