Some people react more calmly in stressful situations than others. Certain genes, such as the so-called COMT gene, are thought to play a role in determining our stress response. Researchers from the Vetmeduni Vienna and the University of Vienna have now studied this gene in macaques, a genus of Old World monkeys, and for the first time have shown that a specific variant of the gene is associated with higher excretion of the stress hormone cortisol. The gene variant may also influence social rank among the animals. The results were published in the journal Hormones and Behavior.