Physically Defining Life: A Thermodynamic Systems Analysis of Biology

Author: Dr. Stephen J. Palmer There has always been a significant challenge in providing a definition of life and biological systems, arisin...

Author: Dr. Stephen J. Palmer

There has always been a significant challenge in providing a definition of life and biological systems, arising from how broad the characteristics of living systems are. Previous definitions of life have included reproduction, metabolism, regulation, a cell structure, possession of DNA and genes and organism structure, the latter often described as ordered. Such definitions are often lists of characteristics of biology that fail to provide a universal physical definition of biology and life. For example, viruses are biological systems but only possess genes specifying their reproduction by hosts: viruses themselves do not metabolise or have a cell structure. 

One new platform for defining life is physical systems analysis based on thermodynamics. This can now encompass information science if quantum-level system behaviour is incorporated into such analysis. Another advantage of considering quantum-level physical behaviour is that it allows the concept of entropy to be clarified in information terms. 

Under such analysis, biological systems can all be identified as information-utilizing systems. This is the characteristic that separates life and biology from purely physical and chemical systems. In physical and chemical system interactions, there may be physical ‘memory’ effects associated with system interactions, but there is no use of information towards a particular goal. The common purpose of information utilization in biological systems is reproduction of a biological system, and this analysis leads to the following new definition of life:

‘A chemical system with a chemical memory which is utilized for environmental fitness, with fitness defined by success in replicating that system.’

This definition of life in “Physically Defining Life: A Thermodynamic Systems Analysis of Biology” is shown to fit with the likely origins of life on Earth and our understanding of the evolutionary development of prokaryotes to provide an explanatory power for biological systems that is currently absent. 

Article link: https://journalspress.com/LJRS_Volume23/Physically-Defining-Life-A-Thermodynamic-Systems-Analysis-of-Biology.pdf