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. 
MOST MEN do not have optimal testosterone levels. If your levels are ‘normal’, you may not be in the optimal range that is best for you. “Optimal levels” mean that you feel like the best version of yourself– you have the energy to perform daily activities and workouts, you build muscle easily, and you have a healthy sex drive. No two men will experience the exact same symptoms even if they are at the same level. If your testosterone is below your optimal level, you can experience fatigue, decreased sex drive or performance, increased body fat or weight, loss of bone and muscle mass, and moodiness or irritability. Not only do these symptoms effect how you feel, but other health issues may arise such as osteoporosis or depression.
Common (1% to 10%): Sinusitis, nasopharyngitis, upper respiratory tract infection , bronchitis
Uncommon (% to 1%): Cough, dyspnea, snoring, dysphonia
Rare (less than %): Pulmonary microembolism (POME) (cough, dyspnea, malaise, hyperhidrosis, chest pain, dizziness, paresthesia, or syncope) caused by oily solutions
Frequency not reported: Sleep apnea
Postmarketing reports: Chest pain, asthma , chronic obstructive pulmonary disease , hyperventilation, obstructive airway disorder, pharyngeal edema, pharyngolaryngeal pain, pulmonary embolism , respiratory distress, rhinitis , sleep apnea syndrome [ Ref ]