Hi, Genomicus.
Thanks for the reply.
Genomicus writes:
In the first place, I'm not envisioning anything like extreme front-loading, where something as specific as the human species is front-loaded.
Thanks for the clarification: though, I already figured you for someone wouldn't make this argument.
Genomicus writes:
So if I'm understanding you correctly, you're saying that if multicellularity was front-loaded, we should expect multicellular life forms to evolve independently. But this is what is believed to have occurred; that is, that multicellular life forms arose multiple times but many of these lineages went extinct...
Well, I wasn't trying to put forward an example yet: I was trying to establish a conceptual principle whereby we could test the predictions of FLE.
And, yes, there are indeed many lineages of multicellular organisms. As the article you cited mentioned, there are probably at least 5 independent emergences of "true" multicellularity. And, depending on how we define "multicellularity," there are also prokaryotes that can count as multicellular (some cyanobacteria, for instance).
So, based only the single criterion I proposed, I would regard multicellularity as potentially consistent with the front-loaded evolution hypothesis.
Genomicus writes:
And there is good evidence of biased trajectories of important biological features: to name just one example, eyes have evolved independently in different lineages - indicative of a biased trajectory.
My concern with the specific example here (eyes) is that the bias in trajectory only emerges in one "later branch" of the Tree of Life (Metazoa). So, it seems that the capacity to develop eyes isn't rooted at the base of the Tree of Life, but at the base of the
animal branch of the Tree of Life.
Unless FLE allows for front-loading within individual branches of the tree, and not exclusively at the base of the tree, I think the proper conclusion is that eyes probably were not front-loaded.
Genomicus writes:
Essentially, it would not be reasonable to argue that "characteristics that only emerged once in Earth's evolutionary history probably were not front-loaded into the original," because lineages can be lost through deep time.
Please observe the parallels between your argument here and a specific statement you made in the OP:
Genomicus writes:
Arguing that the sub-optimal codes once did exist early in life’s history, but vanished once the optimal codes came on the scene (i.e., that they were outcompeted), looks awfully ad hoc.
I will accept your "deep-time" argument if you withdraw your objections to the similar argument in relation to sub-optimal genetic codes.
Edited by Bluejay, : No reason given.
Edited by Bluejay, : No reason given.
Edited by Bluejay, : last time: I swear
-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.