Entitled: "Quoth Hal to Dick, I know its true". A man seeks revenge for the liberties another man is reputed to have taken with his wife. While one man pinches the other's ear, the other man grabs for his hat. Engraving by John Collier, 1773. Aggression is overt, often harmful, social interaction with the intention of inflicting damage or other unpleasantness upon another individual. It is a virtually universal behavior among animals. It may occur either in retaliation or without provocation. In humans, frustration due to blocked goals can cause aggression. Research has suggested that males use more physical aggression than females, while females use more verbal aggression.