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Hype from New Scientist Aside, Lenski’s E. coli Research Shows Evolution of Nothing New

Casey Luskin


As we reported in April, the pro-Darwin media love to print triumphalist articles, declaring on the thinnest of evidence that the “creationists” are deathly scared of the latest discoveries in science. Now New Scientist takes a turn, claiming that the E. coli research of Richard Lenski “has become a poster child for evolution, causing consternation among creationists trying to explain away its compelling evidence.” Yet read the article carefully, and you’ll see that it confirms Lenski’s research did not show the evolution of anything new.

New Scientist frames the article this way:

The biggest evolutionary shift occurred after about the 31,500 generation, when one line in one of the 12 populations evolved the ability to feed on citrate

Except that’s not true. Normal E. coli already have the ability to feed on citrate — they just don’t typically do it under oxic conditions (i.e., where oxygen is present). The interesting thing about Lenski’s research is that his bugs evolved the ability to uptake citrate under oxic conditions. But did anything new evolve? Here’s what the article says:

But a mutation in the citrate-eaters allowed them to make an “antiporter” protein, CitT, that allows citrate to cross the membrane and enter the cell. The gene for this protein already existed, but it’s usually switched off when oxygen is present.

The antiporter is a kind of revolving door. It allows one molecule to be swapped for another. In this case, the citrate is imported into the cell in exchange for one of three smaller, less-valuable molecules: succinate, fumarate or malate.

What really happened? A switch that normally represses expression of CitT under oxic conditions was broken, so the citrate-uptake pathway got turned on. This isn’t the evolution of a new molecular feature. It’s the breaking of a molecular feature — a repressor switch. Of course none of this is disclosed in the article.

But New Scientist isn’t done. It goes on:

Those citrate feeders soon became dominant, outcompeting all but one other strain of E. coli, which in turn evolved to exploit the changed environment — which now contained the three exported molecules.

It did this by making more of a transporter protein called DctA, which imports – at a small energy cost – succinate and other molecules exported by the citrate-eating strain.

But things did not stop there. The citrate-eaters then also started making more DctA to try to claw back some of the succinate and other molecules they were losing in the process of acquiring citrate.

Again, did anything new evolve? No — all we see is overexpression of pre-existing genes.

So in the end, E. coli are able to eat things that they could already metabolize before the experiments began. A molecular repressor switch has been broken, and another protein has been overexpressed.

Nothing new to see here: these are all the kinds of changes we already know Darwinian evolution can do — breaking things at the molecular level, or making more of something you already have. This is how New Scientist spins it:

Turner’s findings are also yet another example of the mindlessness of evolution. The best solution would be to use a little energy to import citrate directly, the paper says, rather than swapping it for succinate and then spending energy to try to get that succinate back before other bacteria can feed on it.

Bacteria are found almost everywhere on the earth — from inside virtually every living organism to the deep sea to deep underground. They seem designed to be able to feed on just about anything they encounter.

What Lenski may be seeing is the designed ability of bacteria to adapt to new environments using a diverse suite of metabolic pathways they have been gifted with, including the ability to break things or make more of them when needed.

The media will tell you that this shows the amazing power of “mindless” Darwinian evolution. A closer look at the facts reveals nothing of the sort.

Image: E. coli, by Rocky Mountain Laboratories, NIAID, NIH [Public domain], via Wikimedia Commons.


Casey Luskin

Associate Director, Center for Science and Culture
Casey Luskin is a geologist and an attorney with graduate degrees in science and law, giving him expertise in both the scientific and legal dimensions of the debate over evolution. He earned his PhD in Geology from the University of Johannesburg, and BS and MS degrees in Earth Sciences from the University of California, San Diego, where he studied evolution extensively at both the graduate and undergraduate levels. His law degree is from the University of San Diego, where he focused his studies on First Amendment law, education law, and environmental law.



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