After 26 years of workdays spent watching bacteria multiply, Richard Lenski has learned a thing or two.
He’s learned that naturalist Charles Darwin was wrong about some things. For one, evolution doesn’t always occur in steps so slow and steady that changes can’t be observed.
Lenski also learned that a laboratory freezer can function as a time machine.
A professor at Michigan State University, Lenski has watched E. coli bacteria multiply through 59,000 generations, a span that has allowed him to observe evolution in real time. Since his Long-Term Experimental Evolution Project began in 1988, the bacteria have doubled in size, begun to mutate more quickly, and become more efficient at using the glucose in the solution where they’re grown.
More strikingly, however, he found that one of the 12 bacterial lines he has maintained has developed into what he believes is a new species, able to use a compound in the solution called citrate—a derivative of citric acid, like that found in some fruit—for food.