Milan Ćirković has written an interesting piece in Nautilus (and featured on RealClearScience) titled, Why Darwin Needs ET. Ćirković is not a biologist; he’s a senior research associate at the Astronomical Observatory of Belgrade and an assistant professor in the Department of Physics at the University of Novi Sad in Serbia and Montenegro. Nevertheless, the questions he poses in his article are interesting ones, and I’d like to hear what readers – especially those with a strong background in the life sciences – think of his questions, and his proposal regarding how scientists could go about answering them.
In order to avoid confusion, I should declare at the outset that Ćirković isn’t asking whether evolution generates the same outcomes elsewhere in the cosmos as the ones it generated on Earth. His question is a deeper one: he wants to know if it’s the same kind of process on other life-bearing planets as it is on Earth. In his own words (emphasis mine):
But does evolution operate the same on life everywhere? The success of Darwinian theory to explain life on Earth has lulled many of us into thinking that it must be. In fact evolution might have functioned by different mechanisms in Earth’s distant past as well as elsewhere in the galaxy. We could envision a planet dominated by Lamarckian inheritance of acquired traits, or a world where large mutations — and not the gradual variation of natural selection — are the main agents of change.
The first thing that strikes me about this paragraph is that it misrepresents how evolution occurs on Earth, in referring to “the gradual variation of natural selection” as the main agent of evolutionary change. It isn’t. Don’t take my word for it; listen to what biologists working in the field have to say.
In a now-famous post titled, The state of modern evolutionary theory may not be what you think it is (February 14, 2014), evolutionary biologist P.Z. Myers handily summarizes the new “post-modern” view, as he describes it:
First thing you have to know: the revolution is over. Neutral and nearly neutral theory won. The neutral theory states that most of the variation found in evolutionary lineages is a product of random genetic drift. Nearly neutral theory is an expansion of that idea that basically says that even slightly advantageous or deleterious mutations will escape selection — they’ll be overwhelmed by effects dependent on population size. This does not in any way imply that selection is unimportant, but only that most molecular differences will not be a product of adaptive, selective changes…
Please note: this does not deny that the selection shapes specific traits in a species occurs — we do undergo evolutionary adaptation! It merely says that most of the genetic changes are random.
Over at Sandwalk, Professor Larry Moran broadly endorsed what Myers had written:
What Neutral Theory tells us is that a huge number of mutations are neutral and there are far more neutral mutations fixed by random genetic drift (than) there are beneficial mutations fixed by natural selection. The conclusion is inescapable. Random genetic drift is, by far, the dominant mechanism of evolution.
Professor Moran then went on to criticize the popular tendency of “dismissing random genetic drift because it only deals with ‘background noise’ while natural selection is the mechanism for all the interesting parts of evolution.”
If Ćirković had read P.Z. Myers’ post, he would have also been interested to learn that Myers gives qualified support to Dr. Eugene Koonin’s view – elaborated in his 2011 book, The Logic of Chance (FT Press) – that “quasi-Lamarckian evolution” is “a major factor of evolution” – at least, for bacteria. Koonin also insists: “Gradualism is not the principal regime of evolution.” As he puts it: “Even single gene duplications and HGT of single genes are by no means ‘infinitesimally small,’ nor are deletion or acquisition of larger regions, genome rearrangements, whole-genome duplications, and, most dramatically, endosymbiosis.” Myers approvingly adds that “even point mutations can have large phenotypic effects.”
Additionally, Myers’ post answers Ćirković’s question as to whether evolution operated by different mechanisms in Earth’s distant past. Koonin’s response is that while “present-day evolutionary processes” have been significant “since the origin of replication,” “major transitions in evolution, such as the origin of eukaryotes, could be brought about by (effectively) unique events such as endosymbiosis” (emphasis mine). Finally, evolution prior to the last universal common ancestor “partially relied on distinct processes not involved in subsequent ‘normal’ evolution.”
In his article, Ćirković proposes a way of answering the questions he poses: “Advances in the field of astrobiology may one day allow us to test evolutionary theory on empirical grounds… Any evidence of life elsewhere in the universe will help us understand whether the mechanisms of evolution extend beyond our planet to the cosmos.”
I would suggest that another way of answering Ćirković’s questions would be to seed other planets (such as Mars) with life, and see what happens. Detecting alien life could take a very, very long time; whereas observing the dominant mechanisms of evolution on Mars would likely require only a few centuries of research.
Ćirković is refreshingly candid about one point, though:
We are not entirely sure how selection works on Earth.
Consider the classic problem of the origin of the complexity of life we see today. The theory of evolution tells us that organisms evolved from a common ancestor starting from the first, simple life form to more complex ones: Independent genes joined up to form chromosomes, organelles came to be incorporated into prokaryotic cells, and single-celled organisms gave rise to multicellular ones. The trouble is we aren’t sure how this hierarchy came to be. (Emphases mine – VJT.)
So far, so good, but I’m a little uneasy with the way in which Ćirković elucidates the problem of how complexity arose:
Natural selection doesn’t give us a clear answer as to why the selection pressures for more simple organisms didn’t get in the way of the development of higher level entities. Darwin touched upon this problem in The Descent of Man when he noted how in some cases, selfish behavior advances the survival of an individual, but the opposite action, self-sacrificial behavior, promotes the wellbeing of a group. (Emphases mine – VJT.)
I have never heard anyone link the problem of the origin of biological complexity with promotion of the well-being of the group before. But perhaps I haven’t read widely enough. Would other readers like to weigh in on this point?
A final question posed by Ćirković concerns the source of genetic variety:
Consider that each major evolutionary innovation opens a larger space for possible variations. For example, before multicellular life appeared, there was only so much that unicellular organisms could do — they could not run, build hives or develop language. In this way, we can speak about all organisms on Earth as constrained by one network of evolutionary processes — a biosphere.
But if we come across life elsewhere, will we find that adaptation involves a rich feedback within a biosphere? Or will we come across a life form whose genetic variety comes entirely from within — like a form of evolutionary bootstrapping — in which all future changes of an individual are pre-programmed? (Emphasis mine – VJT.)
It seems to me that neither alternative quite gets it right, here. I’ll let Professor P.Z. Myers have the last word (emphases mine):
Under the modern synthesis, populations are primarily seen as plastic and responsive to changes in the environment, producing species that are most strongly marked by adaptive changes. In the postmodern evolutionary view, history dominates — most of the properties of a species are a contingent product of its ancestors’ attributes. “Everything is the way it is because it got that way.” Everything you see in an organism is a consequence of its history, with the addition of a few unique adaptive fillips, and that has two significant implications: you can’t understand an organism without recognizing the impact of its phylogeny, and the modern form preserves ancestral relationships that can be analyzed to discern that history.
At this point, I’d like to throw the discussion open to readers. How would you answer Ćirković’s questions, and how would you test the answers that you propose?
I wonder if Allan Miller thinks Neutral Theory and Nearly Neutral Theory are evolutionary theories.
It just happened, that’s all. That’s some theory ya’ll got there!
Why do you wonder that? Only a person who has either read nothing or very little (or didn’t understand) anything Allan Millar has said on this subject, would wonder about that.
They’re components of evolutionary theory (they deal with aspects of the phenomenon of mutation), but not in themselves complete theories of evolution.
Can you quote me a biologist who actually says that and then says this is basically what evolutionary theory is?
The problem with relying on extended quotes from somebody else is that their meaning may not be clear and the original author isn’t available to clarify. I’m not sure what Cirkovic was trying to say, and as you note he seems confused about evolutionary theory.
The nature of evolution clearly must depend on the nature of the organisms, particularly their methods of inheritance. Clearly these differ somewhat among species today. Horizontal transfer by various means may be more or less common depending on several factors. Different sorts of mutations may have greater or lesser frequency. Endocellular symbiosis may or may not exist. It’s conceivable that life on other planets may have more radical departures from life as we know it.
That said, I don’t see either of the options you mention, Lamarckian inheritance or front-loading (if that is indeed what that last bit is supposed to mean), as being plausible.
There are certain universals, I think. There must be inheritance, and the mutation rate must be reasonably low but not zero. Natural selection is unavoidable. Drift is unavoidable. Other than that, it isn’t clear.
Oh, I don’t think your proposed experiment makes any sense, for several reasons. First, seeding Mars seems impractical; I don’t think we have any earth life that could survive there. Second, the time scale of such an experiment would be longer than you seem to suppose. Finally, and most importantly, since evolutionary processes depend on the nature of the organisms, I wouldn’t expect to see any different processes operating in a different environment. Different results, certainly, but this wouldn’t address what you’re interested in.
PZ isn’t really working in the field, let alone Moran.
That said, I can’t see much wrong with what PZ wrote there, other than that he overemphasizes the importance of neutral evolution based on its quantitative effect on genetic change. Perhaps because he’s trying to address an existing imbalance of understanding.
The question is what you’re thinking of as “evolutionary change.” If you’re just thinking of genetic change, fine, neutral or near-neutral evolution apparently is most important. If you’re thinking of dinosaurs evolving flight and “becoming birds,” presumably natural selection matters a great deal more than “neutral evolution.” Natural selection and sexual selection probably are responsible for human intelligence and bipedalism. I would argue that most of what interests people about evolution (why complex functionality exists, and why new functionality arises) involves natural selection (and I’d tend to think of sexual selection as a type of natural selection–it’s not written in stone, though), while neutral evolution’s role in that is in supplying variation that can be selected for adaptation.
As to gradualism vs. larger-scale changes, it doesn’t seem especially important. Natural selection works with HGT and mutations that produce larger effects as well, so that the fact is that Darwin’s sort of gradualism doesn’t seem to be true throughout all of evolution, yet it matters little to the importance of natural selection or of genetic drift.
On the question of whether it would be the same elsewhere, it’s hard to think how it could be substantially otherwise. No one can figure out how Lamarckism (and no, I don’t care at this point what Lamarck was all about, I’m just using the term as people understand it today) could ever work, and today’s evolutionary theory isn’t wedded to strictly gradualistic change anyway.
Glen Davidson
I think it likely that chemistry is the same everywhere. But it does not follow that evolution is the same everywhere.
Given a planet with life:
did life go beyond bacteria?
is there horizontal gene transfer?
did meiosis evolve?
did sexual reproduction evolve?
I don’t see how those can be answered without empirical evidence. Yet they refer to features of biology that are important for evolution on earth.
On another planet, perhaps alternatives to these have evolved. But it might be hard to imagine what those alternatives could be.
Mung,
Does anyone really care? But since you ask, I think that the ‘nearly neutral’ and the ‘neutral’ zones are simply parts of the continuum of selective advantage to which I have alluded elsewhere. Positive and negative selection, the value zero and the region where population size makes small selection coefficients effectively zero all amount to different aspects of the population resampling process. Different things happen at different degrees of differential, but no-one would seriously argue that they are somehow different theories of evolution.
Would they?
What happens at s=0 and what happens at s=0.00001 when Ne > 10000 are different theories of evolution?
I would think that atheists would want to shy away from any thought that there might be universal laws of evolution. That would smack of teleology.
You’ve brought up the term teleology several times. What exactly do you take the word to mean? What concept?
An object or a behavior is said to be teleological when it gives evidence of design or appears to be directed toward certain ends.
http://www.counterbalance.org/evolution/teleo-frame.html
I am not impressed by what Ćirković said. A key issue is what mechanism brings about the bias toward changes that are adaptive. Just having large mutational changes, symbioses or whatever is not going to maintain viability or bring about adaptation. So waving one’s hand in the air and saying “it could be symbiosis, it could be large mutations” is useless. They will result overwhelmingly in things becoming nonfunctional, unless there is natural selection to preserve the ones that work, and that work better. And of course that natural selection is present — you can’t not have it when the changes affect the functioning of the cell. That will be true whether changes are large or small — just having large ones does not eliminate natural selection.
As for “Lamarckian” mechanisms, they are hard to imagine. (I put this in quotes because it is different from the use-and-disuse effects Lamarck actually imagined). You need to have a feedback from, say, your kidneys getting a lot of use to the mutational process, in a way which ensures that mutations are then biased in a direction which tends to cause adaptive changes in the kidneys. I heard François Jacob give a lecture at our university in the 1970s. An audience member asked if he couldn’t give credence to “Lamarckian” views, and he replied that the problem with them was that there was no pathway for information to flow back from the proteins to the genes they encoded, so “Lamarckian” mechanisms wouldn’t work.
I suggest one listen to Ćirković on the subject of galaxies, but ignore what he says about evolution.
Mung,
The newest strategy appears to be to say that teleology is not a problem for evolution, and just hope that no ones notices.
Just ask Neil.
Did you read the last two paragraphs at the link you sent? Dr. Ayala includes the result of natural selection in his definition of teleology.
Do you include that when you use the term teleology?
And one can just as easily say, as evolutionists are want to do with their undefined theory, that the pathways for Lamarckian transfer simply aren’t well known yet, but they are still looking.
Of course. I’m not the one that’s afraid of teleology.
Are you afraid of NS driven “teleology”? That would smack ID
I just thought maybe you would find it useful, as I do, to separate teleology from teleonomy, so there is no confusing the two.
It depends on what you mean by “teleology”.
Water runs downhill. Can we count that as a kind of natural teleology?
There are lots of natural phemonena that can be described as if teleological. And many of them were described that way before science gave us a better understanding of the phenomena.
Nice to see you VJ.
additionally
Real, and observed evolution is toward simplicity, not complexity.
The only place things naturally evolve to be more complex (on net average) is in the imagination of evolutionary proponents, not in actual present-day lab and field observations in real-time.
At the very least, the question of whether it should be the ordinary expectation that things evolve to be more complex is open. It would appear extravagance and complexity is liability for survival, not a benefit. This was brutally apparent when Darwin commented how the peacock’s tail made him sick.
Could evolution of evolved differently on other planets? Hmmm.
Why not? Whats the big boundary?
if evolution is just chance working on material then evolution could be everywhere.
The problem is thats its very unlikely to a careful intellectual reflection that the glory of biology could be organized by chance operations.
In fact its impossible.
Saying this can evolve into that is saying anything can go from this to that. So why not
go back the way it came? Or go into any lineage however crazy.
Its just impossible for a fish to have become a rhino however much time plus mutations one could rustle up.
Evolutionism was made credible in dumber days in the 1800’s in small circles of the upper classes who rejected the bible.
Its being ended as a hypothesis in our time.
Boy I sure hope evolution is towards simplicity. It’s about the only way I stand a chance.
This is a dishonestly selective use of your sources. You should be ashamed. Let’s see the whole abstract:
And it seems to me that a good example of this sort of thing would be the two tetraploid events in the origin of vertabrates (and another in teleosts), followed by differentiation and gene loss in the extra genome copies.
Of course the ordinary expectation is not that things will evolve to be more complex. It’s that sometimes they will become more complex, sometimes they will become simpler, and sometimes they will stay the same, depending on what is locally advantageous.
Appears to be directed towards certain ends, that’s a strange sentence because how do you know it’s “directed” towards something, rather than just having unintended biased outcomes? If a coin is slightly heavier on one side than the other, is it “directed towards” landing on that side? Coins are of course designed, but that doesn’t mean all aspects of the usage of coins are intended (such as it landing slightly more on one side than the other).
Maybe a better example would be some random rock you find on the ground. There’s probably going to be one side it lands on more than another. Is that rock designed to land on that side? Or does it give the appearance of “being directed toward” that “end”?
Mung,
This atheist does not find that ‘universality’ in evolution implies telelogy, so no. I don’t find the idea that gravitation always applies, or sodium and chlorine combine in the same ratios and with the same bond strength everywhere to be teleological, so I have no more problem with the potential universality of the consequences of population resampling.
Oh yeah I left this out:
You mean like “poof” with no explanation, followed by reduction. So what will give an explosive phase for a prokaryote to become a eukaryote. Any laboratory suggestions how a prokaryotic genome will start having spliceosomal introns and spliceosome and histones out of nowhere?
Like an act of special creation followed by genetic deterioration. Maybe I should have included that part of the abstract after all.
In fact, here are some present day field results of increased selection pressure by depletion of habitation and food resources:
Ah, look at what all that increased selection pressure is doing, it’s eliminating species more than originating them. Darwin should have entitled his book: “Elimination of Species by Means of Natural Selection, or the Wiping out of Un-Favored Races in the Struggle for Existence.”
Regarding VJTorley’s question, if evolution follows elsewhere like it does on Earth today, then there won’t be much complex life over time.
And how about the lab, here is a review article by Behe (which is basically taking existing lab experiments and listing them in agonizing detail):
And last but not least you yourself said:
For once we half agree.
That would be because you do not understand the meaning of the term.
Appears to be directed. Like the WEASEL program appears to be directed towards a specific outcome.
If a coin always or almost always lands heads up, it would certainly appear to be directed towards that end.
If it always or almost always exhibits the same behaviour, yes.
That didn’t answer the question I asked.
Again, how do you know it’s “directed” towards something, rather than just having unintended biased outcomes?
Why “almost always” or “always”? Where is the cut off? If it only lands on one side 0.00013% more than the other, is it then “directed towards” landing 0.00013% more often on that side?
Do you think the rock was designed to mostly land on one side simply because it mostly does so?
This teleology term you use, the way you use it seems to say exactly nothing more than “whatever happens, in so far as it is not equiprobable, it’s intended to do something specific”. Am I wrong in understanding it like that?
I find it highly amusing to see creationists mocking the idea of “poof” when that is their entire proposed mechanism.
A tacit admission of defeat. Just like when they mock evolution by calling it a religion
I find it hilarious that you think that poof is a mechanism. But that does explain a great deal.
Mung,
Ah, righto.
So, sodium uniting with chlorine or meteorites plummeting to earth aren’t teleological but the consequences of biased population resampling are? Always? I must confess to confusion on the matter, and bow to the greater knowledge of better minds.
Same here. As best I can tell, it seems to be saying that something that has an equiprobable distribution of possible outcomes isn’t “teleological” and in so far as there is some deviation from an equiprobable distribution, it is teleological.
If that is really the case, then why someone thinks “teleology” has implications for there being an intelligent designer is not clear to me at all. Why are biased probability distributions evidence of intelligent design?
stcordova,
I’m appalled. When I accuse you of quote-mining, you brazenly claim that the part you left out supports you too, and at the end you quote-mine me.
I find it highly amusing to see creationists mocking the idea of “poof” when that is their entire proposed mechanism.
Note also that when I offered an example of a quick and well-explained increase in complexity (tetraploidy), Sal deleted it without comment.
Sal has permissions to delete posts here? gulp…
Allan Miller,
Allan, if neutral theory was correct and not positive theory, then that sorts of makes the whole eye from a light sensitive patch to a precisely fined tuned high speed camera fairytale pretty unlikely.
As a point of information, Sal does not have the ability to delete comments here. If a comment of yours has disappeared, there may be another explanation. Is there any more detail you can supply? It might be best by PM.
It has happened more than once. So maybe it is more likely than you think.
I merely meant that Sal had quoted me in response but had chosen neither to quote nor respond to a major point.
phoodoo,
Neutral theory is not in any way opposed to ‘positive theory’. Each trait has a selective coefficient. A given allele can be neutral, negative, positive or nearly neutral.
FWIW, that covers all my attitudes toward my in-laws.
OK, excuse my paranoia! Sal does tend to do that. He’s studiously ignored my point about reaction rates being temperature-dependent.
So maybe those traits which are most negative are the ones that are passed on the most.
phoodoo,
Why on earth would one think that would happen? If they are negative, they are passed on to fewer offspring than the alternative, by definition.
You could just consider yourself fortunate.
Apparently everything in the cosmos is equally evolved. Ain’t evolution grand!