January 15, 2008—Scientists re-created the heart of a rat and started it beating. The breakthrough could lead to the building of human organs. © 2008 National Geographic (AP)
Get the top photos and news of the week from National Geographic News, plus occasional breaking-news alerts.
Get our news delivered directly to your desktopfree. How to Use XML or RSS
ANIMAL PHOTOS WEEKLY: Albino Eagle, Cloned Pups, More
Green Dream Machines Debut