Canadians' worst fears are confirmed by recent statistics. We believe teenagers are a violent group, so it's not surprising to learn that 84 teenagers were charged with killings last year, most of them gang-related.

What is surprising is that teenagers are not the most violent age group. That distinction belongs to a much, much younger group, according to a documentary produced by the National Film Board of Canada called Origins of Human Aggression, which was recently shown on the Knowledge Network.

Researchers wanted to find out just when aggression started in humans so they started studying younger subjects. They were surprised to learn that babies express a lot of anger and aggression.

This discovery was astonishing because the usual stereotype of babies is that they are cute and cuddly. It also contradicts commonly held theories of the origin of aggression: children are born pure but are corrupted by society; adolescents are like fruit that goes rotten with time; babies are born in sin but their wicked ways are soon beaten out of them.

All of them are wrong, but the last theory is the closest, according to Dr. Richard Tremblay of University of Montreal. He discovered that the apparent wide-eyed innocence of babies is deceptive…..

Adult intervention is important in the socialization of children. Parents and caregivers must make it clear that aggression is not acceptable and that there are non-violent ways of resolving conflict, such as speech and peer pressure.

Physical discipline is counterproductive.

"Children who are hit are more likely to hit later on, and hitting is a very good predictor of crime later on," said criminologist Joan McCord of Temple University…..

Juvenile delinquents represent a huge cost to society. Nobel Prize-winning economist James Heckman studied social spending and found that, from an economic perspective, early intervention is cheaper than bigger prisons.

Canada's Conservative government proposes that we get tough on crime. A good place to start is an investment in child care and parenting skills. It will pay off in the next generation.

However, it's difficult for governments to think past the next election. The politics of fear and stereotypes wins votes, so we constantly clean up the mess left by the neglect of children of a previous generation.

The origins of human aggression are clear and reversible. The sooner we start the better.