Evolution has produced the wonderful diversity of life on Earth, but it is difficult to observe evolution while it is happening. With their rapid generations and the ability to freeze and later revive cells, microorganisms allow one to watch evolution in action. We have propagated 12 populations of Escherichia coli in a simple environment for more than 30 years and 75,000 generations. The aims of this experiment have been to characterize the tempo and mode of evolution, and to examine the repeatability and even predictability of phenotypic and genomic changes. We have quantified the dynamics of adaptation by natural selection, tracked changes in mutation rate, and observed the evolution of a new metabolic function. We have sequenced hundreds of whole genomes to identify the mutations in longitudinal samples from the populations. These data provide insights into the coupling of phenotypic and genotypic evolution during periods of both optimization and innovation.

Professor Lenski is a University Distinguished Professor at Michigan State University. He did his undergraduate studies at Oberlin College, Ohio, and received his PhD from the University of North Carolina, Chapel Hill, where he conducted ecological research on insects.

Wanting a system where he could see evolution in action, he switched to microbiology for a postdoc at the University of Massachusetts, Amherst, and studied the coevolution of bacteria and phages. Professor Lenski joined the faculty at the University of California, Irvine, in 1985, before moving to Michigan State University in 1991.

Professor Lenski is best known for his Long-Term Evolution Experiment, or LTEE, which he started in 1988, and which continues to this day. He and his team have maintained and studied 12 populations of E. coli for 75,000 generations. The LTEE offers a unique record of evolution, providing insights into the dynamics of adaptation by natural selection, the mechanisms of genome evolution, the repeatability of evolutionary changes, and even the origin of new functions.

With an interdisciplinary team, Professor Lenski has also led pioneering research on the evolution of digital organisms—computer programs that replicate, mutate, compete, and evolve to perform new functions. He is a member of the US National Academy of Sciences and a fellow of the American Academy of Microbiology.  Professor Lenski has served as President of the Society for the Study of Evolution, and he received a Friend of Darwin Award from the National Center for Science Education for his public-facing work discussing evolution and its importance. Last, but not least, Professor Lenski has mentored some 30 graduate students and postdoctoral scientists who are now on the faculties of universities around the world.