Hop in a time machine and travel back a half a billions years and you'll discover the weird animals that roamed the ocean's deep. Stick around a few million years and you'll watch the first fish slither out onto land. These are our early relations. In this hour of To the Best of Our Knowledge, primordial life, from trilobites to the walking whale. Also, Darwin on emotions -- why humans blush and dogs wag their tails.

Cambridge University paleobiologist Simon Conway Morris tells Jim Fleming about the wonderful sea creatures he studies in the Burgess Shale -- a rich fossil bed in the Canadian Rockies. Morris' book is "The Burgess Shale and the Rise of Animals."

Carl Zimmer is a science writer and the author of "At the Water's Edge: Macroevolution and the Transformation of Life." He tells Judith Strasser about human beings' early origins in the sea. Also, Ian Tattersall is a paleontologist and a Curator at the American Museum of Natural History. He tells Jim Fleming that what really set our species apart from other animals was our ceative spirit as manifested in early cave paintings.

Tim Severin talks with Steve Paulson about 19th century naturalist Alfred Russell Wallace. Severin has retraced the journey Russell made in the 1850s. His book is called "The Spice Islands Voyage: The Quest for Alfred Wallace, the Man Who Shared Darwin's Discovery of Evolution."

Distribution dates:

• week of 06/14/98 - hour 2
• week of 06/13/99 - hour 2