Scientists have discovered what drives some monkey mothers to give in to their babies' tantrums.
A study of rhesus macaques revealed that females were more likely to feed their bawling babies if irritated bystanders lurked nearby.
The UK-Puerto Rico team noted how the threat of violence from onlookers angered by the shrill cries seemed to prompt the mothers to act.
The research is published in the Proceedings of the Royal Society B.
Footage courtesy of Dr Stuart Semple