Using a training method called "operant conditioning," or clicker training, this traveling troupe of cats have learned an impressive array of tricks.

A researcher uncovers 30,000-year-old skulls from Europe, which appear to be halfway between those of wolves and domestic canines. But do the skulls actually belong to the ancestors of today's dogs?

Researchers use brain imaging to figure out whether dogs love us—or if they just want treats.

Dogs have long been dependable companions by our sides. But it wasn’t always that way, and a look at their closest living relative, the wolf, makes it clear why. Research into dog domestication and intelligence offers clues into what the human-dog relationship. And analyzing dogs’ brain activity and genes may even help answer whether dogs are in it for the food—or if they really love us.

Five stories high and emerging from the Taylor Glacier in the Dry Valleys of Antarctica, Blood Falls seeps into an ice-covered body of water called Lake Bonney. It’s one of the continent’s most enigmatic natural features and has fascinated scientists for decades. What makes it red? Does it always flow? And can anything actually survive near it?

A lake in the Arctic has a lot to say about our planet's fluctuating temperatures over the last 34 million years. Play NOVA's Polar Lab to see how.

When fossil fuels are burned, they release carbon dioxide, an invisible and odorless gas, into the atmosphere. What would happen if carbon emerged from our car tailpipes as a solid?

This cave in Canada remains frozen every summer—and it's been frozen since the last Ice Age 10,000 years ago. What can this tell us about Earth's future climate?

Jakobshavn is Greenland's biggest glacier. And over the past 20 years, it's receded dramatically. Play NOVA's Polar Lab to learn what's behind that change.

Following a trail of fossils found in all the wrong places–beech trees in Antarctica, redwoods and hippo-like mammals in the Arctic–NOVA uncovers the bizarre history of the poles, from miles-thick ice sheets to warm polar forests teeming with life.

Earth's climate has slowly fluctuated between cold and hot periods for millions of years. Today, humans are greatly accelerating that process.

Over its history, Earth has fluctuated between two climate states: Icehouses, with ice caps at at least one of the poles, and Hothouses, when there is no ice at the poles.

Think you know what the Arctic looked like during the Eocene Epoch? Play NOVA’s Polar Lab to find out: You might be surprised by the plants and animals that used to call it home.

Carbon dioxide is an odorless, invisible gas. If we could see that carbon as a solid material on the ground, that might change our perspective on the amount of carbon we emit into the atmosphere. Play NOVA’s Polar Lab to see what effects all that CO2 is having on our planet’s poles.

To illustrate how the coastline might look if Earth's climate continues to warm, paleontologist Kirk Johnson and geologist Maureen Raymo search for 3-million-year-old clams in a Virginia quarry miles offshore.

Paleontologist Kirk Johnson shows a group of high schoolers that plant species in Virginia used to be right at home near the North Pole.

Inhabiting the Ross Sea—as far south as McMurdo Sound—Weddell seals (Leptonychotes weddellii) have the most southerly distribution of any mammal on Earth. Scientists began studying a breeding population of Weddell seals in 1968 and quickly found out these pinnipeds don’t always have it easy.

Trees are living records of Earth’s climatic past. Play NOVA’s Polar Lab to learn how trees grow by simulating how they respond to different environments.