In this section, we will present an accessible three-part strategy for showing how evolutionary theory is consistent with the second law of thermodynamics, and we provide figures to simply convey the main points. We show that entropy, far from opposing evolution, is a thermodynamic driving force that propels natural selection, the mechanism of evolution. Our approach is as follows: (1) We first describe how an inherent characteristic of all living organisms is that they are open systems that maintain greater order than their surroundings by importing free energy (nutrients) and exporting entropy (heat and waste); we focus on the role of the semi-permeable cell membrane as a mediator of internal order. (2) We then discuss how entropy can decrease locally within subsystems and how organismal complexity can increase over evolutionary time as long as there is a greater increase in entropy in another interlocking part of the system; we focus on the Sun as the Earth’s ultimate source of low entropy light and how primary producers (plants and cyanobacteria) capture this low entropy and drive the evolution of complexity. (3) Lastly, we discuss how organisms can be viewed thermodynamically as energy transfer systems, with beneficial mutations allowing organisms to disperse energy more efficiently to their environment; we provide a simple “thought experiment” using bacteria cultures to convey the idea that natural selection favors genetic mutations (in this example, of a cell membrane glucose transport protein) that lead to faster rates of entropy increases in an ecosystem.
ፍትህ ለሁሉም / Justice for All