Biosphere Origin and Evolution


The necessary conditions for the existence of protein–nucleic acid life
are the presence of liquid water, some protection against high-amplitude temperature jumps and cosmic factors (these may be the atmosphere and or a thick
layer of water or same rocks) and the accessibility of biogenes, which are
macroelements and microelements. Two geosphere-related canalizing vectors
of biosphere evolution can be discerned. One is associated with an irreversible
cooling and oxygenation of the planet and the associated complex pattern of
interplaying endogenous cycles, which affect climates as well as the amount and
composition of the biogenes in the ‘‘liquid water zone.’’ Change of the convection mode in the mantle between 3 and 2 Byr ago had the most important
implications for the biosphere: the formation of plate tectonics (a deep ocean
and continents), enrichment of the chemical composition of the effusive material and the ‘‘plume dropper,’’ which changes the oceanic-to-continental area
ratio and the mantle-to-island-arc volcanism intensity ratio every 30 Myr. The
World Ocean operates as a homeostatic system: it tempers climates, distributes
biogene concentrations evenly over the globe and provides the hydrosphere
with direct biogene supply from the mantle, which is how the second vector of
biosphere evolution is set. Life is a homeostatic system too—not due to a
tremendously high buffer’s capacity, but due to high rates of chemical reactions
and a special program (the genome), which warrants autonomy from the
environment. Reduction in methane concentrations and increase in atmospheric O2 in the course of the Earth’s geological evolution caused the extinction of chemotrophic ecosystems. Autotrophic photosynthesis provided the
biosphere with a source of energy that was not associated with the geosphere
and helped the biosphere for the first time to gain independence (autonomization) from the geosphere.