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Socialization and Force from the Kitchen to the Screen

Developmental Origins of Physical Violence

Richard E. Tremblay, Ph.D., FRSC
Canada Research Chair in Child Development
University of Montréal


Youth violence is a major public concern in all modern societies. To prevent this violence we need to understand how innocent young children grow into violent adolescents. Longitudinal studies of large samples of children from infancy to adulthood indicate that the peak age for physical aggression is the third year after birth. Fortunately, because of their size, physical aggression from three-year-olds does not constitute a major threat to the public. It is also providential that most children learn to control these socially disruptive behaviours before they enter school. This natural course of development suggests that the preschool years are the best window of opportunity to prevent the development of cases of chronic physical aggression. Safe streets could thus start with quality early education.

The risk of committing a violent offence is highest during middle adolescence. Because adult violence is generally linked to a history of youth violence, and because all adults are former youth, one would expect that reducing youth violence would also reduce adult violence. Thus, the reduction of youth violence should in the long run have a very large impact on total violence in a given society.

Most criminological studies of youth violence have focused on 12- to 18-year-old youth. During this period they become stronger physically, their cognitive competence increases (e.g., they are better at hiding their intentions), they become sexually mature, they ask and obtain a greater freedom to use their time without adult supervision, and they have access to more resources such as money and transportation, which increases their capacity to satisfy their needs.

This rapid bio-psycho-social development might be sufficient to explain why adolescence is a period of life when there are more opportunities and motives for antisocial behaviour. Adolescents lack experience and feel pressured to choose a career, or to perform in school, within their peer groups, or with possible sexual partners. These factors may explain why proportionally more adolescents than adults resort to violent behaviour.

However, although a majority of adolescents will commit some delinquent acts, most of these are minor legal infractions. Population-based surveys have systematically shown that a small proportion of adolescents (approximately six percent) account for the majority of violent acts and arrests. Of the total number of cases that proceed annually to youth courts across Canada, less than a quarter involve violence, and in nearly half of these cases the principal charge is minor assault.

The challenge is to explain why some adolescents and some adults resort to physical aggression more frequently than others. Although they are relatively small in number, they frighten a large part of the population, and they represent a heavy burden of suffering for their victims, their families and themselves. Adolescents with behavioural problems are also much more likely to be unemployed, suffer poor physical health or have mental health problems. So why do innocent and harmless young children become violent adolescents?

In his book on how humans learn to live in societies (On the citizen) the 17th century British philosopher, Thomas Hobbes, gave a clear and simple, but paradoxical answer: a wicked man is a child that has not grown up. A century later, Jean-Jacques Rousseau, the French philosopher, took issue with Hobbes and argued that children are born innocent and have to be kept away from the bad influences of society. Living alone with nature was the best way for a child to follow nature and avoid becoming corrupted by society. Children had to be kept away from peers and from books. Whatever led Rousseau to this romantic perception of child development appears to be an extremely common experience. Many present day adults, including psychologists and psychiatrists, appear to be convinced that social behaviour is natural ("God-given" or "genetic") and antisocial behaviour is learned from fellow humans. For example, social learning has been one of the most influential theories in the area of children’s aggressive behaviour over the past 30 years.

Recent longitudinal studies of thousands of subjects from childhood to adulthood in many countries around the world, including Canada, have confirmed Hobbes’ paradox. Adults with serious behaviour problems behave like they did when they were young children. However, because their limbs have gained strength, their physical aggressions have more serious consequences for their victims. Indeed, the studies which followed the development of children from infancy to adulthood revealed that the peak age for physical aggression is around the third year after birth. Children who fail to learn alternatives to physical aggression during the preschool years are at very high risk of a huge number of problems. They tend to be hyperactive, inattentive, anxious, and fail to help when others are in need; they are rejected by the majority of their classmates, they get poor grades, and their behaviour disrupts school activities. They are thus swiftly taken out of their "natural" peer group and placed in special classes, special schools and institutions with other "deviants," the ideal solution to reinforce marginal behaviour. They are among the most delinquent from pre-adolescence onward, they are the first to initiate substance use, the first to initiate sexual intercourse, the most at risk of dropping out of school, of having a serious accident, of being violent offenders, of being charged under the Young Offenders’ Act and of being diagnosed as having a psychiatric disorder.

The studies that followed aggressive children into their adult years have indeed shown that there are extremely negative consequences not only for the aggressive individuals, but also for their mates, their children and the communities in which they live. The stage is set for early parenthood, unemployment, family violence and a second generation of poor children brought up in a disorganized environment. From this perspective, failure to teach children to regulate violent behaviour during the early years leads to poverty much more clearly than poverty leads to violence.


Hobbes, Thomas, De Cive (New York: Cambridge University Press, 1647/1998).

Rousseau, Jean-Jacques, Émile or On education (New York: Basic Books, 1762/1979).

Tremblay, Richard E., Hartup, Willard H., & Archer, John (Eds.), Developmental origins of aggression (New York: Guilford Press, 2005)