Cornelius Hunter seems very confused.
…This brings us back to the UC Berkeley “Understanding Evolution” website. It abuses science in its utterly unfounded claim that “natural selection can produce amazing adaptations.”
In fact natural selection, even at its best, does not “produce” anything. Natural selection does not and cannot influence the construction of any adaptations, amazing or not. If a mutation occurs which improves differential reproduction, then it propagates into future generations. Natural selection is simply the name given to that process. It selects for survival that which already exists. Natural selection has no role in the mutation event. It does not induce mutations, helpful or otherwise, to occur. According to evolutionary theory every single mutation, leading to every single species, is a random event with respect to need.
He has forgotten what “adaptation” means. Of course he is correct that “Natural selection is simply the name given to [differential reproduction]”. And that (as far as we know), “every single mutation …is a random event with respect to need”.
And “adaptation” is the name we give to variants that are preferentially reproduced. So while he would be correct to say that “natural selection” is NOT the name we give to “mutation” (duh); it IS the name we give to the very process that SELECTS those mutations that promote reproduction. i.e. the process that produces adaptation.
Cornelius should spend more time at the Understanding Evolution website.
ETA: CharlieM points out below that…
When CH says that natural selection does not produce adaptations he is talking about individual organisms. He is discussing mutations in individuals and adaptations in individuals. Natural selection has nothing to do with the first appearance of an adaptation in an individual.
And that of course is the confusion – I hadn’t seen just where Cornelius’s confusion lay. Because, of course, the term “adaptation” is a population-level concept. At the level of the individual, the equivalent would be “advantageous mutation”. And that makes the Understanding Evolution website absolutely correct.
Who does that? Niches fill, close and become available. The environment is constantly changing and where long-lived stable niche environments are found, organisms that find and occupy those niches are under less selective pressure.
stcordova,
So you are saying that the only mutations that ever become fixed are those that would not be competitive if the ancestors still lived? That’s not supported by anything. Including Lenski.
But if it was … what celestial mechanism opposes this assumed degenerative tendency?
No! I was pointing out the absurdity of the notion of “fit” used by population geneticists to the notion of “fit” in the Darwinian blindwatchmaker functional sense. Equivocation abounds and one that Dennett resorts to in his algorithm that population keep getting fitter (true in a population genetic sense) but not necessarily true in a functional sense.
You’re also making the mistake of defining function in terms of fitness. Sickle cell anemia is highly fit, but it is not functional except in the sense blowing up a bridge is functional to prevent an invasion. An X-box is functional, it’s functionality is not defined by the ability to create reproductive success. Birth control pills are an intelligently designed pharmaceutical — their intelligently designed functionality should not be defined by reproductive success.
There is a lot of extravagance in biology that is selectively unfavored in the long run, but still evidences interdependent Rube Goldberg complex function.
stcordova,
Indeed.
Heck, for the biologist, the reason our cells decay and become old and die, is because that is more fit than an individual that lives forever.
Why can’t humans cut off their legs and just grow back new ones in a few days? Well, because not being able to grow back new ones is a sign of greater fitness.
Wrong, because not being able to grow back new ones is a sign of god’s love for you, little human. Don’t question the almighty god’s plan.
Oh, can’t help myself from asking:
Why doesn’t god ever heal amputees?
stcordova,
That ‘E’ word again. It must be a US thing. No-one uses the term ‘fit’ in an attempt to be ambiguous. Nor to cavil con dodge elude escape eschew evade falsify fence fib flip-flop fudge hedge jive lie palter parry prevaricate pussyfoot quibble shuck shuffle sidestep stonewall tergiversate waffle beat around the bush beg the question cloud the issue cop out cover up double-talk give run around hem and haw mince words pass the buck sit on the fence tell white lie or weasel They even rigorously define their bloody terms, as we have been doing here! That’s a strange kind of equivocation.
‘Fit’ as in ‘fit for purpose’ or ‘physically fit’ is not the sense in which population geneticists use ‘fit’. It was almost an in-joke – that quality that makes ‘survival of the fittest’ true became what population-genetic ‘fitness’ meant. It all reduces to producing more net offspring than your rivals, integrating survival and reproduction.
Dawkins has a nice chapter on this in The Extended Phenotype – “An Agony In Five Fits”. He prefers to avoid the term altogether. Yes, it can be confusing. But that confusion is easily remedied.
I never even mentioned function, so I don’t know where you got that from.
Not really. The heterozygote has certain advantages in certain environments, but not others. The homozygote is stronly detrimental. Cherry-picking ‘broken’ genes or vestigial traits is not really much of a guide to the entirety of evolution’s capacity, either.
With respect Sal, I find most of the above gobbledygook. What is “selectionist theory”? Do you mean the theory of Natural Selection? And why do you say that “what defines ‘fit’ is equivocated”? Do you mean that people use different definitions in different contexts? Or that they don’t define what they mean? Or that they don’t know what they mean? Because it seems to me that people use “fit” in very precisely defined ways. Can you give me an example of equivocation?
What “evidence” are you referring to that “evolutionists falsely presume” is evidence that insulin evolved? Can you cite your source for this claim?
Fitness is not an ill-defined concept. It’s an extremely well-defined concept. Ask Joe Felsenstein.
Any misrepresentation of a hypothesis runs the risk of being an absurdity. Nobody “defines a eugenically ideal phenotype”. It’s not a concept that plays any role in evolutionary theory or biology. Fitness is defined entirely in relation to the current population in the current environment.
phoodoo,
You might want to take the absence of these capacities up with your Designer. Built-in obsolescence and irreplaceable parts. Cheers, God!
Joe:
That bias-that-isn’t-drift-or-mutation is relative fecundity in my scenario. Selection (by Darwin’s and Mayr’s and Gould’s and Allan’s and my definition) is absent, because the environment doesn’t favor either of the two variants. And yes, even Archimedes could have figured out that if variant B produces twice as many offspring as variant A, and all offspring survive and reproduce, then B will come to dominate the population. We certainly didn’t have to wait until 1903 and the development of the quantitative theory. To call that ‘selection’ is a definitional choice, not an empirical one.
Not so fast. Some do, some don’t. There is no canonical definition among either scientists in general or evolutionary theorists in particular. See my response to Steve. (I’d say Ernst Mayr and Stephen Jay Gould qualify as ‘evolutionary theorists’, wouldn’t you?)
I’ll ask again:
Allan,
True, though in my scenario the population is quite easily circumscribed: it’s the original population plus all descendants.
Well thanks anyway for reading and responding. 🙂
Selectionist theory vs. neutralist theory or other evolutionary theory — the primary mode of speculated evolution.
The phrase is not mine alone, it is used here:
http://www.nbi.dk/~natphil/salthe/Critique_of_Natural_Select_.pdf
Population geneticists use the notion of “fit” in terms of reproductive schedules. Sickle cell anemia is considered “fit” in a malaria environment. Tay-sac disease is considered fit in the Darwinian sense as well as well as blindness in cavefish, winglessness in beetles and all the trashing created by reductive evolution and the mass destruction of function via extinction via natural selection.
Clearly the idea of fit as in the medical and engineering sense is equivocated with the definition of “fit” in population genetics which defines it in terms of reproductive success for an existing species line. If you argue that selection is the mechanism that created functional proteins, that’s equivocation on many levels.
A protein being essential for life today is no evidence it was selected for in the past, especially before it even existed. You can’t have selection pressure toward non-existent traits. That’s like working toward a pre-meditated unseen goal which the blindwatchmaker cannot do as a matter of principle. If anything a life critical trait is evidence against selection being the mechanism of evolution, because without the trait, the organism dies, ergo, no evolution! For evolution to work, the trait has to be not-so-critical, maybe even neutral.
So trait being critical today is equivocated with the idea it was favorably selected for in the past (usually even before the trait existed!).
Furthermore, what about all that elimination of function through extinction via natural selection (like we humans dominating the biosphere and torching inferior species, bwahaha)? How is net reduction of functional diversity a net gain of functional diversity?
The confused thinking is not mine, it’s in the mind of evolutionary biologists.
Andreas Wagner said, “fitness is hard to define”.
Wager instead focuses on systems and defines them as “assemblies of parts that carry out well-defined biological functions”. Compare that to Behe:
Now add to all this Lewontin
I’m just relating to you what leading evolutionary theorist have finally realized, and something creationists have been pointing out for a while. Darwinian theory is incoherent on many levels.
Cornelius Hunter is not the one confused, evolutionary theorist are.
So is physics and chemistry, and yet we have transistors. One can choose to quote mine and be a shit, or one can attempt to find coherence amidst popular writing.
No, it is not “equivocated” Sal. Lots of words have more than one meaning. It is not “equivocation” to use them, as long as you, or the context, makes it clear which sense you are using them in. “Fit” in a medical sense is not the same as “fit” in a population genetics sense.
In what way?
As for your Lewontin quote, it is taken from an essay that you might want to read again in its entirety. It certainly doesn’t suggest that Darwinian theory is “incoherent”.
keiths,
Steady on! I’m not an absolutist in these things! I’m more of a shilly-shallying flip-flopper. Selection is fundamentally about alleles having differential effects on rates-of-increase. It doesn’t have to be the environment that determines these rates. Or rather, the environment of any allele includes all the others.
stcordova,
Clearly it isn’t, as any reference to a relevant glossary will show.
Best to avoid words like fitness and stick with differential reproductive success.
That covers everything from beneficial and detrimental mutations to asteroids.
stcordova,
If it is not fixed, then clearly it is not essential in those organisms that don’t have it. This does not mean it must therefore be neutral. This is a ridiculous argument. Once it is fixed, other features can come to rely on the facility provided. You think people imagine a fully-functional eye with all wiring fixing in one go by selection?
An allele does not need to be fixed in a population before individuals having can participate in additional evolution.
As you can see in AVIDA.
keiths:
I disagree. There were several attempts to build a quantitative theory of evolution before 1900 (notably Fleeming Jenkin, Galton, and Delboeuf) but they all failed because there was no understanding of how genetics worked. There was no clear distinction between genotype and phenotype. Some of the confusions can be seen even in Darwin’s writings. As late as 1908 members of the Genetical Society in Britain seemed to think that an allele would spread in a population simply because it was dominant.
So no, Archimedes would not have been able to do this, as simple as the mathematics would be.
Ernst Mayr was not a deep thinker when it came to population genetics.
In any case, I do not see in those quotes anything that is incompatible with the population-genetic definitions of fitness.
No doubt our definitions of fitness are oversimplified. They are designed for use in abstract models. Making the models more realistic (for example, allowing overlapping generations) we need more complicated definitions of fitness. Waving one’s hand and dismissing the mathematical theory is easy. What is hard is to put anything coherent in its place. If you’ve got a replacement, let’s hear about it.
petrushka,
True enough
Allan,
I’m not either. I have no problem with pop gen terminology and concepts, and I don’t want to change them. I use them myself when working out pop gen practice problems.
I’m simply suggesting that the pop gen version of selection isn’t the appropriate one for the current discussion.
It is Steve and Joe who are being absolutist:
Steve:
Joe:
I don’t know Steve very well, but I’m surprised to see Joe being so doctrinaire.
There is no single, canonical definition of “natural selection” among evolutionary biologists or scientists generally.
There is when you use population genetics.
BTW Allan, I had a similar discussion over at UD not to far back in which I questioned how you could tell the effects of drift from the effects of selection, which Elizabeth then started a thread about here.
I was maintaining that people were conflating neutral evolution and genetic drift and arguing that even mutations under selection were not immune to genetic drift. So if I read you correctly you would agree.
So how does one distinguish between the two?
I’m with you. Why doesn’t God force everyone to be perfect or just kill them off?
You can only do it statistically.
If a mutation has increased in prevalence with a rapidity improbable under the null hypothesis of drift, you can infer that is probably conferring a selective advantage.
No, you’re not with me.
I’ve never in my life been a horrible enough person to wonder why god doesn’t “just kill them off”.
keiths:
Joe:
Your claim was far broader:
That’s simply wrong. Not all evolutionary theorists use your definition, Joe. As I’ve already demonstrated.
Joe:
Come on, Joe. Archimedes would have had absolutely no trouble with this:
You don’t need the quantitative theory of evolution to figure it out.
If true, so what? He was an evolutionary theorist (and a well-known one) and his definition of natural selection differed from yours, contrary to your claim:
Joe:
Think about my scenario. There is no death, which means there is no elimination, which means there is no selection according to Mayr’s definition. According to the pop gen definition, there is selection. The definitions are incompatible when applied to my scenario.
I’m not dismissing the mathematical theory at all, nor am I suggesting that it needs to change. I’m simply pointing out that the pop gen definition of selection doesn’t automatically trump all other definitions.
By all means, continue to use the definition you find most convenient for your work, but don’t pretend that it is the only right definition or the only scientific one.
keiths:
Just goes to show Mayr was prone to make population-genetic howlers.
He forgot that two genotypes that had the same mortality, in this case none, but differed in fertility/fecundity thereby had different fitness.
Just goes to show that the particular definition of fitness that he used, and you use, is not useful.
Joe:
He wasn’t talking about population genetics — he was talking about natural selection, which is a concept shared between population genetics and all of the other evolutionary subdisciplines.
Huh? He doesn’t even mention fitness in that quote:
Joe:
You’ve lost the thread completely. I haven’t offered a definition of fitness. Mayr’s quote doesn’t mention fitness. We’ve been talking about natural selection, Joe.
keiths you aren’t making sense
Now that the question has been answered in the affirmative, anyone want to actually face what Darwin himself said about NS, which he would have changed to NP? Funny the equivocation thread in contrast…confident Darwin groupies who promote false Darwin.
hyperbole much?
jeez Gregory, we are talking about science here!
Are you going to attack cosmologists who promote false Newton?
The validity of evolutionary theory is not to be found in a close textual reading of Darwin, but in the development operationalisation and testing of the theory.
No, Lizzie, we’re talking about LIFE. Do you actually wish to deny Darwin wrote that letter to Lyell?!
Schizophrenia studies, music & architecture won’t save you from committing a direct answer.
Is this thread really mainly about “the validity of evolutionary theory”?
Do you make healing the same thing as “forcing something to be perfect?” If not, that was quite an “evolution” you made to hotshoe’s remark.
Mung,
Yes, I would completely agree.
You only get an overall stat, so you can’t strictly distinguish. If you think of the kinds of things that could be selected, they only matter when they matter. So if you escape from a lion, your ‘escape’ genes get a leg-up, and are more likely to persist. But the rest of the time, your escape genes aren’t being tested, and random factors prevail. But also, your ‘escape’ genes get a leg-up every time some slowpoke is eaten, even if you aren’t involved in that transaction. So, the final s value is always an integral of bias and drift.
This doesn’t mean you can’t spot selection, however. For instance, one can get a ratio of the amount of synonymous to nonsynonymous substitution in codons. The rate of substitution of the latter gives a baseline for drift (with caveats), and the former is the departure from the neutral expectation.
Neutral alleles form the baseline, and you can calculate the expected time for them – but this is a probability distribution, so data for a ‘real’ neutral allele could legitimately appear selected. From theory, as soon as you depart from neutrality, two things happen: population size becomes a factor, and expected times to fixation shift. The further your measurements depart from the baseline, the more confidence you can have that selection, not visiting the extremes of the distribution (which must happen, for it to be a distribution), is the deciding factor.
Allan Miller,
*I got synonymous and nonsynonymous the wrong way round (and can’t edit!)
Lizzie,
What’s confusing you?
I’m not confused. I’m suggesting that you are.
(I am a bit hampered by WordPress, which loses quotes-within-quotes when it generates a reply quoting you).
Anyway, sorry for the inattentive reply. OK, let’s talk about Mayr’s definition of natural selection (not fitness).
Apparently it doesn’t include differences in fertility (or fecundity)? Just in viability?
So if genotype A and genotype B have the same viability, and then genotype A comes to have higher fecundity than genotype B, we expect genotype A to increase, but Uncle Ernie wouldn’t call that natural selection? Hmmm.
Lizzie,
What specifically do you think I’m confused about, and why?
Joe:
If they are perfectly viable (as in my scenario), with no individuals being eliminated, then his definition clearly precludes selection:
So yes, a man who is considered one of the greatest evolutionary biologists of the 20th century disagrees with you on the meaning of “natural selection”.
Now do you see how silly it was for Steve to write this…
…and for you to write this?
Well I’ll just leave it with these points:
1. I shook Ernst Mayr’s hand once.
2. I corresponded with him over his request that I read the chapters on phylogeny methods in his (and Peter Ashlock’s) 1991 revised version of Principles of Systematic Zoology. I gave him lots of corrections, and he thanked me and acknowledged me in the book.
3, I have many times talked to other theoretical population geneticists about Ernst Mayr’s misunderstandings of theoretical population genetics. We all agreed on that.
So I have some perspective on Mayr.
If that’s his definition of “natural selection”, I disagree with it.
And so should you.
Joe:
Obviously, although why you think there can only be one scientifically valid definition is beyond me. This is hardly the only example of a technical term that has different definitions depending on the context.
Why?
Because science is critically dependent on effective operational definitions.
The definition that emerged from population genetics does not, in my view, contradict Darwin’s – what it does is show that the scenarios Darwin envisaged were a special case of something that could be formulated more generally.
In discussing the theory of natural selection, it makes no sense to ring-fence it with boundaries that turned out not, in fact, to be boundaries.
Darwin’s idea was even more brilliant than he realised, basically, and capable of being expressed in formal mathematical terms.
That formalisation continues to be refined to take account of new discoveries, including genetics, which Darwin didn’t even know about.
Lizzie,
Sure, but Mayr’s definition is hardly “ineffective”. It just differs from the pop gen definition.
The pop gen definition is more inclusive, so it only contradicts less-inclusive ones in the areas of non-overlap.
The boundaries are created by the definitions. The pop gen boundaries enclose more but are no more real than the boundaries created by Mayr’s definition.
Later today I’ll elaborate on why I think Mayr’s definition is the appropriate one to use in the context of this thread.
The Mayr quote refers to NS as “What Darwin called natural selection”. He is not offering his own, but adopting Darwin’s.
I share a degree of keiths’s reservation that population genetics needn’t have the last word on how to look at evolution. I have argued in the past against evolution being defined as “change in allele frequency”, when change in lineage is clearly important too. The get-out that a new mutation is a change in frequency too isn’t very satisfactory. But … I’m not that bothered about it either!
How does mathematics define the change in frequency from zero to non-zero?
The allele frequency definition reminds me of the definition of a human: a featherless biped with broad flat nails.
All this strikes me as apologetics. Quibbling over semantics.
Evolution in its broadest sense is change in populations over time. Most of the heritable change is in the genome, but there are organelles that could, at least in theory, evolve.
I think it would be more productive to discuss how and why alleles become prevalent or fixed. I would like to see a Larry Moran thread that discusses his assertion that most alleles fix as a result of drift.