Muscle proteins existed before multicellularity.
A core set of muscle proteins are found in jellies and sponges.
Evolution is not the creation of "endless forms most beautiful", it is the unfolding of a beautifully designed, pre-existing program.
Jonathan M. at evolution news recently criticized the hypothesis of a monophyletic origin of the eyes.
The common evolutionary rationalization of this phenomenon is to posit that the gene in question had some kind of propensity for promoting the development of the respective structure. But this solution appears dubious, particularly in the case of the even more spectacular example of eye development…
Scientists call it LUCA, the Last Universal Common Ancestor, but they don't know much about this great-grandparent of all living things. Many believe LUCA was little more than a crude assemblage of molecular parts, a chemical soup out of which evolution gradually constructed more complex forms. Some scientists still debate whether it was even a cell.
New evidence suggests that LUCA was a sophisticated organism after all, with a complex structure recognizable as a cell, researchers report. Their study appears in the journal Biology Direct.
…
The study lends support to a hypothesis that LUCA may have been more complex even than the simplest organisms alive today, said James Whitfield, a professor of entomology at Illinois and a co-author on the study.
If Eoandromeda appeared after the cnidarians, the authors argue, bilateral symmetry would have to have evolved twice — once for the cnidarians and again for the bilateral organisms that came after Eoandromeda. Far simpler is the idea that Eoandromeda evolved first (see 'Simplest solution'). "This model of animal relationships calls for the least number of origins of bilateral symmetry," says Bengtson.
In 2008, Xinjiang Cai of Duke University in Durham, North Carolina, discovered that M. brevicollis has the same calcium channels in its cells as those used by neurons (Molecular Biology and Evolution, DOI: 10.1093/molbev/msn077). Then, in 2010, it emerged that M. brevicollis also has several proteins that neurons use to process signals from their neighbours (BMC Evolutionary Biology, DOI: 10.1186/1471-2148-10-34).
And this year, Harold Zakon of the University of Texas at Austin and colleagues discovered that M. brevicollis has the same sodium channels that neurons use to pass electrical signals along their length (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1106363108).
After the discussion about toolkits and multi-cellularity a few more interesting discoveries were made. For example:
A) Oxygen is Key To 'Cut And Paste' Of Genes.
B) Sodium Channels Evolved Before Animals’ Nervous Systems, Research Shows. (h/t Mike Gene and Nullasalus)
C) Calcium is important for multicellularity and multi-cellular signaling.
These are also interesting facts to take into account:
A) Monosiga brevicollis has an extensive calcium signaling toolkit and emerged before the evolution of multi-cellular animals.
B) Choanoflagellates have five immunoglobulin domains, though they have no immune system; collagen, integrin and cadherin domains, though they have no skeleton or matrix binding cells together; and proteins called tyrosine kinases that are a key part of signaling between cells, even though Monosiga is not known to communicate, or at least does not form colonies.
I recently read this at Homologous Legs:
Consider, for example, an alien race that (hypothetically) created life on Earth through the application of highly advanced synthetic biology. Need they have been omniscient creatures of perfect design? No, they could have easily made simple errors like Venter’s team did. Design errors do not falsify ID and fellow critics need to stop saying that they do, because the Discovery Institute will spit back something like this and you’ll look incredibly silly.
I think that the reason why this argument doesn't follow is because we can see and touch Venter. We can even dissect him if we wanted to. We have independent evidence of the rational designer of his synthetic biology and so we can easily perceive bad design as mistakes. However, we don't have independent evidence of the rational designer of biology. So when you hold up really beautiful design in biology and marvel at it's complexity and all that, and you take that as evidence for rational design, but you don't take bad design seriously, then you aren't being consistent.
However, I think following the trail of "bad design" problems can be fruitful.
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For example, they found a gene in Capsaspora that's nearly identical to the animal gene brachyury. In humans and many other animal species, brachyury is essential for embryos to develop, marking a layer of cells that will become the skeleton and muscles. Ruiz-Trillo and his colleagues have no idea what Capsaspora is doing with a brachyury gene. They're now doing experiments to find out; in the meantime, Ruiz-Trillo speculates that single-celled relatives of animals use the brachyury gene, along with other transcription factors, to switch genes on for other tasks.
Studies by other scientists point to the same conclusion: a lot of the genes once thought to be unique to the animal kingdom were present in the single-celled ancestors of animals. "The origin of animals depended on genes that were already in place," King said. In the transition to full-blown animals , King argues, these genes were co-opted for controlling a multicellular body. Old genes began to take on new functions, like producing the glue for sticking cells together and guarding against runaway cells that could become tumors.
Mike just wrote an excellent post on the The Archaean Expansion. The number of complete genomes is increasing very rapidly. If I'm not mistaken, there are now 1457 complete prokaryotic genomes (98 of archaea and 1359 of bacteria) available at the NCBI; but much more are ongoing, see here.
I have an interest in what LUCA may have looked like, and in particular, the ancestral mechanism for coupling electron flow to proton pumping. Reconstruction of these types of enzymes' evolutionary history seems to show that an A-type O2Red (also called SoxM) was present in the last common ancestor of Archaea and Bacteria. Although there are many proposed explanations for this phenomenon (most of which in my opinion are fle-friendly) , I still find it interesting that LUCA may have been ready for an oxidizing substrate at a time when there was little to no oxygen.
Evolution News and Views has a video of Stephen Meyer arguing against Front-loading and Theistic Evolution. Hoping he might be offering an argument against Mike Gene's hypothesis, and possibly provide a way out of my dilemma (it keeps me up to all hours of the night: Mike Gene or Mike Behe? Mike Behe or Mike Gene?), I watched it.
In my never-ending angst in choosing between Mike Behe and Mike Gene, I came across PZ Myers' thread, Evolve a Car, which links to here.
Will this help me sort it all out?
Comments section has been closed down due to completely irrelevant discussion.
Bonnie Bassler thinks bacteria invented social networking billions of years before Twitter or Facebook.
"We think that bacteria made the rules for how multicellular organization works…you've just evolved a few more bells and whistles."
Stephen considers Theistic Front-Loaded Evolution, and claims that unless there was intervention anytime after the beginning of the universe, there is simply not enough information to "Front-Load" the living cell. I wonder if that means he would endorse the view that the first cells were rationally designed and front-loaded with useful information that later evolved higher organisms through intrinsic control of evolution itself.
Horizontal Gene Transfer turns out to be up to 100 million times more prevalent than previously thought.
Hat tip to Mike Gene. Mike has an interesting post about the implications of this news for Front Loaded Evolution.
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