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Evolution does not equal a feedback loop

A group of Princeton chemists, publishing in Physical Review Letters (which, as you might guess from the name, is not a biological research journal), feel they’ve found a mechanism that shows proteins direct their own evolution based on environmental conditions. Or something like that.

Evolution’s new wrinkle: Proteins with cruise control provide new perspective
A team of Princeton University scientists has discovered that chains of proteins found in most living organisms act like adaptive machines, possessing the ability to control their own evolution.

The quote is from the press release, there’s no citation to the actual article, but, Google being my friend, the abstract wasn’t hard to find.

Mutagenic Evidence for the Optimal Control of Evolutionary Dynamics (pdf)
Raj Chakrabarti, Herschel Rabitz, Stacey L. Springs, and George L. McLendon

Elucidating the fitness measures optimized during the evolution of complex biological systems is a major challenge in evolutionary theory. We present experimental evidence and an analytical framework demonstrating how biochemical networks exploit optimal control strategies in their evolutionary dynamics. Optimal control theory explains a striking pattern of extremization in the redox potentials of electron transport proteins, assuming only that their fitness measure is a control objective functional with bounded controls.

There’s not a lot to go on there, but from that and interviews it seems that these chemists feel that a feedback loop is evidence of directed evolution.

Um. No. Please take a basic biology class.

There are, literally, hundreds of thousands of feedback loops in biology. Some of them involve changes in the way DNA transcription is regulated. Those often involve methylation, and recent research indicates that sometimes, through epigenetic effects, methylation patterns can be inherited. That’s the closest we come to environment affecting genetics. As far as I can tell, that’s not what these authors are discussing.

There’s nothing in what they’ve said so far that indicates the electron transport chain proteins alter DNA, or even methylation. Or, if the proteins are using some totally new mechanism, what that mechanism is.

They also betray a woeful lack of understanding of evolutionary principles.

“The discovery answers an age-old question that has puzzled biologists since the time of Darwin: How can organisms be so exquisitely complex, if evolution is completely random, operating like a ‘blind watchmaker’?” said Chakrabarti

Again. No. Mutations are random, not evolution. No evolutionary biologist would dream of saying evolution is random. It happens in response to specific forces (one of which is natural selection), and if you know those forces, you can predict the outcome. That is just about the opposite of a random process.

It seems Chakrabarti is referring to Dawkins’ famous line about evolution not being a teleological process. That’s yet another kind of confusion. Evolution has no goal, but that doesn’t make it random either.

What this reminds me of is the cold fusion excitement. Totally new physics! In Utah! And then, after some years, not so much. Now it’s “New evolution! In Princeton!” And apparently what’s happened is that some chemists have discovered feedback loops in biology.

Good for them. They should keep studying biology. It’s full of fascinating stuff like that.