AndroGel (testosterone) for Hypogonadism, Male: "I am 33 was tested and had low t my results were 39 which is extremely low. I started on androgel two pumps made me very aggressive and I would snap and get angry so I went to 1 pump in the morning my sex drive went through the roof :) . After 6 wks I was tested the results were 432 that was exciting I also gained 15pounds I use to weigh 140 now I'm staying between 150-156 I am stronger more energy can think better but I do have my days that suck it's all part of the test now not everyone is going to have results like mine so keep trying to find what it is that works also if your eating poorly that maybe the reason also try to eat healthy and workout"
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.