The thermodynamics and evolution of complexity in biological systems

Recent advances in nonequilibrium thermodynamics leads to the conclusion that similar processes, constrained by the second law of thermodynamics, give rise to the emergence of structure and process in a broad class of dissipative systems. The second law suggests that, in systems moved away from equilibrium, processes can emerge so that the system organizes in a way that reduces the effect of the applied gradient. If dynamic and or kinetic conditions permit, self organization processes can be expected. As biosystems grow and develop, they should increase their total dissipation, and develop more complex structures with more energy flow, increase their cycling activity, develop greater diversity and generate more hierarchical levels. As a corollary to this general statement, biosystems which do not increase their total dissipation, are organisms dedicated to death, like observed during the aging of any biosystem. Species which survive in ecosystems are those that funnel energy into their own production and reproduction and contribute to autocatalytic processes which increase the total dissipation of the ecosystem while at same time surviving within the constraints of their changing environment. In a broad class of biosystems, stress and aging have similar thermodynamic properties and suggests common underlying principles. (C) 1998 Elsevier Science Inc. All rights reserved.