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."
I strongly suspect it isn't, nor was it ever, one type of evolution over the other, but a complex interaction between many environmental pressures where both types of evolution played a role.
Why are so many posts with factual errors modded up?
The first 2 parts of Spore are like Horizontal Evolution, and the later parts are all vertical.
It makes perfect sense. Clearly Will Wright is a genius.
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
You know, scientists just keep reforming their ideas until it conforms to observable reality. How can they expect anyone to believe what they say when they're just going to keep changing their minds?
I prefer my religion. It allows me to conform reality to my ideas.
I pass on my genes horizontally
Watch those corners
So does this explain why you can stick "random" genes into a completely different organism and gain traits that wouldn't arise normally? This seems like it'll be very useful in GE if the mechanics of it are explored more.
This really isn't entirely new; Dawkins' book The Selfish Gene is based around the idea that it's individual genes that are selected for, not organisms.
I am going to come over there and take all your stuff and I'm going to kill you and take your weapons and use them for myself!!!
If you're really nice and sweet I'll beat the crap out of you and then stick you in my kitchen to make food for me.
The second is referring to mitochondria not kitchen bitches.
I'd go on a Vegan diet but the delivery time from Vega is too long. --brownkitty
. . . you're better off doing it vertically.
Wearing running shoes.
And ideally permission of the farmer.
(beat)
What?
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?
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.
The notion that life probably started by weak, stochastic replication of families of similar molecules.
By weak, is meant that the replication of the molecule/structure is more imperfect from generation to generation
than in present day life, and so a class of similar molecules (life codes) is being continued through time
rather than a singular particular molecule (same genome).
If this origin theory were true, we would expect the replication capability (continued recreation of imperfect but still somewhat replication-capable molecules)
to be robust to change of DNA/RNA even today.
By stochastic, is meant that such imperfect replication is likely to only be stochastically successful in a huge population of the
initially highly approximate (i.e. weak) replicator molecules.
In other words, we would not expect this proto-life to be as reliable at being able to continue (or to always reliably grow by recruiting
surrounding matter into high-fidelity copies.)
So we might expect these proto-life molecule soups to initially just contain in some regions higher than expected probabilities,
stochastically, from time to time, of weak-replicator molecule classes.
Perhaps there is a binary threshold of replication probability and fidelity at which the process self-sustains reliably in the
generality of environment it finds itself in. Life catches fire, and cannot easily be stopped at its matter and energy recruitment
game from that point on.
Where are we going and why are we in a handbasket?
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.
Horizontal transfer isn't really over, either - we still have retroviruses.
One of the big difficulties I have in understanding evolution is the process of gene syntheses. It seems reasonable that over time certain combinations of genes can win out over others, and certainly in bacteria you see this horizontal gene transfer happen all the time. You even see it in plants now thanks to genetic engineering, and before that you saw it in a more limited way thanks to viruses and cross-pollination and things like that. But all these things have to do with the transfer of genetic information between life-forms.
The question in my mind is where did all the genes come from in the first place. Proteins are complex macro-molecules. It's not like one protein that catalyzes one reaction can simply mutate into a different protein that catalyzes a different reaction. It's more of an all or nothing thing. It doesn't seem like you would ever see transitional "evolutionary" forms of proteins for that reason. Worse still, you can't (as far as we know) start with a working a protein and reverse-transcribe from it into a strand of DNA or RNA that could code for it.
What do you think?
Just why is it that ultra-conservative rants about God or racial superiority or anti-socialism are instantly modded off-topic, troll, and/or flamebait until they sink beneath the thresh hold and yet completely off-topic attacks on Creationism in every story even vaguely connected with biology or evolution get modded +5 insightful?
Same reason why at least someone will look favorably on the fact that you may have served pizza for desert, while you will be forever banished from the kitchen (and other places) if you serve up a pile of dung.
Both are off-topic, but while one still satisfies the basic requirements - the other is a pile of shit.
In the case of pizza - it is still food; in case of pointing out the errors of creationism - it is still a discussion about evolutionary theories, it only digresses towards pointing out the wrong ones.
Creationism and a plate full of dung - a pile of shit.
Mit der Dummheit kämpfen Götter selbst vergebens
Have Woese and Goldenfeld a brilliant new idea? All they're saying, I think, is that "parent" and "child" are the appropriate units of selection only when genes are passed vertically: from parent to child. They're suggesting that horizontal gene transfer is underrated as a historical evolutionary force.
Agree or not, it hardly undermines Darwin. Genes weren't known in the 19th century. Darwin didn't have a clue about genes, so we're gonna knock him for being "wrong" about it? I mean, was Jesus wrong about genes, too? It's anachronistic silliness.
Science is fundamentally dynamic. Any science that hasn't progressed in 150 years ain't doing too well. (Dear creationists: stop calling us "Darwinists." We've moved on.) I mean, The Origin came out in 1859, for crying out loud! Darwin was more brilliant, more insightful, and rightly more famous than I'll ever be. But if we both had to take a biology test right now, I'd kill him.
It is important to note that the idea the "science is about truth" is a common intellectual error of modern society. Science has nothing to do with finding truth or learning how the universe actually works or anything of the sort. Science is about building models of observable natural phenomena. The point of the models is to conform with what is observable and hopefully predict something that hasn't yet been observed, but which can then be tested and seen to work. Good science is about building models that work well, and refining models that don't. Poor science is about building models that sound like they ought to work but don't conform to observation. Really lousy science is about building models that can't be tested against reality and don't predict anything. Are you listening evolutionary psychologists? Take for example: "survival of the fittest" - This is a model for the mechanism by which one organism gets to spread its genes. It sounds perfectly plausible, almost indisputably sensible. But what does it mean? The key is the word "fittest". "Fittest" means best able to survive. So the model mechanism is really survival of the one ones that survived. Now it sounds trite and unhelpful, which it is. How do we know it's not "survival of the luckiest" or "survival of every n-th one"? We don't, but survival of the fittest is more appealing to our cultural sensibilities, so we go with that. If you remember that science is about coming up with ways to get your head around nature, rather than about figuring out what nature really is, then you don't get caught in the trap of "how can you trust science?" You only have to trust it as far as it is working for you, you don't have to build your world view on it.
Science is not the search for "truth". It's the search for an explanation. Unfortunately, it has become the new religion, people simply believe what some scientist says as gospel and, as you identified, are then frustrated and irritated if it is found to be incomplete or utterly false.
That is not how science is to be treated. Science does not have all the answers. Science is the search for those answers, not the answer itself. Science is not about believing, it is about doubting. About offering a theory and offering ways to test that theory. Especially the latter part is often overlooked by people. A good theory offers an angle to falsify it. I may state that at the center of a black hole is cake. Just to make all the Portal players happy. And while we're at it, before the big bang there was a flat world carried by a turtle. You cannot falsify either theory. You cannot test them. So they have to be true. Right? False! Both are non-theories. They have zero scientific value. At least until we somehow find ways to test them.
So presenting any theory that offers no vector of testing is, scientifically, worthless. Unfortunately, that's not easy to convey to people. They want explanations. And science cannot offer them. Science is not about certain answers. It is about questioning theories.
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
I'm not so sure about that. Endo-retro viruses might still be a major factor for more complex organisms and even chordates. I've been wondering about whether super-retro viruses that can cross-infect multiple species while carrying secondary genetic payloads would be a possible agent for punctuated equilibrium.
It's interesting that there are people with varying degrees of immunity to retro-viruses like AIDS. While AIDS is not very contagious, other retroviruses could be much more easily transmitted, so you would think that retro-viral resistance would be a very beneficial and common mutation, however it appears to be quite rare. Why? Well, it's possible that such mutations have drawbacks that are more frequently a disadvantage than the immunity advantage (as a parallel, sickle-cell and Thalassemia resistance to malaria), it also might be because susceptibility to retro viruses provides a significant evolutionary advantage in the Red Queen's race for complex organisms just as horizontal DNA exchange does for bacteria.
Laissez lire, et laissez danser; ces deux amusements ne feront jamais de mal au monde. - Voltaire