If living things existed on other earth-like worlds, what shape would they take? Some scientists have speculated that they would look like nothing on earth. Biochemist Joseph Kraut of the University of California at San Diego suggests a different view. He proposes that life evolving on planets with environments similar to the earth's would quite likely resemble familiar terrestrial forms.
Kraut says that his speculations are merely "vaporings," but he supports them with some striking laboratory evidence. For the past 15 years he has headed a scientific team looking into the three-dimensional structure of enzymes, the long-chained proteins that act as...