Origin and Evolution of Natural Diversity;Proceedings


Origin and Evolution of Life : Endless Ordering of the Earth's Light Elements

Nakazawa, Hiromoto

Permalink : http://hdl.handle.net/2115/38431
KEYWORDS : Thermodynamics;Entropy;Ordering;Earth's light elements;Subsurface;Origin of life;Adaptive radiation;Sea water


The evolution of a living organism, as well as pre-biotic molecular evolution, seems to be inconsistent with the second law of thermodynamics. When a bacterium is compared with some other higher organism, it is clear that all evolution tends to order more and larger molecules into more complex systems. The trick is the radiation of heat from the Earth. The Earth is loosing gravitational energy (~10^[31] Joule) obtained from the accretion of asteroids during its birth 4.55 Gyr ago. Energy loss implies a decrease in entropy which in turn requires ordering of the Earth. As components of the Earth, the lighter elements at the surface must also evolve to larger molecules and ultimately to living organisms, so that the entire surface of the Earth is now covered by low entropy materials of life. Thus, the entropy decrease of the Earth is responsible for the evolution of living organisms. The above argument suggests a new scenario for the origin of life. The concept holds that geological events of the early Earth were the environmental pressure for the evolution of organic molecules, which were in turn necessary for evolution of life. The heavy fall of the extraterrestrial objects containing metallic iron into the ocean would produce a reducing atmosphere thus generating a wide variety of organic molecules at about 4.0 Gyr ago. Of these, only hydrophilic and clay-affinitive molecules could have survived the environment of strong UV radiation and lay particles weak oxidation, because they could be immersed in sea water and be adsorbed on clay particles that were finally deposited on the seabed. Their polymerization would be a further means of survival for the molecules when deposited in sediment that experienced dehydrating conditions of high-pressures and high-temperatures during diagenesis. These polymers would then have had to survive hydrolysis through composite or cell formation, when the polymer-containing sediments reached an accretionary prism of a plate end where might be soaked by hydrothermal water. Cell fusion might be a mechanism to evolve a better cell, and lateral gene transfer and genome fusion in microbes might be relics of such cell fusion. By this mechanism, life could have originated under deep subsurface and radiated adaptively into sea water. It is an a priori assumption and there is no proof that life originated in the early ocean.