Natural selection, my ass (Page 4)
sensus fail: i just read all this natural selection, my ass forum, "...an encapsulation of your powerful theory of natural selection.... "
im never going to read another forum again, cancer
AchillesJaguar: I'm getting the impression that none of our contributors has really grasped what I'm trying to say here. The issue is a subtle one, and the fault may be partly mine for being less than perspicuous. Let me attempt below, then, to be as clear as possible.
Firstly, it matters not for what follows whether natural selection is described, as it variously is, as a "principle" or a "law" or a "force" or whatever you like. For simplicity, I'll just refer to it as PNS (principle of natural selection). Now to business...
Q1: What is my claim/complaint?
Ans1: that PNS as standardly formulated is a tautology, and as such, it is explanatorily vacuous, i.e., it explains absolutely nothing.
For the uninitiated, a tautology, or more generally a "true analytic statement" is one which is true simply in virtue of the meaning of its component terms -- a logical or definitional truth. Standard examples include "All unmarried men are unmarried", "All bachelors are unmarried" and "Vixens are female foxes". The truth of a tautology, such as those just mentioned, tends to be blindingly obvious. To see the truth of others may require a little more thought: consider "All ancestors produce offspring".
My contention is that PNS, though not as in-your-face true as, say, "All unmarried men are unmarried", is nonetheless in exactly the same tautological boat.
Note the following features of a tautology:
(i) No empirical investigation (cf. science) is required to establish its truth. Its truth can be seen purely by linguistic competence and a little thought. One does not have to gather evidence to support, or to establish the truth of, a tautology.
(ii) A tautology would appear to have no explanatory power. Upon enquiring into why Jones is a bachelor, some cerebral relief may be gained by being told that Jones is not very good looking, or that Jones is gay, or that Jones is saving himself for someone special. Surely nothing, though, is explained by being told "All bachelors are unmarried men". A tautology would appear to be "explanatorily vacuous".
(Note: with the exception of a case where, for example, you are explaining what the term "bachelor" MEANS to someone who doesn't know, perhaps a child or a non-native speaker. E.g. "Ah, a bachelor is an unmarried man. I understand now. Thanks for explaining!" )
Q2: Am I the only frothing lunatic out there to suspect that PNS is a tautology?
Ans2: No, the "tautology problem" has been discussed extensively in the literature, mainly among philosophers of science and more philosophically inclined biologists, including some of the most distinguished. (The vast majority of biologists, I daresay, have never even given it a thought.) Consider:
"The phrase 'survival of the fittest' is something of a tautology. So are most mathematical theorems. There is no harm in stating the truth in two different ways." - J. B. S. Haldane
"For what good is a theory that is guaranteed by its internal logical structure to agree with all conceivable observations, irrespective of the real structure of the world. If scientists are going to use logically unbeatable theories about the world, they might as well give up natural science and take up religion." - Richard Lewontin
Q3: Well, supposing PNS is indeed a tautology? What's the problem?
Ans3: Lots! For example...
We are often told of the "explanatory power" of PNS. If I'm right, its explanatory power amounts to precisely zero, misleading appearances to the contrary notwithstanding.
We are often told of the "mountains of evidence" for the theory of evolution. Now, it's never quite clear what is meant by "the theory of evolution", but presumably natural selection is implicated somehow. As noted above, inasmuch as a tautology is true by definition, no evidence is required! If you think you're supporting PNS by accumulating evidence, you're engaged in a fool's errand.
Q4: What are your options?
Ans4: Three come immediately to mind:
(i) Deny the tautologous nature of PNS. To do this, you will have to state PNS in a form that is both non-circular and which captures the essence of the principle acceptable to evolutionary biologists. I've invited my contributors/detractors to do this; thus far, not one has.
(ii) Concede the tautologous nature of PNS, but argue that it is nonetheless useful somehow. As pointed out above, though, it's far from obvious, to say the least, how a tautology can have any explanatory power, at least in matters of empirical science.
(iii) Join me in saying "Natural selection, my ass"
For anyone interested, an overview of the PNS "tautology problem" can be read here:
Sir Loin: Achilles, you pick a scientific theory and try to turn it into a philosophical argument. Natural selection is not a tautology in its strictest definition because it is not a redundant statement. If you think it is, then you really don't understand how it works. If you're going to discuss a scientific topic, do it in scientific terms or you just appear a fool. If you want to discuss philosophy, best to do it in the philosophy forum. I am not a philosopher, I'm a scientist so I stay out of there.
theHating: I think achilles is basically saying "survival of the fittest" is a laymen's term and not a scientific one.
theHating: > join me in saying, "natural selection, my ass"
Darwin only ever used this phrase once in a personal correspondence and never in a publication. He was not a fan of the phrase and it’s one that most biologists avoid because it is a poor description of evolution.
This whole paper hinges on that phrase but it’s a moot point. “Survival of the fittest” is a layman’s phrase, not a scientific one. To that end, I and most biologists would agree with *that argument* from this paper, but then to throw out all of natural selection because of this phrase is beyond stupid.
Natural selection is most succinctly defined by these three observation:
1) organisms in a population vary
2) at least some of that variation is heritable
3) at least some of that heritable variation leads to differential reproductive success
If someone wants to argue against natural selection, they need to argue against these three observations, but of course, you can’t.
theHating: >explains nothing
Tautologies are used in mathematics --- mathematics arguably IS a tautology.
AchillesJaguar: @ Sir Loin -- Your latest post amounts (like all your others) to nothing more than "It's not a tautology. Na na na na na!".
It merits no futher response.
"I think achilles is basically saying "survival of the fittest" is a laymen's term and not a scientific one." - TheHating
No, my point is quite irrelevant to whether PNS qualifies as "folk talk" or "science talk". It's a tautology either way.
"Darwin only ever used this phrase once in a personal correspondence and never in a publication. He was not a fan of the phrase and it’s one that most biologists avoid because it is a poor description of evolution." - TheHating
Partly right. Darwin did not coin the phrase [ "survival of the fittest" ], and I think you're right in saying he wasn't crazy about it. You will find it in later edition(s) of "Origin", though. This may be of historical interest, but again irrelevant to the point at hand.
"If someone wants to argue against natural selection, they need to argue against these three observations, but of course, you can’t." - TheHating
The observations themselves are not questioned by any sane person I know. Neither are they the kind of thing we need to thank Charles Darwin for. They are pre-scientific observations, no doubt familiar to Neanderthals and Cro Magnons. E.g.
"1) organisms in a population vary"
In other words, zebras (or woolly mammoths or humans) are not all identical copies of one another. Gosh!! Who ever thought they were?
"2) at least some of that variation is heritable"
Oh, look!! The baby has got Daddy's nose!!
What IS being questioned here is the inference that can be drawn from these observations, i.e., is it substantive or purely vacuous (a tautology)? So...
"3) at least some of that heritable variation leads to differential reproductive success"
Now we come to the nitty gritty. Which ones? Which heritable variations lead to differential reproductive success?
Let's try a few examples...
H1: "Those polar bears with white fur reproduce more successfully than polar bears with dark fur"
This is a perfectly respectable empirical (scientific) hypothesis. It may well even be true; it certainly sounds plausible enough. Either way, ascertaining its truth or falsity would require empirical investigation.
But natural selection is not a theory specifically about polar bears; it is a general proposition purportedly applicable to ALL species. So now let's generalize to all organisms and see what happens...
H2: "Those organisms with big teeth survive and reproduce more successfully than those with shorter teeth"
Once again, this is a perfectly respectable empirical (scientific) hypothesis. And it's almost certainly false. Big teeth are (presumably) advantageous to some organisms in some environments; disadvantageous to others in other environments. But, again, its truth or falsity could only be established through empirical studies.
But natural selection is not a theory specifically about teeth; it is a general proposition purportedly applicable to ALL (heritable) traits in ALL species. So now let's generalize to all organisms and all traits and see what happens...
H3: "Those organisms with [BLANK] survive and reproduce more successfully than those without [BLANK]"
All we have to do now is fill in the BLANK. And here lieth the problem. How about...
H4: "Those organisms with traits that are advantageous to survival and reproduction survive and reproduce more successfully than those without "
H4 is the principle of natural selection in a nutshell. It is true. Its truth requires no empirical investigation. It is true by definition. It is a logical truth. It is a tautology exactly analogous to "winners win" and "lemurs are lemurs".
Unless you have another BLANK ?
The ball's in your court, pal. And merry Christmas
AchillesJaguar: "Tautologies are used in mathematics --- mathematics arguably IS a tautology." - TheHating
Again, not very relevant, but your claim "mathematics arguably IS a tautology" makes no sense. A single word ( "mathematics" ) cannot be a tautology.
Perhaps what you mean to say is that all (true) mathematical propositions are tautologies?
Many would agree with you. probably most. Of course, there are always exceptions. Notably John Stuart Mill held that the propositions of mathematics are not tautologies, but rather empirical generalizations.
AchillesJaguar: I'm still not sure anyone gets the point. Let's take a trip to the zoo then, chaps...
"Daddy, why do polar bears have white fur? The other bears I've seen here don't"
"Ah, you see, son, that's because white fur gives them an advantage and [blah blah blah]"
So far so good. Whether true or false, Daddy's is at least a perfectly respectable scientific explanation.
But then Daddy adds...
"And that's an example of natural selection in action, son"
... and adds precisely nothing to the explanation.
Daddy might as well have added...
"And all polar bears are polar bears, son"
theHating: >adds precisely nothing to the explanation..
Except that it does. The Neutral Theory of molecular evolution provides a null hypothesis for whether an allele is under selection or not. If the predictions of a neutral allele are violated, then the allele is said to be under selection. In population genetics we can calculate a selection coefficient and predict how the allele will propagate within that population.
**Primer on neutral theory:**
**Some reasons for neutral theory:**
Hughes, A. L. Near neutrality: Leading edge of the neutral theory of molecular evolution. *Annals of the New York Academy of Sciences* **1133**, 162–179 (2008).
**Some reasons against neutral theory:**
Kern, A. D. & Hahn, M. W. The Neutral Theory in Light of Natural Selection. *Mol. Biol. Evol.* **35**, 1366–1371 (2018).
**Historical perspective of neutral theory:**
KIMURA, M. The neutral theory of molecular evolution: A review of recent evidence. *Japanese J. Genet.* **66**, 367–386 (1991).
**Calculating selection coefficients:**
Stern, A. J., Wilton, P. R. & Nielsen, R. An approximate full-likelihood method for inferring selection and allele frequency trajectories from DNA sequence data. *PLoS Genet.* **15**, (2019).
We can also use experimental mutation accumulation(MA)/mutagenesis experiments and/or DNA sequences to determine the relative distribution of fitness effects (DFE) in the genome.
**Primer/review for DFE in MA experiments and sequence data:**
Eyre-Walker, A. & Keightley, P. D. The distribution of fitness effects of new mutations. *Nature Reviews Genetics* **8**, 610–618 (2007).
**Fun paper looking at functional impact of mutations in B cells:**
Zhang, L. *et al.* Single-cell whole-genome sequencing reveals the functional landscape of somatic mutations in B lymphocytes across the human lifespan. *Proc. Natl. Acad. Sci. U. S. A.* **116**, 9014–9019 (2019).
>H4: "Those organisms with traits that are advantageous to survival and reproduction survive and reproduce more successfully than those without "
>H4 is the principle of natural selection in a nutshell. It is true. Its truth requires no empirical investigation.
I disagree. The null hypothesis for natural selection is not H4. The real ways that we interrogate selection are additionally not tautological.
H0: Alleles **are not** selected in a population and are therefore only subject to stochastic recombination properties (this results in a whole slew of testable observations for allele frequencies and types--see neutral theory).
H1: Alleles **are** selected in a population and therefore will show molecular evidence (again, lots of testable predictions here).
theHating: If sir loin is a scientist, that only makes the case for why we shouldn't believe everything scientists say
AchillesJaguar: I wouldn't have said that if he hadn't treated me as a fool.
Well, back to your stuff, Mr Hating...
At least you're trying.
"Except that it does. The Neutral Theory of molecular evolution provides a null hypothesis for whether an allele is under selection or not. If the predictions of a neutral allele are violated, then the allele is said to be under selection. In population genetics we can calculate a selection coefficient and predict how the allele will propagate within that population."
This misses the point.
No one denies that allele ratios change.