GEOCHEMICAL IMPOVERISHMENT AND EUKARYOTIZATION OF THE BIOSPHERE: A CAUSAL LINK

Abstract

Several trends in the early history of the Earth (decrease in the radiogenic heat and volcanic activity; growth of continents, which were mineral traps; changes in the composition of objects of weathering and erosion; drop in the concentration of carbon dioxide; and cooling and oxygenation of the biosphere) led to chemical impoverishment of the hydrosphere and atmosphere. The biota always played a major role in mobilization, transport, and concentration of chemical elements within the biosphere. The elements buried in stable continents were removed from active geochemical circulation. Reduction in the accessibility and mobility of many metals, which demonstrate high catalytic activity and form active parts of enzymes (the true drivers of the metabolic processes in living cells), was a phenomenon of particular importance for life. The eukaryotization of the biosphere, from the origin of the eukaryote cell to the appearance of man, and the increase in the trophic structure of the global ecosystem may be considered as evolutionary responses to the geochemical impoverishment of the biosphere.