Lenski’s Long Term Evolutionary Experiment | The Skeptical Zone

A post by our friend @AlanFox over at TSZ.

Richard Lenski began the LTEE with 12 populations (six ![Ara^+|41x14] and six ![Ara^-|41x13] of the bacterium Escherichia coli on 24th February, 1988. The experiment is currently housed at Michigan State University and has run continuously apart from a short break while relocating to the present site and another during the height of the Covid-19 outbreak.

http://theskepticalzone.com/wp/design-by-natural-selection-the-ltee/

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Blah, blah, blah. The bacteria did not turn into non-bacteria :stuck_out_tongue_closed_eyes:

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My favorite thing about this experiment, other than the simple fact that it exists, is that the aerobic citrate metabolism trait is a directly observed experimental refutation of irreducible complexity (multiple mutations required to have the trait, no selection for intermediate stages with a subset of those mutations), and one of the co-authors on a paper that showed this to be the case was Scott Minnich of the University of Idaho and Discovery Institute. Oops.

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I don’t know if the title of that article is quite apt. One of the more important aspects of the study has been the elucidation of non-selection processes in generating evolutionary novelties.

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One other interesting point is why don’t we see intelligent design emerging in this experiment? Within ID there is no reason why the designer would have stopped designing, if ID is as agnostic towards the identity of the designer as some claim. Why don’t we see irreducibly complex systems emerging through frontloading or outside guidance of mutations in the Lenski experiment?

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Just wondering if comment moderation is appropriate in a thread about me. :face_with_monocle:

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Ooh! Not so sure about that. Mutations are random but in Lenski’s flasks there is a fight for food each day. Natural selection rules.

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Perhaps it should be renamed “The Thunderdome Experiment”.

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I’ve already blocked thousands of messages from your screaming groupies. I think it will be OK. :wink:

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How do you know we don’t? What would they look like that would distinguish them from natural occurrences?

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What selective pressures existed in that one flask that caused the ability to eat citrate to evolve only there and not the other flasks?

One possibility is that an entire irreducibly complex system comprised of 20 completely new genes would emerge over just a few generations.

That would be a very rare event in designed nature and it’s unreasonable to expect that to happen during Lenski’s experiments. The question remains: how do you know that what we did see wasn’t designed?

BTW thanks Dan for rekindling interest in TSZ. It has quietened down a bit lately.

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That it happened once (so far) in one tribe, convinces me that the mutations that switched on aerobic citrate metabolism were random but the proliferation of the new strain was down to natural selection.

ETA and the first mutation was a beautiful example of a neutral mutation. waves in general direction of Mike Behe

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ID/creationists expect other equally improbable evolutionary events to occur in these types of experiments. I’m sure that we can find at least one ID/creationist asking why we didn’t see the evolution of a complex IC system in this experiment.

Personally, I would apply the law of parsimony. If it can be produced by known natural processes then there’s no reason to propose other mechanisms.

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A common ID response to Lenkski’s LTEE is the the ability to eat citrate involves a LOSS of other function, and pretty much abandons any support for design creating any function that is useful in a new environment.

LTEE also gets directly at Behe’s requirement to demonstrate “selectable steps”.
“OK” says Lenski … “Here they are!”

The ID proponent might try to claim the designer enabled these steps, but this is an admission that ID is unfalsifiable.

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If we observe that, how would we determine it was not a natural (i.e. not guided or otherwise abetted by an intelligent being) occurrence?

Is there a Hall of Fame for exceptional science experiments, because the LTEE deserves to be etched on whatever stones lie within. Prof Lenski will surely enter Valhalla and feast with Odin for the 10th wonder of the world which took place under his watch.

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It’s called the Nobel Prize. :wink:

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