Did natural selection favor darker skin tones? Professor Nina Jablonski never believed that cancer could have an effect on the evolution of skin color, and new research may prove her right.

Suzan Murray, Chief Veterinarian at the National Zoo, describes her childhood dream of becoming a veterinarian and makes a special trip to visit her favorite elephant, Shanthi.

Scientist Julie Hall braves the icy waters and freezing temperatures of Antarctica to collect valuable scientific data.