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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."
For anyone familiar with the Red Queen Hypothesis ( http://en.wikipedia.org/wiki/Red_Queen ) 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
We've already known that evolution depends on both inheritance of genetic matter and mutation of genetic matter. This is a third mechanism for generating traits, but it stills falls under the umbrella of natural selection. If the change is beneficial, and leads to more offspring, the change will be selected for. Certainly worth study, and we may not have known the full scope of the phenomena, but it doesn't really contradict Darwinian evolution at all.
As a side note... I wonder if the fact this occurs in nature will silence some of the people objecting to genetic splicing?
Which is nothing more than a restatement of what Darwin said, since a gene is nothing more than an encoded trait. It is the trait that actually matters, not the gene, since the trait is what gives the animal the ability to survive. It doesn't really matter if the trait is encoded as DNA or as biologic etchings on advanced carbon fiber, in either case it is just a representation of a trait.
Qxe4
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.
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.
The enemies of Democracy are
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.
The world's burning. Moped Jesus spotted on I50. Details at 11.
There have been some other interesting discoveries regarding horizontal gene transfer recently. For example, this PNAS paper looks at sea slugs that can photosynthesize by themselves -- http://www.pnas.org/content/105/46/17867.full.pdf). The sea slugs photosynthesize through a combination of harvesting chloroplasts from the algae they eat and via horizontal transfer of genes involved in photosynthesis from these same algae. This is a bizarre and amazing discovery which demonstrates how genes can move from plants and be incorporated in an animal genome.
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.
Now wash your hands.
Exactly. Evolution is a fundamental mathematical process that applies to information, not organisms. To get evolution, you only need two elements:
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.
"I'm too busy to research this and form an educated opinion, but I do have time to tell everyone my uninformed opinion."
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.
This is old news, Woses paper "on the evolution of cells" explained this concept 8 years ago http://www.pnas.org/content/99/13/8742.long. Even within the protocell or primordial soup where horizontal gene transfer is hypothesized to play a dominant role natural selection still takes place. The molecules that replicate best increase in number and those that don't die out. Also, several evolutionary biologists such as Woese himself and many of his collegues have made their careers out of studying this phenomenon, so the suggestion " its consequences have hardly been explored" is a bit disingenuous.