20 April 2012
Vol 336, Issue 6079

About The Cover

Cover image expansion

COVER A young polar bear (Ursus maritimus) on a piece of ice that is drifting in the Barents Sea, northeast of Svalbard, Norway. Polar bears depend on sea ice as a platform for hunting seals, but current melting and retreat of sea ice is increasingly forcing them onto land. A recent study has found polar bears to be evolutionarily older and genetically more distinct than was previously thought. See page 344. Photo: Florian Schulz,