Is natural selection tautological?
From Talk Origins:
Summary: The claim that evolutionary theory is a tautology rests on a misunderstanding of the theory. Fitness is more than just survival.
The simple version of the so-called 'tautology argument' is this:
Natural selection is the survival of the fittest. The fittest are those that survive. Therefore, evolution by natural selection is a tautology (a circular definition).
The real significance of this argument is not the argument itself, but that it was taken seriously by any professional philosophers at all. 'Fitness' to Darwin meant not those that survive, but those that could be expected to survive because of their adaptations and functional efficiency, when compared to others in the population. This is not a tautology, or, if it is, then so is the Newtonian equation F=ma, which is the basis for a lot of ordinary physical explanation.
Jason Rosenhouse:
Writing in National Review Online in December of last year, conservative commentator Tom Bethell expressed the main point more clearly:
“Darwin's claim to fame was his discovery of a mechanism of evolution; he accepted “survival of the fittest” as a good summary of his natural-selection theory. But which ones are the fittest? The ones that survive. There is no criterion of fitness that is independent of survival. Whatever happens, it is the “fittest” that survive — by definition."
…
Let us begin our reply to this argument in the most direct way possible. It is asserted that within evolutionary theory, the fittest organisms are defined as those who survive. This is the crux of the argument, and it is completely incorrect. In reality, the fittest organisms are the ones who, based on their physical characteristics and the environment in which they find themselves, would be expected to leave the most offspring.
Let us imagine that we have perfect information about the environment in which a population of organisms finds itself. Let us further suppose that we are aware of the full range of extant heritable variation within the population. In those circumstances we could make some definite statements about the future evolution of that population. A group of scientists could examine that information and come to a consensus about which members of the population were the fittest. Plainly there are criteria for fitness independent of mere survival.
This is not the whole story, however. Predicting the future is only a very small part of what evolutionary biology is all about. Most of the interesting events in evolution took place in the distant past. Unraveling and explaining that past presents scientists with a problem almost perfectly opposite to the one considered in the previous paragraph. Instead of trying to predict the future evolution of a species given information about its present environment, now we are trying to understand ancestral environments given information about what sorts of creatures survived.
…In this context scientists will, indeed, hypothesize that traits that persisted and developed over long periods of time did so because of the fitness advantages they conferred on their possessors. But here’s the catch: that’s the beginning, not the end, of the investigation.
The assumption that the trait under investigation emerged from the prolonged result of natural selection is used to generate testable hypotheses about the creatures in question. In his book Plan and Purpose in Nature, biologist George C. Williams provides the following example:
Productive use of the idea of functional design, in modern biological research, often takes this form: an organism is observed to have a certain feature, and the observer wonders what good it might be. For instance, dissection and examination of a pony fish shows it to have what looks like a light-producing organ, or photopore, and even a reflector behind it to make it shine in a specific direction. So we accept the conclusion that the organ is good at producing light, but the obvious question then becomes, What good is light? The pony fish photopore is deep inside the body. Can it really be adaptive for a fish to illuminate its own innards?
The organ is situated above the air bladder, and the light shines downward through the viscera. The pony fish is small and its tissues are rather transparent. Some of the light gets through and produces a faint glow along the ventral surface. But what is the use of a dimly lit belly? Perhaps it makes the pony fish more difficult to see in the special circumstances in which it lives. It inhabits the open ocean, where it may move toward the surface as darkness approaches, but spends the daylight hours far below at depths where the light is exceedingly dim by our standards, detectable only as a murky glow from above.
Williams goes on to describe how this hypothesis led to experiments that confirmed that the pony fish’s glow has the intensity it ought to have if its primary function was to provide camouflage. This is a nice illustration of how selection-based reasoning is used in scientific practice.
The reasoning used by scientists in this way is comparable to what historians do in trying to understand why certain events happened the way they did. An historian studying nineteenth century America might begin his investigation with the fact that the North won the Civil War. From this starting point he will naturally ask himself what advantages the North had that allowed them to emerge victorious over the South. But the assumption that the North had such advantages will not be the sum total of his investigation. And no one would consider it reasonable to object to his work on the grounds that it is based on circular reasoning.
Well, populations of organisms that survive through long stretches of evolutionary history are likewise the victors in a war, this time for survival. It is perfectly reasonable to assume that those that survived had certain advantages over those that did not. Determining the precise nature of those advantages might pose a difficult practical problem, but the assertion that those advantages existed is surely unproblematic.
We have thus provided two answers to the tautology objection. The first is that its central premise, that there are no criteria of fitness independent of survival, is false. The second is that natural selection is not applied in practice in the simplistic way the phrase “Survival of the fittest,” suggests. Instead, scientists use selection based reasoning to develop specific, testable hypotheses about the organisms under investigation.
From Wikipedia:
"Survival of the fittest" is sometimes claimed to be a tautology. The reasoning is that if we take the term "fit" to mean "endowed with phenotypic characteristics which improve chances of survival and reproduction" (which is roughly how Spencer understood it), then "survival of the fittest" can simply be re-written as "survival of those who are better at surviving".
However this criticism fails to consider that the expression "survival of the fittest", when taken out of context, is actually a very incomplete account of Darwinian evolution. The reason is that this expression does not mention a key requirement for Darwinian evolution, namely the requirement of heritability. Darwin's mechanism of evolution through natural selection implies that heritable variations lead to differential reproductive success, and therefore (precisely because they are heritable) become over-represented in the next generation. If the characters which lead to differential reproductive success are not heritable, then no meaningful evolution will occur, "survival of the fittest" or not. In other words, Darwinian evolution by natural selection does not simply state that "survivors survive" or "reproducers reproduce"; rather, it states that "survivors survive, reproduce and therefore propagate any heritable characters which have affected their survival and reproductive success".
When the full picture is considered, no tautology exists: the complete mechanism leading from heritable fitness-impacting differences, through differential reproductive success ("survival of the fittest"), to actual adaptive evolution (change in the makeup of lineages toward better adaptation) is a valid, informative reasoning, hinging on the testable hypothesis that such fitness-impacting heritable variations actually exist.
It would be romantic to think that a huge, overwhelmingly accepted branch of science, such as the theory of evolution by natural selection, could be brought crashing down by somebody spotting an elementary flaw in its logic that could be comfortably explained to bright schoolboy. There's one in the eye for the so-called experts!
Sadly, it would also be somewhat far-fetched.
Summary: The claim that evolutionary theory is a tautology rests on a misunderstanding of the theory. Fitness is more than just survival.
The simple version of the so-called 'tautology argument' is this:
Natural selection is the survival of the fittest. The fittest are those that survive. Therefore, evolution by natural selection is a tautology (a circular definition).
The real significance of this argument is not the argument itself, but that it was taken seriously by any professional philosophers at all. 'Fitness' to Darwin meant not those that survive, but those that could be expected to survive because of their adaptations and functional efficiency, when compared to others in the population. This is not a tautology, or, if it is, then so is the Newtonian equation F=ma, which is the basis for a lot of ordinary physical explanation.
Jason Rosenhouse:
Writing in National Review Online in December of last year, conservative commentator Tom Bethell expressed the main point more clearly:
“Darwin's claim to fame was his discovery of a mechanism of evolution; he accepted “survival of the fittest” as a good summary of his natural-selection theory. But which ones are the fittest? The ones that survive. There is no criterion of fitness that is independent of survival. Whatever happens, it is the “fittest” that survive — by definition."
…
Let us begin our reply to this argument in the most direct way possible. It is asserted that within evolutionary theory, the fittest organisms are defined as those who survive. This is the crux of the argument, and it is completely incorrect. In reality, the fittest organisms are the ones who, based on their physical characteristics and the environment in which they find themselves, would be expected to leave the most offspring.
Let us imagine that we have perfect information about the environment in which a population of organisms finds itself. Let us further suppose that we are aware of the full range of extant heritable variation within the population. In those circumstances we could make some definite statements about the future evolution of that population. A group of scientists could examine that information and come to a consensus about which members of the population were the fittest. Plainly there are criteria for fitness independent of mere survival.
This is not the whole story, however. Predicting the future is only a very small part of what evolutionary biology is all about. Most of the interesting events in evolution took place in the distant past. Unraveling and explaining that past presents scientists with a problem almost perfectly opposite to the one considered in the previous paragraph. Instead of trying to predict the future evolution of a species given information about its present environment, now we are trying to understand ancestral environments given information about what sorts of creatures survived.
…In this context scientists will, indeed, hypothesize that traits that persisted and developed over long periods of time did so because of the fitness advantages they conferred on their possessors. But here’s the catch: that’s the beginning, not the end, of the investigation.
The assumption that the trait under investigation emerged from the prolonged result of natural selection is used to generate testable hypotheses about the creatures in question. In his book Plan and Purpose in Nature, biologist George C. Williams provides the following example:
Productive use of the idea of functional design, in modern biological research, often takes this form: an organism is observed to have a certain feature, and the observer wonders what good it might be. For instance, dissection and examination of a pony fish shows it to have what looks like a light-producing organ, or photopore, and even a reflector behind it to make it shine in a specific direction. So we accept the conclusion that the organ is good at producing light, but the obvious question then becomes, What good is light? The pony fish photopore is deep inside the body. Can it really be adaptive for a fish to illuminate its own innards?
The organ is situated above the air bladder, and the light shines downward through the viscera. The pony fish is small and its tissues are rather transparent. Some of the light gets through and produces a faint glow along the ventral surface. But what is the use of a dimly lit belly? Perhaps it makes the pony fish more difficult to see in the special circumstances in which it lives. It inhabits the open ocean, where it may move toward the surface as darkness approaches, but spends the daylight hours far below at depths where the light is exceedingly dim by our standards, detectable only as a murky glow from above.
Williams goes on to describe how this hypothesis led to experiments that confirmed that the pony fish’s glow has the intensity it ought to have if its primary function was to provide camouflage. This is a nice illustration of how selection-based reasoning is used in scientific practice.
The reasoning used by scientists in this way is comparable to what historians do in trying to understand why certain events happened the way they did. An historian studying nineteenth century America might begin his investigation with the fact that the North won the Civil War. From this starting point he will naturally ask himself what advantages the North had that allowed them to emerge victorious over the South. But the assumption that the North had such advantages will not be the sum total of his investigation. And no one would consider it reasonable to object to his work on the grounds that it is based on circular reasoning.
Well, populations of organisms that survive through long stretches of evolutionary history are likewise the victors in a war, this time for survival. It is perfectly reasonable to assume that those that survived had certain advantages over those that did not. Determining the precise nature of those advantages might pose a difficult practical problem, but the assertion that those advantages existed is surely unproblematic.
We have thus provided two answers to the tautology objection. The first is that its central premise, that there are no criteria of fitness independent of survival, is false. The second is that natural selection is not applied in practice in the simplistic way the phrase “Survival of the fittest,” suggests. Instead, scientists use selection based reasoning to develop specific, testable hypotheses about the organisms under investigation.
From Wikipedia:
"Survival of the fittest" is sometimes claimed to be a tautology. The reasoning is that if we take the term "fit" to mean "endowed with phenotypic characteristics which improve chances of survival and reproduction" (which is roughly how Spencer understood it), then "survival of the fittest" can simply be re-written as "survival of those who are better at surviving".
However this criticism fails to consider that the expression "survival of the fittest", when taken out of context, is actually a very incomplete account of Darwinian evolution. The reason is that this expression does not mention a key requirement for Darwinian evolution, namely the requirement of heritability. Darwin's mechanism of evolution through natural selection implies that heritable variations lead to differential reproductive success, and therefore (precisely because they are heritable) become over-represented in the next generation. If the characters which lead to differential reproductive success are not heritable, then no meaningful evolution will occur, "survival of the fittest" or not. In other words, Darwinian evolution by natural selection does not simply state that "survivors survive" or "reproducers reproduce"; rather, it states that "survivors survive, reproduce and therefore propagate any heritable characters which have affected their survival and reproductive success".
When the full picture is considered, no tautology exists: the complete mechanism leading from heritable fitness-impacting differences, through differential reproductive success ("survival of the fittest"), to actual adaptive evolution (change in the makeup of lineages toward better adaptation) is a valid, informative reasoning, hinging on the testable hypothesis that such fitness-impacting heritable variations actually exist.
It would be romantic to think that a huge, overwhelmingly accepted branch of science, such as the theory of evolution by natural selection, could be brought crashing down by somebody spotting an elementary flaw in its logic that could be comfortably explained to bright schoolboy. There's one in the eye for the so-called experts!
Sadly, it would also be somewhat far-fetched.
posted by Brit at 3:49 AM
29 Comments:
Well, the belief that darwinism is tautological is highly correlated with beliefs in demon-caused disease, imaginary deities and ineluctable prophecies.
What kind of logical rigor do ya expect from people like that?
The reasonable kind?
I had a feeling that was for my benefit. However, I try to be careful to delineate between tautological natural selection and non-tautological natural selection. It is non-tautological natural selection that I argue is a weak force in the observed change in phenotypes over the ages.
Notice, however, that in the given example of "non-tautological" natural selection, the "scientist" starts by assuming that there is a pro-survival reason for the pony fish photopore and then, sure enough, he finds one. Of course, fish also survive without a photopore, and they too are assumed to be the result of natural selection.
Given the complete lack of any evidence whatsoever supporting the pro-survival effect of the photopore, the circular nature of this method of reasoning about natural selection and the observed fact that humans are reason generating machines (so that the whole thing simplifies to "the pony fish is the result of natural selection, so what explanation can we think of that is pro-survival, proving the existence of natural selection"), I'm unconvinced by this particular argument that natural selection is not tautological.
I think that when you say 'tautological,' you mean 'I want this to be incorrect but I cannot figure a way that it comes out different'
I'm puzzled, though, by the brit's link. I already knew about multiple copies and the differing phenotypical effects. From Ridley's 'Genome' and, I think, other sources. So while I understand that the new understanding is deeper, I don't get why it is supposed to be so revolutionary.
I'm not looking for it to come out different. Natural history is natural history. I'm just saying that it's more random than generally thought.
As for the copying errors, it's not that it's revolutionary that they happen, it's that it's surprising that individual genotype's within a species can vary so greatly.
What is it about this subject? You've mixed together at least three strings here that really should be kept apart:
First, your suggestion that evolution is 'more random' I can only interpret as implying that genetic drift is more important in evolution, and natural selection is less important, than most evolutionists think. You haven't said how much more important - whether it is a bigger factor than natural selection or just more important than we usually give it credit for; nor have you said whether this applies to the evolution of some particular species, or to all evolution. Nor have you said exactly why you think this - on what evidence from the natural world. This string does however, seem to acknowledge that natural selection is a force in evolution, however weak, and is therefore not an invalid concept.
But the second string is the tautology accusation and that IS a conceptual attack on the validity of natural selection per se. As it is expressed in the post above "Natural selection is the survival of the fittest. The fittest are those that survive. Therefore, evolution by natural selection is a tautology". You've expressed it almost exactly in those terms elsewhere. And it rests on a misunderstanding of 'fittest'.
So the third string is your differentiation between 'tautological' and 'non-tautological' natural selection.
I have to confess I can't see what point you're making here at all - it is all somewhat confusing. What is the difference - do they both exist, or is one an empty concept? Should I be defending natural selection, or defining it?
Brit: It depends.
When you asked me about stasis, I said that before I could answer I needed you to define "fitness." You replied:
I say 'fitness' simply to refer to an individual's likely ability to reproduce, but thinking I could get caught out here, I looked at this page.
So it depends on what exactly you're talking about. You can talk about fitness in retrospect (whether it did reproduce), or probabilities before reproduction, or relative fitness, and you can measure it.
September 24, 2006 3:32 AM
Your first definition (fitness is a probabilistic measure of the likelihood that an individual will reproduce) is clearly not tautalogical. I have no problem using it. However, my argument is that fitness so defined can only be a weak explanation of evolution.
The other definition, that fitness can be determined only in retrospect by looking at whether a particular individual did reproduce is tautological. It explains all of evolution, but only because it's been defined that way.
You have admitted that I am correct to note that some mutations will not have any effect on fitness and thus are not subject to winnowing by natural selection. However, whenever you are faced with a particular individual characteristic, you (like the article you cite) assume that there must be some story by which that mutation was favored by natural selection. You completely ignore the possibility that the characteristic in question, like the number of teeth in a human mouth, is simply unrelated to the probability that the individual will reproduce.
This is where continental drift comes in to play.
Massachusetts spiders will not survive in the Mojave desert, and vice versa. You can say the same for plant and animal in both locations.
All life in the Mojave is adapted to an environment characterized by,among other things, very little rainfall and sporadic surface water, just the opposite of Massachusetts.
Since all land masses have transited all climatological zones, unless there was a systematic adaption to long term trends, there simply would be no life on land.
The alternative, natural selection was weak to the point of being negligible, would mean there should be deciduous trees in Joshua Tree National Park, and Joshua Trees lining David's street.
Random mutation was fed into a non-random feedback loop.
Jeff: We've long since disproved that.
Many people seem to confuse natural selection with artifical selection and eugenics as well.
And they also confuse "fittest" with the "strongest" as do social darwinists which is not natural selection either.
The "fittest species" refers to the species which is best suited to the environement in which it lives and is able to adapt either behaviourally or genetically to changes in the environment which may, or may not be advantageous to its overall survival as a species.
I say "behaviourally" because of the concept of gene expression and the effect it may have on the expression of behavioural traits.
Can't say I am any expert on natural selection though. But I accept that it exists and that all species are potentially subject to its effects.
Actually, 'fittest' just means, 'leaves most offspring who also leave offspring'
It's a moving target. In oriental despotisms, the king usually leaves the most offspring, but he is overthrown by his brother, who kills all the king's offspring and breeds his own, thereby halving the king's contribution to the species down the road; or overthrown by somebody distantly related or unrelated, who kills all the king's family, eradicating most or all of the king's genes down the line.
The moving target aspect of it seems to drive darwin skeptics nuts, because -- as David says -- why aren't the other fish like the pony fish. Them's the experimental conditions; they're a given. It doesn't get you anywhere to quarrel with them.
Now, if the skeptics' objection worked the other way round, we darwinians would be in big trouble. If the 3-legged gazelles reproduced even-steven with the 4-legged gazelles. But they don't.
However, whenever you are faced with a particular individual characteristic, you (like the article you cite) assume that there must be some story by which that mutation was favored by natural selection. You completely ignore the possibility that the characteristic in question, like the number of teeth in a human mouth, is simply unrelated to the probability that the individual will reproduce.
Thanks - I believe I understand now. What you're saying is not that the concept of evolution by natural selection is tautological, but that evolutionists are so obsessed by finding natural selection explanations that they frequently overlook the possibility that many prevalent characteristic can be accounted for by genetic drift.
To which I'll respond thus:
1) I don’t find the ‘tautological’ accusation helpful – I think it confuses matters with the conceptual tautology accusation as detailed in the post – it would be better if you said “evolutionists are too hung up on natural selection” or some such.
2) As Harry says, it is useless to quibble with the conditions of the experiment: that these fish have lights is a given. Therefore we have to start with the fact that somehow lights became prevalent in the population – and we try to find out why. In doing this, we are not seeking to prove natural selection yet again. Instead, natural selection provides us with testable hypotheses, eg. is there a reason why having a light was sufficiently useful in the fish’s environment to convey a reproductive advantage to an individual with a light mutation over his fellow, dimmer fish?
But here’s where natural selection really exposes itself to risk: suppose it turns out that in the fish’s environment, light is a positive disadvantage, and the dimmer fish are more likely to reproduce than the brighter fish, and yet brightness is still a prevalent characteristic – suddenly natural selection is, as Skipper would put it, holed below the waterline.
3) Your accusation that evolutionists unjustifiably downplay genetic drift in favour of natural selection may be true to some extent (do you mean all evolutionists or some in particular?) but I wouldn’t know – and I can’t see how you would know either.
And I would note the following: if natural selection in the environment plays only a weak part in evolution, and the path really is much more random than we have previously thought, then there is some serious explaining to do regarding probability. I mentioned stick insects on the other post, and those horrid parasitic fungi that only attack one particular kind of insect each among the millions in the Amazon jungle – I can’t see how you can explain such ludicrous specialisation, such extreme environmental niche-filling, without reference to the world the creature lives in.
But just as environmental selection pressure can explain rapid niche-filling, so it can also explain stasis: coelacanths, crocodiles, great whites - that is, creatures that have remained unchanged for millions of years while elsewhere life blasts off in all directions around them. Natural selection can explain this…by its absence – by discovering that environmental selection pressures are absent, or very weak, on these creatures. I think it is much more difficult to explain this if you are arguing that random genetic change is the driving force in evolution: if this is the case, over enough generations, why shouldn’t all creatures evolve at a broadly similar rate?
David:
Btw, there is a book that could have been written just for you. It's by Richard Dawkins, it's not about religion, and it's called Climbing Mount Improbable.
Does anyone else have the problem that, when using Firefox, following a link to Amazon results in a blank page?
Brit, I'll trade you. This is a good book that could have been written for you. It discusses the latest in non-Medelian genetics, how these developments effect our understanding of evolution, and a really nifty all-out attack on Dawkins.
Sure, I'll look at it, but I have no problem whatsoever with what is reported to be the premise:
Molecular biologist Gabriel Dover uses imaginary correspondence as a literary device for explaining how our ideas about evolution have evolved since Darwin's day. Dover argues that evolution involves more than just natural selection and cites such phenomena of sampling error as genetic drift.
Nor do I have a problem with the argument that Dawkins's language can confuse:
Dover laments the influence of Dawkins's reasoning on persons who are not equipped to see through it, especially textbook writers and social scientists. Let me clarify what Dover is complaining about. Dawkins decided to call genes, and other things of which copies are made, "replicators." The problem with that term is that in ordinary English, the suffix "-or" refers to the doer of the action. Thus, a replicator should be that which does the replication, not that which is replicated. (Likewise, a photocopier is not the copy that is produced by the machine.) Dawkins's term is apt to dupe the unwary into thinking that a passive participant is an active agent.
It's unarguable that Dawkins's active terms like "selfish gene" and "climbing Mount Improbable" can confuse the unwary - I've seen that over and over. But it's only confusing if you don't read the books, but instead only read stuff about the books and thus misinterpret the terms. Dawkins knows as well as anyone the difference between active and passive: the books are painstakingly clear (which is why he's the best populariser around). David: you are plenty enough "equipped to see through it" and to avoid being "duped", believe me.
And there's nothing in that summary of the book that isn't covered in that more sober work by Mayr, and indeed, on Wikipedia, btw.
The Amazon page understates how much he hates Dawkins.
No, no problems with linking to Amazon pages through Firefox.
As a strict materialist, I have problems with what-ifs that posit 'perfect information.' We cannot have that, so we have to figure out how to operate with less. Again, you should not be allowed to quarrel with experimental conditions.
Heinz Pagels had a good discussion about why you cannot have perfect information in 'The Cosmic Code.' Violates the Second Law.
David:
You keep saying the connection between continental drift and evolution is disproved. Would you please provide a link?
NB: The first definitive evidence for plate tectonics, other than suspiciously congruent coastlines, was fossil evidence.
BTW, you do indeed have a valid point. Whereas Natural Selection was the sine qua non of evolution, it is certainly only one of at least a half dozen elements in the feedback loop, and, except for slow systematic change, likely not the predominant one.
That said, even a tiny, sustained, deviation from complete randomness will produce significant change, given enough time.
I haven't had the blank Amazon page problem. However, at least three times out of five, BrosJudd completely locks up Firefox on my MacBook, but works fine with Safari.
Peter:
Having perfect knowledge of the environment at a certain point in time and also of the heritable variation of a species would tell you little about the future of that species.
Trueish.
Let's say continental drift pushes up a tall, long, mountain range that creates an extensive rain shadow, and separates an ocean mediated climate from a continental climate. This change takes tens of millions of years, and is referred to now as the Sierra Nevada and San Gabriel (plus a couple others) mountain ranges.
If we were to stand at the beginning of this change, and know the eventual outcome, we wouldn't be able to say much of anything about the future of any specific species -- the details of morphology, appearance, and behavior would all be mysteries.
However, we could say, with near certainty, that, absent acts of special creation, all life within the rain shadow will develop, relative to their predecessors, water conserving strategies of one sort or another. Depending on the local degree to which precipitation is reduced, we could also say, with near certainty, that there will be a significant reduction in the number of species.
We could also say, with certainty, that these changes would occur without a deus ex machina.
It is asserted that within evolutionary theory, the fittest organisms are defined as those who survive.
Perhaps this will help. Within naturalistic evolution, the fittest organisms are those whose inherited variations provide differential survival value rates in the face of systematic environmental change.
If the assertion is that perfect knowledge of a species and its environment would allow us to predict which members of the species would be most likely to reproduce, surely such a prediction would only bear out or have any meaning if the environment remained more or less constant. It doesn’t, of course, and neither does the species.
...
However, is there not a problem with the fact that the hereditary history of the species was in response to ... dynamic change and different survival challenges long passed?
Depends upon what you mean by dynamic. Systematic changes are rarely, if ever, dynamic unless one takes a very, very, long view of time. The raising of the Panama isthmus, or the separation of South America from Africa, had huge systematic effects, particularly in the latter case. However, no single generation, or even hundreds of generations, would be capable of noting any significant change.
So your point is very well taken, as natural selection would seemingly have to be perpetually one step ahead of itself. However, given the typical rate of systematic change, it doesn't seem to me that is a problem.
Re: Dawkins. I do share your misgivings with his rhetorical flourishes. However, and this is probably due to the way our brains work, it is extremely difficult to eliminate teleological and anthropomorphic phraseology from this subject, unless one is willing to continually use a far greater number of deadening words.
Jeff: We've disproved it, at least to my satisfaction, by identifying single species that survive over a broad range of climates: from the arctic circle to the Sahara, if you will.
By the way, how's the move to Alaska coming?
Peter: Your point about perfect information is well take. As a quasi-economist, however, I'm willing to treat with perfect information in theory, even if it's never available in practice. Harry's definition, on the other hand, has the benefit of being clear and determinable, but collapses evolution into natural history.
Peter and Brit: We may be making progress. It might help if I refer to what I have previously called the tautalogical/teleological problem as an anthropomorphic problem. We see the world we see because it is the only world available to us to see. This naturally leads to a mistake that I think Brit is making in thinking about probabilities ex post rather than ex ante. Ex post, stick insects or photopores or little ant specific parasites seem unlikely, but that is an necessarily anthropomorphic judgment.
Ex ante, how can we say that any particular mutation is less likely than any other. Is a stick insect really less likely than an intelligent biped? Is a fish with a photopore less likely than a bird? The point is that, ex ante, any species is going to look incredibly improbable. If you're looking at amino acid gloop, the idea that evolution will result in rocket ships is incredibly unlikely, but here we are. Because we are here, we can't really say how likely or unlikely it is. Maybe this is the only time in the history of the Universe it's happened; maybe, as Jeff says, it's happened billions of times.
I also suspect that you guys miss how really astonishing and wonderful the whole thing is because you put such an emphasis on natural selection. It seems to me that "strong theory" natural selectionists elide two separate and distinct things, the wide range of mutations that are generated randomly and the long odds that life beats to look like it does.
Finally, although it is certainly interesting to debate, I don't really care whether photopores or the spider population of Death Valley resulted from chance or natural selection. I do care, quite about, about the genetic determinism and naive darwinism that insists on explaining how evolution resulted in laughter, or polygamy, or anti-semitism.
Re probability and unlikelihood: a load of different species of insects that all look just like the particular sticks they live on are not that unlikely if you allow for environmental selective pressures.
Even allowing for ex post reasoning, they are pretty darn unlikely if you're relying entirely on random genetic drift.
You are making a logical error in thinking I'm making a logical error.
I admire you for rejecting the Argument from Design, and thus for attacking evolution from the precise opposite viewpoint of OJ, but you've gone too far, in that you've forgotten why the Argument from Design was so compelling pre-Darwin.
David:
... by identifying single species that survive over a broad range of climates: from the arctic circle to the Sahara
First I don't think the odd exception (and humans are not one such exception) disproves the rule. I suspect that if you were to transplant every sign of life from Massachusetts to the Mojave Desert, not one would survive the year. A few insects and bacteria, maybe, but nothing else.
That is why I suggest that natural selection is most closely associated with slow, systematic, changes in the environment: climate change and continental drift.
What you may conclude from this is that at one time I would have simply assumed Natural Selection primarily, along with the odd preferences that go into mating choices, constituted the feedback loop, it now seems pretty clear that other things are at work, as well.
Including a whole lot of "stuff" happens.
Question: It seems a single mutation accounts for people of pallor. Why is it that single mutation wasn't simply lost?
By the way, how's the move to Alaska coming?
Right now, we are in the tinkering phase. Nothing much is going to happen until mid-April, when SWIPIAW and the critters are going to spend a week in Anchorage doing a look-see.
Then, come June, we will have a year and a half lease in hand for our house in Michigan, a year and a half lease on a furnished place in/near Anchorage, and we will throw what fits into a pickup and a U-Haul, plus the kids and the dog, and head off for the AlCan highway.
Or something like that.
Ex post, stick insects or photopores or little ant specific parasites seem unlikely, but that is an necessarily anthropomorphic judgment.
I echo Brit here. The sheer range of mimicry, or sightless fish in totally dark caves, or flightless seabirds on oceanic islands, seems to point to a feature of the system, not a bug.
Because we are here, we can't really say how likely or unlikely it is. Maybe this is the only time in the history of the Universe it's happened; maybe, as Jeff says, it's happened billions of times.
Keeping in mind, of course, that I am wholly agnostic on this.
I do care, quite about, about the genetic determinism and naive darwinism that insists on explaining how evolution resulted in laughter, or polygamy, or anti-semitism.
Quite. However, I do care that the everything the Left stands for is predicated upon humans as tabla rosa. Evolution, whatever the means, insists quite the opposite. There are many "unessential" differences between men and women. I suspect evolutionary reasons for each, thereby making them ineradicable.
The Left sees most of them differently.
David sez: 'I do care, quite about, about the genetic determinism and naive darwinism that insists on explaining how evolution resulted in laughter, or polygamy, or anti-semitism.'
A genuine problem, although hardly an important one. It's called deciding ahead of data -- it's what the global warming brouhaha is all about. I cannot think of any critic of darwinism who isn't more guilty of it than the looniest darwinist, only on other topics.
I haven't read the original statement of what a meme is supposed to be and have only a vague idea of what it means.
I think it may be sorta like what the economist Arnold Kling describes as common Freudianism, Marxism, etc.
Some genius writes a thousand-page tome, and the popular consciousness boils it down to 'boys love their mothers too much' or 'one big union.'
Although I've read a couple of Dawkins's later books, I never read 'The Selfish Gene,' mainly because I am agnostic on the nature/nurture argument. I don't think you can disentangle that pudding back into its original constituents of milk and eggs.
Besides, altruism is very difficult to define. If I give my fortune to the American Museum of Natural History to have a hall of evolution named after me when I am dead, is that altruism or the worst kind of egomania?
Simpliste that I am, whenever the topic of altruism comes up, I think of Simone Weil starving herself to death because other people were starving. We are all a little crazy.
As for the Great Trek out of Africa, I think the evidence is now really strong.
Until fairly recently, the evidence was circumstantial, like the fossil evidence for a connection between Africa and South America before plate tectonics. It almost had to be so, since it was hard to think of another explanation but connection; but connection seemed impossible, too.
There were always skeptics, like Wolpoff with his multiorigins hypothesis -- something I always found very undarwinian. He has since admitted his idea is no longer tenable.
DNA analysis has now provided the 'plate tectonics' evidence for the Great Trek, although there are still some anomalies: But Cavalli-Sforza et al have shown a smooth gradient of alleles from Africa to Australia that is in the ballpark with the time assumed necessary for such changes to have occurred.
Sarich and Wilson's 'clock' has always seemed very dubious to me in absolute terms, though. Just this week -- as reported in the Daily Duck -- it looks as if the 'junk' DNA 'not subject to selection' may have been subject to some kind of selection after all. I always thought so.
If so, that screws up the smooth, random evolution of 'useless' DNA that sets the clock.
That helps me, since one of the fossil anomalies that does not fit the time scheme of the DNA evidence is the early Homo in Sinai, about twice as distant in the past as the Great Trek theory calls for.
Still a few kinks in the explanation, but there are so many lines of evidence now that it will take a real revolution to overthrow them all.
Peter:
Why do you assume David's concern is restricted to the Left?
I don't.
The kind of "naive Darwinism" that posits some natural selection reason for the fact that, say, women use language differently than men, may be guilty of wild hypothesizing.
But, as opposed to any kind of Intelligent Design, naive or otherwise, there is at least a possibility of examining the hypothesis.
More to my point, though, is that even naive Darwinism points out the fatal flaw in the very basis of the Left: humanity is not a social construct.
It is ironic that conservatives who most rail against evolution rely on some amorphous explanation that could truly amount to anything under the sun, while decrying the truly conservative explanation.
Here is an email I sent to my physics adviser, re Hawkings (it's a first draft, I haven't decided if I think I'm right yet):
'Here is something I am considering. I'm reading Stephen Hawking's 'Life
Works,' where he writes, ". . . quantum mechanics allows the universe to have a beginning that is not a singularity. This means that the laws of physics need not break down at the origin of the universe. The state of the universe and its contents, like ourselves, are completely determined by the laws of physics, up to the limit set by the uncertainty principle.
So much for free will."
'I think this is mistaken. My first pass at explaining why:
'Stephen Hawking concludes that, because the universe may not have started in a singularity, then the laws of physics may not have broken down. If they are continuous, then the state of everything in the universe is determined. "So much
for free will."
'This is incorrect. There appears to be one truly random process in the universe, and even if it was determined by the laws of physics, so far at least, the uncertainty is huge -- infinite, almost. That is radiation from heavy atoms.
'Most of the time, the emission of a particle by fission does not change the function of any macro system, but DNA is funny that way. Chemically, it is extremely stable, but its information content is very instable. So much so that, in both theory and apparently in practice a single randomly generated particle can change the function of a
macromolecule.
'Though not proven, the origin of Tay-Sachs Disease as hypothesized from the passing of a cosmic ray through the testes of a Jew somewhere in eastern Europe some centuries ago is an example of
what can happen.
'Artificial systems can almost, but not quite, duplicate this feat. The
triggering of a CCD by an electron changes the state of a system dramatically but does not change its function.
'So free will is not excluded even in a completely materialistic universe.'
I don't think I'm just 'saving the appearances.'
I don’t have a problem with the concept of ‘memes’ to the extent that it is a label for little ‘bytes’ of cultural phenomena that is sometimes useful and interesting.
For example, during last year’s World Cup some people started driving around with these little plastic St George’s flags that clip onto your car window. Pretty soon there were thousands of these things around. There’s a good example of a phenomenon that you could describe as ‘memetic’.
There are some parallels between the way memes successfully spread/fail etc, and the way that evolution by natural selection works, but the one is not a logical extension of the other – you don’t have to be a Darwinist to buy into the meme idea.
Well, I still don't know exactly what a meme is, but unless the little flag gets you killed/saved or helps you find chicks, it doesn't seem to have anything at all to do with how natural selection goes.
More like dropping a seed crystal in a supersaturated solution and watching the crystals form.
"Meme" is really just a metaphor, a way to look at ideas as viruses of the mind. I don't think it gives a whole lot of explanatory power. For example, what is the memetic equivalent of an antibiotic (I know, antibiotics don't work with viruses, only bacteria, but I'm purposely mixing the metaphor).
A few people in the 80's thought you could build a whole science around the meme, including an ex-Microsoft developer who coined the term "Memetics" and wrote a book about it. It was much ado about nothing.
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