In a new study, investigators at the University of Pennsylvania in Philadelphia turned to rhesus macaques to investigate the effects of two hormones — oxytocin and vasopressin — on social behavior.
These primates are known for their aggressive, competitive behavior in groups that are highly hierarchized — which typically split members between dominant and submissive individuals.
But rhesus macaques were also chosen for another reason; according to the researchers involved in the recent study, these primates — like humans — live in large social groups, form long-term connections, and present some similar social behaviors.
Study authors Michael Platt and Yaoguang Jiang first turned their attention to the possible effects of oxytocin on social behavior as this hormone has previously been tied to bonding between mother and infant and pair-bonding.
As they note in the study paper they recently published in the journal Scientific Reports, "A single intranasal dose of [oxytocin] in healthy humans [has also been seen to enhance] trust, generosity, and empathy."
But, alongside oxytocin, another horomone called vasopressin has been observed to help shape various social behaviors, including both aggression and pair-bonding— at least in animals.
Certain studies have suggested that vasopressin may be implicated in the regulation of social behavior in humans, too.