Specifically, what is the evidence for common descent?(Not quite) famously, Darwin mused about the similarities of taxonomic hierarchies in linguistics and biology and asserted that the hierarchies must ultimately point to common descent. (Chapter XIV, On the Origin of Species) That’s common descent as distinguished from microevolution.
The linguistic equivalent is the single origin of all languages (eminently unproven and deemed unprovable) as distinguished from a language family (with demonstrable relevant organic shared features).
Darwinists are welcome to present their evidence. From Rumraket, we have the observation that all organisms can reproduce, “Nesting hierarchies are evidence of common descent if you know that the entities sorted into hierarchies can reproduce themselves. And that particular fact is true of all living organisms.” Good start.
From Joe Felsenstein we have the doubt that the border between micro- and macroevolution can be determined, “OK, so for you the boundary between Macro/Micro is somewhere above the species level. How far above? Could all sparrows be the same “kind”? All birds?” Not very promising.
From Alan Fox, “Darwin predicted heritable traits. Later discoveries confirmed his prediction.” Questions: Which heritable traits specifically? Was there a principled improvement over Mendel? And how does this lend credence to common descent?
Thanks to all contributors.
Erik,
A forlorn plea I find myself making repeatedly: how about dropping the analogies altogether? They are an illustrative tool; an attempt to give people a flavour of something that may be unfamiliar by reference to something that is familiar. They are not prescriptive or to be dogmatically pursued to the nth degree – they clearly can’t be: it ought to be obvious that, to be an analogy, they must differ in some respect from the thing being compared to. Otherwise (eg see Hume) they would be the same thing. So gnawing at some aspect of the analogous system isn’t really getting you anywhere (do you actually want to get anywhere? That is unclear, despite the OP being framed as a question).
The basic data available to an intelligent human, even one who admits to knowing nothing of genetics, is that the DNA of an offspring is an almost exact copy of that of its parent(s). You need to know little more than that to grasp the basics of the arguments on molecular phylogeny and common descent. The ‘almost’ and the ‘exact’ are both significant. Instead, like many another here, you retreat into obtuseness. “Oh, that’s like saying you can classify cups with spoons ‘cos …”. Forget it. Look at biology, and screw the analogies.
Thank you for gracing this thread with your presence, Sir.
Evidence such as some specific features of chimpanzees and humans? On the genetic molecular level and/or across more levels?
Based on such data, naturally they would land near each other in the tree. Wouldn’t a ceramic cup and a ceramic vase do the same in your sophisticated program? I suspect they would, given that they are made from the same material in a similar manner. It would be astonishing if they wouldn’t.
If the proximity in the tree is your sole point, then with all due respect you are missing the point again. Proximity in the tree by itself does not tell that the one thing came from the other or that they had a common ancestor. An attested unbroken chain of one species evolving into another would say that. Is there such a chain?
Compare: In linguistics, you may have a group of languages geographically close by, sharing a certain set of features. If there were no literary record at all tracing the evolution of any language group whatsoever, it would be impossible to tell if the similarities are due to common descent or due to contact. Because the similarities can occur either way, due to a break-up of a proto-language or due to areal convergence. Fortunately we have literary records, most notably in Indo-European and Semitic families, so we have material evidence for how a language evolves, what organic evolution looks like and what happens with language contact, and this way we can tell what features to look for when inferring organic evolution as opposed to contact and borrowing. And then this knowledge can be used to classify languages with no literary record.
In biology, is there anything beyond microevolution to tell that a single species can breed an indefinite variety of species? Unfortunately, what I got from you was reluctance to fix the boundary between microevolution and macroevolution. I don’t see how this can be permissible. It’s like Darwin’s reluctance to define species, “I look at the term species, as one arbitrarily given for the sake of convenience to a set of individuals closely resembling each other, and that it does not essentially differ from the term variety…” The terms species and variety do not essentially differ? It’s as bad as a linguist saying a specific language and the sum total of all languages over the globe do not essentially differ. And that the difference between a borrowing and a sound law is not too important. Hence common descent, or something.
People keep telling me I confuse linguistics and biology unnecessarily. But actually I am comparing the scientific standard for evidence across the sciences, fully aware of their different subject matter. The closer I look, the less respect I see for the subject matter when biologists make conclusions based on their classification.
Well, you are the expert. Feel free to show where I went wrong. This is what this thread is for. It will be most appreciated. Thank you.
And this proves common descent how? To me it looks like telling that breeding is an intra-species thing. Am I not intelligent or what?
Hi everyone,
I have a quick question for the biologists. Alternative definitions notwithstanding, the biological concept of a species is fairly well-defined. What about higher taxa? Is there anything objective corresponding to the concept of a genus, family, order, class, phylum or kingdom? I’ve heard it argued that animal phyla correspond to body plans, and I seem to remember reading a remark made by Jerry Coyne over at WEIT some years ago (which I haven’t been able to locate, unfortunately), to the effect that if anything corresponds to the notion of animal “kinds,” then the taxon of “order” would be the best candidate, but don’t quote me on that. More recently, I’ve heard people argue that the cladists are right, and that there is nothing objective whatsoever corresponding to these taxa, which would imply that when species A and B from phylum X are classed in the same genus, and when species C and D from phylum Y are classed in the same genus, all that means is that A and B diverged at about the same time as C and D. That would presumably entail that organisms in any kingdom of organisms belonging to the same genus, family, order, class and phylum would have separated 3 million, 15 million, 60 million, 300 million and about 700 million years ago, respectively (using the times for the first appearance of Homo, hominids, primates, mammaliformes, and chordates). On the other hand, the molecular clock hypothesis has come in for some criticism, too. So what’s the latest thinking on the subject? Thanks in advance.
For fucks sake nobody says nothing further is required. Can you even fucking read?
No Erik. No. That doesn’t follow.
I brought up the point about any organism being born, belonging to the same species as it’s parent, IN THE CONTEXT of YOU asserting that reproduction entails no evolution, because you infer that it is always “within species”.
I explained why that simple observation is NOT a barrier to evolution.
So to make it even more clear. I took a principle that you tried to use to argue against evolution, and I explained why it is COMPATIBLE with evolution.
I’m NOT saying reproduction is irrelevant to inferring common descent. For fucks sake. Take your blinders off. You’r reading with tunnel vision.
Because it IS relevant you fucking dolt. READ FOR COMPREHENSION, THERE IS A CONTEXT.
PLEASE, let’s.
No, you aren’t.
The pattern is a PREDICTION from the mechanism of reproduction, isolation and divergence. The pattern is NOT a prediction by any other process.
So when we FIND such patterns, that implies they were produced by the mechanism of reproduction.
It is not about mere similarity. For the fifth fucking time.
Are you cognitively equipped to understand that sentence? Don’t bring it up again or you just go straight to ignore as an ignoramus and idiot-troll. If you feel compelled to bring it up again, remember that it has now been EXPLICITLY STATED that NOBODY says you can infer common descent from MERE SIMILARITY.
CAN YOU FATHOM IT?
NO, that would NOT be the “proof”. That might make the case stronger than it already is, but it is not necessary to infer common descent.
We have a mechanism, and that mechanism makes predictions about what we should find if the mechanism happened in the past too.
We analyzing living organisms, and it turns out we find what the mechanism predicts. So we infer that, in fact, the mechanism produced the predicted pattern.
That’s really at it’s most basic level what is going on.
Yes it does. Actually. It just takes longer than single human lifetimes for the changes to become so large that they are intuitively obvious.
In the same way that some trees grow tall, but it takes really long. Much longer than human lifetimes, for them to reach their full height. That’s an analogy about change and time, not an analogy about reproduction. So don’t tell me now that I think the slow growth of trees is used to infer common descent. I’m making a point about some processes being slow. Get it? I predict you don’t.
Why don’t you read the fucking references? How much of the work YOU should be doing are we required to do, to “convince” somebody obviously hellbent on not being convinced? Go fuck yourself you ignorant sack of shit. Do your own fucking reading, and don’t expect random strangers on the internet to provide you an education for free, or hold your fucking hands through the most obviously basic logical inferences.
Okay. How is it inferred then? Because Darwin said similar this and similar that, even *trifling* similar, and that’s ALL he said.
What we actually need to establish is what is sufficient for common descent, not just necessary.
Any evidence for species morphing into another species other than Very Long Time? Any attested unbroken chain of a species morphing into another? Such as between chimpanzees and humans that Felsenstein mentioned? Hopefully the evidence is indeed something other than “this one is similar enough in some ways to that one, therefore it came from that one”.
I would like to take this opportunity to put forward my own Theory of Gravity depending on Magical Monkeys (TGMM). I think the effects we call gravity are caused by magic invisible monkeys holding on to everything and pulling them together. Thus planets, stars, and even galaxies are held together by long chains of these monkeys, who live in a giant invisible barrel in the sky. This is my theory, AND NO ONE CAN PROVE ME WRONG!
THIS is the standard of evidence that Erik and Mr. Byers would hold us to; demanding proof to eliminate the imaginary, and meanwhile offering no evidence of their own.
Now I must go, I’m meeting Bertrand Russell for tea somewhere between Earth and Mars.
When things evolve, they change. A lawful (as in laws of nature) change is regular. What are the attested regularities of biological evolution? Such as, when this sort of thing evolves into that sort of thing, such-and-such changes occur, enabling us to tell apart chance resemblances from natural organic evolution. What is the attested stock example of evolution?
That done, how does this support universal common descent? Because, in comparison, in linguistics there are sound laws, such as affrication (e.g. from kaesar to caesar) that have been attested independently in different groups of languages. Thus it is a plausibly natural sound law that can indicate organic evolution of a language, but this does nothing to support the common descent of all languages.
No. Age of divergence, as you note, has been proposed as a criterion, but as you imply there are severe operational problems with that.
vjtorley,
There is no reason to expect that equivalent ranks (e.g., genus, family, order etc.) are going to be comparable across different groups of organisms with respect to number of taxa or divergence times. For example the order Araneae (the spiders) contains more than 40,000 described species and is probably more than 300 million years old. Conversely, the primates are also grouped in to a single order, but the clade is well under 100 million years old and contains only a few hundred species.
There have been some recent papers suggesting that particular developmental patterns line up well with phylum classifications, but I’m not sure how much that generalization applies outside of animals.
God, you’re incompetent at everything, aren’t you? You read the analogy to language, and instead of understanding its purpose you cavilled at an inessential mistake. Meanwhile, in that very area of Origins Darwin actually had quite a discussion about which similarities are meaningful to classification and which are not. The upshot:
Source
Why don’t you learn about it, rather than ignoring everything that is brought up only to repeat your ignorant attacks? You seem not to like ID, and yet you write the same idiotic nonsense that the IDiots do.
Any evidence of, say, the original Indo-European language, other than the descendants and their patterns of preservation of that language? Can we actually infer ancestry where there is no unbroken chain? The thing is, you have utterly failed to comprehend the language analogy with biologic evolution because all you care about is tearing down evolution, not in understanding how one rightfully infers common descent.
No, incompetent bozo, Felsenstein is far too intelligent and knowledgeable to write the stupid tripe you do. Humans did not evolve from chimps, nor vice-versa.
Learn to read properly, Darwin, Felsenstein, and all who took on the hopeless task of educating someone as ineducable as you, and you might learn something for once. Doubtful, of course.
Since it never was that, and you managed to bypass all of the discussion by Darwin of how the evidence actually does matter, it’s unlikely that you’ll ever stray from your caricature of what evolution is.
Glen Davidson
Erik,
I reserve judgement. Sequence commonality certainly does not imply interbreeding capacity.
If you take two ‘blind’ genomes that are almost fully aligned, it is impossible to tell whether they can interbreed or not – ie, if they belong to the same biological species. The DNA lays out as a series of bases, as you know. If you have AGCTGTCCT … (1 million bases omitted) … CTAGGAT in one alignment, and AGCTGTCCT … (1 million bases omitted) … CTACGAT in the other, they could both be Spotted Sandpipers, or one could be Spotted and the other Common.
Now, if given the additional info they were both Spotted, would you be happy to say that the sequences are probably commonly descended? If, alternatively, one was Spotted and the other Common, what would your preferred explanation of the near-identity be (which is, in fact, digital identity except for base 1,000,013)?
Guys, whilst I understand the exasperation, could I ask we wind back on the insults please!
Agreed, Erik WILL not understand, not because of insufficiency of evidence or clarity of explanation, but for ideological reasons lying outside the nominal scope of this discussion. For him, common descent is defined as wrong, and definitions are impervious to logic or evidence. I’d guess the underlying source of his willful ignorance is inaccessible to us. Ironically, it rests on bad faith discussion, which we aren’t supposed to address even though it’s the for this thread.
Nonetheless, my own knowledge is minimal enough so that even determinedly stupid questions elicit responses I find useful and educational. I’m glad those able to know what their ideology permits them to know, are so patient and willing to explain to me.
There are attested unbroken chains of development in several important branches: From Sanskrit, Ancient Latin, Ancient Greek etc. to their modern daughter languages. Same for Semitic languages. This is how we know (1) that languages can evolve gradually over time and (2) precisely how that happens.
Anything like that in biology? Seems like you are saying no.
The thing you quote from Darwin, I quoted the very same thing earlier and stated my objections. Perhaps you missed it.
Neither did I say they did. What I actually said to Felsenstein, “Proximity in the tree by itself does not tell that the one thing came from the other or that they had a common ancestor.”
By now I have clicked around behind the link that Felsenstein gave and bookmarked three potentially interesting papers. It seems to be molecular genetics only, with occasional references to fossils very far and wide. So I was right. The only thing that biological evolution has in its support is genetics. Darwin is totally outdated and forgotten. It should not be called Darwinism anymore, even though his false assumptions seem to be live and well.
Interbreeding is as irrelevant as are hybridization and cloning. One species morphing into another is relevant. Very Long Time by itself is not evidence. A track record is.
Didn’t answer the question, did you? How do we know that they all came from the original proto-Indo-European? See, inference works, and you try to deny it by changing the subject.
Of course there is. Virus evolution, breeding experiments, Lenski, etc. But to really get very far, like to proto-Indo-European, you have to rely on the evidence of what has happened. Like real linguists do.
Apparently you missed it, or you wouldn’t have written “Because Darwin said similar this and similar that, even *trifling* similar, and that’s ALL he said.” Complete nonsense, easily shown to be false. You blither on as if you hadn’t written something entirely false, though.
Yeah, you wrote:
I don’t care what you wrote about your “understanding,” which is meaningless, but your mischaracterization of Felsenstein’s point. Which I’m sure you know.
No, you’re wrong about almost everything involved with evolution. Fossils are crucial for certain aspects, although there are hugely more genetic data out there.
Frequency of reference isn’t the issue, although I wouldn’t expect you to know that.
Oh, now you say that, long after we called you on your pathetic attacks on Darwin as an authority figure. Yes, no one does or should care about your meaningless attacks on Darwin.
First off, it isn’t. You don’t even get that right, but follow the lead of IDists, etc. In the UK they still often stick to that term, true, but scientists in most other places typically don’t bother with that name. “Darwinian” is a little more common, as an adjective denoting natural selection.
You haven’t shown any of his “assumptions” to be false, except according to your own lack of understanding.
Glen Davidson
No, that’s not how. All of this was explained in the 29+ Evidences for macroevolution by Theobald.
Again. If all of life shares common descent, then we should be able to arrange multiple, independent, genetic, molecular, and morphological characteristics into highly congruent nesting patterns (the individual trees constructed from different data, must match to a high degree of significance).
And the reason why this WOULD imply common descent is because the mechanism of reproduction PREDICTS such a pattern. That’s why the inference on the basis of trees works for LIFE, but not for Ceramics, or cars, or other man-made objects that don’t imperfectly reproduce themselves.
In so far as an organism’s genetic, molecular, and morphological characteristics are not highly congruent and fits into the standard phylogenetic tree, we cannot infer that it shares descent with the rest of life.
Yes, we need both.
Very Long Time is not erected as evidence for anything. Very Long Time, if we had no genetic or fossil data to build trees from, would only be an extrapolation. An entirely reasonable and rational one. If small change takes little time, more change takes more time, and lots of change takes lots of time. This inference is so basic and reasonable only a psychotic and religious individual would deny it. It’s basically like saying that if you can walk 10 steps in 10 minutes, you can walk 20 in 20.
In other words, what we know from direct observation is that species change over time. But we’ve only been around for a short time to observe it. Like with Very Large trees that grow very slowly. No single human being has witnessed the General Sherman tree grow to it’s present size. Yet it is a trivial inference that it did, because we have seen trees grow.
It’s the same with evolutionary change of species. What we have seen is enough to infer that, if they can change a small amount in a short time, they can change a lot in a long time. That’s just from the observation of evolution happening in the here and now. If that inference about the tree is reaonable, then the inference about evolutionary change is reasonable. Because the logic supporting it is basically identical.
Now, we can throw fossil data on top, and demonstrate through that, that large-scale morphological change has happened in the past, and that said large-scale morpholgical change is what gave rise to extant biodiversity.
You first need to define what an “attested unbroken chain of a species morphing into another” actually is. What does it mean to be unbroken? How fine-grained must the resolution be? Must we have have a photo of a direct ancestor from every single generation? If so, why? Why is THAT the standard of evidence you require to accept large-scale morphological evolution, and what OTHER topic of science or history do you demand a similar standard of evidence for? Were you around to see the General Sherman tree grow from a seed to it’s present size? Do you have a photo of it in 10, or 100 year intervals?
You wouldn’t want, I presume, to be erecting hypocritical standards of evidence you don’t consistently apply for all your beliefs about science and history.
Mutations. The biochemical causes of mutations are known, and happen universally in all life.
The fact that mutations happen aren’t invoked as an indication which alone implies that all life presently known to exist on Earth, shares common descent.
So nothing beyond microevolution?
Because, you see, from Ancient Latin to modern Romance languages etc. is not comparable to microevolution. It’s macroevolution. Indo-European proto-language was well established before Lithuanian became common knowledge. Lithuanian confirmed the reconstructions in such a manner that it’s called the living dinosaur in the Indo-European family.
So there’s nothing like that in biology.
So Theobald said we should be able to observe speciation, even if very rarely. Then he lists hemp nettle, primrose, radish and cabbage, maize, fruitflies and even house mice. The thing missing in this list: Into what other species did all those species turn to?
This is something we are sorting out in this thread: What is the standard for evidence in biology?
I know. And all living organisms are cellular and they reproduce.
Any mutations beyond microevolution so that you could say speciation is observable?
And, as I have pointed out earlier, even this would not prove common descent, just like the mere fact that languages change, sometimes radically and rapidly, they diverge, converge, pidginize etc., but none of this implies common descent.
There is no common descent in linguistics. Darwin thought he knew better and you agree. What’s the evidence?
Whatever. The fact is that we’d know about the language evolution without texts, too. Because some of us don’t deny the evidence left from it.
I actually don’t care, you know, even though one could quibble over the matter. The point is that we have copious evidence of Greek and Latin evolving from a common ancestor without any textual evidence, and an intelligent linguist would acknowledge that with or without textual evidence of other languages evolving. That you dance around the fact to stick to your unreasonable demands in biology only shows that you’re not willing to accept what the evidence of common descent shows where you don’t like it.
Yes, and evolution was well established before genetics confirmed it, too. That’s what happens with good theories.
Sure there is, there are fossils. You didn’t hear any language change to another one, did you? You’re relying on “fossil evidence” to indicate certain changes in language, and we have similar (though not as clear-cut, to be sure) evidence from fossils. But the fossils can go back to a kind of “proto-Indo-European,” at least in lines that fossilize reasonably well, like most vertebrates do. Language evolution lacks similar evidence of the larger scale of changes
Glen Davidson
No, you don’t even know the difference between common descent and universal common descent. There’s lots of common descent in linguistics, something you should know. Universal common descent is argued, but the evidence for universality of common descent that exists in biology is lacking from languages.
The important fact is that real linguists would be open to the sort of evidence of universal common descent that exists in biology, if it existed in languages.
That’s another fact that you keep ignoring, the whole point of you blowing up the mistake Darwin made is that if the evidence of derivation from a common ancestor that we find in life existed in language, real linguists would accept that evidence. You could only do so by applying a double standard. Indeed, you can only argue as you do because you are using a double standard, since you use the fact that languages lack the kind of evidence needed to show universal common descent in order to disparage the fact that life actually does have evidence for universal common descent. The trouble is that if you used the same standard for both you’d have to admit that there is great evidence for universal common ancestry in life but not in languages.
Glen Davidson
Yes, we should. And that would be sufficient? In addition, I would expect a track record of gradual speciation, some indication that species can actually evolve into other species, that it’s a natural thing for them across kingdoms, plants into animals no problem.
Predicts in what sense? I expect something like: There were those two-or-more such-and-such species that implied such-and-such common ancestor and that ancestor was found in the fossil record or so. Or, there were those two-or-more such-and-such species that implied such-and-such other species and those other species were found.
Predicted in this sense, like Mendeleev predicted germanium? Any such cases in the literature?
Actually, I have. Where I live, the language change has been rapid within two decades. There was a pidginization effect with two neighboring languages.
And so have you seen at least, e.g. new words formed, perhaps a morphological feature altered so that an aspect of grammar is realigned. Has happened where I live.
So, not a different language?
Thought not.
Glen Davidson
Yes, a different language. A bunch of effects that started like this https://en.wikipedia.org/wiki/Language_transfer
It didn’t survive too long though, just over a decade. But it happened and it was not a language outsiders could recognize well.
Nobody has been alive to witness the entire transition from Ancient Latin to Modern Roman. The transition is inferred from snapshots in time.
So, in fact, biologic and linguistic macro-evolution on that scale is inferred, not directly observed. In this way, they are analogous.
They evolved from ancestors and became the modern species we see. Cabbage (for example) is not a single species, it is an entire family. There are many known species of cabbage that evolved from a common ancestral species.
So answer my question. You brought up the concept of an unbroken chain, now you’re running away from explaining exactly what that is. You want me, instead, obviously as a diversion, to try to answer what the “standard of evidence” is in biology.
A question so broad it is practically meaningless.
And you asked for what the cause of change is, and I answered. I didn’t say that the mere fact that mutations happen proves that all life shares common descent.
I have already explained what it is that makes it possible to infer common descent.
You’re very confused. It is becoming clear that you can’t keep track of the multiple discussions here. Nobody said mutations prove common descent. Or that mutations are macroevolutionary events.
You just asked about what-it-is, that makes species A change into species B.
The answer is mutations. Nobody has claimed, or implied, that the mere fact that mutations is the cause of species A changing into species B, proves that all life that is known to exist on Earth shares common descent. Nobody makes such an inference.
I truly have your best interest at heart when I say you should probably take a small break and try to sort out exactly what you’re asking, and exactly what people who respond to you, are responding to. Instead of, apparently as you do, think every sentence anyone writes is supposed to constitute a standalone proof of common descent.
Nobody cares, because nobody disagrees.
Mutations happen therefore all known life shares common descent is an inference NOBODY makes.
And when I brought up mutations, I was not answering the question “what is the proof of common descent”? I was answering your question about the general cause of change, if and when speciation happens.
I agree with what, specifically? Don’t speak to me in generalities, or make vague unferenced hints to Darwin’s putative thoughts. Tell me exactly what it is Darwin said, with a quote of Darwin. And then ask me if I agree. I don’t take your word for it about what Darwin thought he knew. Give me openly accessible references, or direct quotes, or shut up about Darwin.
For what, specifically? Common descent? If so, this: 29+ Evidences for Macroevolution
The Scientific Case for Common Descent.
Rumraket,
Rumraket,
Do you approve posts?
I have one on consciousness ready for few days now…
In combination with the known fact that the mechanism of reproduction inexorably leads to data that can be objectively sorted into multiple, independent but highly congruent nesting patterns of genetic, molecular and morphological characteristics (aka phylogenetic trees). Yes. That would be sufficient.
All of those would be bonuses, but are not necessary.
The last one is nonsensical. Why would plants become animals? That never happened even once in the entire history of life, as far as we are aware. Plants and animals share a common ancestor, but it was neither a plant nor an animal. In the same way that mammals and birds share ancestry, but their common ancestor was neither a bird nor a mammal.
Is there multiple senses of predict?
I can barely parse out what you’re asking for here. Is it predicted fossils?
So fossils, you want predicted fossils. Yes, there are cases of those in the literature. Off the top of my head, Archeopteryx.
Predicted by none other than Charles fucking Darwin .
Fun thread.
J-Mac
Write it, post it, then go to Moderation Issues and request that it be approved.
You may already have posting privileges.
No, I am not a moderator.
Positively hilariouos. Or at least, it’s some form of entertainment.
J-Mac,
I wrote this for you, here a while ago. It might be helpful to you if you followed the link and read the comment.
You find the evidence for common descent compelling. Is there some unwritten law by which believers can’t set other believers straight on evolution related stuff?
Just curious
Erik, the questions here may have escaped notice. I’m trying to concentrate on molecular phylogeny – sequence data – in order to establish where you place your razor between reasonable and unreasonable inference, based on sequence commonality.
The only known mechanism generating long stretches of sequence identity is template copying of DNA, as occurs during reproduction. Would you rule this out in the case where the 2 sequences came from different species? If so, on what grounds? And what would you replace it with?
Do we need 2 causes for sequence identity, one within species and one between?
In what sense is Erik “a believer.” Just curious.
Yes I find common descent compelling. But is there some unwritten law by which “skeptics” can’t challenge their beliefs and the beliefs of other “skeptics”?
Is there a standard for evidence in biology, and if so what is it?
Allan Miller, who doesn’t care for analogy, appears to prefer metaphor instead. What is the advantage that metaphor has over analogy? Just wondering.
Call him a theist if you will
OK, go ahead then. Why is that?
I’ve seen that happen here multiple times. Do you need examples?
Erik asks in this post “Specifically, what is the evidence for common descent?”
So will you help shed some light on the topic at hand?
Parsimony is not evidence. There is some serious work to be done here at TSZ.
Again.
😉
Fortunately there’s only one single right way to do probabilities, therefore common descent is a fact.
Mung,
You could perhaps wonder with a little more clarity. I don’t know what you mean.
So deeply ingrained that you don’t even know you’re doing it. So what qualifies you as a critic of others’ use of analogy?
You wrote of species as having ancestors and descendants. Surely that’s metaphor.
dazz, to Mung:
Ooh, yes. Mung, tell us in your own words why you accept common descent.