Katrina D. Favret and Robert M. Craig allegedly commissioned and distributed 'videos depicting acts of sadistic violence against juvenile and adult monkeys.' Muhammed Selim Korkutata/Anadolu via Getty ...

People living in different communities follow different social customs or norms. In some places, for instance, it might be standard practice to greet each person you see on the street, while in others ...

Reciprocity—I scratch your back; you scratch mine—has long been thought to be one of the hallmarks of friendship and other close relationships. In the world of nonhuman primates, the back-scratching ...