Justin Bieber praised for ‘captivating performance’ as he makes Grammys return - The 31-year-old performed Yukon from Swag.

Luckily, we live in a time where we don't have to worry about smallpox anymore. It's a horrible disease, but through smart ...

Over its lifetime, the Earth has seen plenty of climate change. About 50 million years ago the planet experienced extreme cooling, and all from a little fern. Hosted by: Hank Green Support SciShow by ...