Evolution: caught in the act!

Richard Lenski (top) and Jeffrey Barrick view bacteria cultures in Lenski's lab.: They have watched the bacteria's DNA evolve over 40,000 generations.
Richard Lenski (top) and Jeffrey Barrick view bacteria cultures in Lenski's lab.: They have watched the bacteria's DNA evolve over 40,000 generations.Courtesy Michigan State University / photo by G.L. Kohuth

Sometimes you’ll hear people cast doubts on evolution because no one has ever seen it happen. As if that’s some sort of great insight. No one has eve “seen” atomic fusion, either, but the fact that the Sun was shining this morning is pretty strong evidence that, yep, it happens. No one has ever “seen” gravity. Seen gravity’s effects, sure. But seen gravity itself? Like Ms. Ono once asked, Who Has Seen The Wind?

Evolution used to be in the same boat. The effects of evolution are visible everywhere, in every cell of every living thing on the planet. But seeing the actual process of evolution? That was another matter.

Until now. Scientists at Michigan State University (go Spartans!) have been growing bacteria in bottles for the past 21 years. Every so often, they would freeze a sample for later study. Well, “later” is now. DNA sequencing and computer analysis have advanced to the state where they can readily map the genome of each sample. And guess what? The bugs evolved exactly as evolution says they should. Mutations in the genome pop up at random intervals. Mutations that help the bug survive—like make more efficient use of food, or fend off disease—get passed on to future generations, and eventually spread through the entire colony.

Twenty-one years may not seem like enough time for a species to change. But, as Mia Sorvino said in the truly awful 1997 movie Mimic, think generations, not time. In the two decades of study, the little bacteria went through 40 thousand generations—the equivalent of roughly 800,000 years in human terms. Plenty of opportunity for evolution to do it’s thang.

And the experiment continues. Understanding mutations in bacteria might help us understand the mutations that lead to some forms of cancer. In recent generations, the rate of mutation has increased; the scientists would like to know why.

Richard Lenski, the scientist heading up the research, has put together a video explaining his work.

Your Comments, Thoughts, Questions, Ideas

mdr's picture
mdr says:

Interesting post, Gene. And I'm sorry to report that the Spartans did go but they left with their tails between their legs. But in more serious matters, what's with the "gun control" "revolution" and "sound of soul" in your tags? Actually, I suspect you didn't add them. I think we've been getting spammed in that area as I noticed in one of my recent evolution posts someone tagged it with some rather offensive words and phrases. I'll leave it for you or Bryan to correct. But I'm wondering why we even allow readers to add tags. I don't know that it's an important function.

posted on Sun, 11/01/2009 - 9:41pm
Gene's picture
Gene says:

"People movin' out
People movin' in -- why?
Because of the color of their skin.
Run, run, run, but you sure can't hide..."

It's Ball of Confusion by The Temptations, the very first record my older brother ever bought. Surely, I'm not the only person on this blog who grew up in the '70s?

I see the problem -- the tags are out of order. It's supposed to read: "evolution, revolution, gun control, sound of soul." See, it kinda rhymes.

"Say ooga-booga cancha hear me talkin' to ya?
Singing ball of confusioooooonnnnnn"

posted on Mon, 11/02/2009 - 2:19pm
mdr's picture
mdr says:

I guess that kind of makes sense now that you've "explained" it. I will say I saw the Temptations in 1969 at a gymnasium in Superior, Wisconsin, and it remains to this day one of all-time favorite concerts.

posted on Thu, 11/05/2009 - 8:45pm
bryan kennedy's picture

Wow, around 2:35 in the video he talks about how the bacteria originally could only eat and grow on the simple sugar glucose. They didn't have the ability to eat this other "food" citrate. But somewhere in their experiment one of the populations started to be able to grow on the citrate after evolving the specialization. So fraking cool.

posted on Fri, 11/06/2009 - 5:52pm
adam's picture
adam says:

Sounds more like simple adaptation to me, how is it that you think that is evolution?

posted on Wed, 12/23/2009 - 3:48am
JGordon's picture
JGordon says:

It's genetic adaptation. Genetic changes passed on and accumulated through generations. So, you know, evolution. How is it that you think it's "simple adaptation"? What do you mean by "simple adaptation"?

By the way, Gene—Mimic? Ha! I think that's the first time anyone in the world has referenced Mimic since... maybe ever.

posted on Wed, 12/23/2009 - 11:54am
Gene's picture
Gene says:

Christmas 1997. My buddy Brian was in town for the holidays, and we went out for dinner to catch up. Decided to catch a film afterward. Our movie of choice -- some gross-out comedy, no doubt -- was sold out. Looking over the other options, our eyes alighted upon Mimic. I can still hear Brian saying, "Mira Sorvino. Giant bugs. How bad can it be?"

We were soon to find out...

posted on Wed, 01/13/2010 - 10:30pm

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