Thermodynamic Dissipation Theory of the Origin and Evolution of Life

Karo Michaelian (IF-UNAM)

The "Thermodynamic Dissipation Theory of the Origin and Evolution of Life" postulates that the hallmark of the origin and evolution of life is the microscopic dissipative structuring of organic pigments and their proliferation over the entire Earth surface. Any model for the origin of life must take into account the fact that life is an irreversible thermodynamic process and, like all irreversible processes, its origin and persistence as a "self-organized" system is due to its dissipation of an imposed generalized chemical potential, i.e., the production of entropy. Entropy production is not incidental to the process of life, but rather the fundamental reason for its existence. Present day life augments the entropy production of Earth in its solar environment by dissipating ultraviolet and visible photons into heat through organic pigments in water. This heat then catalyzes a host of secondary dissipative processes such as the water cycle, ocean and wind currents, hurricanes, etc. If the thermodynamic function of life today is to produce entropy through photon dissipation, then this probably was its function at its very beginnings. It turns out that both RNA and DNA when in a water solvent are very strong absorbers and extremely rapid dissipaters of UV light within the 230 - 290 nm wavelength region, which is a part of the Sun's spectrum that could have penetrated the prebiotic atmosphere. The amount of ultraviolet (UV-C) light reaching the Earth's surface within this spectral range in the Archean could have been on the order of 4 W/m2. In fact, not only RNA and DNA, but many fundamental molecules of life (those common to all three domains of life; archea, bacteria, and eucaryote) are also pigments that absorb in the UV-C, and many of these also have a chemical affinity to RNA and DNA. Nucleic acids may thus have acted as acceptor molecules to the UV-C photon excited antenna pigment donor molecules by providing an ultrafast channel for dissipation. I show that there would have existed a non-linear, non-equilibrium thermodynamic imperative to the abiogenic UV-C photochemical synthesis and proliferation of these pigments over the entire Earth surface because they augmented the solar photon dissipation rate.