Tag Archives: bacteria

The Long awaited paper on observing evolution in E. Coli

Some sixteen months ago, we here at The Big Upshot took note of an amazing 21 year study in which bacteria were grown in a high citrate environment to which they were poorly adapted. After some 40,000 generations, the bacteria actually invented a new phenotype, true evolution in action.

This was not mere adaptation, but real bona-fide generation of novel “designed” attributes. This is like an animal with a beak turning into an animal with teeth given sufficient time and incentive. It turns out that what might seem “irreducibly complex” is not actually all that irreducible. Richard Lenski’s lab carefully saved samples of the little creatures all along the way, like an artificial fossil record. So not only is the proof eating citrate in a petri dish, something its ancestors couldn’t do, but the precise genetic changes that got it there are all “on file,” so to speak.

I’ve been waiting with bated breath for the follow up study where they go through the lineage of the Strain that Evolved. And lo, it has arrived. I’m going to level with you all, this is really, really cool. Kudos to all of the authors. If anybody ever tries to sell some intelligent design (deity-sign?) to you, slap this on the table like it’s your enormous stick of science.

-Peter

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Bacteria ‘invent’ new enzyme in the lab under scientific supervision

The importance of this cannot be overstated. There are levels of understanding of evolutionary theory. In Chemistry, my chosen field, you learn the “basics” of chemistry about 5 times before you’re done with an undergraduate degree. Every time you re-learn it, you learn all of the problems with the old way you learned it and all of the ways the new way of understanding is better. It’s unrealistic to teach graduate chemistry to elementary school students – they need the context of a few benign simplifications in order to approach the deeper understanding. It’s the same way with evolution. I’m not an evolutionary biologist, but I understand that there are levels of subtlety and that the simple explanations are not the whole story.

One of the most hard-to-believe concepts is that biologcal ‘designs’ come from the vast sea of probability. How could randomness produce an invention? Doesn’t invention require intelligence? It all comes down to amplification. Looking for a fully formed functional enzyme in the sea of randomness would take forever (almost literally). But if you had a way to amplify every useful step along the way from any random junk all the way to something useful, then the whole thing can happen pretty fast.

How fast? About 30,000 generations. Scientists have put bacteria in an environment where it would be advantageous to invent an enzyme. The bacteria did it in 30,000 generations. That’s ‘macro-evolution’ on a pertri-dish. It’s a terrible blow to those who have touted the idea of ‘irreducible complexity,’ and people who consider evolution to be an unproven hypothesis.

Of course, they hold themselves to a different standard of truth, so there’s really no basis for rational argument. I’m not sure about it being a ‘miracle,’ but I will concede this: the wow factor is really high for the feat of making critters invent an enzyme on cue.

-Peter