title: A system's view of the evolution of life.
abstract: Previous treatments of biological evolution have concentrated upon either the general appearance or habits of organisms or the sequences of molecules, such as their proteins and DNA (RNA), within species. There is no consideration of the changing relationship of the chemistry of organisms to the elements and energy available from the environment. In essence, organisms at all times had to accumulate certain elements while rejecting others. Central to accumulation were C, N, H, P, S, K, Mg and Fe while, as ions, Na, Cl, Ca and other heavy metals were largely rejected. In order to form the vital biopolymers, C and H, from CO2 and H2O, had to be combined generating oxygen. The oxygen then slowly oxidized the environment over long periods of time. These environmental changes were relatively rapid, unconstrained and continuous, and they imposed a necessary sequential adaptation by organisms while increasing the use of energy. Then, evolution has a chemical direction in a combined organism/environment ecosystem. Joint organization of the initial reductive chemistry of cells and the later need to handle oxidative chemistry has also forced the complexity of chemistry of organism in compartments. The complexity increased to take full advantage of the environment from bacteria to humans in a logical, physical, compartmental and chemical sequence of the whole system. In one sense, rejected material can be looked upon as waste and, in the context of this article, leads to the consideration of the importance of waste from the activities of humankind.
authors: Inorganic Chemistry Laboratory, University of Oxford, Oxford, UK. bob.williams@chem.ox.ac.uk
authors: Robert J P
authors: RJ
authors: Williams
mesh_terms: D005075:Biological Evolution; D017753:Ecosystem; D008954:Models, Biological; D000069497:Origin of Life; D049490:Systems Biology