I come from the Michael Behe school if ID. I accept common descent, by which I mean universal common ancestry. It seems to be the consensus view in science, it seems reasonable to me, and I don’t have any compelling reasons to doubt it.
But could I actually defend my belief in common ancestry if asked? All living organisms share certain features in common. Organisms leave offspring. Therefore, universal common ancestry. That sounds pretty weak, I admit. I need to do better.
I don’t believe that new organisms appear out of thin air, so to speak. I accept that the organisms of today are the offspring of prior organisms. Even young earth creationists accept common descent prior to the flood and common decent after the flood, though they resist the idea of universal common ancestry. I still haven’t figured out how and where they draw the lines though, so why should I draw a line that I cannot defend. Therefore common ancestry. That still sounds pretty weak, I admit. I still need to do better.
So time to hit the books. What are the arguments for universal common ancestry in the books on evolution that I have. Erm… Halp!
Why do folks believe in universal common ancestry and what is the best book on “the evidence for evolution” to refer to in order to find the best arguments in favor of universal common ancestry?
What if it’s not the evidence for the theory of common descent per se that leads people to accept it, but rather how the theory of common descent provides an explanatory framework. Does its explanatory power outweigh the need for evidence for it and do people confuse what it can explain with what constitutes evidence for the theory?
What is the evidence for universal common ancestry and why is it considered evidence for universal common ancestry?
No shit! Only that nobody concludes that organisms can replicate because one can draw lineages, are you kidding? We KNOW organisms replicate.
In lieu of actual observation, the illustration becomes the reality, forgetting that whole map/territory thingy that evolutionists here keep reminding us about.
And Mung, who believes in common descent, but questions gradualism, agrees Erik’s caricature of macroevolution can’t happen, despite the fact that such ridiculous saltationism is all he’s left with.
#creationistCoherence
dazz is spouting bs. again.
#FoS
A crucial nuance: We know organisms replicate along the lines of species.
The number of the studies does not matter at all. The nature of the studies is what matters.
You mean a word like “internet” cannot be borrowed between unrelated languages?
Over and out.
Just like languages. Have you lost track of what’s being discussed?
All words draw the same tree in the hypothetical example I proposed, that’s the point
Not in the example I’m proposing: again IF horizontal word transfer was observed to not happen….
Would the tree produced by the study of many independent words indicate common descent of languages under THESE PARTICULAR conditions?
The answer is clearly YES
Yes, and you didn’t find any species that has remained the same since the Cambrian.
Do you know what a species is? It is not a horseshoe crab or a chambered nautilus, it is a particular kind of horseshoe crab or chambered nautilus, when not putting a very fine point on it.
By the way, your link did not say that the horseshoe crab is known from the Cambrian (it is not, at least not as of 2008), but that it looks like it came from the Cambrian explosion. The link below mentions that there is reason to suspect that the horseshoe crab could be found in the Cambrian, but hadn’t been at the time that it was written in 2008.
Here’s what an article on the oldest horseshoe crab fossil (at least in 2008) states about the find:
Oldest Horseshoe Crab Fossils Found in Canada
It is remarkable how enduring some life forms are, such as the nautilus and horseshoe crab. But since you were making claims about species, well, it’s a fact that no species remains the same species from the Cambrian Period.
Glen Davidson
I just love evolutionists and their “kinds.”
Glen doesn’t actually know this. And it’s not something that he can empirically demonstrate. But trust him anyways. LoL.
You are mistaking the correspondences. You seem to think that difference species, each descended with modification from a single ancestral species, can’t be compared but that different manuscripts, each “descended” with modification from a single “ancestral” manuscript can. The analogy is of species to manuscripts, and the methods are quite similar, as that Trends in Genetics article I cited makes clear.
You persist in supposing that the species similarities being used for phylogenetic analysis are surface features like size and color, and people keep telling you that, if you must consider books, that a better analogy to the way the data actually are would be to those manuscripts with inherited copying errors.
I should mention that it’s very seldom that someone infers an ancestor-descendant relationship among species. Generally it’s more like a sibling relationship. Back to the manuscript analogy, we don’t generally have the ancestral copies, just a bunch of copies that share ancestry. Of course when analyzing manuscripts, you can infer the nature of an ancestral copy from its descendants; same with species.
And again, you completely misunderstand the nature of phylogenetic data if you think it’s anything like size and color rather than the shared copying errors that make up the real analogy.
You mean there are no manuscripts (discovered and extant) from which other manuscripts have been copied? Of course there are. They might be rare but how is this supposed to change anything?
As to species, you mean extinct species are not ancestors to some of the living species? So you have genetic features shared within a group of species which makes you group those species together in taxonomy, but you cannot identify the species where the feature originated? Then what makes you say that this genetic feature originated in a particular manner (for example as a “copying error”) in one species and then propagated further to other species? Just by the mere fact that it’s there? If it’s an error, then why does it persist instead of getting corrected somewhere along the line?
The point that I am getting at, and that you keep missing, is that, completely apart from drawing any trees, we know how manuscript errors come about (namely, a copyist makes the error). We also know how an error propagates (namely, the text looks normal, it’s not perceived as an error, or maybe copyists have a strong culture of staying faithful to their source manuscript and generally resist the urge to correct perceived errors).
Is there anything similar we know about genes so that we can say they propagate across species and that ancestor species and descendant species are indeed a real thing? Given the point I am driving at, “similarity”, “nested hierarchy”, “we can draw a tree” and also Very Long Time™ are all wrong answers.
Ability to draw trees when grouping stuff says that the stuff is groupable in that way due to some perceived features. This ability in itself doesn’t say anything at all about how those features came about. It only says that the features are there, according to the people who do the grouping. Vases, cups and bowls have the shapes they have because potters make them that way. Manuscripts have the features they have because scribes make them that way. The features don’t come about by themselves and creep into further artefacts on their own. This knowledge is completely apart from drawing any trees and time by itself, no matter how long, does not make them happen.
What is that which justifies saying that genetic features need nothing but Very Long Time™ to propagate across species and ability to draw a tree proves it? A manuscript lineage links a single text. Manuscript lineages cannot link different texts. Linguists can group together language families, but there are more language families than one, and the separate language families cannot be grouped on organic (inherited) features, even though they can on areal (contact) features. In contrast, biologists group the entire biosphere into a single tree of life. What’s going on?
Erik,
On the basis of the sequence identities. “We are talking about species” indeed! Species have members have genomes. Those can be aligned, which raises the question “why?”.
If you had two genome sequences that were 99% identical, what would be your first thought about the cause of that identity? If not common descent – a known cause of sequence identity – then what?
Here’s what a 1% difference looks like, in a 332-letter stretch. I chose 332 because that happens to be the length of lactate dehydrogenase, a molecule I intended to use as illustration. But there’s no point dumping those sequence variants out – I’m sure you realise I could, and the same pattern would be visible: tiny difference in a sea of identity.
Text The First:
Text The Second:
Did I Commonly Design those sequences, or did I copy them?
Moving on to molecules, what is the likeliest cause of the same basic pattern?
So common descent is a known cause of genome sequence identity. Known how?
Followup question: You compare two individuals with 99% identical genome sequences. How do you tell whether they are different species or the same?
Furthermore, we can look within species, at individual genotypes. These are more similar in close relatives(*). And common descent is directly observed by animal and plant breeders, and in humans by parents, nurses, and doctors. And amazingly enough you can use DNA sequences to do paternity tests (or is that Common Design Tests?)
* see: Mendel, Gregor.
Erik,
Known because DNA is template-copied. One double-stranded DNA molecule is unwound and each separate strand has its complement synthesised against it. Voila, 2 copies. This is the basic cause of sequence identity among family groups, in genealogy and migration studies, forensics, disease tracking and so on. It has been very well characterised.
From a simple alignment, you can’t.
Still, if your criterion as to whether they could possibly be commonly descended or not is based on interbreeding capacity, you would need to come up with an alternative explanation for sequence identity among those genomes whose possessors cannot interbreed. What would that be?
Me:
Ok, I anticipate a ‘gotcha’ on my use of the word ’cause’. Bring it on! Template copying is the cause, of course.
Within species, yes. But beyond that?
So the theory of evolution works just fine once we let go of the notion of species. Awesome.
The gotcha is that you ignore the reality of the species. Yes, DNA is template-copied, but the important nuance is that this only occurs along the lines of species. Across species requires separate observation.
So I have to correct you. The known cause of genome sequence identity is self-reproduction of species. Common descent is not a known cause, but an inductive leap of faith extrapolated from intra-species variation.
Erik,
You can’t be serious. Can you?
Allan:
Erik:
That’s your problem. As Allan asked:
Well, I suppose if you think every species is separately created, then common design would be the only possible explanation for DNA sequences being very similar in two species.
Erik,
Given that I don’t see species as hermetically-sealed containers, there is no ‘beyond that’. Change occurs within a succession of copies due to mutation. You may or not wish to declare a new species at some point (that’s a chronospecies, in the jargon). Speciation – again, in the jargon – is the division of lineages of copy-sequence into two separate streams between which gene flow – interbreeding – is prevented.
So, you insist it’s not like that, or hasn’t been shown to be like that.
But if it isn’t like that, what is the cause of sequence identity? By what means are we ruling out template copying back to an ancestral sequence from the two aligned ones, and what are we ruling in instead?
Joe,
Common design at an evolution-mimicking level of detail. The Designer has, um, strange hobbies.
It’s as if Erik thinks species boundaries are fixed for eternity, and cannot even conceive of one species transforming into a new one via gradual change.
Joe Felsenstein,
I’m sure that’s the case, though I’d like it laid out explicitly. Because then the question becomes: why do we need 2 explanations for one basic phenomenon? It is only required because one insists that species are separate containers, and one only insists that species are containers because it hasn’t been shown directly that they aren’t. Reasonable evidence against species being containers is provided by sequence alignment, but that is not admissible, because species haven’t been shown to not be containers!
It’s a paradox and no mistake!
Tacit admission that there are no direct observations of common descent. Good that we are approaching a reasonable standard of evidence.
Linguists cannot determine how Semitic and IE language families came about. The evidence is insufficient to posit common descent for them, so it’s not posited. Let’s just be honest about how far the empirical evidence takes us. Not as far as we’d like, but who says life is supposed to be the way we like?
At this point, my guess is as good as yours. It’s certainly good that we found out that it’s just a guess.
You know, I’m not insisting that it’s this or that way or not this or not that. All I’m saying there’s no evidence to tell. You say you even can’t tell the difference between species, so…
This is amusing.
Erik,
So what, exactly, is your guess? My guess is the observed process of template copying of DNA. Your guess is ____
Erik,
Not by looking at a dump of their DNA I can’t. Is that something I should be embarrassed by?
Allan Miller,
I didn’t like biology at school. I always thought there was something fishy about Darwinian theory of evolution. I suspected there must be foul play with the evidence. My suspicions were not far off. That’s good enough for me. I will continue to dislike biology as always.
Erik,
So, your guess is?
What foul play do you think is going on in a published genome sequence – something one could even invest in a machine to cross-check oneself? Certainly, it would not be beyond the resources of the Discovery Institute.
This is priceless.
Oh, the genome sequences are okay. The issue is what the DNA is claimed to do and how it is said to propagate.
Back to analogies again: Let’s say the same text in multiple manuscripts has minor differences. Did the minor differences replicate themselves or was there someone replicating them? The same with DNA. Yes, the same DNA with some differences can be found across the biosphere, but this does not mean it hops around from species to species by itself.
For a linguist, you sure are bad at understanding language, specifically clearly written sentences in English. I was trying to preserve the analogy. In the analogy, we don’t have ancestral manuscripts, or at least we can’t tell whether a manuscript is ancestral or a cousin of the ancestor. I wasn’t trying to reflect the actual situation with manuscripts, just bring it into line with phylogenetics.
No. I mean that we can’t tell if a known fossil species is ancestral to any living species, because a species, perhaps one we haven’t found, that’s closely related to that known species could be the actual ancestor. Fossils don’t come with signs on them. And given that our sample of past diversity is both biased and fragmentary, it’s unlikely that we have found any particular ancestor.
You attach the wrong meaning to “error”. It just means a lapse from perfect copying, with no implication that the lapse has good, bad, or no effects. And in fact the great majority of mutations have no effect, i.e. are neutral. Most of them are eliminated quickly, by chance, but a few of them persist, by chance. Those are the ones we see. Now what makes me think these errors are propagated is the nested hierarchy they make when you look at them, consistent across data. There is no other explanation for that pattern than common descent.
True. And my point is that we know how mutations come about. We see them happening in every generation of every species, and they’re exactly the same sort of mutations that differences among species consist of. And we know how they propagate: reproduction. A mutation, once it’s in the genome, will be copied faithfully just like any other feature of the genome, because DNA polymerase doesn’t know or care what was there a while ago, only what’s there now.
What would keep genes from propagating across species, by which I mean a population slowly changing due to accumulated mutations? We know there are mutations, we know they accumulate over time, we know that accumulated mutations can result in speciation, and we know that the genetic differences between extant species are exactly the same sorts of things that we see happening in populations.
Is it your position that speciation doesn’t happen and that each and every species was separately created? Because that doesn’t fit the data at all. And before you discount the nested hierarchy as evidence, you have to come up with another reason for a nested hierarchy to exist. Do you have one?
Again, we know how mutations happen, and equating the entire genomes of multiple species with a few shape similarities in pottery is nonsense. You seem to be going for the notion that the nested hierarchy of life is an arbitrary human construct, but the fact is that different random samples of genomes tend to give the same tree. It’s not a subjective thing at all.
I’m starting to wonder what you mean by “propagate across species”. What do you mean? And why are you making fun of time?
That’s because the entire biosphere can be analogized to a single text with copying errors. In contrast to all human languages, enough of the text is retained in recognizable form that homologies can be recognized. Have you looked at Theobald 2010?
Anyway, you don’t appear to be questioning just universal common descent. You appear to be questioning the idea that we can find relationships among any small group of species, cardueline finches for instance. Is that correct? Otherwise your “across species” stuff makes no sense.
So you’re saying that you’re completely ignorant of biology and uninterested in learning, but you still know it’s spinach and to hell with it. OK, that’s a position.
There’s a difference between an analogy and a hypothetical. In reality, we can tell the ancestry of manuscripts just fine – given the relevant evidence.
So not enough evidence. Got that.
If I were a Darwinist (or driven by hasty generalizations), I would be compelled to agree that this is a pretty convincing chain of reasoning. Now let’s see this backed up by evidence too.
I got good grades in biology. And I can safely say I learned enough, because all the stuff that I have read right now to bolster this discussion has brought about just one revelation: The objections that Darwin got during his lifetime still apply today.
this is not accurate. the likeness in parents/babies does not make a case for common descent of biology.
Its just using very raw data and then a line of reasoning.
if common design was true , IT ALSO, would be true we would look like our parents due to dna trails but we would also look like apes due to a common design unrelated to actual biology breeding trails.
why not?
its not proving common descent. common design works, welcomes, like biology from a creator.
AGAIN its just a line of reasoning and unrelated to scientific investigation.
Your side is still say god couldn’t create a diversity of creatures on creation week UNLESS each creature had no common bits and pieces and plans and laws that were alike to other creatures.
It is a option and sO the option nullify’s common descent as the only option AND SO forces common descent to have to have biological scientific evidence behind it.
NOT a line of reasoning from the maternity ward!
Come on you guys and do better.
or is it over sooner then I thought.
here on these forums!
Erik,
So even though there is an observation of self-replication of DNA, you have decided that the DNA held in common between non-interbreeding groups did not self-replicate from common ancestors. On what basis? It’s as if someone had to come along and act exactly as self-replication does. That is a little … uh … ad hoc. Certainly, converting the reasonable inference of actual common descent into ‘foul play’ seems a little ungenerous.
How To Generate Species.
Find a pair of groups with reduced gene flow between, but still a little. ‘Of course’ it’s common descent (with divergence), because they can interbreed. Move them to two different islands and wait a while. Maybe speed the process up by culling [sorry, I mean ‘sending to a farm’] those individuals showing the highest levels of interfertility, though clearly this is an optional extra for the impatient.
Eventually, we may reasonably suppose/assume/conjecture/hypothesise that we will end up with two populations that now cannot interbreed (or do we deny even that?). Have we had to replicate any genomes ourselves during this process, in mimicry of self-replication?
Allan Miller,
Yes. We deny even that!
There is such observation? Source, please, let’s take a look.
In vitro replication and amplification of DNA samples might be of interest. Here
Alan,
Erik and Allan are talking about replication in vivo, not in vitro.
Erik,
Every time yeast causes bread to rise, DNA replication is happening. This is news to you?
Erik,
Goodness, the difficulties some people have with Google. DNA polymerase is part of the genome. Rather (hey, is that a ‘gotcha’ I spy galloping up?) it is a protein synthesised from the genome. It replicates the entire DNA strand, including the DNA that ‘codes for’ itself.
The point is that this is what causes offspring to closely resemble their parents – template copying of DNA. You synthesise two identical DNA molecules on the template provided by the single strands. More foreign concepts that you might care to look up.
Is the process different in vivo from in vitro? You’re not a vitalist, are you? *shock*
Alan,
Erik was asking for an observation of natural DNA replication.
You do realize that he and Allan are talking about the sequence similarities found among organisms in nature, don’t you?
It does make me wonder what Erik is expecting to have been ‘observed’, though. These things are a bit small, and buried in gonads.
As usual, you are vague. What is the relevant evidence? How does it differ from the evidence we have for species?
No, I don’t think you did get that. First, the question being addressed is whether we can identify particular fossil species as ancestral to particular living species, not whether species are related to each other through common ancestors. To answer the latter question, we don’t need to identify the ancestors. Would you agree?
Second, there is almost no conceivable evidence that would establish a particular fossil species as ancestral. Even if it had every single characteristic of the hypothesized ancestor, so could a close relative of the actual ancestor. The fact is, we can’t even conclusively tell whether two fossils belong to the same species, because the idea of species we generally use is all about reproductive compatibility, and that’s the sort of character that isn’t generally preserved in fossils. But of course manuscripts are similar. You can’t tell if a particular manuscript is ancestral to some other or if it was just copied perfectly from an ancestor, and you can know two manuscripts are descended from a common ancestor without having the ancestor available.
I’m not quite sure what you are asking for evidence of. Could you be more specific?
Sadly, getting good grades in biology doesn’t show that you know anything about it. And as usual, you are vague about your objections. Which objections that Darwin got during his lifetime still apply? Please don’t just say “all of them”. Be specific. It’s should be clear to you, for example, that Fleeming Jenkin’s point about blending inheritance doesn’t hold up.
You are a vitalist! Natural vs what exactly?
When you never mentioned those foreign concepts before, then how could I have looked them up? This is why I asked for the source. And you did not give any. Noted.
As to yeast, how is that supposed to be self-replication of DNA? Yeast is a cellular organism, right? Basically it multiplies like bacteria. What’s special about it?
Indeed. At least I’m sure that is what Allan is talking about. The interesting thing to me is how much of the properties of DNA emerge from their chemical structure. It’s made for replicating!