Saturday, August 05, 2017

Eden: 4 Billion BCE

After taking a few whacks at some of the older theories for the original biogenesis, Nick Lane presents his best guess at a candidate. After pointing out some crucial flaws in the primordial soup and black smoker theories, he picks Mike Russell's alkaline vent theory. What you need, he says, is a flow through reaction chamber with appropriate chemistry and catalysts that concentrates crucial reaction products and flushes wastes.

Alkaline hydrothermal vents provide exactly the conditions required for the origin of life: a high flux of carbon and energy that is physically channelled over inorganic catalysts, and constrained in a way that permits the accumulation of high concentrations of organics. The hydrothermal fluids are rich in dissolved hydrogen, with lesser quantities of other reduced gases including methane, ammonia and sulphide. Lost City and other known alkaline vents are microporous – there is no central chimney, but the rock itself is like a mineralised sponge, with thin walls separating interconnected pores, micrometres to millimetres in scale, altogether forming a vast labyrinth through which the alkaline hydrothermal fluids percolate (Figure 13). Because these fluids are not superheated by magma, their temperatures favour not only the synthesis of organic molecules (more on this soon) but also slower rates of flow. Rather than being pumped out at a furious speed, the fluids wend their way gently across catalytic surfaces. And the vents persist for millennia, at least 100,000 years in the case of Lost City.

Lane, Nick. The Vital Question: Energy, Evolution, and the Origins of Complex Life (pp. 109-110). W. W. Norton & Company. Kindle Edition.

I should mention that the figures in my Kindle edition are all black and white, and rather touch to visualize. If you are reading this Lee, and have the paper version, you might let me know if it is better.

Once again, this is a terrific book for anyone interested in the origin of life and the deepest look I have seen at many of the crucial issues.