Guest: Jonathan Weiner.

In the twentieth century alone, the human life expectancy has increased by more than thirty years. Some scientists believe that it's time for the next big leap—this time into complete immortality. Today on Focus, science writer Jonathan Weiner joins the show to explain some of the science behind this heart-pounding research and the dramatic tale of how aging may be conquered once and for all—even in this lifetime.

Guest: Thea Singer.

When we poke and prod at our gray hairs and wrinkles, we don't normally think of stress as being their cause. In fact, says science journalist Thea Singer, the true culprit may not just be the wear and tear of age, but chronic stress. Today on Focus, she'll explain some of the research that led her to these findings, and offer tips on recognizing and treating stress.

Guests: S. Jay Olshansky and Bruce Carnes.

At the start of the last century, the average life span was just 45 years. Today the average for women is 79 and for men 72. What brought about this change? Can we expect even greater gains in human longevity? Today on Focus, we'll talk with researchers S. Jay Olshansky and Bruce Carnes on how to live as long as possible.