Watch NOVAs

1918 Flu (Nov. 2006)

A virus that killed up to 50 million people is brought back to life to decipher its deadliness. Watch now (13 mins.)

Aging (Jan. 2007)

Will research into "longevity genes" help us live longer and healthier lives? Watch now (13 mins.)

Anthrax Investigation (June 2009)

In this bonus video, see how scientists could tell whether the anthrax in the 2001 attacks was specially engineered to disperse through the air. Watch now (14 mins.)

Autism Genes (July 2009)

Researchers have begun to zero in on genes that might be responsible for autism. Watch now (15 mins.)

Bird Brains (July 2008)

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

Brain Trauma (July 2008)

Even so-called "mild" head injuries turn out to be anything but. Watch now (11 mins.)

Cracking the Code of Life (Apr. 2001)

Follow the race to decode the human genome and see how this newfound knowledge is already changing medicine. Watch now (105 mins.)

Doctors' Diaries (Apr. 2009)

Seven doctors, 21 years... Saving lives is only part of the story. Watch now (50 mins.)

Dying to Be Thin (Dec. 2000)

Life-threatening eating disorders such as anorexia and bulimia are on the rise among America's youth. Watch now (51 mins.)

Epigenetics (July 2007)

Our lifestyles and environment can change the way our genes are expressed, leading even identical twins to become distinct as they age. Watch now (13 mins.)

Forgotten Genius (Feb. 2007)

Against all odds, African-American chemist Percy Julian became one of the great scientists of the 20th century. Watch now (108 mins.)

Killer Microbe (July 2008)

A relatively benign bug becomes a highly lethal pathogen, known to U.S. soldiers as Iraqibacter. Watch now (8 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.)

Life and Death in the War Zone (Mar. 2004)

An American combat hospital mobilized in Iraq faces a daily drama of wartime treatment. Watch now (50 mins.)

Life's Greatest Miracle (Nov. 2001)

Lennart Nilsson's microphotography chronicles the growth of a baby from embryo to newborn. Watch now (52 mins.)

Marathon Challenge (Oct. 2007)

Explore what it takes—physically and mentally—for novice runners to make it through a classic test of endurance. Watch now (50 mins.)

Marathon Mouse (July 2009)

With an "exercise pill," researchers turn couch-potato rodents into champion runners. Watch now (15 mins.)

Of Mice and Memory (June 2008)

Mice placed in enriched environments can recover lost memories, giving hope to those who study Alzheimer's. Watch now (12 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.)

Obesity (Oct. 2006)

Examine the biology behind the compulsion to eat. Watch now (12 mins.)

Pandemic Flu (Jan. 2006)

Will the virus that causes bird flu develop the ability to move from person to person? Watch now (6 mins.)

Personal DNA Testing (July 2008)

Genetic testing to assess risk factors for a handful of serious illnesses is now commercially available. But is it a good idea? Watch now (12 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: Judah Folkman (July 2008)

Once scorned for his ideas about how cancer grows, the late Judah Folkman is now hailed as a visionary. Watch now (11 mins.)

Profile: Naomi Halas (Apr. 2005)

Naomi Halas is a pioneering nanotechnologist bent on seeing practical applications for her work—and soon. Watch now (8 mins.)

Profile: Alfredo Quiñones-Hinojosa (July 2008)

He jumped the fence from Mexico to work as a farmhand and ended up a leading brain surgeon. Watch now (10 mins.)

Profile: Pardis Sabeti (July 2008)

By night she's a rocker. By day, she's a Harvard geneticist tracking the evolution of the human genome. Watch now (8 mins.)

RNAi (July 2005)

A wayward petunia leads to the discovery of modest little molecules with enormous medical promise. Watch now (15 mins.)

The Science of Picky Eaters (July 2009)

Don't like broccoli? Your DNA may explain why. Watch now (15 mins.)

Sleep (July 2007)

Why do we need sleep? Part of the answer may be to strengthen memories. Watch now (13 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.)

Stem Cells Update (Jan. 2006)

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

A Walk to Beautiful (May 2008)

A powerful story of healing and hope for women in Ethiopia devastated by childbirth injuries. Watch now (52 mins.)