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Chicken? Egg? None of the above?

William Dembski
March 7, 2006
Intelligent Design
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Beyond the standard chicken-and-egg positions on the origin of life (i.e., ploynucleotides-first vs. proteins-first), there is now fast emerging a lipids-first position (cf. the work of Pier Luigi Luisi and coworkers). For more on the fat-first position and its potential to revolutionize origin-of-life studies, see O. Mouritsen, Life — As a Matter of Fat: The Emerging Science of Lipidomics (Springer: 2005). Question: What is the natural route to lipid membranes in the absence of other cellular machinery?

Comments
Dr. Dembski wrote: "Question: What is the natural route to lipid membranes in the absence of other cellular machinery?" The egg (or the chicken's) side of the question is: "What is the route to free-floating, unbounded nevertheless functionally integrated cell machinery absent lipid membranes?"Red Reader
March 7, 2006
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More on fat: http://www.sciencemag.org/cgi/content/full/311/5765/1232 http://www.sciencemag.org/cgi/content/full/311/5765/1251 http://www.sciencemag.org/cgi/content/full/311/5765/1258 http://www.sciencemag.org/cgi/content/full/311/5765/1263Patrick
March 7, 2006
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While I've not looked over the entire article, this 'lipids first' position is particularly unsatisfying to me. Certainly sequestration of biomolecules from the environment, and the ability to maintain non-equilibrium conditions inside the cell demonstrate the importance of lipids to the question of biological origins. I do admit that the issue of membrane bilayers is a relevant question to the origin of life. However, I don't understand how a 'lipids first' scenario eases the burdens that the information contained in the genome present, or how it helps to overcome the enthalpic and entropic constraints that preclude biological polymer formation in the absence of enzymes.

I could see the appeal of a 'lipids first' position. It seems like there are less problems to overcome with lipids... fatty acids, for example, are not chiral and are probably much easier to 'get to' via a naturalistic pathway. But I would imagine that a lipids first scenario would have problems of it's own. If I recall correctly, the 'form' that a lipid adopts in an aqueous environment, that is monolayer, micelle, or bilayer, is dependent on the nature of the head group and the length of the fatty acid tail... both of which wouldn't be controlled were lipids to arise via a naturalistic mechanism.

mattison0922
March 7, 2006
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