Some scientific research can't be completed in days or months — projects can take years, or even decades or centuries. This poses a challenge for scientists who must make plans for experiments that often outlive the experimenter.
A biologist who has been watching a dozen bottles of bacteria evolve for nearly a quarter of a century is hoping he can find someone to keep his lab experiment going long after he dies. Meanwhile, just by coincidence, a botanist who works across campus is carefully tending an experiment that started before he was born, all the way back in 1879.
These two researchers, both at Michigan State University in East Lansing, represent different sides of an unusual phenomenon in science: experiments that outlive the people who started them. Most researchers design studies to churn out results as quickly as possible. But because nature can work on vast time scales, some questions can take longer to answer than any one scientist's career.
Richard Lenski began his evolution experiment in 1988 with a simple question: Does evolution always lead to the same end point? If he started with 12 identical flasks, full of identical bacteria, would they all change over time in the same way? Or would random mutations send each bottle's population spinning off in a different direction?
For the first decade of his experiment, the bacteria in each flask mostly changed in similar ways. For example, they all were producing larger cells. Then things got kind of boring for a while because the changes started coming more slowly. Lenski had other projects going on in his lab, and figured that maybe he'd learned all he could from this one. "And so I was sort of thinking, 'OK, maybe it's time to stop the experiment,' " he says, recalling that he asked a few colleagues what they thought of that idea. "And they basically said, 'Nope, you can't stop it, it's gone on too long.' " So he stuck with it. And a few years later, in 2003, something happened. The liquid in one flask looked strange. "This flask was considerably more cloudy," says Lenski. "I was suspicious that we had a contaminant." It turns out that the bacteria in that one flask had actually changed in a dramatic way. After 30,000 generations, they had suddenly gained the ability to consume citrate, a chemical that had always been in the flasks — but that was never intended to be a food, since laboratory E. coli normally can't eat it. What's more, Lenski was able to trace exactly how that new trait emerged. Over the years, he's been freezing samples of his bacteria, so he was able to go back and track every little genetic change that's taken place through the generations, using technologies that didn't even exist when he first started this study.