The extended second law of thermodynamics suggests a thermodynamic imperative driving the evolution of life systems towards increased complexity

From a thermodynamic point of view life structures can be viewed as dissipative systems capable of self replication. Energy flowing from the external environment into the system allows growth of its self replicative components increasing the system complexity concomitantly with an increase in the entropy of the universe, thus observing the second law of thermodynamics. However, general thermodynamic models of life systems have been hampered by the lack of precise equations modelling far from equilibrium driven systems operating in non-linear response regimes. Recent theoretical advances, applying time reversal symmetry and coarse grained state transitions, have provided theoretical insights into the thermodynamic constraints that bind the behaviour of such far from equilibrium life systems. Setting additional constraints based on empirical observations allows us to apply this theoretical framework to gain a further semiquantitative insight on the thermodynamic boundaries and evolution of complex self replicative life systems. This interpretation suggests a thermodynamic hierarchical organisation based on increasing accessible levels of usable energy, which in turn drives an exponential punctuated growth of the system’s complexity. For the earth life system this growth has historically not been limited by the total energy available from the external driving field, but by the system’s internal adaptability needed to access higher levels of usable energy. Therefore, in the absence of external perturbations, the emergence of an initial self replicative dissipative structure capable of variation that enables access to higher energy levels is sufficient to drive the system’s growth irreversibly towards increased complexity across time and space in a hierarchical manner. This interpretation is consistent with current empirical observation of life systems across both time and space and explains from a thermodynamic point of view the evolutionary patterns of complex life systems on earth.