On progressive animal evolution and the place of humans in nature

Resumen

In disagreement with the reigning view that animal evolution is only the result of contingency and of catastrophic events, this article presents a view which considers animal evolution as a cumulative process of information buildup, channeled by irreversible constraints. The roots of the prevalent anti-progressivist views are briefly reviewed.

The role of the animals in biospheric evolution is analyzed on the background of the general entropy increase in the solar system. Animals act as energy traders and stimulators of the expansion and efficiency of the biosphere. The basic functions of animality are defined, and their improvement is seen as a yardstick of progress. Progressive evolution in the animal kingdom is followed along its winding and narrow path, as their respective structural and physiological burdens successively bind the different phyla. Natural selection at the phyletic level is seen as acting, rather than the extraterrestrial catastrophes. Increasing segments of the animal world are induced into establishing subservient relationships with the dominant phyla. Terrestrial animal life, with its high demands for homeostasis compensated for by an ample vegetal biomass and rich oxygen supply, had the uniquely capacity to give rise to the most complex animal forms. Among the homeothermic vertebrates, mammals are singled-out by natural selection to produce the most intelligent and energetically active animal beings. The rise of the humans is not an accident, but the present crowning of a long ‘post-hoc’ foreseeable process. It is a new and, again, irreversible stage in organic evolution, with long-lasting and profound effects.