Part I Problems of Biosphere Evolution and Origin of Life On Important Stages of Geosphere and Biosphere Evolution N. L. Dobretsov, N. A. Kolchanov, and V. V. Suslov Abstract The necessary conditions for the existence of protein–nucleic acid life are the presence of liquid water, some protection against high-amplitude tem- perature 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 convec- tion 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 mate- rial 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 atmo- spheric O2 in the course of the Earth’s geological evolution caused the extinc- tion 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 (autonomiza- tion) from the geosphere. As a result, the biosphere develops a solid film of life spread out over the continents, pelagic and abyssal zones, and the geosphere N. L. Dobretsov Institute of Geology and Mineralogy, SB, RAS, Novosibirsk, Russia e-mail: [email protected] N. Dobretsov et al. (eds.), Biosphere Origin and Evolution. 3 Ó Springer 2008 4 N. L. Dobretsov et al. supplemented its geochemical cycles with biogeochemical ones which are com- parable, if not by the mass of the matter involved, by annual balance. The necessary condition for the existence of DNA/RNA/protein-based life is the presence of liquid water, an atmosphere and the accessibility of bio- genes: macroelements (O, C, H, N, Ca, P, S, K, Mg, as well as Si and Al) and microelements (Fe, Ni, Mn, W, Mo, V, Zn, Cu, Co, Se, Cr) in the form of soluble substances. It was not before these conditions were established in the course of the Earth’s evolution that the biosphere could start or, if it is of cosmic origin, resume its evolution. Due to gravitational separation, the primary material began to arrange itself into a crust enriched in light elements and a core, into which heavy elements had been migrating. The process of separation of the metal core into a stand-alone entity played an important role in the Earth’s temperature dynamics: it is responsible for the meltdown of the mantle and crust at the Earth’s earliest, moon-like stage (4.6–4 Byr ago). The heat accumulated during that process accounts for 35% of the Earth’s current total, a major portion of which dissipates and is lost into space, and a minor portion of which is accumulated by the biota and is in part preserved in dead fossil organic matter (in particular, caustobiolites, including hydrocar- bons, are nothing else than the preserved portion of the Earth’s thermal energy). The heat provided by the solidification of the Earth’s growing inner core composed of a solid iron–nickel alloy with some diamond admix- tures accounts for additional 15%, the growth of the outer core accounts for additional 10–15% (this is due to separation of Fe and Ni from the mantle) and radioactive decay accounts for the rest (Trubitsin, Rykov, 2001). The inner core grows due to the material coming from the outer liquid metal core. The outer liquid core supports the magnetic field, the vanguard protection network of the biosphere, and plays an important role in heat transfer in the Earth’s interior. Over 4.5 billion years, the average mantle temperature dropped from 3000 to 2100 8C, and the heat flow reduced. The curve q(t) (Fig.1A) allows the integral heat losses to be estimated as Z4:6 Q ¼ S0qðtÞdt 0 Given the hot Earth model and assuming that the Earth’s area, S0, has been subject to little variation, we obtain an estimate for the heat lost over the first 150 million years: 9 % of the total heat lost over the Earth’s history (6 % per 100 million years). Over 650 million years that followed and were associated with an intensive separation of the core and intensive one-layered mantle convection, the heat loss amounted to 28 % (or 4.3 % per 100 million years). Over 1.1 billion years that followed and were associated with the separation of a liquid core from Important Stages of Geosphere and Biosphere Evolution 5 a solid core and one-layered mantle convection, the heat loss amounted to 26 % (2.5 % per 100 million years). Over the period between 2.6 and 1.2 billion years associated with the transition to two-layered mantle convection and a reduction in the rate of core solidification, the heat loss amounted to 17% (the heat loss rate reduced to 1.3 % per 100 million years). Finally, over the past 1.2 billion years, which are associated with two-layered mantle convection and a slow- paced core solidification with periodic faster-paced laps, the heat loss amounted to 11% (0.9% per 100 million years) (Dobretsov, Kirdyashkin, 1998). Thus, irreversible trends in the Earth’s evolution are its cooling, which proceeds with periodic variations on the background of total slowdown (Tajika, Matsui, 1992, Dobretsov, Kovalenko, 1995), and change of the ratio between the mobile and bound oxygen in rocks and the atmosphere,1 which have resulted in rock oxidation and atmosphere oxygenation (Dobretsov and Chumakov, 2001). As a result of the cooling, the moon-like stage of the Earth’s history gave way to the nuclear one. As long ago as 4.3–4.2 Byr, the Earth had a thin crust, sufficiently cool (no hotter than 100 8C) for the formation of the hydrosphere. This time is deduced from findings of corroded zircon grains (de Laeter and Trendall, 2002). The first traces of life, probably, prokaryotic, are recorded in 3.8–3.7 Byr old rocks of earthly origin (Schidlowski, 1988). Hence, at least since that time, two conjugated systems existed: the biosphere and the geosphere, and geosphere evolution determines the direction of irreversible evolution (Fig. 1). There are two aspects to the concept of evolution: (1) the process of de novo formation of an archetype2 (biologically speaking, phylogenesis); and (2) the process of the canalized (pre-programmed) individual development of an exist- ing archetype (biologically speaking, ontogenesis). Discussion of the possible relevance of ontogenesis and phylogenesis to geology was started by V.I. Vernadsky, E.S. Fedorov and Grigoryev D.P., but reasoning has never been perfected into any scientific concept (Grigoryev, 1956; Rundkvist, 1968; Rundkvist et al., 1971; Izokh, 1978), except for those occasional events in which the concepts of ontogenesis and phylogenesis have been applied to analyze the genesis of mineral and ore associations. It was proposed to apply the concept of the phylogenesis of minerals (ore bodies, parageneses, mineral species and others) to the geological processes that span over time and space 1 It should be noted that before photosynthesis, rock oxidation was determined mainly by hydrogen dissipation, directly depending on the Earth’s temperature. Thermochemical degra- dation of mobile hydrogen-containing compounds is accompanied by dissipation of hydrogen and binding of oxygen to metals (in particular, to iron, to generate magnetite crystals). Photosynthesis is also degradation of hydrogen-containing compounds (hydrogen sulfide in the anoxic bacterial photosynthesis and water in oxygenic photosynthesis by cyanobacteria and plants). Therefore, since the beginning of photosynthesis, metals have been oxidized by biogenic oxygen as well. 2 The archetype is assumed to be a set of traits and characters that make a particular group of members, or individuals, that share them stand alone as a species among all the others groups (Grigoryev, 1956; Liubischev, 1982). Important Stages of Geosphere and Biosphere Evolution 7 intervals considerably (by a factor of in excess of dozens) exceeding both the age of any particular ore body and all the room it has ever required (Rundkvist et al., 1971). These processes shape environments so that the development of particular ore bodies can only go the way it does. Here the canalization is obviously very much similar to that in biology; however, the mechanisms underlying it are quite different.3 In biology, the canalization of ontogenesis is largely performed by a program made in the form of a special structure, the genome (Kolchanov et al., 2003). This mechanism of canalization ‘‘from inside’’ rather than ‘‘from outside’’ allowed the biological forms to embark upon a course of development independent of the rule of the environment (Shmalgau- zen, 1968) and eventually to form an independent vector of biosphere evolution. By saying ‘‘a code,’’ we mean any type of monomer context that carries, within a polymer, information, the significance of which for a particular function is set not directly, but by matching rules.