The effects of early exposure to gonadal steroids have been described for a variety of vertebrate species. Aggression in males is facilitated by implants of AVT in the limbic system and inhibited by implants of AVP. Men with fewer CAG repeats have more active androgen receptors and enhanced testosterone action. All the above studies have methodological limitations because of the small number of subjects and samples. In more sensitive laboratory paradigms it was observed that a participant’s testosterone rises in the winners of competitions and dominance trials, or in confrontations with factitious opponents. Most of the studies, however, were conducted by self reported questionnaires, the accuracy of which is questionable. In this study testosterone was measured among 87, 14-year-old adolescents (36 boys, 51 girls), and externalizing behavior was measured at age 8, 11 and 14 years. The study used the Achenbach Child Behavior Checklist and the Youth Self Report Form to assess externalizing behaviors. These factors may also explain why sex differences may exist in the link between testosterone and aggression. Another observational study also documented positive correlations between testosterone and aggression during early follicular and late luteal phases of menses (33). There are, however, studies suggesting that the strength and direction of the association between testosterone and aggression may not be different among men and women (30). Results of previous studies on the association between testosterone and aggression are therefore not conclusive. In this view, higher levels of testosterone lead to more aggressive behavior, irrespective of the fact that the range may be more limited among women. For instance, those studies that show a smaller relationship between testosterone and aggression among females may be due to range restriction (5). Another study measured plasma levels of testosterone and also externalizing behaviors among 51 boys and 68 girls at age 14. Our findings revealed a positive correlation between the level of testosterone and violent behaviors among young female, but not among young male adults. The study was conducted in response to the gap in knowledge about sex differences in the association between testosterone and violent behaviors at the community level. Means and standard deviations (SD) were reported for age, testosterone, and violent behaviors for both males and females. Understanding how testosterone may interact with these neurotransmitter systems provides crucial insights into the neurobiological mechanisms contributing to the testosterone-aggression link. Serotonin’s role in impulse control and aggression inhibition, as well as dopamine’s influence on reward processing and motivation, is elucidated. This section explores the intricate interplay between testosterone and neurotransmitter systems, specifically focusing on serotonin and dopamine, which have been implicated in the regulation of mood and aggression. The section emphasizes the importance of considering contextual factors and individual differences in interpreting correlational findings. Acknowledging these challenges is essential for interpreting and generalizing findings from controlled experiments to broader human behaviors. The synthesis of evidence from diverse species contributes to a more comprehensive comprehension of the underlying mechanisms and evolutionary aspects of testosterone-mediated aggression. Therefore, individual differences in T levels (Prediction 1) and seasonal patterns in T secretion (Prediction 2) are unlikely to stem from simple additive effects of variation in recent aggressive experiences and ensuing feedback on T production. Bidirectional relationships between T and territorial aggression are woven into the fabric of evolutionary behavioral endocrinology. This result suggests that once again, endogenous hormonal and behavioral responses may not mirror effects of exogenous hormone treatments on behavior. We have not tested Prediction 4, whether brief T elevation within an individual's reactive scope leads to a temporary increase in aggressive behavior. (A) Baseline T can be positively correlated with aggression among individuals and (B) post-challenge T can be negatively correlated with aggression among individuals if (C) within-individual hormonal reaction norms (dotted lines) co-vary with aggressiveness. On the other hand, there are studies that failed to show such associations with externalizing behaviors (17). Testosterone levels may also predict social presentation of masculinity and toughness (14), among males. Thus, the findings of the current study may potentially help us increase our understanding of sex differences in biological mechanisms for violent behavior in a community sample. Higher baseline testosterone that was found in individuals who rejected unfair offers, was interpreted as confirming this positive relation (13). The Point Subtraction Aggression Paradigm (PSAP) has been used more commonly to assess the relationship between testosterone with aggressive tendencies. With this test it was reported that baseline testosterone concentrations, despite individual differences, were positively correlated with the intensity of the aggressive reaction. In sports it has also been reported that winners have higher testosterone levels than losers (26). The relationship between testosterone and aggression is complex and multifaceted, influenced by a range of biological, environmental, and developmental factors. Environmental factors, such as stress and social status, can significantly impact the testosterone-aggression relationship. The relationship between testosterone and aggression is not uniform and is influenced by a variety of factors, including genetic predispositions, environmental factors, and developmental considerations. Lastly, clarifying the role of testosterone in aggression can help dispel myths and misconceptions surrounding the hormone's effects on behavior. The knowledge gained from this exploration may pave the way for innovative interventions or treatments targeting aggressive behaviors.
