Some of you will be aware of the large threads I mentioned at The Skeptical Zone on common descent. Just for completeness I thought I should post a list of links to them:
I suspect that there are others, but my brain gets numb thinking about these threads. I have no immediate way of checking, but I think that the 5,163-comment thread started by Sal Cordova is the longest-ever thread at TSZ.
The main problem with the thread on TSZ was that the participating creationists were completely unable to separate the idea of intelligent design from the idea of separate creation. And so from the very beginning instead of confronting the evidence for common descent they changed the subject to the supposed inadequacy of unguided evolution, and they could not be convinced that it was a change of subject.
You’ve presumably seen Bill do that right here in exactly the same way he did there. If we can’t even agree on what the subject under discussion is, how can there be any way forward at all?
I was never a creationist, but I’ve certainly been reasoned out of beliefs I didn’t come to have by reason. It may be true to say for some people that they’re not possible to reason with, at least on some subjects, but it’s an overgeneralization.
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.
From Sal’s post. Where the discussion gets tricky is when you are dealing with the claim that common descent is the best explanation for the nested hierarchy yet the hierarchy contains orphan features. If common descent does not explain the emergence of orphan features then how can it be the best and only explanation?
Almost everyone agrees common descent is at least a partial explanation for the signal.
Uh no it’s not. It’s claim is that species are related. It’s silent on how this happens. Evolutionary theory explains how it happens. Common ancestry is not a mechanism…
I mean do you really think wolves and foxes sharing a common ancestor is supposed to explain the origin of orphan genes?
