In 1920s and '30s America, there are state fairs held across the country which sponsor, along with the traditional livestock competitions, "human stock" competitions: "Better Babies" and "Fitter Family" contests. "Fitter Family" competitions are a battle of wits -- or intelligence -- medical fitness and pedigree. They are also a part of a growing movement called Eugenics.

Adherents believe that biology is destiny, and that selective breeding can improve the human animal just as it does livestock. The movement attracts a curious range of supporters in the US, from Calvin Coolidge to Helen Keller, from Ivy Leaguers to the Ku Klux Klan. Different backgrounds, different politics -- but they all share a common vision of a better society and how to achieve it. Unfortunately, Eugenics is based on the misuse of the emerging science of genetics, a misuse that has sinister consequences an ocean away in Nazi Germany. And while Eugenics is eventually discredited, the urge to find simple biological answers to complex human behaviors persists to this day, as rampant speculation about "criminal" or "gay" genes reminds us.

The story of Eugenics in the United States is just one of the human dramas played out in "In Search of Ourselves" (premieres Tuesday, January 13, 1998, 8pm ET), the third of A Science Odyssey's five-part series. "In Search of Ourselves" explores both the scientific theories and popular thinking about what drives human behavior as these ideas change throughout the twentieth century. At the heart of these stories is a debate that still rages today: Are we mostly the product of our biology or are we the sum total of our environment and life experience? Is it nature or is it nurture that has the primary responsibility for shaping us? From shell shock in World War I to the anti-psychotic thorazine in the 1950s, from the advertising strategies of behaviorist John Watson in the '30s to the Human Genome Project of the '90s, "In Search of Ourselves" is filled with the powerful profiles of people, from the struggling scientist to the ordinary citizen, as they use all of the available scientific ideas and technologies of the day to try to understand and explain human behavior.

In World War I, a debilitating trauma called "shell shock" affects as many as 80,000 soldiers; some suffer from unexplained tremors, others have gone blind or deaf overnight. Could these symptoms be the result of damage to the central nervous system? Could the effects of poison gas or chemicals be responsible? Doctors turn to the conventional wisdom, searching for a biological cause. When they come up empty-handed, reluctantly they turn to psychological explanations popularized by Viennese psychiatrist Sigmund Freud. And for the first time, it becomes clear that life experience and the mind -- especially under tremendous psychological stress -- can shape and explain behavior. Unexpectedly, the battlefields of World War I offer a sudden proving ground for a psychological -- rather than biological -- theory of human behavior, confirming on a massive scale that emotional and environmental factors can have wholly unpredictable effects on human beings. What was then a radical new perspective is still controversial today in the debate about the causes of Post-Traumatic Stress Disorder.

The nature-versus-nurture debate takes a surprising twist in the 1950s when a drug called chlorpromazine (now called thorazine) is found to be effective in treating schizophrenia. Its discovery comes at a time when fully half of America's hospital beds are taken by patients suffering from schizophrenia. Psychoanalysis, in its heyday in the United States, is the treatment of choice at private hospitals like Chestnut Lodge, where patients like Joanne Greenberg -- who later writes of her successful experiences in "I Never Promised You a Rose Garden" -- are treated by the pioneering therapist Frieda Fromm Reichmann. But most psychotic patients in the '50s can't afford the luxury of psychotherapy and spend their days in state mental institutions, where their options range from lobotomy to electric shock to other biological treatments. Still, whether in private or state care all these therapies have only limited, occasional success. But that will all change in 1952. When chlorpromazine and other medications for the mind are serendipitously introduced, psychiatrists discover a whole new way to think about and treat major mental illness.

But ironically, psychotropic drugs open a window onto the healthy brain, as well as the disturbed. For the first time, there is a chemical link between behavior and the brain, giving rise to a revolution in the neurosciences. Age-old questions suddenly take on a new urgency: How do we make sense of human behavior now? Where does the brain fit in? Is our behavior shaped primarily by genes, or by education, environment, and experience? Is it nature or nurture -- or an inextricable combination of the two?

Through these and many other gripping stories, "In Search of Ourselves" highlights the critical thinking and the scientific innovations in the study of human behavior, tracking the biology versus the environment argument in a fresh way: looking at how and why these seemingly diametrically opposed ideas have held powerful sway at different moments throughout the twentieth century.

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Major funding is provided by the National Science Foundation.

Corporate sponsorship is provided by IBM. IBM is a registered trademark of IBM Corporation.

Additional funding comes from public television viewres, the Corporation for Public Broadcasting, The Arthur Vining Davis Foundations, Carnegie Corporation of New York, and Becton Dickinson and Company.