We encounter them on a regular basis, especially on our highways. They race up from behind, riding our bumper and flashing their lights, demanding that we move from their path. Others weave among the traffic or speed along on their motorcycle, sans helmet. Some appease their aggression by signing up with the military, by joining gangs or by participating in violent sports. Unfortunately, many end up in prison, in brain injury centers or in our cemeteries.
Aggression in young males is a natural trait, reflecting the testosterone-fueled conflicts in our hominid ancestors. Driven away by their father (nature's effort to discourage inbreeding), young males had to fight for their own territories and assemble their own clans. Those unable or unwilling to engage in confrontation were marginalized and their genes did not contribute to the tide of human evolution.
To succeed in the modern world, however, young men must keep their physical aggression in check. Mentorship from fathers (or their male surrogates) is vital in this regard and those deprived of their discipline and influence are more likely to suffer the consequences of aggressive behavior. With all due respect to, and admiration for, single mothers (victims, themselves, of irresponsible males), highly involved fathers play an essential role in the development of young men.