“I’m not sure I can tell you how it’s affected my thinking, because I’m not sure I can conceive of being in this field without this experiment existing,” Michael Baym, an evolutionary biologist at Harvard Medical School, recently told Discover. For his work, Lenski, now in his sixties and at Michigan State University, has received a MacArthur “genius” grant and a Guggenheim Fellowship. Lenski’s Long-Term Evolution Experiment, or L.T.E.E., as it’s called, has yielded fundamental insights into the mutational capabilities of microorganisms. Different populations have taken different paths to enhanced fitness, but, after decades, most have arrived at reproduction rates within a few percentage points of one another. Compared with their distant ancestors, the latest versions of the bacterium reproduce seventy per cent faster it once took them an hour to double their ranks, but now they can do it in less than forty minutes. In this way, Lenski and his team have studied more than seventy thousand generations of E. coli a day the bacteria woke up as babies and went to bed as great-great-great-grandparents. Lenski’s flasks produced about six new generations of E. How quickly, effectively, creatively, and consistently do microorganisms improve their reproductive fitness? His goal was to understand the mechanics of evolution. Each day, as the bacteria replicated, Lenski transferred several drops of each cocktail to a new flask, and every so often he stored samples away in a freezer. Each flask was kept at thirty-seven degrees Celsius, and contained an identical cocktail of water, glucose, and other nutrients. He divided a population of a common bacterium, E. In 1988, Richard Lenski, a thirty-one-year-old biologist at UC Irvine, started an experiment.
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