“The tree of life is being politely buried”
| January 22, 2009 | Posted by Paul Nelson under Biology |
Here’s the story from today’s London Telegraph, and here is a related, more in-depth piece on the same question from the latest New Scientist.
While Darwin argued for a single Tree — probably the most powerful image he introduced into biological perception — he was always cagey about the structure of its root. Life was “originally breathed ['by the Creator,' added in the 2nd edition of the Origin] into a few forms or into one” (1859, 490). There’s a world of (inferential / phylogenetic) difference, however, between divinely created first life and naturally arising first life, when the single most important question in the latter scenario concerns the probability of abiogenesis. “A few forms” that independently evolved (say) ribosomal structure, versus a single origin for the ribosome, would entail radically different consequences for phylogenetic reconstruction.
Move the red bead of the probability of abiogenesis down its wire, away from zero and towards one, and funny things happen to the structure of the monophyletic tree of life. The tree comes apart from the bottom, and the fracturing process rapidly climbs up into the branches.
32 Responses to “The tree of life is being politely buried”
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So rather than a universal common ancestor and a tree of life, what is now being proposed is several different trees of life?
That mammals and reptiles, birds and dinosaurs have no connection to one another?
Platonist said,
“what is now being proposed is several different trees of life?”
I believe that this is all that can definitely be concluded at the moment. At present I think the term common ancestry is more appropriate than common descent. But this is me personally.
Maybe as I read more of the Darwinian literature, I will learn more and change my mind. That is the best place to find the information. Right now SINEs, LINES, pseudo-genes, ERVs and other homologies indicate some commonalities and if one assumes a gene pool of a population that is much larger than what exist today for any species, genera, family, order or class, micro evolution would explain a lot of what we see in the world. But no naturalistic process can explain where all the variation came from. Allen MacNeill shows up periodically and has told us at least 47 times about his 47 engines of variation but as you can see I asked him above for data on what each produced and as of yet have not had an answer.
This speculation about an original gene pool is all conjecture but fits the data as far as I know. The origin of these large gene pools is what is truly a mystery. The creation of variation is the issue not natural selection or common elements in various species. It will always be the main issue.