Four issues relevant to sex differences in human aggression
and violence are considered. (1) The motivation for play and
serious aggression in children and juvenile animals is different.
Consequently, the evolutionary explanations for each may be
different. (2) Sex differences in intrasexual aggression may be
due to effects of the attacker or the target. There is evidence that
both males and females are more physically aggressive against
males and less physically aggressive against females. The evolutionary
explanation for each component of the sex difference in intrasexual
aggression may be different. (3) Aggression and violence are defined.
The former is the attack, and the latter is the consequent injury or
death. The evolutionary explanation for each may not be the same.
(4) Most men and women are neither physically aggressive nor
criminally violent. The evolutionary explanations of sex differences
in aggression and violence should take this polymorphism into
account.