“For polar bears, profound obesity is a benign state,” says Eline Lorenzen, a postdoctoral fellow at University of California, Berkeley. “We wanted to understand how they are able to cope with that.” “Polar bears have adapted genetically to a high fat diet that many people now impose on themselves,” says Rasmus Nielsen, of UC Berkeley’s …

We go wide-eyed with fear because a larger visual field makes it easier to see threats, and the expression can help others spot the source of danger. “Emotional expressions look the way they do for a reason,” says Daniel Lee, a graduate student at the University of Toronto. “They are socially useful for communicating emotional …