Richard Lenski and his research team at Michigan State University have designed an extended experiment in evolution (Lenski and Travisano 1994). Evolution is often difficult to observe in action because it takes so long. It takes many generations for evolutionary changes to accumulate in a population, and so we seldom see such changes happening before our eyes in populations with long generation times. However, Lenski realized that it might be possible to test ideas about medium-scale evolutionary processes by using populations of bacteria. Since bacteria reproduce asexually, scientists can create multiple populations that all have the same genes, with each population living in its own petri dish. Lenski and colleagues created twelve such populations of E. coli bacteria and let the populations evolve in the lab. Once per day, they would add sugars to the dishes for the bacteria to feed on, and the populations would subsequently grow. As the food disappeared, the classic Darwinian “crunch” would occur, and many of the bacteria would die off. The scientists repeated this daily routine for thousands of bacterial generations, a long enough time to observe evolution in action and still not have to wait a ridiculously long time before they could obtain results.