Violence is the very nature of man, an inheritance from our animal past. 
Our emotions (pleasure, anger, kindness and cruelty and even love and
sacrifice) are the function of our limbic system (the so-called "primitive
brain" or "animal brain"), although almost all emotions can be magnified or suppressed by the cerebral cortex, our thinking brain (that we share with other Primate species, although somewhat more developed in humans).
  From the evolutionary point of view, males evolved as hunters (fighters and defenders) and the hormones (androgen group) secreted by specialized cells (Leydig cells) in the male testes prepare their bodies and brains for the task ahead. Whereas the main function of the testosterone (the so-called male hormone, that surges at puberty) is to enhance libido, energy, immune function, and protection against osteoporosis, it also provides us with "hunting tools" (defense of territory, aggressiveness, and ability to kill and camouflage).  In females, the major role is played by the estrogens (secreted by the ovaries) to prepare them for their role as farmers and gatherers, and for child-bearing.  Estrogens also influence the psyche of the female (thus, whereas a male sees the overall picture, a female concentrates on the microscopic details).  Both male and female behavior is further strengthened by the culture (within the family and the social group)
 
Thus, one can summarize that, yes, our brains are hotwired for violence but violence can be controlled both chemically and by changing the culture.
Regards
Muhammad Akhtar Alikhan

December 02, 2005