Dolly the cloned sheep may have shocked the public, but the science of selective breeding shouldn't. From time immemorial - or at least since the ancient Greeks - people have tried to improve on nature. Next time on To the Best of Our Knowledge, the quest for perfection, and the science of the cell.

SEGMENT 1

Science writer Gina Maranto talks with Judith Strasser about the long history of human efforts to breed better babies. She says no matter how good our technology gets, life will always be messy. Maranto is the author of "The Quest for Perfection: The Drive to Breed Better Human Beings." Also, Alta Charo teaches Medical Ethics at the University of Wisconsin, Madison. She tells Steve Paulson that it's important to separate the acquisition of knowledge from the possible application of this knowledge. She thinks research should be unrestricted but that we may choose not to act on everything we know.

SEGMENT 2:

Lawrence Alderson is exective director of the Rare Breeds Survival Trust, an English organization that conserves traditional (and now rare) breeds of animals by creating a market for their meat. Alderson tells Jim Fleming that he values these animals for their historical and aesthetic value, as well as for their superior quality as food for humans.

SEGMENT 3:

Boyce Rensberger is a science writer for the Washington Post and the author of "Life Itself: Exploring the Realm of the Living Cell." He tells Steve Paulson how he became interested in the world that can only be seen through a microscope and some of the things he finds fascinating about it.

Distribution dates:

• week of 03/09/97 - hour 2