Given a choice between eating chocolate alone and rescuing their pals, rats will apparently save their pals and then share the chocolate with them. Trapping a rat in a cage sparks its cagemate into action, as it figures out how to open the cage and liberate its jailed friend. This is an unusual example of rats expressing empathy, a trait thought to be reserved to us higher mammals, the primates.
Just yesterday we learned that Caltech researchers can use pulses of light to toggle aggressive behaviors in the mouse brain. Today we learn that elsewhere on the West Coast scientists are turning social behaviors in mice on and off using the same method, and that could have big implications for social disorders like autism and schizophrenia in humans.