The two marmosets - small, New World monkeys - had been a closely bonded couple for more than three years. Then, one fateful day, the female had a terrible accident. Her partner left two of their infants alone in the tree and jumped down to apparently comfort and mourn her. Humans mourn their dead, of course, and some recent studies have strongly suggested that chimpanzees do as well. This new observation suggests that mourning is more widespread among primates than previously thought.
