Biological fitness - What Is It? (Page 5)

duncan124
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CoIin
CoIin: Erm, I probably have no readers left, let alone interlocutors , nevertheless...

This writer I mentioned in the post above, David Stove, is BRILLIANT! The man is a genius!

I began this thread with only the vaguest notion of what "fitness" meant. It wasn't something I'd thought about much. Well, I thought about it a great deal during the evolution (sorry ) of the thread and discovered that it could be interpreted in (at least) two ways, moreover if you pay attention you'll catch people, even biologists, oscillating between one interpretation and the other without even knowing it.

Well, what's remarkable is that David Stove noticed something very similar in his analysis of the notion of "Inclusive Fitness" in the writings of prominent sociobiologists such as Richard Dawkins, viz., is inclusive fitness theory a theory of what CAUSES altruism, or a DENIAL of altruism, in other words, is altruism genuine or only apparent. The writers in question, he claims, bounce willy-nilly from one to the other position apparently oblivious to the contradiction.

It cannot logically be both. Stove's hypothesis is that the writers are genuinely confused (the alternative is worse - deliberate deception? ). And there's no disgrace in that. This stuff IS perilously confusing, as we've seen throughout the thread.

If you're interested you'll find it in Essays VI-VIII (link in previous post).

Stove is a professional philosopher and openly admits to being a layman when it comes to biology, although he clearly did a great deal of homework in preparation for his book. I admit to being an even bigger layman and to doing the bare minimum of homework , but bear in mind, this is not a challenge to scientific expertise, it's a matter of pure logic. And Stove is VERY good at that; that's what philosophers do. He's marvellously witty too.

I'd recommend anyone who is genuinely interested in these matters to have a read. I always seem to be taken the wrong way - this is not about science-bashing or discrediting or whatever, and I don't believe either Stove or myself is deluded.

This is about a sincere desire for clarity and understanding. And dare I say "truth"? Come on now, we all want these things, don't we?
(Edited by CoIin)
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duncan124
duncan124:
Where is the link?
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duncan124
duncan124:
I don't think you meant this one,-

"Stove made controversial arguments in some of his works,[4] most notably in "The Intellectual Capacity of Women" and "Racial and Other Antagonisms" (both of which appear in Cricket versus Republicanism and Against the Idols of the Age). In the former he argued that women are "on the whole" intellectually inferior to men, while in "Racial and Other Antagonisms" Stove asserted that racism is not a form of prejudice but common sense:"

...but then again you ' Wordy Evolution ' thread was a bit odd!!
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duncan124
duncan124:
A definition of Fitness can be found at;-

en.wikipedia.org/wiki/Physical_fitness
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nasdaquero
nasdaquero: Colin wrote:
"If fitness is defined purely in terms of survival/reproduction then the maxim "Survival of the fittest" IS circular. It tells us absolutely nothing. It has zero explanatory power."

Actually no: because we're always talking about a population of a species in a particular place at a particular time. For example, let's posit a population of bacteria that is adapted to the fresh water pond in which it exists. Now populations are not uniform; some individuals in the population have a greater capacity to tolerate salt water than others. One day a berm erodes and there is an influx of salt water. Suddenly the population of fresh water adapted bacteria plummets, yet some of the bacteria, those with a higher tolerance for a brackish environment, survive and eventually reproduce to reach the same population size as before. This sort of thing is testable, has been tested, and is continually encountered, especially but not exclusively in the case of microorganisms which we are always assaulting with antibiotics. Fitness is the superior capacity to produce viable offspring in a particular environment. It's not ahistorical, and it has to be looked at in ecological context. Also, "survival of the fittest" isn't the same as speciation, though it can be a factor in how speciation occurs.
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CoIin
CoIin: Thanks for that, but...

@ - "Fitness is the superior CAPACITY to produce viable offspring in a particular environment."

We must pay very close attention to our wording. This has been one of the points of the thread. Do you mean the "capacity" to do so, or the brute fact of doing so? These are not the same thing. Having the capacity to dance well does not entail that one WILL dance well. You might be struck by lightning on the way to the ball

Or as I suggested earlier in the thread, "having what it takes to succeed" and "actually succeeding" are not the same thing.
(Edited by CoIin)
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CoIin
CoIin: re - "If fitness is defined purely in terms of survival/reproduction then the maxim "Survival of the fittest" IS circular.

This is not the kind of thing which can be refuted by empirical evidence; it is irrelevant to what happens to individuals or groups in a fresh water pond or any other milieu. This is a truth of language, a truth by definition.

If you define "bachelor" as unmarried man, then you don't need to worry about the claim "all bachelors are single" being disproven, no matter what empirical discoveries are made. Likewise, if fitness is defined purely in terms of survival/reproduction then our chances of finding unfit survivors, or fit non-survivors (i.e. fit but childless organisms), are precisely the same as your chances of finding a married bachelor, namely, zero.

On the other hand, a claim like "all bachelors are young" is not true by definition and could only be verified or falsified through empirical investigation.

Similarly, if fitness is defined as the PROPENSITY to survive and reproduce, then "survival of the fittest" is an empirical claim and could, at least in principle, be refuted by empirical findings.
(Edited by CoIin)
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duncan124
duncan124:
If you change ' Fitness ' to ' Snugness ' I am sure you could understand that the environment could change and one set could go from snug to weather beaten just as the strong could fall ill or the weak gain health.

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nasdaquero
nasdaquero: Colin, you elided the second part of my statement: "...in a particular environment." Fitness is indeed subject to testability AND prediction. I can predict that if I subject the pond to an infusion of salt water, there will be a change in allele frequency in that population. I can predict with some confidence that the individuals who have the capacity to reproduce better in brackish conditions will survive and reproduce. By the way, this sort of inference is common in evolutionary biology and often leads to interesting discoveries, exactly because it has predictive power. All this fits our concept of what science is.
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CoIin
CoIin: Hi again and thanks for the remarks. I'm not denying the testability of evolutionary theory, but I'm afraid the logical point I'm making is still eluding you. I emphasize that this is a point of logic, completely unrelated to whatever happens out there in the pond or the jungle.

Let me ask you again. Are you defining fitness in terms of:-
(1). Successful reproduction, OR
(2). The CAPACITY (or propensity or ability if you prefer) to successfully reproduce

If we define fitness as (1) then the "fittest" CANNOT FAIL to be the most successful reproducers ("Survival of the fittest" is a logical certainty, and thus, obviously, non-falsifiable). Even if God decided to get involved somehow, the fittest would still survive - BY DEFINITION. If Charles Atlas has 4 kids while that 90-pound weakling has none, then CA is fitter. If the kid count is reversed then the weakling is the fitter. Physical characteristics (affinity for brackish water, or anything else) are utterly irrelevant to fitness under this definition.

If we define fitness as (2), then it is an empirical matter whether or not the fittest organisms, or groups of organisms, are the most successful reproducers.

When you talk about "brackish conditions", you clearly have fitness(2) in mind. Fitness in this case is a matter of physical characteristics of the organisms involved; not just a simple "kid count".

In other words, you are saying "I can predict that organisms with particular traits will survive and reproduce more successfully in a given milieu". I DON'T DENY THIS!

Pay very close attention to your sentence "I can predict with some confidence that the individuals who have the capacity to reproduce better in brackish conditions will survive and reproduce."

If you remove the word "capacity" from this sentence, it makes all the difference in the world. In doing so you would thereby flip from an empirical claim (which at least in principle should be testable) to a tautology - a logical certainty, namely "I can predict with some confidence that the individuals who reproduce better in brackish conditions will survive and reproduce."

In this case, there's no need to stop at "some confidence". You may enjoy complete confidence .
(Edited by CoIin)
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nasdaquero
nasdaquero: The "simple kid count" or differential reproductive abiilty is the essence of fitness, but there's no tautology because fitness is always conditional for a specific population or populations in a specific environment at a specific time. Fitness is always in relation to ecological pressures, and of course there are other factors like genetic drift and the founder effect, so predictions are never 100%. Its also worth recalling that the phrase itself was not one that Darwin used except incidentally. For him, evolution was "descent with modification." I dont think there is much to be gained by trying to ignore the concept of fitness as understood by biologists.
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nasdaquero
nasdaquero: I use capacity because there can always be mitigating factors-- again because the history of any population or species is exactly that: a unique history. Say a meteor mostly wipes out a bunch of species: the individuals that remain by chance may not be the most optimally adapted to the environment, or others may colonise the environment from outside, which may have been impossible prior to the catastrophic event. So you may have survival of the luckiest. This in no way negates the process whereby the environment, in the absense of a catastrophe, provides selection pressures on organisms that favor adaptive fitness, i.e. differential reproduction of fertile offspring.
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CoIin
CoIin: I'm afraid you're contradicting yourself. First you say:-

"The "simple kid count" or differential reproductive abiilty is the essence of fitness"

So, according to the above, to know who is fit/fitter, we just count the kids, right? There is nothing else we NEED to know. Reproductive success is the ONLY criterion for fitness.

But then you say:-

"So you may have survival of the luckiest"

In other words, you're telling us now that sometimes those who survive/reproduce most successfully are NOT the fittest but the luckiest. But according to what you said first, reproductive success is THE ONLY MEASURE OF FITNESS - it is the very DEFINITION of fitness - and therefore, these lucky organisms that survived the catastrophe may indeed be lucky, but they are also, by your own definition, the fittest.

You're bouncing between Fitness1 and Fitness2 without even noticing it. Don't worry, you're in good company . It seems like almost everyone does it. I certainly did until a few weeks ago.

(Try my quiz on the previous page)




re - "I dont think there is much to be gained by trying to ignore the concept of fitness as understood by biologists."

Well, this is one of the interesting discoveries I made while developing this thread. Fitness1 (reproductive success) is indeed current orthodoxy in biology as far as I understand. But it has not always been that way. Darwin, Galton and their contemporaries (see my post at the bottom of the previous page) clearly took fitness to mean Fitness2 (fitness as a product of physical traits).

As the birth rate of the lower classes ( "the indolent, the improvident, the unintelligent, the dishonest, the constitutionally weak, the carriers of hereditary disease, the racially inferior, and so on" ) continued to increase in Victorian England, the distraught Darwinians of the day clearly did not believe that the fitness level of the riff-raff was RISING. Their numbers may have been rising but not their fitness. However, this is the conclusion we would HAVE to draw under current orthodoxy (more kids = higher fitness).
(Edited by CoIin)
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CoIin
CoIin: P.S. I've no idea when or why Fitness1 replaced Fitness2 as orthodoxy in biology. If anyone knows I'll be fascinated to learn.

CrisC pointed out on page 1 of this thread that the slogan "Survival of the fittest" is no longer encouraged in academia. Well, perhaps now we know the reason, or one of the reasons. In Darwin's day SOTF was a substantive claim about how the world works. Since the switch from Fitness2 to Fitness1, however, SOTF is nothing more than a tautology of language, a trivial truth bereft of any empirical content.

Biologists, of course, do not enjoy a monopoly on how terms should be interpreted. Fitness2 is clearly our intuitive sense of fitness; fitness1 is a contrivance of modern biology. As long as we keep the two clearly distinguished there's no problem, but as we've seen, equivocation between the two is rife.
(Edited by CoIin)
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CoIin
CoIin: @ nasdaq

I encourage you to read the article on page 3 of this thread which begins "The following overview by Roberta L. Millstein is even clearer. Enjoy!"

Each time you see "propensity" substitute "capacity" and there's no reason why we should ever argue.

In a nutshell...

Q1 : Is the maxim "Survival of the Fittest" viciously circular?

Ans1 : If fitness is defined purely in terms of survival/reproduction, then yes
Ans2 : If fitness is defined in terms of the PROPENSITY to survive/reproduce, then no

Q2 : Is the theory of evolution viciously circular?
Ans : No! (regardless of your answer to the previous question)

So rest easy
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nasdaquero
nasdaquero: My point is there is no such maxim in modern biology (which is based on the combination of Darwinian evolutionary theory with the later insights into genetics that is called the modern synthesis, and subsequent discoveries).Fitness is defined as differential reproduction: it simply means that environmental pressures select for certain traits in a population. This is the primary driver for adaptation in organisms. Selection isn't random, and each species ( or population) has a unique history. There is no orthodoxy in science that proclaims that any individual organism we look at exists because it is "the most fit"-- biology recognizes the effects of catastrophes, as well as genetic drift, the founder effect, etc. You can read 50,000 scientific papers published since 1940 and never see the term "survival of the fittest"--and not simply because of its associations with eugenics and racism-- its just not how biologists think about fitness.
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nasdaquero
nasdaquero: And just to be clear, I accepted your use of the term for the sake of the discussion. I don't have a problem with it as a description of something that occurs in nature, as long as it isnt treated as some sort of law or principle that exists outside of the context of real organisms in the real world.
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CoIin
CoIin: This is interesting reading....

http://philsci-archive.pitt.edu/9833/1/eLS_Preprint.pdf

Now you know why scientists hate philosophers

It would be awfully nice if a concept such as "fitness" could be nice and cozy and simple. But you can always rely on philosphers to demonstrate that it's not.
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duncan124
duncan124:
Do you always spell it like that??

And how should it be translated for your European readers, hmmm such as the portuguese eh?
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nasdaquero
nasdaquero: Actually, biologists don't hate philosophers, they simply realize that the sorts of questions posed by philosophers of science often don't much relate to what biologists do on a day to day basis. The, to me, quite funny aspect of the paper you cited (I read it) is that it entirely ignores (as in does not mention at all) the central "problem" of evolutionary biology, which is speciation. Ever since Mayer and Dobszansky, and subsequently Gould, the focus of evolutionary studies, with concomitant philosophical and theortical debate, has been on how species come to be, and what defines a species. It would seem to me that the author of the cited paper has an at best rudimentary understanding of current evolutionary theory and possibly doesn't understand at all how "descent with modification" occurs.
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nasdaquero
nasdaquero: Oh, and I doubt you could find one biologist in a thousand who would claim that any biological process or explanation for that process is cozy and simple. Nature is notoriously complex, surprising and difficult to observe. There always seem to be exceptions to any rule, and myriad evolved modes of survival. I believe that this is why, in the actual community of scientists, people like Dawkins do not have much status: his sort of neat reductionism appeals to laymen because it seems to offer a simple explanation for everything. In fact his concepts are highly disputed both on biological grounds and for philosophical reasons. Oh, and sociobiology sensu lato is pretty much considered a joke.
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CoIin
CoIin: @ nasdaq

@ - "The, to me, quite funny aspect of the paper you cited (I read it) is that it entirely ignores (as in does not mention at all) the central "problem" of evolutionary biology, which is speciation."

Well, the topic of the paper was "Fitness", not speciation . Those with masochistic proclivities will not be perturbed by a paucity of philosophical lucubrations on speciation in the literature out there.

@ - "Actually, biologists don't hate philosophers"

I was being slightly facetious

I'm glad you said what you did about Dawkins. I don't feel so alone now . I can't say I think very highly of the man. I'm sure he's quite proficient in his own area of expertise, but when he steps back and attempts commentary on anything less parochial (scientific method, religion, philosophy, etc), he always sounds to me embarrassingly naive (well, "dim" to be quite frank) - a bit like listening to George W Bush on ethics - "They're bad; we're good"

(And I find it very hard to listen to a sombre exposition of "meme theory" without wincing. Perhaps it's just me . Is that stuff taken seriously by mainstream biologists? )

@ - "sociobiology sensu lato"

Um, what's that?


You seem very knowledgeable, Nas. Are you a biologist yourself?
(Edited by CoIin)
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duncan124
duncan124:
Ness farewell.

YouTube
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nasdaquero
nasdaquero: Colin, I'm an amateur biologist; no degree, or faculty position, but I'm an authority on a small group of beetles. I was making a comment on sociobiology in the broad sense, or at least the popular sense. It's mostly just a bunch of conjectural B.S.; it's too bad people like Dawkins and perhaps worse, E. O. Wilson, have given it legitimacy. Wilson's an excellent entomologist, and great when writing about the things he knows (evolution, biological diversity, etc), but he's a terrible philosopher, and never even realized that many of his positions had long ago been discredited in philosophy/philosophy of science. Both he and Dawkins seem obsessed with justifying their personal political and religious philosophies through an appeal to nature--never a tenable argument. In any case, all the pop psychology and anthropology articles where some "sociobiologist" argues that some behavior evolved among australopithecines and is therefore ingrained in "human nature" are fantasies. There is simply no fossil evidence for the sorts of conjectures they make. For example, they'll typically claim some behavior was evolved on the plains of Africa in response to some environmental factor--but they have no evidence to support it. Perhaps it was a behavior that was evolved by our prosimian tree dwelling ancestors tens of millions of years previously? How would they, or anyone else know?

Regarding Dawkins's anti religious rants, I haven't read his book, but I imagine that, like me, the majority of biologists simply aren't interested in his argument. There are plenty of atheist and agnostic biologists, but also plenty of church going biologists, and I'd say most would consider faith a personal issue that doesn't have much bearing on their work as scientists. I think Dawkins has a lot more impact on non-scientists than he does in the scientific community.
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