With all the violence in the world, it is natural to wonder, as Pat Shipman did recently in these pages (Macroscope, November-December 2001), whether aggression is deeply rooted in human nature. Perhaps it is. But we would argue that human aggressive incli nations are balanced by equally strong tendencies to cooperate with one another?an argument Prince Piotr Kropotkin made a century ago in Mutual Aid, a survey of altruistic societies. This view flies in the face of much current thinking on the subject, which presupposes there are deep bi ological roots to violence. Molecular biologists have, for example, sought to identify genes that control aggression in mice on the assumption that similar mechanisms operate in human beings. In deed, scientists have regularly attempted to ex plain people's more savage tendencies by mak ing comparisons with animals, particularly since Konrad Lorenz (an Austrian zoologist and Nobel laureate) theorized about the evolutionary roots of such behavior in his 1966 classic On Aggression. Lorenz's view was that aggression is an in evitable character trait for most creatures because it is functional: A combative disposition helps males acquire resources, and it aids females in protecting their young. Guided by the assump tion that aggression is a basic animal instinct, Lorenz and those who followed in his footsteps readily applied this principle to explain the be havior of men and women. The many violent acts making the daily headlines would only seem to confirm their suppositions. Fortunately, and counter to prevailing ideas, there is now a large body of work on the psycho logical development of children that suggests