Evolution of life

In the 1950s it was assumed that the primitive Earth atmosphere consisted of methane CH4, ammonia NH3, hydrogen H2 and water H2O and S.L. Miller and H.C. Urey carried out a famous experiment at the University of Chicago. They simulated the primitive Earth atmosphere and ran continuous electric currents simulating lightning storms, which were very common on the early Earth, to this environment. After one week, 10-15 amino acids were found in this primordial soup. 

Sagan and Chyba (1997) [287] proposed that the early Earth had an organic haze layer in its atmosphere. Such a layer can be found in the atmosphere of Titan, the largest satellite of Saturn and is produced by methane photolysis in the presence of nitrogen. An organic haze layer would preferentially absorb ultraviolet light, thereby allowing ammonia and methane to persist in the atmosphere. 

In the 1970s black smokers (Fig. 2.2) were detected. These are chimney-like structures above hydrothermal vents. In these smoker chimneys sulfides of iron, copper and zinc are found. At the mixture of the hot mineral rich water with cold water, these sulfides are precipitated and the vent water therefore appears black in color. The most striking discovery was that these warm chemical rich environments are the living space for many species. Huber and Wachtershauser, 1998 [166], modelled volcanic or hydrothermal settings. They showed that amino acids were converted into their peptides by use of precipitated (Ni, Fe)S and CO in conjunction with H2S (or CH3SH) as a catalyst and condensation agent at 100°C and pH 7 to 10 under anaerobic, aqueous conditions. Thus a thermophilic origin of life seems plausible. 

Summarizing there are basically three different theories about where life has evolved on our planet the primordial soup theory (Urey-Miller experiment), life has originated in the atmosphere (Sagan) and black smokers (hydrothermal vents). The primordial soup theory seems to be no longer acceptable without strong mod- 

In the early twentieth century S. Arrheniusdeveloped his panspermia hypothesis. According to this theory life might have originated somewhere in the universe and would have spread out automatically. 

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When considering how the evolution of life could have come about, the seeding of terrestrial life by extraterrestrial bacterial spores traveling through space (panspermia) deserves mention. Much is said about the possibility of some form of life on other planets, including Mars or more distant celestial bodies. Is it possible for some remnants of bacterial life, enclosed in a protective coat of rock dust, to have traveled enormous distances, staying dormant at the extremely low temperature of space and even surviving deadly radiation The spore may be neither alive nor completely dead, and even after billions of years it could have an infinitesimal chance to reach a planet where liquid water could restart its life. Is this science fiction or a real possibility We don t know. Around the turn of the twentieth century Svante Arrhenius (Nobel Prize in chemistry 1903) developed this theory in more detail. There was much recent excitement about claimed fossil bacterial remains in a Martian meteorite recovered from Antarctica (not since... 

Succession of flora and fauna refers to the deposition of sedimentary material, which will include the remains of plant and animal life that existed at the time of the deposition of these rock particles. The fossils of these plants and animals will be found in the rock formations that result from the deposition. The presence, absence, or change of the plant and animal life within a sequence of the geologic column provide important information that allows for the correlation of rock formations (and, thereby, relative time) from location to location. Also, the fossil records within sequences give important information regarding the evolution of life through geologic time. 

The evolution of life on Earfh has depended on a sustained supply of nutrients provided by the physical environment. Life, in turn, has profoundly influenced the availability and cycling of these nutrients hence the inclusion of bio in biogeochemical cycles. The involvement of the biosphere with biogeochemical cycles has been determined by the evolution of life s biochemical properties in the context of the physical and chemical properties of planet Earth. 

The philosophical and conceptual ramifications of the nonequilibrium Second Law are very deep. Having established the credentials of the Law by the detailed analysis outlined earlier, it is worth considering some of these large-scale consequences. Whereas the equilibrium Second Law of Thermodynamics implies that order decreases over time, the nonequilibrium Second Law of Thermodynamics explains how it is possible that order can be induced and how it can increase over time. The question is of course of some relevance to the creation and evolution of life, society, and the environment. 

Archaea or Archaebacteria, which live in sulphurous waters around undersea volcanic vents. An extraordinarily stable enzyme which functions even at 135 °C and survives at pH 3.2-12.7 has been identified [142]. This enzyme has been termed STABLE (stalk-associated archaebacterial endoprotease). It is suggested that such exceptional stability may be attributable to unusually large Mr and tight folding of the protein chain. Suggested uses include washing powders and detergents, as well as industrial catalysts. It is even proposed that such remarkable properties may have contributed to the early evolution of life on earth [142]. 

Fig. 1.5 Schematic representation of the evolution of life from its precursors, on the basis of the definition of life given by the authors. If bioenergetic mechanisms have developed via autonomous systems, the thermodynamic basis for the beginning of the archiving of information, and thus for a one-polymer world such as the RNA world , has been set up. Several models for this transition have been discussed. This phase of development is possibly the starting point for the process of Darwinian evolution (with reproduction, variation and heredity), but still without any separation between genotype and phenotype. According to the authors definition, life begins in exactly that moment when the genetic code comes into play, i.e., in the transition from a one-polymer world to a two-polymer world . The last phase, open-ended evolution, then follows. After Ruiz-Mirazo et al. (2004)...

Chyba CF, Sagan C (1997) Comets as a Source of Prebiotic Organic Molecules for the Early Earth. In Thomas PI, Chyba CF, Me Kay CP (Eds.) Comets and the Origin and Evolution of Life. Springer, Berlin Heidelberg New York, p 147 Chyba CF (2005) Science 308 962 de Bergh C (1993) Orig Life Evol Biosphere 23 12... 

Which results led to the idea that comets are important in the evolution of life For more than ten years, some scientists have believed that life has (possibly) existed on Earth for more than 3.5 billion years recently, however, doubts have arisen as to whether this is really the case. It does seem clear that the heavy bombardment of the primeval Earth slowly started to decrease about 3.8 billion years ago. Many biogenesis researchers believe that a period of about 300 million years after the bombardment ceased would not have been long enough for life to evolve from inanimate systems. Thus the idea that comets (or perhaps even meteorites) played a role in the biogenesis process on Earth is quite appealing. Three possibilities are under discussion ... 

After a certain stage in the development and evolution of life, genetic continuity was ensured by RNA replication. 

We do not yet know what the optimal temperatures for the evolution of life were. It is generally accepted that the prebiotic chemistry on the primeval Earth must have taken place at moderate temperatures. It is, however, also possible that various... 

This clear preference for one of the two enantiomeric forms is called homochirality of biomolecules and is seen by many biogeneticists as a precondition for the evolution of life forms. 

Given the intensity of discussion of both creation and intelligent design, both of which propose an outside influence on evolution which has no simple scientific explanation, we must make our position clear. As far as we can see the directional character of evolution of our ecosystem, illustrated by the cone on the cover of this book, requires only one act for which we can see no explanation. We know of no cause of the Big Bang and the limitations it imposed on the cosmos observed in the laws of Nature. It is these laws alone which we use in our analysis. The laws contain possibilities both of systematic development which is the centre of our discussion and of random events. The first we relate, in the evolution of life, to chemotypes and the second to the appearance of species within chemotypes, see the cover of this book. At no time in this chapter, or in any other chapter do we invoke any other kind of activity. 

The history of carbon in our universe has been of great importance in the evolution of life on Earth and quite possibly in other galaxies as well. Elemental carbon was formed sometime... 

Negus, N. C. and Berger, P. J. (1988) Cohort analysis environmental cues and diapause in microtine rodents. In M.S. Boyce (Ed.), Evolution of Life Histories of Mammals, Theory and Pattern. Yale University Press, New Haven, pp. 65-1 A. 

Robinson T (1974) Metabolism and function of alkaloids in plants. Science 184 430 135 Roff DA (1992) Evolution of life histories theory and analysis. Chapman Hall, New York Rohde S, Molis M, Wahl M (2004) Regulation of anti-herbivore defence by Fucus vesiculosus in response to various cues. J Ecol 92 1011-1018... 

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