This study used data from 6 sites and 3 countries to examine the developmental course of physical aggression in childhood and to analyze its linkage to violent and nonviolent offending outcomes in adolescence. The results indicate that among boys there is continuity in problem behavior from childhood to adolescence and that such continuity is especially acute when early problem behavior takes the form of physical aggression. Chronic physical aggression during the elementary school years specifically increases the risk for continued physical violence as well as other nonviolent forms of delinquency during adolescence. However, this conclusion is reserved primarily for boys, because the results indicate no clear linkage between childhood physical aggression and adolescent offending among female samples despite notable similarities across male and female samples in the developmental course of physical aggression in childhood.Children's behavior problems have long been considered precursors of juvenile delinquency and adult criminality (Carpenter, 1851;Horn, 1989; Roosevelt, 1909). The development of these behavior problems during the elementary school years was the object of intensive investigations over the last quarter of the 20th century. A number of large-scale longitudinal studies in different industrialized countries used repeated measurements over many years to trace the development of behavior problems. These studies followed older pioneering longitudinal studies that were retrospective (e.g., Robins, 1966) or that had limited their prospective assessments to one time point during childhood and one or two time points during adolescence and adulthood (e.g., Lefkowitz, Eron, Walder, & Huesmann, 1977; West & Harrington, 1973).Having reviewed this long-lived literature, the U.S. National Research Council's Panel on Understanding and Preventing Violence concluded, " [I] NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript to become violent teenagers and adults" (Reiss & Roth, 1993, p, 358). There is indeed ample evidence that, at least for boys, childhood disruptive or troublesome behavior is one of the best predictors of adolescent and adult criminality, including violent offending (e.g., Farrington, 1994;Fergusson & Horwood, 1995;Huesmann, Eron, Lefkowitz, & Walder, 1984;Moffitt, 1990;Pulkkinen & Tremblay, 1992;Stattin & Magnusson, 1989;Tremblay, Pihl, Vitaro, & Dobkin, 1994). However, Nagin and Tremblay (1999) and Tremblay (2000) pointed out that extant research generally does not distinguish physical from nonphysical aggression or violence. Thus, it is only possible to conclude that disruptive or troublesome behavior during childhood predicts later delinquent behavior, not that physical aggression during childhood per se is a distinct risk factor for physical violence in adolescence or adulthood.A determination of whether physical aggression is a distinct risk factor for later physical violence is important for both conceptual and practical reasons. Conceptually, the nature of ...

A semi-parametric mixture model was used with a sample of 1,037 boys assessed repeatedly from 6 to 15 years of age to approximate a continuous distribution of developmental trajectories for three externalizing behaviors. Regression models were then used to determine which trajectories best predicted physically violent and nonviolent juvenile delinquency up to 17 years of age. Four developmental trajectories were identified for the physical aggression, opposition, and hyperactivity externalizing behavior dimensions: a chronic problem trajectory, a high level near-desister trajectory, a moderate level desister trajectory, and a no problem trajectory. Boys who followed a given trajectory for one type of externalizing problem behavior did not necessarily follow the same trajectory for the two other types of behavior problem. The different developmental trajectories of problem behavior also led to different types of juvenile delinquency. A chronic oppositional trajectory, with the physical aggression and hyperactivity trajectories being held constant, led to covert delinquency (theft) only, while a chronic physical aggression trajectory, with the oppositional and hyperactivity trajectories being held constant, led to overt delinquency (physical violence) and to the most serious delinquent acts.

ABSTRACT. Objectives. Physical aggression in children is a major public health problem. Not only is childhood physical aggression a precursor of the physical and mental health problems that will be visited on victims, but also aggressive children themselves are at higher risk of alcohol and drug abuse, accidents, violent crimes, depression, suicide attempts, spouse abuse, and neglectful and abusive parenting. Furthermore, violence commonly results in serious injuries to the perpetrators themselves. Although it is unusual for young children to harm seriously the targets of their physical aggression, studies of physical aggression during infancy indicate that by 17 months of age, the large majority of children are physically aggressive toward siblings, peers, and adults. This study aimed, first, to identify the trajectories of physical aggression during early childhood and, second, to identify antecedents of high levels of physical aggression early in life. Such antecedents could help to understand better the developmental origins of violence later in life and to identify targets for preventive interventions.Methods. A random population sample of 572 families with a 5-month-old newborn was recruited. Assessments of physical aggression frequency were obtained from mothers at 17, 30, and 42 months after birth. Using a semiparametric, mixture model, distinct clusters of physical aggression trajectories were identified. Multivariate logit regression analysis was then used to identify which family and child characteristics, before 5 months of age, predict individuals on a high-level physical aggression trajectory from 17 to 42 months after birth.Results. Three trajectories of physical aggression were identified. The first was composed of children who displayed little or no physical aggression. These individuals were estimated to account for ϳ28% of the sample. The largest group, estimated at ϳ58% of the sample, followed a rising trajectory of modest aggression. Finally, a group, estimated to comprise ϳ14% of the sample, followed a rising trajectory of high physical aggression. Best predictors before or at birth of the high physical aggression trajectory group, controlling for the levels of the other risk factors, were having young siblings (odds ratio [OR]: 4.00; confidence interval [CI]: 2.2-7.4), mothers with high levels of antisocial behavior before the end of high school (OR: 3.1; CI: 1.1-8.6), mothers who started having children early (OR: 3.1; CI: 1.4 -6.8), families with low income (OR: 2.6; CI: 1.3-5.2), and mothers who smoked during pregnancy (OR: 2.2; CI: 1.1-4.1). Best predictors at 5 months of age were mothers' coercive parenting behavior (OR: 2.3; CI: 1.1-4.7) and family dysfunction (OR: 2.2; CI: 1.2-4.1). The OR for a high-aggression trajectory was 10.9 for children whose mother reported both high levels of antisocial behavior and early childbearing.Conclusions. Most children have initiated the use of physical aggression during infancy, and most will learn to use alternatives in the following years before...

Research on human aggression has been a flourishing industry in the 20th century. As the attention shifted from an instinctual paradigm to a drive paradigm and a social learning paradigm, what have we learned on the development of aggressive behaviour during childhood? Are children born with an aggressive instinct or do they have to learn to aggress?This question has deep philosophical roots, but it also has important practical implications. Should interventions prevent children from learning to aggress or should they help children learn to inhibit aggressive reactions? Since most of the 20th century work on the development of aggression was concentrated on adolescents and elementary school age children, there appeared to be an implicit assumption that aggression is learned during these developmental periods. It is argued that to understand the origins of aggressive behaviour and prevent chronic cases of physical aggression we will need to focus on the development of aggressive behaviour during the first few years after birth, and differentiate among forms of aggressive behaviour. The form of agressive behaviour that is generally considered more “serious” or “socially unacceptable” (physical aggression) is clearly ontogenetically antecedent to less “serious” forms of aggressive behaviour, such as verbal aggression or indirect aggression. Furthermore, as a rule the frequency of physical aggression appears to decrease with age. However, infants’ physical aggression has generally not been considered developmentally significant. This is probably because of “the weakness of their limbs” and the apparent lack of “intentionality”. To have a relatively complete description of the life-span developmental trajectories of human aggressive behaviour by the end of the 21st century, we will need to start recruiting pregnant women very soon.