The popular opinion holds as males being more aggressive than females.
As proof they cite boys as being physically and verbally move aggressive than girls and the relative lack of women in the world’s armed forces or even in physically aggressive and demanding sports like rugby, football and ice-hockey.
In addition, there is corroborative evidence from anthropology showing that killing — whether it be in war or in daily life — occurs in thousands of different cultures and that the people who do the killing are chiefly men.
If a sex difference is universal among human beings even though they grow up in very different cultures, there is a good chance that the difference comes not from the way people are brought up but from biological factors that are presumably the same in every society.
But as to the question of whether or not aggressiveness is based largely on biology — on physiological differences between the sexes rather than on learning — some scientists consider the evidence now available to be inconclusive.
However, there are a number of scientists who are convinced that aggression can be traced to the male hormone testosterone.
Males have the AMYGDALA 4 times larger than females leads to more agressive behaviour ,fight or flight response observed in them .
In one especially provocative study of male juvenile delinquents, the most aggressive ones were those with the highest levels of testosterone in their bodies.
But, finally remember, not all men are more aggressive than women; some women are more aggro than most men.