Lynn Margulis and Natural Selection

[I hope this is the right board for this question…]

I received a horrid science education, so excuse me if this is a stupid question:

My friend recently read an interview with Lynn Margulis in a recent Discovery Magazine issue. He tells me Margulis says that “natural selection eliminates and maybe maintains but it doesn’t create.”

Isn’t that in contradiction to Dawkins’ assertion in The Greatest Show on Earth that “I have yet to meet a serious biologist who can point to an alternative to natural selection as a driving force of adaptive evolution – evolution towards positive improvement” ?

While Dawkins is skeptical of the Gaia Hypothesis, he seems here to very much respect Margulis as a biologist.

They’re both correct. Selection cannot introduce new genetic variants - that job is done by mutation (or recombination). Selection only chooses from among variation that is already present. That’s why it’s called “selection”, see, because it’s selecting.

Dawkins is correct in that this selection is indeed an important driving force in evolution. Without selection of some sort, you’d have no evolution. You’d just have a bunch of random mutations happily living side by side with no competition and, ultimately, no overall change.

Margulis is speaking of a technical definition, while Dawkins is speaking of an overall paradigm. There’s no contradiction.

Well, this is all third hand but it seems to me that Marguilis is pointing out that natural selection is just the selection process. It is limited by whatever variation it has to work with. If a particular genetic variation doesn’t happen to appear, whether by mutation, sexual reproduction or human meddling, then natural selection can’t select for it.

Among other things, it is an answer to the question “If ‘X’ quality would be so useful, why hasn’t it evolved?” The answer can simply be that the genes for “X” have never appeared to be selected for.

My science is not so hot either, but what the hell, I’ll give it a go. I believe the idea is this:

Natural selection is not the same thing as evolution; it’s a small part of the larger phenomenon.

Evolution is constantly creating minutely different versions of every species. Some of these minute changes have a net positive or negative effect on a given species’ likelihood of reproducing. If it’s negative, natural selection tends to weed it out; if it’s positive, natural selection tends to maintain it. This would lead to overall “positive improvement” of the species. But natural selection itself doesn’t create those changes - it just selects for or against them.

Yeah, basically, natural selection is what “directs” evolution, but combination and mutation of genetic material is what creates the raw material for selection to work on. ETA: and in the larger scale, the two “processes” can be said to be influencing each other, but natural selection is what makes evolution more than a random process.

Don’t try to answer this question if you’re not familiar with Margulis’s thesis. Her argument, as I understand it (I only briefly perused the same article in a doctor’s waiting room) is that the standard Neo-Darwinist model of mutation and natural selection is not only incapable of creating the full variety of modern life from its humble prokaryotic beginnings, but that it’s not even capable of creating differentiable species. She calls Neo-Darwinism a “sect,” and predicts that it will disappear and be mostly forgotten (this might just be rhetoric, though – some people love to hear themselves say outrageous things).

She continues on to discuss other mechanisms, and appears to attribute the lion’s share of genetic variation to endosymbiosis, and the resulting transfer of genetic information between bacterial cells or viruses and eukaryotic cells. She’s a major author of the theory that eukaryotic organelles are captured prokaryotes, and her ideas on the origin of species seem to proceed from there.

Oh, and I forgot that she thinks AIDS might be caused by spirochetes.

Lynn Margulis is a brilliant evolutionary biologist who introduced one of the most radical theories since Fisher’s modern synthesis, endosymbiotic theory (that eukaryotes evolved by cooperation between individual organisms) but suffers from a combination of unabashed arrogance and a habit of presenting her scientific hypotheses in a larger framework that encompasses political and social theory without fundamental basis. (Dawkins hardly gets a pass on this–his vengeful, thrashing attacks on theism of any sort go beyond merely debasing rationalizations for any factual basis for religious faith and enter into an arena that a pit bull would fear to enter–but he has the good sense to largely separate his technical work from his personal hobby horse.) Margulis literally challenged the central dogma of molecular biology, albeit from an abstruse angle, and has succeeded in establishing that eukaryotes–which rely on mitochondria or chloroplasts with their own unique genome to provide energy conversion and regulation–are the result of radical symbiosis, a theory that has been almost universally accepted in evolutionary biology.

Margulis’ expansion of The Gaia hypothesis as originally crafted merely stated (that organisms do not merely evolve into or in compliance with an environment, but actually modify the environment to make it more suited to their needs) is the essential source of controversy. No “neo-Darwinist” would deny the essential necessity of co-evolution, least of all Richard Dawkins whose essential technical work in the field was focused on the fig wasps (of family Agaonidae), each species of which has definitively co-evolved with a particular varietal of fig tree. In fact, Dawkins own hypothesis of the extended phenotype–that the influence of and upon genes extends far beyond the organism and into the environment that the gene carrier interacts with–is a complementary theory to endosymbiotic theory. In essence, the utility of phenotypes of a unitary gene carrier–the expressions of its genetic code–are more than just the sum of its own individual features, but the environment and other organisms with which it interacts, are core to neo-Darwinist theory, and the roots of this can be found in Darwin’s own writings, in which he recognized that organisms influence their environment as much as the environment influences them.

Taken to the logical extension, the sum total of organic activity on the surface of the planet–the biosphere as a gestalt–evolves in a way that stabilizes conditions for life. In other words, any organism or species that is “too successful” in a destructively competitive fashion ends up weeding itself out of the gene pool, whereas a species that is competitive but also provides benefit (in evolutionary terms) to the species it relies upon ends up being ultimately more successful, just as a businessman who forms alliances with competitors to ward off short-sale operators is ultimately better regarded and more successful than “Chainsaw Al”.

Where Margulis diverges from a purely scientific approach is in her assertions that there is some fundamental principle above and beyond reproductive success that drive cooperation. The notion that the biosphere is one large cooperative organism is not supported by any conventional or accepted hypothesis of evolutionary development, and while the Earth’s biosphere may ultimately venture toward a Nash-type equilibrium as the optimum state in regard to energy regulation (i.e. that radical changes in vegetative and atmospheric albedo are regulated by the presence of biomass) this is not the result of some kind of teleological principle but merely the tendency for evolved systems to self-regulate to an equilibrium state, which occurs regardless of whether the media is organic or otherwise. In other words, once a system tends toward an equilibrium, in absence of radical changes it tends to maintain that equilibrium.

Natural selection–sometimes misleadingly referred to as “survival of the fittest” (not Darwin’s words)–is but a single, albeit significant mechanism in the overall theory of evolutionary development of life. While competitive selective pressures are one substantial mechanism that drives evolutionary change, it is not the exclusive input. Mutation, gene exchange (performed by viruses and perhaps by other mechanisms), radical change in environmental equilibria, hybridization, and other potential influences on ostensible species can all contribute to novel evolutionary development and ultimate speciation.


Oh my, have some of you not even read the Margulis interview in Discover? She certainly does contradict Dawkins, et al. She absolutely destroys the neo-Darwinists and much of basic Darwinism. e.g., There is no gradualism in the fossil record, etc., etc. It is very refreshing and wonderful material!

Of course, her own stuff is equally nonsensical and based on her own theories which have such little basis in facts or proven science. Just read her detractors on the other side of the evolutionary aisle. This is hilarious stuff to watch them shoot themselves down so effectively. Go Lynn!!

I haven’t had so much fun since I heard the debate between the two bird/flight evolutionists. One guy said the critters couldn’t possibly have learned to fly by jumping/gliding out of trees b/c of basic laws of physics. The other guy said the critters couldn’t have possibly learned to fly by running and flapping faster and faster b/c of basic laws of physics. They completely destroyed each other with science!

Kudos again to Lynn and her courage to admit that the emperor is naked!! :slight_smile:

No, I haven’t seen that interview. Is it available online? (It’s certainly not on the current Discover site.)

So, glsi, how do you define “proven science”?

Nitpick: Lynn Margulis is a ONCE brilliant evolutionary biologist who has descended into quackery. Her endosymbiotic theory for the origin of cellular organelles was groundbreakingly brilliant and she deserves the accolades she received for it.

Unfortunately, she has fallen prey to a common disease of the formerly brilliant. Over the years, she has moved to ascribing symbiosis as the mechanism behind all evolution, even in the face of very good evidence to the contrary. This has led her to do some very goofy stuff, like sponsering this ridiculous paper for publication in PNAS, one of the most prestigious scientific journals. (it got published because members of the National Academy of Sciences can bypass the normal peer-review process - they can submit their own papers directly, or as in this case, they used to be able to sponsor other peoples papers (after this debacle, PNAS eliminated the latter option). She was rightly pilloried by the scientific community after that one.

Margulis deserves recognition for her accomplishments, and pity for what she has become. She’s like the formerly awesome grandparent now deep in the throws of dementia - all you can do is sigh and try to remember her as she was.

To be fair, my pit bulls are afraid when people argue. They prefer everything to be lovey-dovey.

Uh…I thought gradualism went out for good with Gould and Eldredge and punctuated equilibrium. That was in 1972.

Speaking of Gould, he had an essay about this tendency of successful scientists to become reigning authorities and ascribe everything in the field to the theory that made them famous.

Holy cow, that reads like the sort of natural philosophy some second-rate Victorian idler would get published only because his father owned the publishing company.

Gosh, Sailboat, if the idea of gradualism in fossils went out for good in 1972 you should let Mr. Dawkins know about that. He’s associated with some cute pictures of “gradual whales” in the Exploring Evolution exhibit which is currently in some museums around the country that they’re foisting onto a lot of unsuspecting school kids. Don’t think they mention gradualism is out.

And how is it that punctuated equilibrium put anything “out for good”? Was there some hard evidence finally discovered that gives that whopper any credence at all?

It’s like Lynn Margulis is saying in her interview: Go outside and take a look at the nature of the world. It just doesn’t line up with prevailing theories. That’s what Gould did and he decided he’d better come up with a more convenient and creative theory. Trouble is you gotta find some convincing evidence to go along with it. On the other hand I guess he made a good living on it even without the evidence. Not a bad gig if you can get it!

So–where can we read this interview?

You clearly do not have an understanding the process and cycle of scientific hypothesis proposal and falsification. That two experts disagree, enthusiastically, on a proposed mechanism does not undermine the basic theory of competitive selection as a fundamental basis for evolutionary change, any more than two guys arguing over the supremacy of the Yankees or the Mets gives reason to question the rules of baseball.

I think that she is clearly still quite intelligent, all the more so for her energetic defense of a hypothesis with little to support it. I think she is wrong, or at least, standing out on a very slender branch, but she very effectively anticipates challenges to the position she advocates and provides substantive, if unqualified responses. She’s no blithering Mary Midgley; the understands the limitations of practical application of modern evolutionary synthesis and the ability to simulate large scale evolutionary systems and bases her criticisms on that. Her sociopolitical screeds, her September 11 conspiracy wankering, and theological and teleological extensions of the Gaia hypothesis, on the other hand, are unsupportable and distasteful, but no moreso than the cracktastic theories espoused by many brilliant figures in evolutionary biology and other scientific fields.


Moving thread from IMHO to Great Debates.

True. I work with many highly intelligent but crazy persons. The crazy is why we love them…

And I don’t have a problem with her theories presented as hypotheses. But while she is quick to say “its just a hypothesis”, she really does present it as fact. And there are already multitudes of extant data to suggest that she is wrong in the big picture sense (of course, you can find specific examples where she is likely correct).

And that’s where a on the issue - does it happen? Of course it does. Does it explain most big-picture questions in evolution? Certainly not.

And not to hijack, but I’ve never understood the fight between gradualism and punctuated equilibrium. You can find evidence for both - likely they both happen. To say “one is more important” than the other misses the point.

How does she explain adaptive radiation in terms of endosymbiosis, then? Adaptive radiation into new niches (a la Darwin’s finches, or a zillion other examples), via either selection or genetic drift, is one of the major drivers of speciation. Does she address this, or is biogeography beneath her notice?

Hell, for that matter, what about allopolyploidy and autopolyploidy?

So, basically, she’s into horizontal gene transfer as the major driver of evolution?

but I’ve never understood the fight between gradualism and punctuated equilibrium. You can find evidence for both - likely they both happen. To say “one is more important” than the other misses the point.

Yes, folks, LET’S NOT FIGHT ABOUT THAT!!!. Let’s use Darwin’s gradualism until the kids point out that it doesn’t hold water. Then we go to punctuated equilibrim!

And Bridget, I read my copy for free at Borders with a latte. But I think I’ll go back and buy it. This interview is pure gold!

Do you have an actual stand on the matter that you’d like to reveal to us? This fake cheerleading for one side just to get a fight going seems a bit immature to me.

I think his side is agin’ that “Darwinist” stuff…