Evolution by natural selection is a process that enters into a physical medium. Through iterated replication-with-selection of large populations through many generations, it searches out the possibilities inherent in the ``physics and chemistry'' of the medium in which it is embedded. It exploits any inherent self-organizing properties of the medium, and flows into natural attractors realizing and fleshing out their structure.
Evolution never escapes from its ultimate imperative: self-replication. However, the mechanisms that evolution discovers for achieving this ultimate goal gradually become so convoluted and complex that the underlying drive can seem to become superfluous. Some philosophers have argued that the evolutionary theory as expressed by the phrase ``survival of the fittest'' is tautological, in that the fittest are defined as those that survive to reproduce. In fact, fitness is achieved through innovation in engineering of the organism . However there remains something peculiarly self-referential about the whole enterprise. There is some sense in which life may be a natural tautology.
Evolution is both a defining characteristic and the creative process of life itself. The living condition is a state that complex physical systems naturally flow into under certain conditions. It is a self-organizing, self-perpetuating state of auto-catalytically increasing complexity. The living component of the physical system quickly becomes the most complex part of the system, such that it re-shapes the medium, in its own image as it were. Life then evolves adaptations predominantly in relation to the living components of the system, rather than the non-living components. Life evolves adaptations to itself.