Saturday, January 19, 2008 | Science : Evolution and Biology | print version

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New Findings Confirm Darwin's Theory: Evolution Not Random

by Science Daily

Thanks to David Hobson for the link.

Reposted from:
http://www.sciencedaily.com/releases/2008/01/080118134531.htm

ScienceDaily (Jan. 20, 2008) — According to Darwin's theory of evolution, individuals in a species pass successful traits onto their offspring through a process called "deterministic inheritance." Over multiple generations, advantageous developmental trends — such as the lengthening of the giraffe's neck — occur.

An opposing theory says evolution takes place through randomly inherited and not necessarily advantageous changes. Using the giraffe example, there would not be a common neck-lengthening trend; some would develop long necks, while others would develop short ones.

Now, the findings of an international team of biologists demonstrate that evolution is not a random process, but rather occurs through the natural selection of successful traits. The collaborative study by researchers at the Technion-Israel Institute of Technology in Israel, the U.S, France and Germany is published in the November 2007 issue of Current Biology (vol. 17, pp. 1925-1937).

To settle the question about whether evolution is deterministic or random, the researchers used various tools — including DNA strand analysis and electronic microscopy — to study female sexual organ development in 51 species of nematode, a type of worm commonly used to better understand evolutionary processes.

When the researchers measured changes in 40 defined characteristics of the nematodes' sexual organs (including cell division patterns and the formation of specific cells), they found that most were uniform in direction, with the main mechanism for the development favoring a natural selection of successful traits, the researchers said.

"Since random development would not create such unifying trends, we concluded that the observed development was deterministic, not random," said Professor Benjamin Podbilewicz from the Technion Faculty of Biology.

The findings, which constitute a significant milestone in establishing and reaffirming the mechanism of Darwin's theory, will help in understanding how evolution works in all living creatures, said Podbilewicz.

Adapted from materials provided by American Technion Society.

Posted: Saturday, January 19, 2008 | Permalink

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1. Comment #113375 by AshtonBlack on January 19, 2008 at 1:06 pm

Erm.....

"through the natural selection of successful traits"

I thought that WAS evolution.
The "successful trait" creature got to make babies (on average) more than "non-successful trait."

What am I missing?

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2. Comment #113378 by LoneStarAssman87 on January 19, 2008 at 1:13 pm

"Evolution Not Random"

We didn't know this already? I think I'm missing the significance of these findings...

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3. Comment #113379 by Steve Zara on January 19, 2008 at 1:15 pm

Erm.....

"through the natural selection of successful traits"

I thought that WAS evolution.
The "successful trait" creature got to make babies (on average) more than "non-successful trait."

What am I missing?

Nothing that I can see. I would be interested to know what the opposing theory is - one that suggests that significant changes occur either without, or against, the pressures of selection. Sounds a bit odd to me.

I do wonder if they have things a little confused here. There is a perfectly acceptable theory suggested by Motoo Kimura that there are plenty of neutral mutations, and genetic drift is possible without the involvment of selection. But that only works because the mutations have little or no effect on the phenotype - the structure and functioning of an organism. (Note the last phrase. Part of my new Plain English/Science approach, resulting from a message that was complementary about my posts, but pointed out (fairly) that they may be hard for a lay-person to follow).

"Evolution Not Random"

We didn't know this already? I think I'm missing the significance of these findings...

We know that mutations are almost always random. The idea that is being opposed here is that evolution - accumulated changes in organisms - is random, and is not always a result of selection.

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4. Comment #113380 by Diacanu on January 19, 2008 at 1:15 pm

Evolution Not Random

You could engrave this on the side of a wrecking ball, and smash a creationist in the fucking head with it, and they'd still get up, dust themselves off, and say it was.

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5. Comment #113381 by Paula Kirby on January 19, 2008 at 1:15 pm

Shouldn't this article have a dateline of 1859?

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6. Comment #113386 by LorienRyan on January 19, 2008 at 1:24 pm

"through the natural selection of successful traits"

Wouldn't it be more acurately put - 'through the natural interaction of an organism with it's environment successful traits emerge.'

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7. Comment #113387 by Zakie Chan on January 19, 2008 at 1:25 pm

The obviousness of this article makes me feel like I am missing something.

Maybe its an attempt to get the majority of the American public to realize that contrary to what the creationists say, it not a random process... though, I doubt many of them will read Science Daily.

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8. Comment #113391 by Ian on January 19, 2008 at 1:36 pm

Part of me feels that these people have just charged an open door.

Whatsmore, I think things are confused by using the random/determined distinction. Saying evolution is determined implies predetermined.

I prefer the terminology which says natural selection tracks the environment, thus avoiding any confusion determined and guided. This way it is clear that evolution is not random or guided.

Am I the only person to be picky this way?

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9. Comment #113393 by Steinsky on January 19, 2008 at 1:39 pm

I _love_ scientific press releases. There are some absolute crackers out there. I subscribe to EurekAlert's biology press releases and it really is marvelous. I've yet to see one that demonstrates any actual understanding of the research being reviewed, but they show such incredible creativity in their attempt. There are a selection of them linked here.

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10. Comment #113394 by Goldy on January 19, 2008 at 1:39 pm

I always saw evolution as water flowing down a flat sloping surface surface. It starts at the top and gets to the bottom but the path in between is up to chance. It isn't celestially predetermined in that the environment dictates the outcome.

Using the giraffe example, there would not be a common neck-lengthening trend; some would develop long necks, while others would develop short ones

Like the okapi, perchance?

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11. Comment #113395 by Steve Zara on January 19, 2008 at 1:41 pm

Am I the only person to be picky this way?

No. I think you are right. What they are showing is that Evolution has a direction, not that it is deterministic.

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12. Comment #113396 by Diacanu on January 19, 2008 at 1:45 pm

Steve Zara-

Evolution has a direction

You've gotta be careful with language like that though, cuz it gives comfort to assholes like social darwinists, who think evolution is a ladder going towards human ideas of strength and intelligence.

Evolution isn't a path or a ladder toward any particular ideal.
Evolution doesn't give a shit about ideals.

But saying it has a direction leaves it open that it has a destination, and that's all those nazi types need.

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13. Comment #113397 by Steve Zara on January 19, 2008 at 1:47 pm

You've gotta be careful with language like that though, cuz it gives comfort to assholes like social darwinists, who think evolution is a ladder going towards human ideas of strength and intelligence.

Yes, you are right. What I should have said is that "Evolution is driven by selection pressure"

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14. Comment #113399 by Goldy on January 19, 2008 at 1:50 pm

Given the way English can be so misread at times, I think it's high time scientific thesis were written in Latin again ;-)
Now, how did it go again? Mensa, mensa, mensam, mensae.....

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15. Comment #113401 by Double Bass Atheist on January 19, 2008 at 1:57 pm

Shouldn't this article have a dateline of 1859?

Paula, I had the exact same thought while reading this!
Great minds, my friend. Great minds.
(you do have the alluded to saying in UK, don't you? There's always that 'separated by a common language' thing hanging over our heads)
:-b

Diacanu

Evolution isn't a path or a ladder toward any particular ideal.
Evolution doesn't give a shit about ideals.

True. Very true. Far too many creationists (and even quite a few evolution supporters) have this gross misunderstanding that our human evolution was this steady, linear march from one humanoid creature to a better more humanoid creature, and so forth, right up to homo sapiens.
Fact is that the evolution of humans (and indeed all life) has had many 'dead ends' where a sub-species died out.

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16. Comment #113403 by Donald on January 19, 2008 at 1:59 pm

[ Edit: This post was made before I read the paper, and turned out to be irrelevant and inaccurate speculation. I have left it here because later comments referred to it. ]

I think what is being claimed is that observed variation is not random in respect of whether it is advantageous or disadvantageous to the organism. Rather, that advantageous variation is much more common than disadvantageous variation.

This implies that there is well-developed layer of genes that control variation (I nearly wrote "control mutations", but it might be necessary to distinguish the two).

How could that possibly be?

Well, one obvious suggestion is that species on earth have gone through numerous repetitive cycles of the environment. Evolving for a warmer climate, then evolving back to a cooler climate, evolving for wetter conditions, then drier, etc. (Perhaps on a faster scale, for much simpler organisms that reproduce in days rather than years, evolving for longer days, then for shorter days, etc.)

In such an evolutionary history, if any genes existed that could control the direction of evolution of certain other genes which themselves directed such things as size, weight, bodily proportions, etc, then genomes with that extra layer of elaboration would evolve/adapt faster than simpler organisms. For example, imagine a master gene that could be switched to "mutate to larger size more often than smaller", or "mutate to smaller size more often". An organism with such a master gene would adapt to changes in environment that favoured a change in size, faster than random mutations. Those organisms with the master switch set to larger would tend to die out in environments that favoured smaller organisms until the organisms were about the right size, than the allele frquency of the master switch would again approach 50-50 until the next change in the environment.

To go back to the nematodes, perhaps the nematodes being studied did not come from an environment in which they had achieved evolutionary equilibrium, and evolution control genes were biased in a favourable evolutionary direction.

In general, of course, environments are continually changing due to evolution itself. The environment of orgainsisms is partly non-biological and partly the presence of the other species, all continually evolving too, and providing competitive pressure along the way. Master genes, controlling the mutation/evolution of other genes might themselves be subject to natural selection. I suspect there is a whole complex layer of master genes in higher animals.

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17. Comment #113406 by octopus on January 19, 2008 at 2:04 pm

...perhaps if you add
"towards optimal solution for given organism and the conditions at the time"
?

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18. Comment #113408 by Steve Zara on January 19, 2008 at 2:10 pm

Donald:

In fact this is fascinating research. I think what is being claimed is that observed variation is not random in respect of whether it is advantageous or disadvantageous to the organism. Rather, that advantageous variation is much more common than disadvantageous variation.

Are you sure? I agree it is a confusing article, but what it seems to say is this:

Now, the findings of an international team of biologists demonstrate that evolution is not a random process, but rather occurs through the natural selection of successful traits.

It does not seem to say anything about the variation, only about what is selected. It could well be that there is considerable variation in genes, but only a few survive the process of development. That is how I read it, anyway.

I think the idea of genes that control the direction of evolution is a highly problematic one. I can see how a gene could potentially control the rate of mutation (by changing the amount of DNA repair enzymes), but not the direction.

I agree that Dawkins' views would be very interesting.

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19. Comment #113411 by Vinelectric on January 19, 2008 at 2:14 pm

Steve

This is the conclusion of the abstract:

We propose that developmental evolution is primarily governed by selection and/or selection-independent constraints, not stochastic processes such as drift in unconstrained phenotypic space.

The message is, apparently, that evolution is deterministic but if you read the paper you'll see that they chose to study an organ which is known to be highly conserved anyway. You may argue that the development of certain organs can 'lock' the evolutionary process into a certain direction but the authors did not make an effort to justify applying this conclusion to evolution in general.

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20. Comment #113412 by Rational_G on January 19, 2008 at 2:14 pm

"New Findings Confirm Newton's Theory - Gravitational Force Inversely Proportional to the Square of the Distance"

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21. Comment #113416 by jshuey on January 19, 2008 at 2:32 pm

I'd love to hear RD chime in on this one...

Perhaps there's something we're missing.

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22. Comment #113423 by BGordon on January 19, 2008 at 2:43 pm

Hi all,

I also read this as saying that the observed -mutations- are directed, not random. That's really different, implying that the big spook has a finger in the pie unless the answer is similar to the one Donald (16) describes. Is this just a case of bad reporting?

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23. Comment #113425 by ianmkz on January 19, 2008 at 2:45 pm

Here is another article on the same subject
http://www.eetimes.com/rss/showArticle.jhtml?articleID=205901264&cid=RSSfeed_eetimes_newsRSS
Seems to say the same thing, though it uses the word "successive" instead of advantageous.

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24. Comment #113433 by Donald on January 19, 2008 at 3:00 pm

Steve:
I haven't read the paper. All my speculations in the previous post should be taken as just that - speculations.

Plus, the ScienceDaily article confuses development with evolution. I thought I could read though that to a reasonable interpretation of what the paper said. But on reflection I'm much more doubtful. Thanks for the sentence from the abstract Vinelectric - do you have the whole abstract?

As far as genes controlling direction of variations goes - I didn't have in mind direct control of mutations. I rather had in mind that things like size might be the result of promoter genes or other forms of control gene that might be switchable up or down from generation to generation.

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25. Comment #113437 by athegan on January 19, 2008 at 3:09 pm

An opposing theory says evolution takes place through randomly inherited and not necessarily advantageous changes. Using the giraffe example, there would not be a common neck-lengthening trend; some would develop long necks, while others would develop short ones.

Who advocates this opposing theory?

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26. Comment #113443 by Shane McKee on January 19, 2008 at 3:12 pm

What this seems to be saying is that phenotypic traits themselves (or at least the ones studied) are rarely selectively neutral. It's a bit of a dumb-arse question - most of us are interested in how the "cool stuff" arose - complex adaptations. In these situations there is really no question - selection is how you get good adaptations. For things like eyes and wings etc, it's pretty clear that selection is operating, but it is perhaps less clear for things like height, eye colour, shoe size (in humans).

So it seems that when we see a change in some phenotypic variable within a subpopulation, we should cherchez la sélecteur, rather than just necessarily pinning it down to drift or founder effect. But a lot of this is predicated on what genetic factors are responsible for the *variability* in a trait in a population - this is not necessarily totally the same set of genetic factors that was involved in the trait being there in the first place. If you get my drift. Or selection.

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27. Comment #113444 by Vinelectric on January 19, 2008 at 3:14 pm

Donald

This is the Medline entry:

Curr Biol. 2007 Nov 20;17(22):1925-37

Trends, stasis, and drift in the evolution of nematode vulva development.
Kiontke K, Barri�re A, Kolotuev I, Podbilewicz B, Sommer R, Fitch DH, Félix MA.

Department of Biology, New York University, Main Building, Room 1009, 100 Washington Square East, New York, New York 10003, USA. kk52@nyu.edu

BACKGROUND: A surprising amount of developmental variation has been observed for otherwise highly conserved features, a phenomenon known as developmental system drift. Either stochastic processes (e.g., drift and absence of selection-independent constraints) or deterministic processes (e.g., selection or constraints) could be the predominate mechanism for the evolution of such variation. We tested whether evolutionary patterns of change were unbiased or biased, as predicted by the stochastic or deterministic hypotheses, respectively. As a model, we used the nematode vulva, a highly conserved, essential organ, the development of which has been intensively studied in the model systems Caenorhabditis elegans and Pristionchus pacificus.
RESULTS: For 51 rhabditid species, we analyzed more than 40 characteristics of vulva development, including cell fates, fate induction, cell competence, division patterns, morphogenesis, and related aspects of gonad development. We then defined individual characters and plotted their evolution on a phylogeny inferred for 65 species from three nuclear gene sequences. This taxon-dense phylogeny provides for the first time a highly resolved picture of rhabditid evolution and allows the reconstruction of the number and directionality of changes in the vulva development characters. We found an astonishing amount of variation and an even larger number of evolutionary changes, suggesting a high degree of homoplasy (convergences and reversals). Surprisingly, only two characters showed unbiased evolution. Evolution of all other characters was biased.
CONCLUSIONS: We propose that developmental evolution is primarily governed by selection and/or selection-independent constraints, not stochastic processes such as drift in unconstrained phenotypic space.

PMID: 18024125 [PubMed - in process]

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28. Comment #113447 by ianmkz on January 19, 2008 at 3:16 pm

This is a much more helpful summary of the findings
http://ts-si.org/content/view/2758/991/

with a link to the pdf of the paper
(still don't get it though)

From the intro of the paper

Much of research in evolutionary developmental biology
is concerned with elucidating how divergent and novel
features have evolved or how the same type of feature
has evolved convergently [1�5]. However, there are
many features that have remained largely static, even
over vast evolutionary distances between species [2].
It might be expected that purifying selection would
also prevent change to the developmental mechanisms
that give rise to such features. Indeed, one of the main
architects of molecular evolution, Emile Zuckerkandl,
predicted that stabilizing selection on the phenotype
would be reflected in stability of the underlying molecular
features [6]. Nevertheless, several examples from
a variety of different systems demonstrate that a large
amount of variation has evolved in the development of
homologous, highly conserved features [2].

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29. Comment #113448 by Steve Zara on January 19, 2008 at 3:18 pm

Vinelectric:

Does make one wonder how they got from that to the Science Daily article... a lot of mutations in the process it seems!

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30. Comment #113450 by Vinelectric on January 19, 2008 at 3:22 pm

innit?

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31. Comment #113451 by ianmkz on January 19, 2008 at 3:22 pm

To be fair to Science Daily, problem seems to be with the American Technion Society press release

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32. Comment #113455 by Donald on January 19, 2008 at 3:28 pm

Ok, I've read the paper now. http://www.current-biology.com/content/article/fulltext?uid=PIIS0960982207021938

Cancel my inappropriate speculations.

It's an interesting paper, but it's not about whether variations tend to be favourable or not.

It's about alternative ways to get a successful result in the adult organism. The question was: do the different developmental steps found in different worms (for "development" read "growth from egg to adult via embryo") arise from neutral variation in the genes (neutral = giving neither advantage nor disadvantage to the individual) or from natural selection pressure.

They found that the gene evolution (as inferred from gene similarities) was largely due to natural selection pressure, not drift amongst equally satisfactory alternatives.

Apologies for the earlier post.

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33. Comment #113465 by quill on January 19, 2008 at 4:18 pm

This just in--evolution occurs by natural selection! x_o

In other news: Moon devoid of atmosphere, astronomers say.

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34. Comment #113488 by Nick6742 on January 19, 2008 at 6:16 pm

I don't think the journalism in this piece was of the highest quality. i.e. 'electronic microscopy'

I assume they meant electron microscopy, which is a very different thing than electronic microscopy ( which could describe almost all modern microscopy)

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35. Comment #113517 by dragonfirematrix on January 19, 2008 at 9:33 pm

It is great to hear Darwin still rocks! I think we learn more everyday just how brilliant was Darwin.

I do have a couple of questions, the first of which confounds me a bit.

How does deterministic inheritance explain the profound genetic problem so evident in those who follow imaginary gods like those of the Abrahamic religions? Are these followers of imaginary gods those who will ultimately become extinct?

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36. Comment #113518 by Socrates on January 19, 2008 at 9:46 pm

This article is just so bizarre...

I don't understand why Science Daily would post something like this.

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37. Comment #113528 by oriole on January 20, 2008 at 12:01 am

In "The Blind Watchmaker", Dawkins talks about mutationists, a strange school of evolutionists who accept not just micro-evolution but also macro-evolution (they are not ID'ers), but think random DNA mutations alone do the trick; they reject natural selection, or at least think it plays a relatively trivial role. Dawkins points out that they do not have an alternative explanation of why evolution proceeds so rapidly and obviously leads to favourable outcomes, and it's pretty clear that he regards the theory as at best incomplete and perhaps even incoherent. The research mentioned in this article would seem to be intended to refute the mutationists.

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38. Comment #113546 by rodch on January 20, 2008 at 1:51 am

Steve Zara:

Does make one wonder how they got from that to the Science Daily article... a lot of mutations in the process it seems!

Mutations are not a problem, provided the selection process works. Seems not to have been the case in editing of the article.

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39. Comment #113571 by d4m14n on January 20, 2008 at 4:23 am

So is this basically saying that genetic drift is BS?

http://en.wikipedia.org/wiki/Genetic_drift

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40. Comment #113823 by Godless Heathen on January 20, 2008 at 5:06 pm

In other breaking news, president Roosevelt (Teddy, not Franklin) met with his cabinet this afternoon...

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41. Comment #113850 by Bobington on January 20, 2008 at 6:51 pm

This article confuses and angers me.

Why in the heck did they post this in the front page? I might be a complete idiot, but this study/article seems like the most ridiculous thing ever.

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42. Comment #113852 by kezz on January 20, 2008 at 6:53 pm

I agree with bobington

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43. Comment #113954 by Azven on January 21, 2008 at 4:40 am

I'm glad I'm not alone in being confused by this article. Either they are explaining the obvious (that successful traits become successful in successful generations) or else they've proved something, but haven't explained exactly what!

I suspect that this article was chopped up before publication to make it shorter and to take out all that too confusing scientist talk that we folk just won't understand!

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44. Comment #114284 by TSSI on January 21, 2008 at 6:41 pm

The press releases, such as Science Daily uses, are but one source for TSSI articles. In addition to the release, we do independent research on a subject, including various university and institute sources as well as the paper itself before we write and publish an article.

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45. Comment #114720 by ianmkz on January 22, 2008 at 4:00 pm

So is this basically saying that genetic drift is BS?

No. While most of the developmental features they looked at showed the hallmarks of natural selection , a few did not. So some new characteristics give a selective benefit and are retained through future generations, and others (a significant minority) don't give a selective benefit and are "free" to mutate back to the original form in future generations.

While it may seem a bit of a non-finding, perhaps the point is that this is an examination of a real phylogenetic tree that shows the majority of characteristics studied were arrived at by selection and not "luck". It is one thing to theorize about natural selection, to see how elegant and obvious it all is, but quite a different thing to prove it. I don't know what other proofs (at the genetic level) are out there.

While this summary of the paper is desperately bad the TS-SI one is quite helpful
http://ts-si.org/content/view/2758/991/

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46. Comment #117684 by Spin-oza on January 29, 2008 at 11:28 am

BIZARRO... studying vulvar development among Nematodes... sheesh!

But seriously... or more accurately, philosophically, as an utter Determinist, it is a nice result to have the uniform direction of genetic variation during evolution so neatly confirmed.

Randomness has no place to hide in our causal Cosmos... but then again, neither does a soul-based, free-willing, ethereal moral agent, eh?

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