Darwinian Evolution Considered As a Phase 313
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."
Well duh? (Score:3, Informative)
For anyone familiar with the Red Queen Hypothesis ( http://en.wikipedia.org/wiki/Red_Queen [wikipedia.org] ) this should be obvious.
While direct DNA transfer is not the component usually referred to by this "arms race," it is merely an extension of a known theory.
No one makes a big hype about this theory, because it doesn't say your grandfather was a monkey and piss off the religious nuts
Still natural selection (Score:4, Informative)
As a side note... I wonder if the fact this occurs in nature will silence some of the people objecting to genetic splicing?
Re:It's still natural selection (Score:4, Informative)
Original paper on arXiv (Score:5, Informative)
For those who do not care to register for that New Scientist, we still have arXiv... :)
http://arxiv.org/abs/q-bio/0702015 [arxiv.org]
Paul B.
Re:Capitalism? (Score:5, Informative)
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.
Re:Well duh? (Score:3, Informative)
To be precise, there is no theory that says your grandfather was a monkey. The religious nuts made that straw-man up all on their own. :P
Here's A Tip, Folks (Score:5, Informative)
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:Well duh? (Score:5, Informative)
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.
Recent discoveries... (Score:2, Informative)
Re:Here's A Tip, Folks (Score:5, Informative)
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:Original paper on arXiv (Score:5, Informative)
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:Here's A Tip, Folks (Score:5, Informative)
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:It's still natural selection (Score:3, Informative)
Not the individual's genes, the individual gene. In all plants and animals it is reproduction combined with mutation and recombination that is driving evolution.
Social animals posses genetic traits which promote social or herd behaviour. In these animals the trait survives because for these animals in the environment in which the trait emerged it increases the chance of survival and reproduction. The gene promotes itself.
Worker ants are infertile. They share common genetic information with the queen. To protect the nest and the queen increases the chance of propagation of their genes even though they do not reproduce themselves. There's probably a gene for that.
I have no idea about infanticide but I do recall hearing of a study recently which observed that homosexual men frequently have one or more close female relatives who are unusually fecund. I can't find the link and the research may have since been debunked but the idea is interesting as it suggests the possibility of a gene which increases the reproductive fitness of one individual while reducing the reproductive fitness of another.
Of course that assumes that being homosexual reduces your chance of reproduction.
Re:It's still natural selection (Score:3, Informative)
1. An information storage medium.
2. A mechanism for reproducing that information such that certain pieces of information are more likely to get reproduced than others.
Once you have those, everything else follows, and it doesn't matter what the precise storage mechanism or copying mechanism is. Horizontal gene transfer is just another way for genetic information to reproduce.
Re:Here's A Tip, Folks (Score:3, Informative)
Anyway, back on topic. Icebike did not say that horizontal gene transfer cannot influence fitness, but that the mechnaism itself has no effect. What has the effect is the genes, not how they got there.
Here's evolution by natural selection in a nut shell - organisms are different; some organisms are more suited to their environment than others; better ones survive and reproduce - their traits survive.
Furthermore, Darwin had no knowledge of genes, as they were not known of in his day. This means that his theory does not even touch on the cause of the differences, but focuses on how they propogate. Thus Icebikes statement "Further it has nothing at all to do with Darwinism." because, as I said, Darwinism has nothing to do with genes.
We now know how different traits come into being and what causes the changes (if not completelly then at least to a large degree - there's always more to be learned) so we can fill in the gaps, but that is evolutionary theory, not darwinism (the latter is a part of the former).
Re:Here's A Tip, Folks (Score:5, Informative)
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:It's still natural selection (Score:3, Informative)
You just missed the flaw in your reasoning - you confuse an individual's GENES with the INDIVIDUAL. Consider that a parent only has 50% of their genes in a child; if it turns out that killing the child would allow for the opportunity to invest more in other children, and increase their probability of having offspring (i.e. getting more copies of your genes in circulation), it might be very RATIONAL to kill your own child from the standpoint of increasing the frequency of your genes in the population. This behavior is observed frequently in animal species besides man. Consider how violently men react to adulterous women and thier offspring - the possibility that they might have been investing resources in a child with 0% of their genes means they have nothing to lose, genetically, by offing them. The math of kin selection has been worked out quite precisely, in many different species with different mating habits, and the numbers work out; we (as in man and virtually every other species) tend to behave in such a way as to maximize the spread of our genes, regardless of whether the copies come from us or from our kin.
You mention ants - ants behave the way they do because of the highly unusual way they pass genes on - or should I say, the way most ants DON'T. In a given colony, all the future ants (and future genes) come from the queen, who has sex briefly (for a day or two) with between 1 and 10 males, and stores their sperm to produce eggs for the rest of her life. The reason so many ants work themselves to death, engage in combat to the death to protect the queen, and in general seem to not care for themselves as individuals, is they are, as individual reproducers, done. The only chance they have for enhancing the odds of their GENES being spread is by doing everything possible to protect and nuture the only possible reproducer of those genes - the queen. And guess what - the genes that influence aunt behavior in that way are the ones that have been the most successful.
Group level selection has very little evidence going for it, although in highly advanced creatures (like us), it may play a greater role than in general. You should read The Selfish Gene, and The Extended Phenotype, by Dawkins, to see the arguments about group vs. individual vs. genetic selection really hashed out in detail.
Re:I realize scientists need a breakthrough (Score:2, Informative)
Re:Well duh? (Score:4, Informative)
I wonder why this is moderated insightful?
This is a very different kind of 'acquisition' as the genes for making chlorophyll acquired from the algae are not transferred to its offspring..
Re:Here's A Tip, Folks (Score:2, Informative)
Actually Francis Crick - who was a very strong atheist - used to like making pseudo religious phrases to torment the religious
http://en.wikipedia.org/wiki/Central_dogma_of_molecular_biology#Use_of_the_term_.22dogma.22 [wikipedia.org]
Re:Well duh? (Score:3, Informative)
This is a very different kind of 'acquisition' as the genes for making chlorophyll acquired from the algae are not transferred to its offspring..
According to this article [foxnews.com], the genes are transferred, but the offspring, like the parents, can't produce their own chloroplasts, so have to eat enough algae to acquire the necessary chloroplasts before they can survive like that.