Materials of the International Conference
50th Anniversary of the International Geophysical Year
and Electronic Geophysical Year

16-19 September 2007 • Suzdal, Russia

Ancient biosphere: The becoming, trends and events

M. A. Fedonkin

Paleontological Institute, Russian Academy of Sciences, Moscow, Russia

Abstract

Origin of life, improbable for the most of the Universe factor space, seems to be not only possible but apparently inevitable in the conditions of early Earth. The physical-chemical parameters of our planet and of the nearest cosmos about 4 Ga ago were radically different from the modern ones. Some ideas of those conditions can be derived from the data of Earth sciences, comparative planetology or astrophysics, and even biology (enormous range of the physiological tolerance and biochemical diversity of Bacteria and Archaea gives hints to the environment of their origin). Among the key factors of the biogenesis we suppose availability of the metal catalysts and hydrogen. Metal ions as cofactors of the most enzymes still play a fundamental role in the biocatalysis. The main source of hydrogen on early Earth could be 1) degassing of the mantle releasing the neutral or slightly acidic fluids saturated with the molecular hydrogen (H2) and its volatile compounds CH4 and H2S, as well as CO2; 2) serpentinization, reaction of the rocks, rich with olivine and pyroxene, with water; 3) photolysis of water by the energy of UV light; and 4) radiolysis of water by the ionizing radiation. Various kinds of hydrogen metabolism common for the prokaryotic organisms and some eukaryotes are catalyzed at present by the metalloenzymes. Virtually all hydrogenases contain Fe- or Fe-Ni cofactor. Having in mind that Ni makes 5–20% of the iron meteorites one can suggest that Fe and Ni played a key role in the origin of hydrogen metabolism, presumably the oldest one on Earth. However the parameters of biosphere departed from the initial conditions of the biogenesis. Protection of ancient biochemistry and its effectiveness in the changing environment has been realized by compartmentalization of the archaic metabolic modules and by formation of the additional ones in the cell – all that was resulted in the biological complexity growth. Metabolic cascades in the living cell seem to recapitulate biochemical evolution and geochemical changes in biosphere, the two processes that should be considered as complementary. Synthesis of data from Earth sciences, paleontology, biochemistry and genomics reveals the timing and causes of the most important events of the biological evolution such as origins of the oxygenic photosynthesis, eukaryotic cell, and multicellular animals. Those events exerted tremendous influence upon the global biogeochemical cycling, sedimentogenesis and climate of our planet. This research is supported by the RAS Presidium Program 18, Program "Scientific Schools of the Russian Federation," and by the Russian Fund for Basic Research.

Citation: M. A. Fedonkin (2007), Ancient biosphere: The becoming, trends and events, in: Materials of the International Conference '50th Anniversary of the International Geophysical Year and Electronic Geophysical Year', GC RAS, Moscow, doi:10.2205/2007-IGY50conf.

© 2007 Geophysical Center RAS and authors


Webmaster