By AWT the life evolution follows an ancient Oparin's coacervate theory. Certain liposomes can behave like walking droplets, described recently.
We can imagine, such droplets were precipitated from waves of ancient lakes at places, where organic compounds were pre-concentrated by wind and solar radiation and they were thrown at coast surface, covered by various surfactants. The droplets are attracted to them, so they started to climb around coast, collecting these materials in their cells. The most successful droplets become so large by such way, they fragmented into smaller ones under impact of next breaker wave, and whole process has repeated many times.
posted by Zephir Zephir
June 17, 2009 @ 3:44 PM
The Miller/Urey experiment demonstrated that natural environmental conditions involving the introduction of chemical energy, given the right chemistry, would result in the formation of some of the molecules of life. What Miller/Urey provided was metabolism, redox coupling, like that found at volcanic vents were thermal radiation has wavelengths just less than one micron, and down to .4 microns, where UV begins, and where hydrogen sulfide is oxidized on contact with water to create sulfurous acid and a cloud of electrons. No catalyst was needed. The energy was there already.
The question is, how did this first life make it from black smokers and mantle plumes to the surface? The answer is shown quite clearly in the mathematics of metabolism. I refer you to a paper at Theoretical Biology and Medical Modelling entitled "The Terrestrial Evolution of Metabolism and Life - By the Numbers," that addresses this issue. The numbers deal exclusively with water, salt, energy, and organic molecules; and illustrate how organic biomass is shaped by thermodynamic pressures for equilibrium, and hysteresis, given fluctuations in energy supply.
Both replication and selection are contained in the curves generated, and appear as changes in the electrical and electrochemical properties, and size of the biomass. The numbers say metabolism is inseparable from replication. The citric acid cycle may be a foundation for complexity, but the foundation is not in the molecules or atoms. It is instead in the electromagnetism that acts upon these chemicals, and others like them, from the beginning to now. Complexity is not an issue. Life and biological organization are epiphenomena of the interaction of electromagnetism and organic chemistry.
Trefil, Morowitz and Smith call for 'an extension of ordinary thermodynamics so that it can apply to systems maintained far from equilibrium by the flow of energy.' Again, what started life and shapes it is ordinary thermodynamics pressuring systems to return to equilibrium. Again, hysteresis and this pressure do not need to be supplemented by new thermodynamics or, as Schrodinger called for, a new sort of bio-physics that would explain complexity and emergence.
The authors recognize this on a vague level, and write, "The important feature necessary for chemical selection in such a network, which remains to be demonstrated, is feedback-driven self-pruning of side reactions, resulting in a limited suite of pathways capable of concentrating reagents as metabolism does. The search for such self-pruning is one of the most actively pursued research fronts in Metabolism First research." You have to ask yourself, why are these people dismissing the mathematics of metabolism, which is exclusively about the essentials of all life? And the reason is they are biochemists and geochemists interested in things like stoichiometry rather than electromagnetism.
"In the same way, we argue, the current complexity of life should be understood as the result of a multistep process, beginning with the catalytic chemistry of small molecules acting in simple networks—networks still preserved in the depths of metabolism—elaborating these reaction sequences through processes of simple chemical selection, and only later taking on the aspects of cellularization and organismal individuality that make possible the Darwinian selection that biologists see today." Right on! But this is what the math deals with!
Well, here is the problem: "We note that there is a fundamental difference between the way chemical reaction systems could have operated before the appearance of the first self-replicating molecules and the way they operate now that self-replicating systems have developed. In the beginning, the only potential source of order would have been networks of chemical reactions operating according to the laws of chemistry and physics. After molecules appeared that could replicate more or less independently, such as RNA, however, evolution could have proceeded according to the rules of natural selection, with the success of subsequent generations dependent on adaptive properties." Replicate more or less independently? Replication is part of metabolism. Independently of what? Of physics and chemistry? The authors start to slip into dualism, in thrall to the manifold forms of emergent complexity that, for them, is not capable of being modeled in terms of essentials.
What they claim is that: "Instead they [more complex organic molecules] acquired the ability to run the cycle in reverse, extracting energy from the breakdown of molecules similar to those the cycle formerly produced. This is not reverse. This is also metabolism. The authors labor under the same misconception that troubled Schrodinger, that somehow life was able to overcome entropic deterioration in a reversal of the second law of thermodynamics. In fact life is the intensification of that law. Witness how nature came up with organisms that would drill and excavate to release stored energy that otherwise would last eons.
What do they say instead? "Current research into this foundational question now centers on the fact that the chemical substrate of living systems is much more complex than that of simple physical systems that have been examined so far. One important new direction of research involves the development of small-molecule catalysts in increasingly complex cooperative networks. The hope is that when a full theory is available, we will see the formation of life as an inevitable outcome of basic thermodynamics, like the freezing of ice cubes or the formation of magnets." Nice hope, but you are not advancing this research with this paper.
"Distributed control is likely to be a central paradigm in the development of Metabolism First as a viable theory." The math shows this clearly, only 'distributed control' is change in biomass due to change in metabolism. "We eagerly anticipate more experimental efforts like these to explore the many facets of small-molecule system organization." The wonderful thing about the math is that it presents clear, testable inferences, in lab or clinic, that are based upon the idea the forces and pressures there at the start are still working, and fundamental to the understanding of aging, cancer, and weight loss. The equation explains why caloric restriction might work on a rat, but why it won't work on a human or large mammal. These forces and pressures are shown to be manipulable in terms of the variable in the equation however, leading to extended life, cancer prevention, muscle building and the reversal of the degeneration of aging. It's worth a look even if you don't believe it.
posted by Gregorio Kelly
September 3, 2009 @ 8:16 PM
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