I promised John Harshman for several months that I would start a discussion about common design vs. common descent, and I’d like to keep my word to him as best as possible.
Strictly the speaking common design and common descent aren’t mutually exclusive, but if one invokes the possibility of recent special creation of all life, the two being mutually exclusive would be inevitable.
If one believes in a young fossil record (YFR) and thus likely believes life is young and therefore recently created, then one is a Young Life Creationist (YLC). YEC (young earth creationists) are automatically YLCs but there are a few YLCs who believe the Earth is old. So evidence in favor of YFR is evidence in favor of common design over common descent.
One can assume for the sake of argument the mainstream geological timelines of billions of years on planet Earth. If that is the case, special creation would have to happen likely in a progressive manner. I believe Stephen Meyer and many of the original ID proponents like Walter Bradley were progressive creationists.
Since I think there is promising evidence for YFR, I don’t think too much about common design vs. common descent. If the Earth is old, but the fossil record is young, as far as I’m concerned the nested hierarchical patterns of similarity are due to common design.
That said, for the sake of this discussion I will assume the fossil record is old. But even under that assumption, I don’t see how phylogenetics solves the problem of orphan features found distributed in the nested hierarchical patterns of similarity. I should point out, there is an important distinction between taxonomic nested hierarchies and phylogenetic nested hierarchies. The nested hierarchies I refer to are taxonomic, not phylogenetic. Phylogeneticsits insist the phylogenetic trees are good explanations for the taxonomic “trees”, but it doesn’t look that way to me at all. I find it revolting to think giraffes, apes, birds and turtles are under the Sarcopterygii clade (which looks more like a coelacanth).
Phylogeny is a nice superficial explanation for the pattern of taxonomic nested hierarchy in sets of proteins, DNA, whatever so long as a feature is actually shared among the creatures. That all breaks down however when we have orphan features that are not shared by sets of creatures.
The orphan features most evident to me are those associated with Eukaryotes. Phylogeny doesn’t do a good job of accounting for those. In fact, to assume common ancestry in that case, “poof” or some unknown mechanism is indicated. If the mechanism is unknown, then why claim universal common ancestry is a fact? Wouldn’t “we don’t know for sure, but we believe” be a more accurate statement of the state of affairs rather than saying “universal common ancestry is fact.”
So whenever orphan features sort of poof into existence, that suggests to me the patterns of nested hierarchy are explained better by common design. In fact there are lots of orphan features that define major groups of creatures. Off the top of my head, eukaryotes are divided into unicellular and multicellular creatures. There are vetebrates and a variety of invertebrates. Mammals have the orphan feature of mammary glands. The list could go on and on for orphan features and the groups they define. Now I use the phrase “orphan features” because I’m not comfortable using formal terms like autapomorphy or whatever. I actually don’t know what would be a good phrase.
So whenever I see an orphan feature that isn’t readily evolvable (like say a nervous system), I presume God did it, and therefore the similarities among creatures that have different orphan features is a the result of miraculous common design not ordinary common descent.
I accept the fact that biologists can draw the tree. It’s there to stay since Linnaeus. I don’t accept that the tree represents actual biological descent. The argument extrapolating from reproduction, variation and adaptation to speciation and common descent is inadequate.
“Common descent” in the sense “we can draw a tree” is just fine. Manuscript lineages also look like trees, no problem. It’s just that manuscripts don’t breed themselves and Harshman says we don’t need to know that. Okay, so I can believe whatever I want regarding how the biological tree of life came about – or think nothing about it. Nobody needs to know, according to Harshman.
Erik,
Well, no, you’re a Creationist, so you wouldn’t. I don’t know why that isn’t just stated up front, then we all go out and play in the sun. But there is supposed to be some purpose in discussion, rather than endlessly restating a position.
So, where does it stop representing actual biological descent? Take the Common and Spotted Sandpipers mentioned earlier. Maybe add in a couple of other related birds. Does the tree represent actual descent in that group, or not even there?
It’s been up front all the time, if you can follow an argument. I have always talked about what the tree represents, no problem with the fact that we can draw a tree. As I have been saying, we can draw trees on many things, and we do, more or less justifiably.
It doesn’t even begin to represent it. It only combines similar characters. In the words of Darwin, “…we have to make out community of descent by resemblances of any kind.” I’m basically with Darwin on this point, as far as it goes – the tree represents resemblances that he calls “community of descent”. The connection to evolutionary descent in biological manner remains unestablished.
ETA: Ability to interbreed is a factor in the tree, I assume, but it only applies to very closely related species, so it does not have any impact on wider branches. For wider branches, things like “salivation” and “hair” work much better, and ultimately “has genes” to draw the entire biosphere together. This is somewhat equivalent to “has vowels and consonants, words and sentences etc.” in linguistics to draw all human languages together. It does not mean that all languages stemmed from a single one, but it’s a similarity that one can draw a tree on.
Erik,
I can follow an argument; you just don’t make one.
‘Don’t believe it’ is all you can seem to say. Fine, you don’t believe it follows from the basics of DNA replication. I don’t see how it can not follow from the basics of DNA replication. Now what?
Erik,
That’s why I much prefer molecular data, and avoid endless gibbering about ‘Darwin’. There is a digital sequence, preserved with reasonable fidelity by template-based DNA copying. There is much more here than mere subjective ‘similarity’.
Erik,
No, it’s actually irrelevant. As divergence progresses, it becomes less and less possible to interbreed. But interbreeding is not a factor, except inasmuch as it can introduce some noise at the tips.
No, it isn’t.
That’s like saying you can collect pennies but never reach $100 because, well there could be some magical barrier that stops you from collecting more pennies.
Or, you can take 100 steps, but could you take a thousand? Preposterous!
For the 10th time or so, common descent is not inferred merely from the fact that one can draw a tree.
And as I and several others have been telling you, it is the fact that trees drawn from independent data sets corroborate each other, which is what implies a common genealogical relationship.
You brought up the silly notion that you could “draw a tree” for cups, bowls and vases earlier. What you failed to understand is that it is the mutual corroboration of trees drawn from different characters you need. You can’t do that with cups, bowls and vases. Or indeed, anything else you can imagine. It doesn’t works.
As I explained back here in this comment.
In the case of ‘universal’ Flood stories, we have an example in which commonality is presumed to have arisen from descent. The languages in which these stories are told may or may not have come from a common ancestor, and if they did they may have mutated beyond all recognition and lost all documentary intermediates. But the story itself goes on, preserving in pristine detail an actual event.
Meanwhile, the extreme digital commonalities presented in DNA, even in species that can still interbreed, are dismissed as not representing actual descent relationships. This strikes me as something of an inconsistency.
No they don’t, but they actually are copied.
Try making multiple trees from independent characters for a set of objects which don’t udergo multiple iterative copying with slight modification. If this is not the process by which the entities come about, you’re not going to get convergence on trees from independent characters.
OK, that helps. This wasn’t very clear to me either. Since we are on a roll here, let’s have some other things clear as well:
Do you accept that the tree isn’t arbitrary, but has an objective nested hierarchy? That is, that any group defined by distinguishing characters (say flower carrying plants) will be nested within larger groups (vascular plants), rather than scattered throughout the tree?
If you don’t accept this, discussing common design versus common descent is going to be very unsatisfactory.
The argument that John is (repeatedly) making requires you to accept two things only:
1) That populations occasionaly acquire unique novel distinguishing characters, like a copied manuscript would acquire copying errors. Since you are a Creationist: loss of genetic information (deletions, gene loss) will do as well as long as we can identify the unique event.
2) That a population occasionaly splits, just like a manuscript lineage would branch. Speciation is not necessary. Just geographically separated populations are fine.
Acceptable?
Irrelevant altogether? No, just look at the definition of biological species, at some point even elaborated by Harshman in this thread – breeding is all over the place.
Irrelevant on the wider scale? That’s what I said.
Except when it becomes again possible to interbreed. You can separate populations, prevent them interbreeding, and at some point they may seem to have lost the ability, but then suddenly they may regain the ability. So “less and less” as one-way highway could be an illusion. This is what I am reading here https://blogs.scientificamerican.com/science-sushi/evolution-watching-speciation-occur-observations/
So, three closely related species (therefore common descent, right?) from different areas. According to your “less and less” theory, they should not interbreed, but upon interaction, they began to. And the “classic definition of new species” in this case did not come about by diverging from some earlier species, but by converging.
There are a number ways to interpret events like this. Your theories will be as good as mine. According to Harshman, we don’t need to know.
Or you could say, if you can run 100 metres without a stop, then sure as hell you can run a 1000 miles without a stop. At the same speed too. There is no magical barrier, is there?
For you, apparently, money grows on trees or something.
And long long before that, I actually quoted and reiterated Darwin’s argument that biological taxonomy (which implies common descent, because it’s the “inevitable conclusion”) is one-on-one comparable to linguistic taxonomy. These are more comparable, because the complexity of the respective subject matters is comparable. Thoroughly enough, we have been over the reasons why the alleged inevitable conclusion does not follow.
I quoted Darwin, didn’t I? “…we have to make out community of descent by resemblances of any kind.” Sure the tree is “objective”, as long as we are 100% clear on the standard for drawing it.
Good, so now you’ve brought an example of something we know has some physiological limitation. We know people can’t run 1000 miles and we know why.
The problem is you don’t have any evidence that there is such a limitation for the degree of change species can undergo, you seem to think there just has to be one. Why?
You seem unable to fathom that it’s not just about “drawing a trees”. It is the consilience of independent phylogenies that implies descent. There is no other collection of entities known to exist, that exhibit consilence of independent phylogenies derived from independent sets of their characteristics, which did not also undergo common descent. Including manuscripts being copied over time.
The fact that you CAN draw multiple trees which corroborate each other, using data sets from independent characters, is BECAUSE there was common descent. Of species, or of DNA molecules, or of manuscripts.
Whether they commonly descended by being copied by human scribes, or they copied themselves, is immaterial. Manuscripts are copied by humans. DNA molecules pretty much copy themselves. In other words, the entity responsible for the copying mechanism is irrelevant. It is the fact that they are copied, iteratively, with errors in them that is key.
Yes, and we have discovered that it does in fact follow contrary to this blind assertion of yours.
This could mean anything.
1) Is someone born with one leg missing the same as acquiring a unique novel distinguishing character? There has to be a standard for what qualifies as such and what doesn’t. Once we have established the standard, then look around if evolution occurs in that way.
2) Population splits. So, the French live over there, we live over here. A population split? Evolution? I am getting the sense that you also need to add Very Long Time with a bunch of other assumptions into the mix. Contrary to Mayr, you can’t extrapolate the whole tree of life from the fact that a blue-eyed mother got a brown-eyed son who moved abroad and begat half-French children of his own. Something like from pre-ape to apes and humans does not work this way, much less from reptiles to birds to mammals. All the assumptions must be clear and open.
Trees in linguistics have a strict standard. Darwin with his …we have to make out community of descent by resemblances of any kind” would be laughed out loud. The *kinds* of the characters have priority, resemblances are secondary.
It categorically does not matter how consistent or consilient the tree is. It does not matter how similar the said characters are. It does not matter at all what they look like. First and foremost, it matters what those characters *are* and what they *do*. Drawing on similarities, no matter how consistent, is trivial.
Erik,
Sure it is, but – as also stated by John – not necessary for drawing the tree.
Yeah, sure, ‘except’. If you think life is solely made up of exceptions, that’s great. Either way, Interbreeding Not Relevant For Tree.
The point is to find where you think a tree-like relationship of molecular data can legitimately be inferred to result from common descent. You say ‘nowhere’.
Erik,
Absolutely wrong. You don’t need any information at all about function to be able to draw a tree – particularly on molecular data, something you seem singularly uninterested in. Perhaps because you suspect that is where your arguments crash and burn, I dunno.
Absolutely! But not a character that is likely to be heritable and become fixed in humans, wouldn’t you agree? A little bit further up this thread, there was a lot of discussion about gene loss. We are pretty good at identifying the specific mutations that inactivate a gene. Would that do?
This! This is the thing we ought to be discussing! You reject branching evolution. Not even species radiation after the flood? Do you believe in special creation then? If so, how do you reconcile special creation with the nested hierarchy of life?
This is your chance to be the first person in this thread to engage with the actual issue (apart from Mung then, but he doesn’t count).
If we wanted to pinpoint ‘kinds’, phylogenetic analysis would be an excellent tool for the job! The discontinuity would be unmissable.
On a previous go-around of this never-ending argument, I asked about the Common and Spotted Sandpipers. Erik was beside himself on discovering that they occasionally interbred at contact zones, and hence were somewhat like dogs, and no problem.
But above, he has introduced a set of varieties where interbreeding was not possible (Not Commonly Descended) and has subsequently become so (Commonly Descended … ?). This doesn’t form a serious problem for evolution – diminution of interfertility is stochastic, and without testing every single gamete combination in the populations, a division ‘on the cusp’ may conceivably be ‘mostly infertile’, but a fertile lineage may still arise.
But, it does seem to form a problem for the Fixity Brigade. Interbreeding was introduced, and not by me, as a kind of get-out criterion for subspecies. If they can interbreed, Common Descent is unobjectionable, because look at people, or dogs. So here we have an example that was Commonly Descended … no, wait, Commonly Designed … oh hang on, Commonly Descended … on that criterion. All the while, their gene trees would be unperturbed by this classificatory activity.
Well if that was really how a common descent was inferred then I’d be right there with you. But it isn’t how it is inferred. So when you say “Darwin with his…” as if you are actually referring to the method by which common descent is inferred, you are simply attacking a straw man.
“The tree” can’t be consilient. Different, independent trees can be consilient with each other. That is the crucial point. Look at my response to your cups, bowls and vases idea earlier.
I agree, those are not how common descent is infererd.
No, what matters is that those characters are heritable traits. THAT is what matters. The independent characters (independent in the sense that one is not the cause of the other) used to built trees from have to be heritable traits. The kind of thing you infer common descent of has to be the kind of thing that actually has a line of descent, whatever that mechanism might be (human scribes copying texts with small changes or errors, or DNA molecules copying themselves with mutations in them).
That sentence doesn’t even make sense. Nobody has been drawing on “consistency of similar characters”. Where do you even get that turn of phrase from?
Erik has an odd modus operandi:
1. Disagree with something.
2. Learn as little as possible about it.
3. Raise naive and dimwitted objections about it, demanding that more knowledgeable folks spoon-feed the subject to you.
4. Carefully ignore what they are telling you and repeat the dimwitted objections.
It’s a good MO for maintaining ignorance and crackpottery. Not so good for science.
We would expect Tiktaalik to end up somewhere on the branch connecting tetrapods to their common ancestor with lungfish, and probably on a fairly short branch.
Moved a post to guano.
That’s not an entailment of any addition of function. C’mon Bill, think about for more than a few seconds. Here’s the definition of entailment:
The key part of the concept is the reference to consequence. So, what consequence comes out of the addition of function that can only be explained by design and nothing else. If you can’t come with anything (and seriously…millions of people before you have tried and failed), it’s likely not an entailment.
This is not scientific, but as a layman I have a rule of thumb. If I find myself disagreeing with the consensus of experts, I assume that I just don’t understand the topic. If I really think I understand and still disagree, I put it on the back burner and wait. Sometimes for years. Not much in my life hinges on the outcome of esoteric arguments.
I think Bill is stuck in the old “ladder” understanding of evolution. Everything is progressing in stages to man. So zebrafish are on a lower rung than chickens, which are on a lower rung than mice, which are on a lower rung than humans is my guess. So to Bill there are 73 genes that zebrafish have, which then disappear in the rungs between them and humans. And then reappear in humans.
…or something…
Yeah, I hadn’t read ahead, but Bill’s comment supports my contention. Bill is having the same problem Sal had a few months back with the whole lungfish big. He doesn’t understand that the zebrafish hasevolved along with all other organisms around today. So the ancestors of zebrafish might well have been ancestral to all mice and chickens and humans, but current zebrafish are not.
I don’t think Bill gets that.
This is generally a good scheme.
So he has an excuse for making false statements. I get it. But they are still false.
Not so. Erik is quite clearly making an argument. If you don’t want to address it, or can’t, just say so. No need to blame Erik.
I just love the idea of “independent phylogenies” as evidence for common descent. #EvoSpeak
What is this Fixity Brigade? Another of your straw-men?
Your comments about other members are an invaluable contribution to the site.
Thank you
#MungIsConfusedAgain
Theobald’s figure could be explained by common design, also, Theobald doesn’t explain orphan systems does it?
Where’s the evidence for a designer more interested in making life look evolved than in making things rationally?
Uh, have you? And WTF does explaining orphans have to do with Theobald’s tests?
Glen Davidson
While that’s true in that case the designer had to do that explicitly, as it’s unlikely to be the case that it just happened on it’s own.
And that’s kind of the point of the work.
What does “common design” mean? Really, what is the “method” here?
Anything can be explained by “common design”. That’s why it explains nothing.
Well, that was a short flounce. I do hope it means that Erik is now prepared to give up his quote-mining of Darwin and look into more recent phylogenetic research. Once more I offer by own quite simple example:
Harshman J., Huddleston C.J., Bollback J., Parsons T.M., Braun M.J. True and false gharials: A nuclear gene phylogeny of Crocodylia. Systematic Biology 2003; 52:386-402.
The odds of something being designed in a certain way by an omniscient, omnipotent, unpredictable designer are always a finite number over infinity.
So yeah, there’s always a chance that common design produced life as we see it, but the odds of it having happened are indistinguishable from zero.
Glen Davidson
Common descent doesn’t explain orphan systems does it? No one here has shown that Theobald’s research explains orphan systems. I’ve provided some examples of orphan systems, including Orphan Genes, Taxnomically Restricted Genes, but that’s just the tip of the iceberg.
Common design doesn’t have to be an explanation, it can be an OBSRVATION. The octopus eye vs human eye, the placental and mammalian convergences are common designs independent of common descent.
Common descent can explain some common designs, but not all of them. That is clearly the case in the issue of convergences.
Common Design can mean simply the observation. It can also mean Common Design as in special creation of similar designs without common descent.
What do you mean it explains nothing. What if the explanation of how God did it is beyond human comprehension. If it happened by a miracle, then by definition you won’t get an explanation. If you won’t accept facts unless you can comprehend them by being fed and explanation, then there are lot of truths in the universe you probably shouldn’t be accepting, including the evolution of orphan systems. You’re not applying the same standards of evidence to common descent, yet you apparently accept it, even without an explanation beyond, “it happened.”
That’s why it explains nothing.
You didn’t notice?
Glen Davidson
Robin,
A functional sequence of more then a few characters requires design.