Biological Explanations for Bullying Behaviours

Genetic Factors

Twin studies suggest a genetic basis for aggressive and bullying behaviours.
Some researchers argue that certain genes may predispose individuals to aggression, leading to bullying behaviours.
Heritability estimates indicate that approximately 50% of individual variations in aggression could be due to genetic factors.

Neurological Factors

Studies suggest that a malfunctioning limbic system, particularly the amygdala and hypothalamus, may lead to inadequate control over impulses and emotional responses, leading to bullying behaviours.
Some argue that an imbalance in neurotransmitters, such as serotonin and dopamine, can contribute to bullying behaviour. Low serotonin and high dopamine levels have been associated with impulsivity and aggression.
Brain injuries, particularly to the prefrontal cortex, might result in changes in personality traits including increased aggression and decreased self-control, leading to bullying behaviours.

Hormonal Factors

Testosterone is often linked to aggression and dominance-seeking behaviours; thus, high levels could lead to bullying behaviours.
The stress hormone cortisol can also contribute to bullying behaviour, as individuals may use bullying as a coping mechanism to manage stressful situations.

Evolutionary Factors

Some believe bullying can be explained by natural selection, as intimidating or dominant behaviours may have helped our ancestors to survive and reproduce.
The Social Dominance Theory suggests individuals compete for resources and status; those who can bully effectively may ascend in social hierarchy.

Remember, each explanation has its strengths and weaknesses, and no one explanation can fully explain the complex behaviour like bullying. Combining biological explanations with those from other approaches (like cognitive, behavioural etc.) may provide a more comprehensive understanding.