Posts Tagged ‘e. coli’

E. coli evolutionary breakthrough

June 19, 2008

This is old news, so you can feel free to move on if you already know about it. (Unless you want to see me tear into Answers in Genesis at the end!)

Dr. Richard Lenski of Michigan State University (my mother’s alma mater! Represent!) has been observing 12 populations of E. coli bacteria for twenty years. Recently, one of these populations did something remarkable: it evolved the ability to metabolize a nutrient that is normally unusable by E. coli.

This is only the beginning of the excitement, however. When Lenski revived samples of that particular population that he had frozen periodically over the course of the experiment, he found that only the samples frozen after about 20,000 generations, or halfway through the experiment’s duration, evolved the new trait again. Some presumably unlikely mutation occurred which “primed” that population to evolve the trait. The other 11 populations have not evolved the trait, and presumably will not unless a similar mutation occurs within their numbers.

The experiment establishes the role of historical contingency in evolution. Organisms are never perfectly adapted to their environment, because the adaptations available to them are constrained by the changes that have happened in the past. Just like humans can’t evolve wings at the shoulders, because no structures exist there to give rise to wings, E. coli can’t evolve the ability to metabolize previously unusable nutrients unless some more fundamental change takes place first.

Of course, these results fly in the face of creationists who claim that such unlikely events simply can’t happen. Right on cue, Answers in Genesis released a statement on the research. I won’t do a point-by-point breakdown of the argument, because there really is only one point: this is an example of micro-evolution, not macro-evolution. The new bacteria are still bacteria, they’re not cows or dogs or peach trees. This cannot be taken as evidence for “molecules-to-man.”

My rebuttal? Until they demonstrate how small changes cannot add up to large changes over time, their argument is worthless. While they’re at it, they should also explain why one cannot walk to New York from LA, given enough steps, or how someone cannot deposit a thousand dollars in the bank, given enough pennies.

Enough of that. This is very exciting research. Next, scientists should try to produce a strain of E. coli that can metabolize dust and clutter; then I won’t have to clean ever again.