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"The field of evolution attracts significantly more speculation than the average area of science."
May 29, 2007 11:05 AM   Subscribe

"Nothing in biology makes sense except in light of evolution." Despite Theodosius Dobzhansky's succint description of natural selection at the core of biological research since Darwin's fateful trip to the Galapagos, evolutionary biologist Michael Lynch respectfully dissents, asking "whether natural selection is a necessary or sufficient force to explain" the complexity of multicellular organisms we see today, where mutation, recombination and genetic drift are often overlooked, but critical factors in evolutionary theory and understanding.
posted by Blazecock Pileon (90 comments total) 8 users marked this as a favorite

 
I thought mutation was the basis for natural selection.
posted by East Manitoba Regional Junior Kabaddi Champion '94 at 11:13 AM on May 29, 2007


When we question evolution, the fundies win. Right?
posted by No Robots at 11:14 AM on May 29, 2007


I always favored the Demiurgic powers theory. Things evolve but follow a kind of gameplan set in motion by forces operating in spectra we can't quite detect with the instruments currently at our disposal.
posted by Burhanistan at 11:21 AM on May 29, 2007


ODIN!
posted by ND¢ at 11:24 AM on May 29, 2007


I always favored the Demiurgic powers theory. Things evolve but follow a kind of gameplan set in motion by forces operating in spectra we can't quite detect with the instruments currently at our disposal.

It's almost like some kind of "intelligent" "design"...
posted by East Manitoba Regional Junior Kabaddi Champion '94 at 11:27 AM on May 29, 2007


Lynch is talking here about what mechanisms of evolution are important, not about whether evolution has happened.
posted by gubo at 11:32 AM on May 29, 2007


It's almost like some kind of "intelligent" "design"...

Yes, so? I think it's rather abhorrent what is taught in the name of that idea, but the basic concept holds merit. Anyways, this is a useless hot button issue, really.
posted by Burhanistan at 11:33 AM on May 29, 2007


Er... are people somehow reading this as a refutation of evolution? Dude just seems to be emphasizing the role of random genetic drift vs. directly adaptive processes. His article seems pretty pointless outside of the context in which he's writing it, which apparently is a bunch of dudes he doesn't like who play up the role of natural selection at the expense of genetic drift.
posted by gurple at 11:37 AM on May 29, 2007


I thought mutation was the basis for natural selection.

No. You can have natural selection without mutation. Genetic algorithms, for instance, often (always?) don't have mutation.
posted by DU at 11:40 AM on May 29, 2007


When we question evolution, the fundies win. Right?

No, no, they prefer that nobody questions anything. As long as there's questioning going on, the fundies don't win.
posted by phrenq at 11:42 AM on May 29, 2007 [1 favorite]


"I have no data yet. It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to fit theories, instead of theories to suit facts." -Sir A.C. Doyle, A Scandal in Bohemia
posted by SaintCynr at 11:43 AM on May 29, 2007


As long as we all agree it wasn't an invisible sky man. Feel free to argue about what causes evolution.
posted by Megafly at 11:47 AM on May 29, 2007 [1 favorite]


I thought mutation was the basis for natural selection.

That's a non-sequitur.
posted by delmoi at 11:48 AM on May 29, 2007


Who here has seen the elephant?
posted by Burhanistan at 11:50 AM on May 29, 2007 [1 favorite]


Genetic algorithms, for instance, often (always?) don't have mutation.

It's possible to turn mutation completely off in a GA program, but you wouldn't get very interesting behavior that way.
posted by gurple at 11:52 AM on May 29, 2007


Hmm, interesting. here we have a seemingly reasonable disagreement within the scientific establishment (at least based on the FPP text) and it can only be viewed through the filter of the evolution vs. crazies debate.

There is some real legitimate debate about how evolution works within the scientific community people.
posted by delmoi at 11:52 AM on May 29, 2007 [1 favorite]


No. You can have natural selection without mutation. Genetic algorithms, for instance, often (always?) don't have mutation.

What? Genetic algorithms are defined as algorithms using mutation and selection (obviously not 'natural' selection). If it doesn't have mutation, then it's not a genetic algorithm.

unless you're doing what gurple's suggests and setting the mutation factor to zero, which would mean that nothing would happen

There are other optimization algorithms that do not use "mutation" in the same way, such as simulated annealing, hill climbing, back-propagation neural networking, etc.
posted by delmoi at 11:57 AM on May 29, 2007


Lynch's comments cut to the heart of much recent debate among Neo-Darwinians and those, like Stephen Jay Gould, who emphasized the role of mechanisms other than natural selection in exerting macroevolutionary change. SJG actually went much further than this but the debate has nothing to do with the veracity of evolutionary theory. Something semi-literate fundies and creationists don't seem to understand is that this sort of debate is endemic to all scientific inquiry, and that debate or disagreement isn't a sign that the theory is invalid, it's a sign that the theory is being improved. And the only reason it appears to attract "significantly more speculation than the average area" is that the implications are more widely felt in other disciplines.
posted by inoculatedcities at 11:58 AM on May 29, 2007 [1 favorite]


It's possible to turn mutation completely off in a GA program, but you wouldn't get very interesting behavior that way.

I personally have written a (very simple) GA program that solves the Traveling Salesperson Problem. No mutation.
posted by DU at 11:59 AM on May 29, 2007 [1 favorite]


Here's another unsubstantiated claim for you: Studying evolution probably calls Heisenberg's Uncertainty principle into motion. The more we look into evolving structures the more our own attention is altering them. It might even create a kind of positive feedback loop that is too fast to detect by those who are looking for static or rigid structures.
posted by Burhanistan at 12:01 PM on May 29, 2007


I personally have written a (very simple) GA program that solves the Traveling Salesperson Problem. No mutation.

You may think you have, but it's possible you were confused about what you were doing.
posted by delmoi at 12:05 PM on May 29, 2007


What? Genetic algorithms are defined as algorithms using mutation and selection...

*checks internet*......nope.
posted by DU at 12:07 PM on May 29, 2007


delmoi writes "What? Genetic algorithms are defined as algorithms using mutation and selection (obviously not 'natural' selection). If it doesn't have mutation, then it's not a genetic algorithm. "

Yeah, you're wrong about this. A lot of GAs just use recombination and selection. The recombination is random (or random-like), though.
posted by mr_roboto at 12:10 PM on May 29, 2007


DU: check again. Maybe try a different internet.
posted by boo_radley at 12:10 PM on May 29, 2007


As long as there's questioning going on, the fundies don't win.

Glad to hear you say so, Phrenq.
posted by No Robots at 12:23 PM on May 29, 2007


Burhan:

Intelligent Design is undisprovable, just like the Easter Bunny.

The Uncertainty Principle does not apply to macro phenomena.
posted by bornjewish at 12:36 PM on May 29, 2007


Something semi-literate fundies and creationists don't seem to understand is that this sort of debate is endemic to all scientific inquiry, and that debate or disagreement isn't a sign that the theory is invalid, it's a sign that the theory is being improved. And the only reason it appears to attract "significantly more speculation than the average area" is that the implications are more widely felt in other disciplines.

Well said inoculatedcities, but "the theory is invalid" also has to be on the table of scientific inquiry. There is a little too much semi-literate anti-fundie and anti-creationist attachment to the theory of evolution as fact when it is not. Scientific theories are not proved - they are disproved.

What is beyond dispute is that there is no scientific support for the creationist belief.
posted by three blind mice at 12:39 PM on May 29, 2007


The Uncertainty Principle does not apply to macro phenomena.

Who said evolution is a macro-phenomenon? Cells and molecules are the first things to mutate, no?
posted by Burhanistan at 12:41 PM on May 29, 2007


I think Burhan was kidding. I hope Burhan was kidding.
posted by LordSludge at 12:47 PM on May 29, 2007


Well, according to wikipedia a genetic algorithm uses recombination "and/or" mutation. Obviously what is and is not a genetic algorithm is a value judgment, unlike, say, the complexity class of a problem.

But simply writing a program and calling it a "genetic algorithm" does not make you an expert. I do think a GA with zero mutation would be pretty boring, and "solving" the traveling salesman problem is easy, it's finding the optimal solution that's difficult (and by difficult, I mean NP-Hard). Saying that a program solves traveling salesman is not the same thing as saying it did anything interesting or useful.
posted by delmoi at 12:49 PM on May 29, 2007


Heisenberg was concerned with velocity and location of subatomic particles. It really doesn't apply.
posted by COBRA! at 12:56 PM on May 29, 2007


The title of this article bugs me, in that it extracts the most inflammatory-sounding phrase out of the entire paper. The actual sentence is "Because it deals with observations on historical outcomes, frequently in the face of incomplete information, the field of evolution attracts significantly more speculation than the average area of science." Chopping off the first part leaves it open to intrepretations like "the field of evolution attracts significantly more speculation than the average area of science, BECAUSE IT'S MADE UP BY SATANIC ATHEIST LIBERALS!!!1!!!
posted by gamera at 1:00 PM on May 29, 2007


ODIN!

Yep!
posted by ericb at 1:05 PM on May 29, 2007


where mutation, recombination and genetic drift are often overlooked

I need evidence of this.
posted by docgonzo at 1:06 PM on May 29, 2007


Ah, my bad. I should've used a term like "observer effect" rather than Heisenberg's Uncertainy Principle.
posted by Burhanistan at 1:07 PM on May 29, 2007


I think Burhan was kidding. I hope Burhan was kidding.

I get the feeling that a credulous viewing of What the #$*! Do We Know!? is somehow involved.
posted by BoatMeme at 1:07 PM on May 29, 2007


Nope! I hated that stupid movie.
posted by Burhanistan at 1:10 PM on May 29, 2007


I'm a biologist but not an evolutionary biologist. Can someone explain why "natural selection" is not universally considered to include multiple sources of genetic variation e.g. genetic drift, recombination, replication error, and so forth? I don't get what the argument even is. I mean, if you eliminate these things, there's nothing to select for, because everything is identical and never changes.

I understand from the abstract that the author is arguing against the idea that each individual change in a species must have a distinct survival advantage for that species, and so-called "nonadaptive" changes must necessarily be adaptive changes that we don't understand. But it just seems like common sense that the author's point of view is correct, and what he's arguing against is a really thick-headed way of thinking about evolution.
posted by rxrfrx at 1:10 PM on May 29, 2007


Heisenberg was concerned with velocity and location of subatomic particles. It really doesn't apply.

I wanted to say that, but I've read that researchers have found that some protein folding does indeed use quantum tunneling to get the proteins into the right configuration. So it some cases evolution does "use" quantum physics. That said, Burhanistan is still mostly wrong.
posted by delmoi at 1:11 PM on May 29, 2007


Obviously what is and is not a genetic algorithm is a value judgment

Bah, it is not. You don't need mutation for GAs, but you have more risk of getting stuck in local optima.

I once ran a genetic algorithm in reverse. Found God. Then the funding was cut.
posted by logicpunk at 1:11 PM on May 29, 2007


this is tough stuff. much easier to believe in GOD
posted by Postroad at 1:15 PM on May 29, 2007


Cells are "macro" from an atomic and subatomic standpoint, yes.
posted by absalom at 1:21 PM on May 29, 2007


Can someone explain why "natural selection" is not universally considered to include multiple sources of genetic variation e.g. genetic drift, recombination, replication error, and so forth?

Darwin's evolution is not "natural selection", but rather reproductive fitness. In general, species strive to reproduce copies of themselves. This is what SJG was onto and the fossil record spotty as it is tends to support this observation.
posted by three blind mice at 1:22 PM on May 29, 2007


I'm a biologist but not an evolutionary biologist. Can someone explain why "natural selection" is not universally considered to include multiple sources of genetic variation e.g. genetic drift, recombination, replication error, and so forth? I don't get what the argument even is. I mean, if you eliminate these things, there's nothing to select for, because everything is identical and never changes.

Well natural selection is something that happens after those things, right? so how can natural selection "include" recombination? that doesn't make any sense to me. Like saying toast includes a toaster. You could say that natural selection acts on phenotypic changes caused by all of those things, but that doesn't prove that natural selection is the only reason that phenotypes might change. It could just happen randomly or for no reason if there was a population decrease.
posted by delmoi at 1:24 PM on May 29, 2007


So what the hell happened here, then?
posted by Burhanistan at 1:26 PM on May 29, 2007


delmoi- hm, maybe I'm just misusing terms. When I see "natural selection" I think "the selection of the most-fit phenotype, whatever caused that phenotype to arise." This must include those unnamed causes, including recombination.

Again, can you simplify the argument so I understand both side?


Three blind mice- what's the difference between natural selection of the most-fit (fit for the survival of that collection of phenotypes that make a species) and "reproductive fitness?" I'm still not seeing both sides of an argument.
posted by rxrfrx at 1:35 PM on May 29, 2007


three blind mice - You are correct, sir. I should have been more clear. I do not mean to suggest that it can't be disproven. Paraphrasing Dawkins "There's one thing that could easily disprove the theory of evolution: rabbit fossils in the Precambrian." The point, and Dobzhansky's point as well, is that evolution has been confirmed over and over again so many times in the past 150+ years that it's absurd to talk about it the way Creationists (i.e. ID crackpots like Behe) do: that if there something not quite understood or confirmed yet with regard to evolution, then "god" is somehow a better explanation; of course, he wins by default the way they argue.
posted by inoculatedcities at 1:37 PM on May 29, 2007


Burhan,

The shark reproduced asexually.
Like other, less complicated, animals & bacteria do regularly.
Sex is a "Recent" invention, which has the advantage of shuffling genes.
posted by bornjewish at 1:39 PM on May 29, 2007


bornjewish,

Yes I realize it produced asexually. But sharks, while primitive compared to newer species, evolved from sexual reproduction. What was the mechanism that caused the shark to fuse its genetic material as it did? Or rather, since that can be deduced, what kind of shock was needed for a species to revert like that. It's not like the individual shark (or komodo dragon as mentioned in the article) made a decision based on any environmental clues or empathy for its species' survival. But instead something from beyond the shark's own limited awareness acted upon it or shocked it somehow into spontaneously subverting the sexual process. What is that, then?
posted by Burhanistan at 1:53 PM on May 29, 2007


When I see "natural selection" I think "the selection of the most-fit phenotype, whatever caused that phenotype to arise." This must include those unnamed causes, including recombination.

I suspect that the disagreement is really over the relation of genotype to phenotypic expression and its consequences for macroevolution. Darwin of course knew nothing about genetic drift, population genetics, etc. so some assume that 'natural selection' as defined by the man himself somehow excluded these significant actors (doctrinaire "phyletic gradualism"). Gould and Eldredge, who stressed the punctuated equilibrium model -- which is an argument in favor of the organism as the unit upon which selection pressure acted, as well as the emphasized role of catastrophic extinctions, drift, etc. -- of course wrote extensively against Dawkins and others who argued that the gene was the unit of selection. I tend to favor Dawkins' gene-centric explanation, and I think Gould always emphasized factors that have more to do with his training as a paleontologist than a biologist, but this debate has been raging for decades and shows no sign of letting up. This looks to be a good read on the controversy.
posted by inoculatedcities at 1:57 PM on May 29, 2007 [1 favorite]


The full-text HTML version of the article is here, if you'd rather not download the PDF. I actually took a couple of graduate-level classes from Dr. Lynch about fifteen years ago. Unfortunately the part of my brain that contained all that I learned about molecular evolution has been emptied out and is now used for lolcat storage.
posted by gamera at 1:57 PM on May 29, 2007 [1 favorite]


>> thought mutation was the basis for natural selection.
>
> That's a non-sequitur.

How so? There must be some source of variability, either from mutation or from something else, upon which selection can operate in favor of the more adaptive--more reproductively successful--variation(s) at the expense of the less. You can certainly claim there are other sources of variability in addition to mutation, but mutation remains either the source or a source of the variability without which selection has nothing to operate on.

> Three blind mice- what's the difference between natural selection of the most-fit (fit for the survival
> of that collection of phenotypes that make a species) and "reproductive fitness?" I'm still not
> seeing both sides of an argument.

They're saying that natural selection isn't the only cause of heritable phenotypic change.

I was in a group being shown around the Yerkes primate field station in Georgia by Irwin Bernstein, a primatologist. We came to an enclosure containing the only remaining living individuals (8 of them) of a particular kind of mangabey. Bernstein made the point that even if these 8 survived and reproduced and the population was restored, the species was essentially dead. The frequency distribution of alleles (alternative forms of a given gene) in the restored population would be so different from that of the original population that it would be wrong to call them the same kind of monkey. This kind of alteration of allelic frequency (which will almost certainly cause phenotypic changes also) can happen in nature, for example when almost all members of a particular species get killed off (by, e.g., a volcano on their island) leaving only a few breeding individuals which preserve a very skewed subset of the original gene pool.
posted by jfuller at 1:58 PM on May 29, 2007 [1 favorite]


This paper starts out as a rant on why Lynch hates the methods of public education being used and proposed by Sean Carroll. As we go further into the paper I doubt many scientists will argue against his points that non-adaptive processes play a large role in evolutionary processes. It's like he's arguing with himself, trying to create a non-existent divide, or preaching to the choir (It's rare for regular folks to read PNAS).

"Evolutionary biology is not a story-telling exercise, and the goal of population genetics is not to be inspiring, but to be explanatory." - Michael Lynch, a deep thinker

I am saddened by Lynch's presupposition that biologists do not understand that natural selection is only one of several processes that can act to shape the evolutionary history of an organism. However, the three main non-adpative forces he speaks of will likely occur in the absence of natural selection (he states this) and while they can impose strong directionality to evolutionary processes this is not to say that they are not under the explicit control of natural selection. Regardless of the mechanism of how a change came to be its prevalence and preservation within a population will act in accordance to the theory of natural selection (population genetics). Passive emergence of a trait (modular gene structure/regulatory module) will only be preserved in a geological/evolutionary timescale if natural selection acts, so it is not productive to say that organismal complexity does not have it's roots in adaptive evolutionary processes, an obviously inflammatory suggestion. If Michael Lynch ever comes to my university, and likely he will, I will be sure to remind him that it does matter how things are written even within the community.
posted by available at 2:06 PM on May 29, 2007 [1 favorite]


Well said inoculatedcities, but "the theory is invalid" also has to be on the table of scientific inquiry. There is a little too much semi-literate anti-fundie and anti-creationist attachment to the theory of evolution as fact when it is not. Scientific theories are not proved - they are disproved.

What is beyond dispute is that there is no scientific support for the creationist belief.


The theory of evolution is like the theory of gravity: it will never be "disproven," only improved, because evolution, like gravity, is directly observable close at hand. What is at issue is not the existence or importance of evolution (gravity), but a full, quantitative, and accurate articulation of what it is and how it works.
posted by Mental Wimp at 2:07 PM on May 29, 2007


I fear the role of Jack Kirby style Space God Robot Things is sorely underestimated.
posted by Artw at 2:20 PM on May 29, 2007


Close-at-hand observability is not a viable determinant for the validity of a scientific theory. Indeed, the opposite is the case: the objective generalizability of a theory is what determines its validity. Our close-at-hand observations are always conditioned by our own close-at-hand limitations. The theory of evolution is conditioned by our own close-at-hand observation of our own superiority in comparison with other organisms. The less close-at-hand we observe the entire biosphere, the more we see it as an organic unity, with ourselves merely a constituent element thereof.
posted by No Robots at 2:27 PM on May 29, 2007


I am saddened by Lynch's presupposition that biologists do not understand that natural selection is only one of several processes that can act to shape the evolutionary history of an organism.


I don't know, there is a ton of really poor evolutionary thinking out there, (see anything labeled evolutionary psychology). So I think this kind of warning is very useful.

As for Genetic Algorithms and mutations, GAs do not need mutation, but they do need random variation. Mutation is what assures variation in the natural world, but it isn't necessary in a GA, though it is very useful.
posted by afu at 3:05 PM on May 29, 2007 [1 favorite]


Again, can you simplify the argument so I understand both side?

Imagine a log washed up on the beach. It would be silly to say that the log ended up there because that was the 'best' spot for it to be based on Newtonian physics. It's possible it ended up there for no reason. If mutation and other genetic changes are the result of a random process then it can end up anywhere. Some mutations may be beneficial, some may be harmful, and some may not affect anything. Those mutations that affect nothing might be pretty in creating biodiversity as well. Natural selection doesn't mean only the "best" survive, it means anything "good enough" can.

At least that's my guess.
posted by delmoi at 3:16 PM on May 29, 2007


As for Genetic Algorithms and mutations, GAs do not need mutation, but they do need random variation. Mutation is what assures variation in the natural world, but it isn't necessary in a GA, though it is very useful.

What do you mean by "random variation" that's not a "Mutation"? Can you give a specific example of what you consider mutation in a GA and what you consider a non-mutation random variation?
posted by delmoi at 3:20 PM on May 29, 2007


OMFG! EVEN THE SCIENTISTZ DONT AGREES ON EVILOUTION!!!1 WTF?!?!?!?lol
posted by wfrgms at 3:26 PM on May 29, 2007


I believe the most serious challenge to natural selection is coming from cellular automata, specifically Stephen Wolfram, who has famously questioned the importance of natural selection.

Intelligent Design is undisprovable.

The arguments used to support ID are invalid or fallacious. This can be called disproof by anyone who cares to label it as such. The best example is the ID concept called the "mousetrap" theory. It says that if a "part" of something is conceivably taken away so that it ceases to function, then it was therefore designed. However, this totally ignores that evolution is inherently via a two-stage process of enhancement to survival, then later becoming indispensable to survival. For example, if the GPS system is an option on today's car models, but later evolves to be integral to all road travel so that cars can't function without it, then this illustrates evolution and refutes the theory.

The other two theories are by a mathematician/theologian by the name of Dembski. He argues that if humans create camera that is found in nature, then this is an argument for ID. However, the main assumption is that there is a specific function goal for evolution, when these goals don't really exist because there are things like eyes on creatures that have gone into disuse and degenerated after being fully formed.

The other argument by Dembski is the "No Free Lunch" search algorithm model, from the idea that if a random search environment is assumed, then no single search algorithm is more suited than another. Dembski then makes the assumption that evolution is such a search algorithm in search of overcoming a specific problem. Therefore, he says, there is no "necessity" for chance evolution to make complex machines to surmount special challenges. However, this conclusion completely ignores co-evolution where every challenge is basically another life form competing for survival. The necessity of special complexity is clearly needed for competition.
posted by Brian B. at 4:03 PM on May 29, 2007


Funny! ... evolution is "controversial", while rivers flowing are not.

I guess someone needs to do a Dick & Jane:
1. Nothing just pops out of nowhere.
2. The little deer with the spots is harder to see.
posted by Twang at 4:12 PM on May 29, 2007


Im not sure if anyone mentioned this.. but when dealing with evolutionary biology remember that variations exist regardless of selection. Only if those variations gives a selective advantage does it become prevalent in a population. Also not all variations are: 1) genetic (some are chromosomal), 2) are in the germ line (sexually transmittable), 3) are in the nuclear material (mitochondria DNA), 4) passable, development abnormalities are not passable to children, but may affect sexual selection.

Some variations are fatal, some do nothing. Also there is the issue of even if a gene variation does give an advantage is there enough environmental pressure to pass it to the decedents? Is it dominant or recessive? Lets assume for the moment that someone has a 'super healthiness' gene and it prevents them from contacting pandemic flu totally. Clearly its a selective advantage. However all the persons potential partners survived the flu for other reasons.. living in a cave, some other gene what have you. The super health gene it recessive, meaning that any children will only be carriers. And there is only 50% chance the grand children will be carriers. The gene may cease to exist in a handful of generations and likely wont ever be expressed again.

Evolution is more about selection criteria than about 'mutation'. No selection pressures, evolution is less likely. I don't want to say it won't happen because its sometimes hard to tell what is a selection criterion until after the fact.
posted by MrLint at 4:19 PM on May 29, 2007


What do you mean by "random variation" that's not a "Mutation"? Can you give a specific example of what you consider mutation in a GA and what you consider a non-mutation random variation?

I'm not an expert, but in my personal studies, mutation seemed to refer to a random change of a particular piece of genetic information. For a GA, perhaps selecting a bit at random and flipping it.

Non-mutation random variation could/would come from cross-over or other operations (cross-over being the major one that I'm aware of). Cross-over being taking the first X bits of the new genetic string of bits from the parent A and the rest from parent B.

During my experimentation, cross-over was the main driving force. I tried various mutation rates (ie. 50%, 5%, .001%, 0%) and was surprised to see no noticeable change in the rate of convergence to a solution, not in the quality of solution. Well, not positive noticeable change - when the rate was too high, you couldn't get a solution to converge.

One problem with cross-over without mutation is that once every member of the population has the same bit in the same position, say a 1 at position 3, then a zero can never show back up in that position.
posted by Bort at 4:43 PM on May 29, 2007


I'm not sure anybody knows what the biggest contributor to genetic variation is. Whether it be mutation, gene duplication, sequencing errors, retroviral influences, or recombination events (or anything else I've missed, haven't studied genetics for a few years now). We continue to say mutation more often than not, because that was the first mechanism to be provided, and it continues to live in our daily vocabulary.

Needless to say, there now is plenty of variation out there in every population (with the exception of unfortunate, near-extinct species like the cheetah) for selective forces to exert their effects. But ultimately, that variation had to have come from somewhere.
posted by kisch mokusch at 4:46 PM on May 29, 2007


I believe the most serious challenge to natural selection is coming from cellular automata, specifically Stephen Wolfram, who has famously questioned the importance of natural selection.

Can you state his argument or provide a link to it? I hadn't heard of that one. (I have that big book he put out, but was disappointed in it and didn't read it all).
posted by Bort at 4:50 PM on May 29, 2007


One problem with cross-over without mutation is that once every member of the population has the same bit in the same position, say a 1 at position 3, then a zero can never show back up in that position.

And that's why mutations are useful. GA's aim to explore a rugged, multi-dimensional fitness landscape. Without mutation, there are potentially various paths, various locations in that landscape that can't be tested - as you say, if all individuals have a 1 at position three, then the possibility of a solution involving a 0 at position three can never be explored. But a high mutation rate mean that if a 0 is found to be good at position three, it might not be preserved, and that solution may be lost again when it randomly gets flipped to a 1.

That's why GAs are such fun.
posted by Jimbob at 7:26 PM on May 29, 2007


Sure, there are other factors to evolution than natural selection, but it's all broadly "descent with modification". But in the main, at least among multi-cellular life, it's natural selection.

Sure, we should talk about and learn about the other factors, some of which are incredibly fascinating (take a look at segregation distorters, B chromosomes, non-Mendelian inheiritance in plants, etc., etc.)

But there are two problems here: one, you get scientits like Gould taking it to ridiculous, hand-waving extremes like "Punctuated Eqilibrium".

Worse, you get the plain people thinking that scientists fundamentally disagree on evolution, and that it's therefore a subject of legitimate contention within science. And then some plain demagogue convinces them that "disputed EVILution" has the same standing as "Intelligent Design" or flat-out (flat Earth) "Creationism".

Sure, Einstein's equations refine Newton's: but at speeds not a significant fraction of light or masses less than planetary, you'll get the same answer with either, for any practical purpose. Same thing here.

I've learned that within any subject, as you learn more and more, there are more and more layers of exceptions, specials cases, technicalities. But just because we can't solve the Three Body Problem, doesn't mean we can't tell within acceptable error where Pluto will be 100 years hence; just because we can't calculate PI exactly doesn't mean we can't design wheels; just because the magnetic pole moves (and occasionally reverses) doesn't mean compasses don't work.

If you understand any subject well enough, you can discuss the technicalities intelligently, and understand that overall they contribute to the main idea; but they don't obliterate it.

The problem comes when ill-educated people, or those with an agenda, grab onto the minor terms of the equation to proclaim that "math is disputed by scientists!"

Understand natural selection, then deal with the refinements. The refinements are not a substitute for learning the core of the matter.
posted by orthogonality at 7:48 PM on May 29, 2007 [1 favorite]


I thought this was an interesting and intelligent criticism about how even career biologists can come to "lazily" equate evolution and natural selection in their field to the exclusion of other demonstrably important aspects of the theory.

I'd like to make it clear that I didn't intend for creationism to enter into this discussion, except where the dogmatic creationist mindset is applied to interpreting everything through the lens of natural selection — and applying this in undergraduate and graduate biology pedagogy, another (to me, interesting) aspect of Lynch's criticism.

Those who read the article will notice the reason I quoted Dobzhansky, namely that Lynch focuses his argument on how evolution is broader than selection alone, particularly on complex organisms: "Nothing in evolution makes sense except in light of population genetics."

Population genetics is about stochastics, about probability models and statistical testing of allele distributions, and much of the research has been made much easier with the advance in available computational power from the 1990s onward. There has been a change in understanding of evolution — not so much "refinement" so much as empirically verifiable "confirmations" of previously controversial "speculation".
posted by Blazecock Pileon at 8:23 PM on May 29, 2007


Burhan,

Who says the species "Reverted"? I see no reason to discount the possibility that this is something that simply "Can happen" in the shark genome. Rare, like Siamese Twins, but possible. Why do you assume any process was "Subverted"? There was no sexual process, that something rare simply "Happened".
posted by bornjewish at 7:36 AM on May 30, 2007


bornjewish, well, the biologists mentioned in the article seemed to be concerned. Since as you said when you tried to school me on asexual reproduction, sexual reproduction has the advantage of shifting genes (thereby allowing for adaptation) whereas asexual reproduction doesn't.
posted by Burhanistan at 8:07 AM on May 30, 2007


Burhan,

Concerned? In what way?

I see this: Robert E. Hueter, director of the Center for Shark Research at the Mote Marine Laboratory, said the finding helped fill a gap in understanding of parthenogenesis, which has been found to occur in most vertebrate lines except mammals and, until now, cartilaginous fishes like sharks.

Sexual reproduction has certain huge advantages, when you have other members of your species about. But when you do not, it has a distinct disadvantage. Having the diversity to able to use BOTH methods has yet another advantage.

Environments change. Adaptability is quite important.
posted by bornjewish at 9:54 AM on May 30, 2007


The Uncertainty Principle does not apply to macro phenomena.

Heisenberg was concerned with velocity and location of subatomic particles. It really doesn't apply.

Now why do black holes evaporate? Here's one way to look at it, which is only moderately inaccurate. (I don't think it's possible to do much better than this, unless you want to spend a few years learning about quantum field theory in curved space.) One of the consequences of the UNCERTAINTY PRINCIPLE of quantum mechanics is that it's possible for the law of energy conservation to be violated, but only for very short durations. The Universe is able to produce mass and energy out of nowhere, but only if that mass and energy disappear again very quickly. One particular way in which this strange phenomenon manifests itself goes by the name of vacuum fluctuations. Pairs consisting of a particle and antiparticle can appear out of nowhere, exist for a very short time, and then annihilate each other. Energy conservation is violated when the particles are created, but all of that energy is restored when they annihilate again. As weird as all of this sounds, we have actually confirmed experimentally that these vacuum fluctuations are real. [my emphases]

Hawking has also used the energy/time reformulation of the uncertainty principle to argue that the Big Bang cannot have a defined location in time.

Black holes and the Big Bang are macro enough for me.
posted by jamjam at 11:54 AM on May 30, 2007


Jamjam,

Look carefully into your own quotation: "One particular way in which this strange phenomenon manifests itself goes by the name of vacuum fluctuations. Pairs consisting of a particle and antiparticle can appear out of nowhere, exist for a very short time, and then annihilate each other."

Sure "The Big Bang" and "Black Holes" are macrophenomena. However, the parts where the uncertainy principle applies are in the tiny bits.

Evolution and genetics are macrophenomena that do NOT extend into the realm of particle physics. Black Holes & the Big Bang are macrophenomena that do.
posted by bornjewish at 12:17 PM on May 30, 2007


Can you state his argument or provide a link to it? I hadn't heard of that one. (I have that big book he put out, but was disappointed in it and didn't read it all).

Here is one link attempting to contrast the two positions. Here is Wolfram's premise.

His famous quote on the matter was that he simply didn't think natural selection was all that important.
posted by Brian B. at 3:32 PM on May 30, 2007


Oops, first link above is wrong. Here is the essay contrasting Wolfram with Darwin.
posted by Brian B. at 3:34 PM on May 30, 2007


OMFG! EVEN THE SCIENTISTZ DONT AGREES ON EVILOUTION!!!1 WTF?!?!?!?lol

Um, isn't that the point of science, continual discussion and improvement?
posted by Mental Wimp at 12:20 PM on May 31, 2007


Close-at-hand observability is not a viable determinant for the validity of a scientific theory. Indeed, the opposite is the case: the objective generalizability of a theory is what determines its validity. Our close-at-hand observations are always conditioned by our own close-at-hand limitations. The theory of evolution is conditioned by our own close-at-hand observation of our own superiority in comparison with other organisms. The less close-at-hand we observe the entire biosphere, the more we see it as an organic unity, with ourselves merely a constituent element thereof.

As on an earlier thread, some are mistaking the word "evolution" for "getting better". It's not what it means in the biological context. And I'm not sure what you mean by "viable determinant for the validity..." All observations are viable determinants of validity, since validity is determined by the ability to predict observations, whether close at hand, like observing the evolution of microbes in the presence of an antimicrobial, or the product of complicated observations, like counting mutations in the genome of a particular pair of species.
posted by Mental Wimp at 12:24 PM on May 31, 2007


Wolfram's just plain wrong, as he uses statements like

For in effect it is being asked to predict what changes would need to be made in an underlying program in order to produce or enhance a certain form of overall behavior.

There is no predicting. It's a process of selecting the random mutations that occur. Selection is so strong, that long-lasting, stable species exhibiting the same phenotype for eons have different genes than the earliest populations of the species, because genes HAVE to change. Mutations of all kinds, including single nucleotide polymorhpisms, deletions, exchanges, permutations, etc., happen continually. That's why they're used as clocks timing the divergence of species. To say that natural selection has to "look ahead" and predict is utter nonsense.
posted by Mental Wimp at 12:31 PM on May 31, 2007


To say that natural selection has to "look ahead" and predict is utter nonsense.

Perhaps he agrees. I think that what Wolfram is referring to is that by assuming the iteration of a complex program that produces gene expression, then natural selection doesn't fit in the driver's seat without resorting to the absurdity of prediction. Or, to put it another way, if one assumes his theory of iteration, in all its forms, then to explain all possible life, natural selection takes a back seat as pruner, or else it must predict, which would be as problematic as you suggest.
posted by Brian B. at 4:12 PM on May 31, 2007


Perhaps he agrees.

Oh, he agrees all right, at least that the idea natural selection can look ahead is absurd. But his assertion that such a belief is necessary for natural selection to be the driving force in evolution is nonsense and he would disagree with that assertion.

More or less random changes occur in nature, without direction or purpose. The only thing that gives them importance is the "pruning" (really more than this, since enhanced reproductive success is more like "budding") driven by natural selection. Without this selection, all is entropy and life ceases as it becomes less fit for survival in a changing environment. You can watch organisms with maladaptive mutations die off rapidly. It's a strong "pruning" effect, directly observable in the relative frequency of the relevant alleles in a population. Likewise, the frequency of adaptive alleles grows quickly in a population. To suggest that these processes are not in the "driver's seat" begs the question of what more powerful effect is. Wolfram doesn't present a convincing alternative.

Further, he mischaracterizes natural selection as "scouring" and other active verbs in order to form a straw man to make his specious point. Rather than doing any scouring, it is the hard edge upon which these random changes are tested and either found to be a detriment, of no consequence, or a competitive advantage. He struggles to make it seem like complexity, per se, is the end purpose of evolution and so fit his findings of the spontaneous nature of complexity to his assertion that selection plays a minor or supporting role in adaption. In so doing, he is attempting to elevate his mathematical models to a higher role than is warranted by the facts.
posted by Mental Wimp at 4:53 PM on May 31, 2007


Mental Wimp, you have assumed Wolfram's theory is wrong by his regard for natural selection if he is right.
posted by Brian B. at 7:17 PM on May 31, 2007


Mental Wimp, you have assumed Wolfram's theory is wrong by his regard for natural selection if he is right.

I've tried to parse this for half and hour and am not getting anywhere. Care to explicate?
posted by Mental Wimp at 10:01 AM on June 1, 2007


I've tried to parse this for half and hour and am not getting anywhere. Care to explicate?

Gladly. You forgot to demonstrate that he is an unconvincing alternative, but instead assume that his lesser role for natural selection proves him wrong. Seems like you skipped a step there. It would appear that his theory is downplaying mutation as a phenomenon that is more predetermined than previously assumed. My point is that you would need to address his theory directly.
posted by Brian B. at 4:03 PM on June 1, 2007


It would appear that his theory is downplaying mutation as a phenomenon that is more predetermined than previously assumed.

No wonder I didn't understand you. No, I disagree. He's not downplaying mutation, near as I can tell, but rather up-playing spontaneous complexity regardless of the source of variability. It's based on genetic algorithms that really don't care about the mechanism of variability. Near as I can tell, he is dismissing natural selection because he can make complexity appear without it. But in evolution complexity is not the issue, per se. It is adaptation. I think that's his fundamental mistake (only a mistake if he wasn't trying to redefine evolution, which is, of course, his prerogative, but then, he has to get everyone else to go along, and then we need a new word for what used to be called "evolution").
posted by Mental Wimp at 4:29 PM on June 1, 2007


But in evolution complexity is not the issue, per se. It is adaptation. I think that's his fundamental mistake (only a mistake if he wasn't trying to redefine evolution, which is, of course, his prerogative, but then, he has to get everyone else to go along, and then we need a new word for what used to be called "evolution").

You seem to be quoting the definition of evolution in order to reject him again, and then you say it is only his mistake if he was subscribing to standard evolution, and not trying to redefine it? Obviously he is trying to explain reality, and not our understanding of the word evolution.
posted by Brian B. at 5:36 PM on June 1, 2007


I'm getting a little lost here. If he is trying to describe reality, doesn't he have to use words? And don't they either have standard meanings or new ones? If the former, doesn't he have to adhere, and if the latter doesn't he have to clearly define?

Explaining reality is all well and good, but he is also making claims about primacy, viz.,

And typically it is thought that this must be a consequence of the rather unique processes of adaption and natural selection that operate in biological systems. ... what I have come to believe is that many of the most obvious examples of complexity in biological systems actually have very little to do with adaption or natural selection.

So, no, he isn't merely explaining reality, he is making a further claim about the evolution of complex biological systems and their independence from ("...have very little to do with...") adaptation or natural selection. His explanation of how complexity arises, however, doesn't dismiss their role in allowing complexity to persist one iota, as far as I can see. He merely claims it. But I'm willing to be enlightened.
posted by Mental Wimp at 11:01 AM on June 4, 2007


If he is trying to describe reality, doesn't he have to use words? And don't they either have standard meanings or new ones? If the former, doesn't he have to adhere, and if the latter doesn't he have to clearly define?

If he is trying to describe the reality of evolution from a newer complexity viewpoint then he needs readers who don't assume that evolution can only refer to adaption. It isn't his problem to convince you in order for him to be right.

You wrote:
But in evolution complexity is not the issue, per se. It is adaptation.
posted by Brian B. at 9:10 PM on June 6, 2007


Ah, then he is making up new meanings for words. In that case, he can have at it. Just don't expect the rest of us to go along.

Might I suggest he just use the phrase "biological complexity" and avoid invidious comparisons with established concepts. If he wants to say, for example, that biological complexity doesn't depend upon selection, then, by all means, he can say so. But when he posits that evolutions doesn't, he is redefining an established concept and then the argument becomes semantic rather than scientific.
posted by Mental Wimp at 12:58 PM on June 8, 2007


Er, "evolution" that is. There is only one. I think.
posted by Mental Wimp at 12:59 PM on June 8, 2007


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