Scientists have found evidence that parts of North America and East Antarctica were joined in a supercontinent called Rodinia 1.1 billion years ago.
Robin E. Bell/Lamont-Doherty Earth Observatory
Doctors perform a kidney transplant operation in Spain in 2010. One in three people with kidney failure has antibodies that make it hard to receive a transplant, but a new treatment can get rid of them prior to transplant.
Xurxo Lobato/Cover/Getty Images