Living and Adapting to Its Own Habitat - Building the Most Complex Structure on Earth - page 192

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Living and Adapting to Its Own
Habitat

Adaptation—Surviving in a Changing Environment

A living system, from birth to death, struggles against the thermodynamic forces of
degradation to maintain its delicately balanced structure and functions. Even under
ideal and constant conditions in the environment, living will ultimately depend on an
organism's ability to avoid the “unavoidable” structural and functional decay by con-
tinually restoring degraded structures. Obviously, the task is much harder under natu-
ral conditions, which involve continual and often drastic changes in the environment.
The Darwinian “struggle for life” or self-preservation is inherent to living systems
but a related property of “self preservation” can be traced back to chemical systems
in equilibrium, as described by Le Chatelier's principle that “in a system in equilib-
rium any change in the equilibrium displaces the equilibrium in the direction that
counteracts the imposed change by reaching a new equilibrium.” Both biological and
chemical systems strive to counteract the imposed change, but an essential qualita-
tive distinction is that biological systems restore the former equilibrium, rather than
establish a new equilibrium as chemical systems do. The evolutionary progress of
living systems, compared to the Le Chatelier's systems, relates to the evolution of a
control system within the organism that involves a mechanism to restore the system's
previous state.
The evolution of living organisms is characterized by an incessant adaptation and
response to the changing environment. “Adapt or die” has been a basic law of the liv-
ing world from the beginning. Successful adaptations and failure to adapt determined
the evolutionary fate of the extant species populating the earth as well as the fate
of long extinct species. Failure to adapt to changes in the environment has caused
massive extinction events of species, higher taxa, and whole phyla. The fossil record
shows us as much with certainty. If survival is the reason to exist, adaptation is the
means to achieve and sustain survival in a continually changing world.
Adaptation increases the probability of survival and success of an organism in its
environment. Despite the inherent tendency to adapt in response to the continually
changing environment, living organisms are never perfectly adapted to it. Besides,
inherent constraints exist in the capability of living organisms to adapt their pheno-
type to their environment.
The actual state of adaptation for an organism is rarely, if at all, the perfect adap-
tation to its particular environment. A cat would like to be able to dive for a fresh
fish snack but, being a skilled four-legged hunter preying on mice and finless as she
is, she has to be content with a dish of preserved fish. A wolf has sharper night sight