Leonid Andreev
Part II: https://systemity.livejournal.com/4661607.html
Original paper "View on Lipids of Microorganisms from the Standpoint of Prebiotic and Biological Evolution" published in: Voprosy Evolutsii Bakterij (Evolution of Bacteria), USSR Academy of Sciences, Center for Biological Research, Institute of Biochemistry and Physiology of Microorganisms, Pushchino, 1984, pp. 93-119 (https://www.dropbox.com/s/

Macromolecular chronometry
It would seem that this logical deadlock could be resolved by comprehensive investigation of regularities in the evolution of those macromolecules which perform same functions in evolutionarily distant contemporary organisms. With the fundamental capabilities created by molecular biology methods, it is possible now not only to investigate evolutionary relations between various organisms but also to estimate a relative time point of their divergence, i.e. evolutionary distances. The idea of the “molecular evolutionary clock” was first proposed by Zuckerkandl and Pauling [34] in 1965. It is based on the fact of existence of a great variety of macromolecules that, having different sequences of monomers, are capable of performing same functions. Consequently, mutational changes in proteins and nucleic acids can provide a measure of the evolution time. Woese [33] recently made a detailed analysis of the results obtained with the use of the molecular chronometry method and discussed the ways for further improvement of the method and overcoming its limitations.
For instance, one of the major limitations of the method is caused by the fact that the relative speed of homologous macromolecular clocks can be different in different organisms. Also, in bacteria, an intensive interspecies transfer of genes with totally different evolutionary backgrounds may contribute into different genealogy of macromolecules of one and the same organism. Both of those limitations can be resolved in one or another way. For instance, it was shown that the use of two independent molecular clocks – cytochrome c and ribosomal RNA – provided consistent data on purple synthesizing bacteria [22]. Phylogenetic structures based on molecular chronometry studies [25, 29] attract a lot of interest in biologists of various areas of specialization, and there is a hope that this method can help to develop objective criteria for evaluation of evolutionary relations between various groups of organisms. Nonetheless, the areas in which molecular chronometry is either ineffective or insufficiently effective include, first and foremost, the issues of prebiotic evolution, emergence of life and the functioning of early life forms. It is also important to realize that the discovery of the paths of evolution of life on Earth is not an answer to the question about the reasons for the choice of those paths.
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