Testosterone is significantly correlated with aggression and competitive behaviour and is directly facilitated by the latter. There are two theories on the role of testosterone in aggression and competition.  The first one is the challenge hypothesis which states that testosterone would increase during puberty thus facilitating reproductive and competitive behaviour which would include aggression.  Thus it is the challenge of competition among males of the species that facilitates aggression and violence.  Studies conducted have found direct correlation between testosterone and dominance especially among the most violent criminals in prison who had the highest testosterone levels.  The same research also found fathers (those outside competitive environments) had the lowest testosterone levels compared to other males. 
What's up Chris thanks for another great article on test. I've been taking tribulus recently and noticed that my test feels way higher, I have more energy, better moods, better libido, etc. But I'm also starting to get worse gyno. I seem to be very prone to gyno whenever I drink, smoke weed or when my test goes up, so I take an OTC estrogen blocker called erase (androsta-3,5diene-7,17-dione) whenever my gyno is getting too much.
I have a question about TRT though, I read an article on boldanddetermined that suggested that every man should get on TRT if they have symptoms of low test, even younger men. I'm 19 and have had symptoms of low test including ED and depression, and I'm planning on getting my levels tested next time I go to the doctor. Would you recommend I get some kind of "low health impact" AI like exemestane and take that while I'm on TRT to avoid getting my estrogen too high?
While testosterone is typically seen as a "male" hormone, it's also present (albeit in much smaller amounts) in women. However, between 4-7% of American women produce too much testosterone in their ovaries, which usually leads to a condition called polycystic ovary syndrome.  Too much testosterone in women can lead to infertility due to lack of ovulation, as well as some embarrassing symptoms like acne, a deepening voice and facial hair growth. Reducing testosterone levels in women is often accomplished with medication, although dietary change can make a positive impact also.