|
In this article the major changes in evolution from the simplest prokaryote cells to man and his industrial activity are described as a progressive change in the organization of chemistry in spatial compartments. The changes reflect the changing availability of chemical elements, produced first through the unavoidable production of oxygen by organisms and most recently through man's exploitation of the environment. We assume that initially Earth had a reducing environment from which it was necessary for organisms to obtain 20 chemical elements in simple cells. Particularly important was the need to make carbon-based polymers from CO2, CO, H2O, and nitrogen, using energy from the sun. These polymers had to be, and have to be to this day, made in a central reducing compartment, the cytoplasm, and the release of oxygen, O2, was therefore unavoidable. The oxygen then converted the reduced forms of elements of the primitive environment into more oxidized states. The process was slow as oxygen tension rose to its present levels over 2–3 billion years. Elements were oxidized following their thermodynamic redox potentials. To survive in the constantly shifting environment organisms had to both protect their reductive cytoplasmic chemistry and to obtain the required elements from the new poisoned oxidized environment. The new chemicals provided new sources of energy. We postulate that the only way to manage the situation was to evolve more and more compartments, keeping incompatible chemicals and chemistry separated from the cytoplasm. Effectively this explains the development of ever more complex compartmental organization in the series prokaryotes, single-cell eukaryotes, multicellular organisms, and finally organisms managing external compartments. Any organization requires communication networks. We view the networks as arising progressively, utilizing again, of necessity, gradients of ions, for example, calcium, sodium, and chloride rejected by primitive cells. The networks had to be cross connected as organization and numbers of coordinated compartments increased; we see this in the evolution of the brain in animals. The brain allowed exploration of the environment in new ways through the application of scientific empiricism. We see again in this advancement ways of obtaining new elements that were forced into constructions now in spatial compartments outside the organism, here man. There was the further requirement to organize the use of elements in these external compartments and to connect them by communication networks. In summary, we view the whole progress of life as a one-way development of evolving ever increasing chemical organization in ever more divided space. It is, we consider, the only way to change in a changing environment. Superimposed on this gross scheme has been the arrival of millions of species for which we offer no novel comment. They are but variations on the major theme.
|
Citation
