Darwinian Evolution Considered As a Phase

LucidBeast tips a mind-bending report at New Scientist on the latest paradigm-breaking work of Carl Woese, one of whose earlier discoveries was the third branch of life on Earth, the Archaea. Woese and physicist Nigel Goldenfeld argue that, even in its sophisticated modern form, Darwin's theory of evolution by natural selection applies only to a recent phase of life on Earth. Woese and Goldenfeld believe that horizontal evolution led to the rise of the genetic code itself. "At the root of this idea is overwhelming recent evidence for horizontal gene transfer — in which organisms acquire genetic material 'horizontally' from other organisms around them, rather than vertically from their parents or ancestors. The donor organisms may not even be the same species. This mechanism is already known to play a huge role in the evolution of microbial genomes, but its consequences have hardly been explored. According to Woese and Goldenfeld, they are profound, and horizontal gene transfer alters the evolutionary process itself."

Comments

Original paper on arXiv

[PaulBu]

For those who do not care to register for that New Scientist, we still have arXiv... :)

http://arxiv.org/abs/q-bio/0702015

Paul B.

Re:Original paper on arXiv

[radtea]

Thanks, as the New Sensationalist article is full of lies and hyperbole, completely idiotic, transparent falsehoods like, "This code is universal, shared by all organisms, and biologists have long known that it has remarkable properties"

This simply a lie, as is the claim that 64 combinations producing 20 codons is "redundancy". The reason there are only 20 is well-known to anyone with the least little bit of familiarity with the subject: it is the maximum number of unambiguous combinations, so that if you get six bases in a row there is exactly one way to read them, because no two codons together can result in a third codon being read between them.

The arXiv article may have something interesting to say, although inter-species genetic transfer has been known to occur amongst micro-organisms for a long time. From a Darwinian perspective the genes available in the environment are just that: another perfectly ordinary part of the environment. Since Darwin's Law depends only on the laws of probability and the fact of imperfect replication, it applies to situations where horizontal transfer takes place just as much as when imperfect copies of genes come from ancestors.

The details of Darwinian evolution will change a little in the context where organisms are taking genetic resources directly from the environment, but it's still a Darwinian process.

The weird statements about "questioning if organisms even exist as individuals" are just idiotic marketing hype that pretty much ensure the whole argument is vastly less interesting and important than the authors want to make it appear. Otherwise, why the need for such anti-scientific hype? Unless it is the New Sensationalist characteristically ripping an innocent statement out of context.

Re:Capitalism?

[Chris Burke]

However, I've always read Darwinian evolution as "survival of the fittest", with no qualifier as to how you go about surviving.

"Survival of the fittest" aka Natural Selection was half of Darwinian evolution. This was the half about how traits were selected for in the environment.

The other half was how an organism's traits came about, and his theory was that traits were passed from parents to offspring in the reproductive cells via some biological mechanism that allowed for combination and mutation. Eventually we discovered DNA, the very biological mechanism in question that had traits like Darwin predicted (though Mendel was the one who really nailed down the probably behavior of this then-unknown mechanism).

"Horizontal" evolution doesn't fall into that category, though. So it's not "Darwinian". Even though natural selection (obviously) still applies to what gene transfers result in successful organisms.

As the summary mentions, this is well known in micro-organisms. In fact as far as I can tell they aren't arguing that it applies to anything but microorganisms. The argument seems more like that because these are the most common life forms on earth and also the oldest, Darwinian evolution is not the most common or dominant form of evolution.

Which is a good point. Though really, as far as what affects us and other sexually reproducing creatures, Darwinian evolution is still 'it' more or less. The real importance of this breakthrough is in studying how the evolutionary mechanisms themselves evolved -- evolution is of course not immune to evolution. ;) This is going to be a powerful way of thinking about how early aspects of DNA came to be.

But just to be clear -- if someone says that this proves Darwin was wrong, evolution is a sham, and therefore their beliefs are probably right, go ahead and slap them. :) All this means is that evolution is even more complicated and powerful than previously thought.

Here's A Tip, Folks

[MightyMartian]

Here's a tip, folks. The minute you see some science journalist use the word "paradigm", as in "paradigm shift" or "paradigm breaking" you can be quite certain that what follows will be neither.

Horizontal gene transfer has been known about for decades, and the notion that the root of the tree of life is more a tangle of interconnecting branches has pretty much been accepted for some time now. We know that particularly with prokaryotes, horizontal transfer happens, and that while more difficult with eukaryotes, can still happen (ie. endo-retroviral insertions). It is yet another facet of evolution, not some independent force.

Re:Here's A Tip, Folks

[icebike]

Horizontal gene transfer has been known about for decades, and the notion that the root of the tree of life is more a tangle of interconnecting branches has pretty much been accepted for some time now.

Further it has nothing at all to do with Darwinism.

A mechanism of gene transfer plays no role in the "Survival of the Fittest" (a phrase coined not by Darwin, but rather by Spencer), or natural selection. Its not germane.

Natural Selection is a winnowing process, and a mutation amplifying force, but says nothing about the acquisition or dispersion of said mutations. It was never meant to.

Re:Here's A Tip, Folks

[icebike]

I fail to see the point of confusion.

Acquisition of a trait (by whatever means) would never amount to a significant percentage of the gene pool of an organism unless it proffered some usefulness. Mutation or horizontal genetic transfer are but mere mechanisms. Darwinism discusses the overall process, not the details.

How that transfer took place is mere details. When that transfer takes place is not fixed in time. Horizontal transfer still exists in larger and more complex organisms and their symbiotic partners.

Re:Here's A Tip, Folks

[BrokenHalo]

I'm sorry, but I've never heard of this theory before, and I daresay I'm not the only one.

OK, here you go, then: Prokaryotes (i.e. bacteria, archea and so forth), by virtue of the comparatively "exposed" genetic material (not condensed or "bunched up" like ours typically is) and because of the structure of their cellular membranes, are very capable of "scraping up" any loose genetic material that may be lying around (e.g. as a result of cellular lysis). If these nucleic acids confer an evolutionary advantage, they are propagated in successive generations. This is why, and how "superbugs" like MRSA are thought to have evolved.

Microbiologists have used this feature for decades in the genetic engineering of bacteria to induce desired characteristics. The process is much harder and more complicated in eukaryotic (e.g. animal or plant) cells, but it can and does happen.

Re:Well duh?

[Guido von Guido]

I can't read the article without registering but I wonder if homosexual behavior could be causing horizontal gene transfer in humans, possibly using viruses as a transport mechanism.

If viruses are your transport mechanism, I'm not sure you need homosexual behaviour. You may, yes, but there are plenty of other mechanisms for viruses to spread.