The reciprocal interaction between serotonin and social behaviour

► High 5-HT levels are associated with increased sensitivity to social factors. ► This leads to prosocial behaviour and cooperation. ► And context dependent 'for-better-and-for-worse' behavioural outcomes. ► In turn, the 5-HT system is shaped by environmental stimuli, leading to complex reciprocal 5-HT × environment interactions.