Ian Wilmut, Keith Campbell, and Colin Tudge

In 1996, scientists Ian Wilmut and Keith Campbell made history by cloning a sheep—which they named Dolly—from an adult ewe. Writer Colin Tudge collaborated with Wilmut and Campbell to write a book about their experience called The Second Creation: Dolly and the Age of Biological Control. In the following viewpoint, the authors contend that scientists can use cloning to produce more suitable laboratory animals and more productive dairy cows, and to reproduce endangered species. The authors claim that cloning avoids the problems associated with inbreeding, which frequently results in offspring plagued by genetic disorders.

As you read, consider the following questions:

1. According to the authors, what is homozygosity"
2. What is the difference in milk production between wild cows and the most productive domesticated Friesians, according...