Watch NOVAs

Ape Genius (Feb. 2008)

Experts zero in on what separates humans from our closest living relatives. Watch now (49 mins.)

Bird Brains (July 2008)

Clues to the origins of human language are turning up in the brains of birds. Watch now (13 mins.)

Booming Sands (Jan. 2005)

Scientists look into a generations-old conundrum: how and why do certain sand dunes produce mysterious noises? Watch now (7 mins.)

Capturing Carbon (July 2008)

An eighth-grader's science fair project prompts her scientist father to develop a new way to pull excess carbon dioxide out of the atmosphere. Watch now (12 mins.)

Emergence (July 2007)

How does the "intelligence" of an ant colony or the stock market arise out of the simple actions of its members? Watch now (12 mins.)

Fastest Glacier (July 2005)

A glacier moving way too fast reveals how unpredictable the effects of global warming can be. Watch now (7 mins.)

First Primates (July 2008)

Our most distant primate ancestors, which took the stage shortly after the dinosaurs left it, were tree-dwellers the size of mice. Watch now (13 mins.)

Fish Surgery (Oct. 2005)

Veterinary medicine has caught up with Americans' love for their number one choice of pet: the fish. Watch now (6 mins.)

The Four-Winged Dinosaur (Feb. 2008)

Surprising fossils from northeastern China spur a debate over how birds evolved. Watch now (50 mins.)

Frozen Frogs (Apr. 2005)

The common wood frog freezes solid every winter and then, come spring, defrosts and mates. Watch now (4 mins.)

Hurricane Katrina (Oct. 2005)

Scientists' warnings proved sadly prescient about New Orleans' risk from hurricanes. Watch now (4 mins.)

Hurricanes (Jan. 2005)

Predicting a hurricane's intensity is notoriously difficult, but new tools may make it easier. Watch now (12 mins.)

The Incredible Journey of the Butterflies (Jan. 2009)

Follow the 2,000-mile migration of monarchs to a sanctuary in the highlands of Mexico. Watch now (50 mins.)

Ivory-Billed Woodpecker (Jan. 2006)

An enchanting bird believed extinct mysteriously reappears...maybe. Watch now (7 mins.)

Judgment Day: Intelligent Design on Trial (Nov. 2007)

Science is 'Exhibit A' in a landmark trial on the teaching of evolution. Watch now (108 mins.)

Megabeasts' Sudden Death (Mar. 2009)

Scientists propose a radical new idea of what killed off mammoths and other large animals at the end of the Ice Age. Watch now (50 mins.)

Leeches (July 2008)

A century after falling out of favor among doctors, medicinal leeches are back in hospitals, sucking away on patients' wounds. Watch now (11 mins.)

Lightning (Oct. 2005)

Experts still aren't sure what triggers it, but they suspect cosmic rays from outer space. Watch now (9 mins.)

Lizard Kings (Oct. 2009)

Meet the monitors, the largest, fiercest and craftiest lizards on Earth. Watch now (50 mins.)

Lord of the Ants (May 2008)

Naturalist E.O. Wilson's fascination with little creatures has led him to some very big ideas. Watch now (50 mins.)

Mirror Neurons (Jan. 2005)

A recently discovered system in the brain may help explain why we humans can get so worked up watching other people. Watch now (14 mins.)

Mt. St. Helens: Back From the Dead (May. 2010)

Thirty years after the massive eruption, could it happen again? Watch now (50 mins.)

Ocean Animal Emergency (Nov. 2008)

Wildlife veterinarians struggle to save injured seals and sea lions on the California coast. Watch now (50 mins.)

Profile: Maydianne Andrade (July 2009)

By peering into the sex lives of Australian redback spiders, this evolutionary biologist has shown the upside of cannibalism. Watch now (15 mins.)

Profile: Bonnie Bassler (Jan. 2007)

Her insight into how bacteria "talk" has launched a revolution in biological and medical research. Watch now (13 mins.)

Profile: Sangeeta Bhatia (July 2009)

Intrigued by the idea of artificial organs, a biomedical engineer uses computer-chip technology to craft tiny livers. Watch now (15 mins.)

Profile: Erich Jarvis (Oct. 2005)

The work of neuroscientist Erich Jarvis demonstrates the power of open-mindedness in the lab. Watch now (12 mins.)

Profile: Edith Widder (July 2008)

Meet a marine biologist and explorer who has engineered new ways to spy on deep-sea creatures. Watch now (9 mins.)

Rat Attack (Feb. 2009)

Why do huge swarms of rats overrun a bamboo forest in India once every half-century? Watch now (50 mins.)

The Search for ET (July 2008)

Astronomers have their radio telescopes tuned to receive signals from alien worlds. But is anybody out there? Watch now (11 mins.)

Smart Sea Lions and Talking Walruses (July 2009)

Marine mammals are wowing researchers with more than just circus tricks Watch now (15 mins.)

Stem Cells (Apr. 2005)

A new technique for creating stem cells may ease ethical concerns. Watch now (8 mins.)

Stem Cells Breakthrough (July 2008)

Three separate teams overcome a biomedical hurdle—creating stem cells without the use of human embryos. Watch now (13 mins.)

Stronger Hurricanes (Jan. 2006)

Is global warming making hurricanes more intense? Watch now (6 mins.)

T. Rex (Apr. 2005)

An astonishing adolescent growth spurt accounts for T. rex's enormous size. Watch now (8 mins.)

T. Rex Blood? (July 2007)

Preserved soft tissue, including possible blood vessels and red blood cells, are turning up in dinosaur fossils. Watch now (13 mins.)