EVOLUTION:
Test Tube Evolution Catches Time in a Bottle
Tim Appenzeller
By running experiments on microbes for thousands of generations, researchers are exploring the roles of chance and history in evolution. So far they are finding that identical populations facing similar conditions can follow parallel courses, although the underlying genetic changes often differ. But over time, in new environments, the effects of those differences can grow, steering evolution into radically different courses and giving chance and history ever larger roles in a population's fate.