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.     
So, how does one ensure that testosterone levels remain in balance? Some doctors suggest that monitoring testosterone levels every five years, starting at age 35, is a reasonable strategy to follow. If the testosterone level falls too low or if the individual has the signs and symptoms of low testosterone levels described above, testosterone therapy can be considered. However, once testosterone therapy is initiated, testosterone levels should be closely monitored to make sure that the testosterone level does not become too high, as this may cause stress on the individual, and high testosterone levels may result in some of the negative problems (described previously) seen.
Whether you want a Testosterone Cycle, Cutting, Bulking up or a Weight Loss Cycle , you should make the right choice before you start. Make sure that you decide if you want to cut, lose weight, or gain muscle. Maybe even lose weight and gain muscle all at the same time.
A healthy diet along with a good protein supplement will greatly improve performance in any good Cycle. Remember that by losing fat around the body you will increase your strength to mass ratio and improve lean muscle tissue, giving you that lean physique appearance.
Bulking and Cutting Cycles - Those individuals who already have a lean physique wont achieve fat loss gains as quickly as those with more weight and therefore would more than likely opt to go for a combined all in one Bulking and Cutting Cycle to start with.