Chapter 6 - Origin of Biological Homochirality: Directed Selection or Random Motion?

Abstract

There are several points that enable the judgment about the relevance of the idea that asymmetry of the bioorganic world is the result of mirror symmetry breaking at the chemical stage of evolution. The first inference is that chiral physical factors, irrespective of whether they are local or global and of conditions under which they reveal themselves, could not be of significant consequence in terms of the origins of biological homochirality. The second inference is that there is no ground for accepting the most widely known version of the scenario of spontaneous symmetry breaking, according to which formation of a chirally pure medium at the chemical stage of evolution and its subsequent polymeric takeover could collectively provide conditions for the straightforward realization of a prebiotic transition. These discrepancies do not invalidate the hypothesis of asymmetrical origins of life but emphasize crucial obstacles standing in the way. The chapter also discusses one of the approaches to evolutionary problems based on the idea of random motion in sequences spaces with extremely high dimensions.