Doesn’t pretty much everyone think that DNA has been the most important?
No, only people who work with DNA. Paleontologists tend to think that paleontology is most important. Population geneticists tend to think that population genetics is most important. In my experience.
Eh, I mean DNA very broadly, to include population genetics. I don’t disagree that paleontology is important, but genetics is what makes the inference far less subjective, and more quantitative. Right?
Population genetics has not, historically, dealt with DNA. Molecular population genetics is more recent and restricted. I’m sure that classical population geneticists think their stuff is most important, while molecular population geneticists think their stuff is most important. I agree that DNA sequence characters are easier to code than morphological characters, but that doesn’t necessarily make morphological inference significantly subjective or less quantitative.
As far as geneticists are concerned…
I am not a geneticist though. I am a computational biologist.
I fairly surprised at the resistance here. Educate me please.
From my point of view, anatomical traits in phylogeny are certainly valid, and produce results broadly consistent with genetics (or visa versa). However, they were subject to the critique of being cherry picked. By picking different features, or weighting them differently we might get very different trees. Genetics does not suffer from this problem in the same way, because there is far less subjectivity in selecting traits. That makes the inference far less subjective in some of the most important ways.
Yes, there are principles for selecting informative traits. These principles, however, are difficult for appreciate with out a lot of domain specific knowledge, and this is also vulnerable (at least rhetorically) to a critique of circularity. Genomic features are far less subject to this critique, especially in large scale genomic analysis. Cherry picking is just not a valid critique.
Moreover, because of neutral theory, we have much stronger and verifiable quantition. Sure, we see nested clades in anatomic features (and biochemical), but we do not have anything approaching the same confidence as the molecular clock.
So, what am I missing? From an objective point of view, what is the stronger line of evidence? Or perhaps this is a sort of “capstone” bias, in that it looks the most important because it the evidence that really seals the deal, even though sufficient evidence was already available?
As a geneticist, my objective point of view is that the sequence evidence is stronger.
I say that because the magnitude of morphological changes does not correlate well with the magnitude of the sequence changes that cause them.
Well, of course the molecular evidence is, all things being equal, stronger. But the paleontologists don’t think so, which is the point. The benefits of molecular data include, as you have said, objectivity in choice of characters, ease of scoring, better ability to model, and I would add sheer volume of available data. But morphology does have certain claimed benefits, some of which may be correct: availability of fossils, which can both inform about unknown states and break up long branches, less susceptibility to long branch attraction, greater ability to detect homoplasy because of character complexity, less susceptibility to homoplasy because of more available character states. Whether any of those are true isn’t relevant as long as morphological systematists still make the argument.
Anyway, what’s objectively stronger evidence isn’t that important if each sort of evidence would be sufficient by itself, which it is.
Incidentally, I’m disappointed that the topic has already departed so far from Darwin’s Doubt, probably never to return.
So it seems that everyone here thinks that genetics is the strongest evidence. Who are these elusive disenters that disagree? Are you sure they aren’t mythical?
Um, you mis-spelled RNA.
I do. DNA offers the best quantitative data we have. That isn’t to say qualitative data from other fields is bad evidence, it just isn’t as good as DNA evidence. As Dr. Francis Collins put it:
I also tip my cap to @John_Harshman. It is entirely possible that molecular biologists are blinded by the attachment to their own field of work. However, I just can’t help but look at a comparison of genes and not be amazed at the evidence that is seen. When you look at sequence conservation you see a signal of conservation in the exons and a lack of conservation in the introns, just as you would expect to see. The divergence in sequence between exons and introns increases with evolutionary distance. It’s quite spectacular evidence.
Uh, as a layman, I don’t know what evidence is most important but I do know that what’s going to make laymen believe in evolution are human remains.
As in, physical remains that you can see with a naked eye, not DNA or RNA.
Your post reminds me of this quote:
Evolution was already considered proven (beyond a reasonable doubt) before DNA evidence became available. As Zuckerkandl and Pauling say, the DNA evidence was just a really big stick to beat an already dead horse.
Given that there are plenty of human fossils, why hasn’t that convinced all the creationists?
Don’t ask me!
I’d offer there isn’t any one strongest line of evidence for evolutionary theory any more than there is one “best” piece of a 1000 piece jigsaw puzzle. The strength of evolutionary theory comes from the consilience of dozens of independent lines of investigation which considered as a whole clinch the case.
There aren’t any paleontologists here; that’s your problem. Or plain morphological systematists. I’ve encountered quite a few of them. For years, none of the paleontologists were willing to believe the molecular data on crocodylian relationships; not sure they still do. Or you could read something from Jeffrey Schwartz on primate phylogeny. Plenty of examples.
Can you invite a few to join us?
Now, now. You ventured an opinion. I’m asking you to support it.