Extras
Do speech buttons really allow dogs to talk to us? Scientists investigate.
New evidence sheds light on the remarkable life—and mysterious collapse—of the ancient jungle city.
What if violent asteroid impacts actually jump-started life on Earth? Explore a dramatic theory.
Adam Riess takes us inside the discovery of dark energy.
They're older than King Tut, Ötzi the Iceman, and even the ones found in the Atacama Desert.
From fruit flies to snake venom, evolutionary biologist Sean Carroll explains what drives evolution.
Can we really bring extinct species back? Evolutionary biologist Beth Shapiro says yes.
Astronauts and Mission Control relive terrifying moments during construction of the ISS.
A small piece of insulation caused catastrophic damage.
A dangerous spacewalk, a toxic leak, and a breathtaking view of Earth.