Friday, March 07, 2014

Molecular mechanisms of evolution

“Molecular mechanisms that generate biological diversity are rewriting ideas about how evolution proceeds”. I couldn’t help noticing how similar that sounds to what I was saying in my Nature article last spring, “Celebrate the unknowns”. Some people were affronted by that – although other responses, like this one from Adrian Bird, were much more considered. But this is the claim put forward by Susan Rosenberg and Christine Queitsch in an interesting commentary in Science this week. They point out (as I attempted to) that the “modern synthesis” so dear to some is in need of some modification.

“Among the cornerstone assumptions [of the modern synthesis]”, say Rosenberg and Queitsch, “were that mutations are the sole drivers of evolution; mutations occur randomly, constantly, and gradually; and the transmission of genetic information is vertical from parent to offspring, rather than horizontal (infectious) between individuals and species (as is now apparent throughout the tree of life). But discoveries of molecular mechanisms are modifying these assumptions.” Quite so.

This is all no great surprise. Why on earth should we expect that a theory drawn up 80 or so years ago will remain inviolable today? As I am sure Darwin expected, evolution is complex and doesn’t have a single operative principle, although obviously natural selection is a big part of it. (I need to be careful what I say here – one ticking off I got was from a biologist who was unhappy that I had over-stressed natural selection at the molecular level, which I freely confess was a slight failure of nerve – I have found that saying such things can induce apoplexy in folks who see the shadows of creationism everywhere.) My complaint is why this seemingly obvious truth gets so little airplay in popular accounts of genetics and evolution. I’m still puzzled by that.

I realise now that kicking off my piece with ENCODE was something of a tactical error (even though that study was what began to raise these questions in my mind), since the opposition to that project is fervent to the point of crusading in some quarters. (My own suspicion is that the ENCODE team did somewhat overstate their undoubtedly interesting results.) Epigenetics too is now getting the backlash for some initial overselling. I wish I’d now fought harder to keep in my piece the discussion of Susan Lindquist’s work on stress-induced release of phenotypic diversity (S. Lindquist, Cold Spring Harb. Symp. Quant. Biol. 74, 103 (2009)), which is mentioned in the Science piece – but there was no room. In any case, this gives me the impetus to finally put the original, longer version of my Nature article online on my web site – not tonight, but imminently.


Arv Edgeworth said...

The human brain simultaneously processes an amazing amount of information. Your brain takes in all the colors and objects you see, the temperature around you, the pressure of your feet against the floor, the sounds around you, the dryness of your mouth, even the texture of a brochure in your hand. Your brain registers emotional responses, thoughts and memories. At the same time your brain keeps track of the ongoing functions of your body like your breathing pattern, eyelid movement, hunger and movement of the muscles in your hands.

Even if only one hundredth of the connections in the brain were specifically organized, this would still represent a system containing a much greater number of specific connections than in the entire communications network on Earth.

Because of the vast number of unique adaptive connections, to assemble an object remotely resembling the brain would take an eternity, even applying the most sophisticated engineering techniques.”
Michael Denton - British-Australian author and biochemist.

Accidental, random, chance, mutations and survival of the fittest? Really?

geoffrobinson said...

"such things can induce apoplexy in folks who see the shadows of creationism everywhere"

Maybe because the evidence of creation is everywhere and they don't want it to be true.

Arjen ten Have said...

It is definitely true that the so-called Modern Synthesis of Evolution needs an update. That is common knowledge. The problem is that there are not really leading figures that can come down with what might be called The Standard Model of Biological Evolution. I phrase it as such since as such it might also help against the ID movement. ID is constantly challenging biologists and other scientists. The thing they do understand all too well is that every new finding comes with many new questions, which they subsequently abuse to attack evolution. One of the issues they keep on coming back is that evolution is "just a theory". Besides the fact that apparently they misunderstand the scientific meaning of theory, they easily put aside the enormous of evidence that backs up this theory. The reason why they keep on doing this is that there are still a number of "battle areas" , albeit much less then it seems. Here The Standard Model of Biological Evolution might come in quite handy. But who should define it? Andreas Wagner, Jerry Coyne?

Philip Ball said...

Well said, Arjen. And who indeed? I'd certainly be interested in what Wagner would say on this.

apalazzo said...

"The problem is that there are not really leading figures that can come down with what might be called The Standard Model of Biological Evolution."

To gain a more up-to-date view of evolution, you should read Michael Lynch. See