April 10, 2003

America's environment was affected by early explorers and settlers. The species that were introduced into the "new" continent influenced the world we know today. Pigeons, Starlings, and reindeer are a few examples of non-native species that were brought to America, as author Kim Todd explains. Her book is "Tinkering With Eden: A Natural History of Exotics in America".

Dacher Keltner is researching how and why we smile. He describes a genuine smile, and why we smile when not particularly happy. He explains how a person's smile affects their success and place in life. Keltner is an associate professor of psychology at the University of California at Berkeley.

Journalist Jon Entine talks with Todd about African and African-American athletes. The reason for their success, he says, depends not only on social factors but also on practice and biological differences. He talks about why we do not want to acknowledge genetic differences. His book is "Taboo: Why Black Athletes Dominate Sports and Why We're Afraid to Talk About It".