These monkeys surprised scientists by sharing even more when no one was looking

By Melissa Healy

What explains the marmoset’s generosity toward little ones? Not the audience effect, new research finds. (Getty Images)

Marmoset monkeys exist on a branch of the evolutionary tree that is distinct from the one that led to humans. But these fellow primates consistently astonish researchers with social behavior that seems, well, pretty highly evolved.

Marmosets engage in rigorously polite patterns of communication and do not talk over or interrupt each other. Though territorial, they are so inquisitive that they will watch videos of marmosets they do not know and learn from them…