Thursday, November 22, 2012

Evolution & Chaos

Chaos theory has grown so much over recent years in both theoretical importance and practical applications that it is sometimes thought of as one of the three most transformative theories of our time, together with relativity and quantum physics. In terms of its applications, it is hard to find an area of science in which it is not used in some form. It can describe natural phenomena in such diverse areas as population growth, cloud structure, structure of ferns and other plants, coastlines, mountain ranges, military operations, epidemics, stock market swings, graphic technology, washing machines, weather predictions, and so on.

One of the characteristics of a chaotic system is fractal geometry and fractal scaling in which the shape of the detail (branching of tree branches, shape of a coastline) is similar at various levels of magnification.

In human physiology, the structures of lung bronchioles, arterial, venous and lymphatic systems, neuronal structure, surfaces of proteins, etc., all display fractal properties.
Skarda and Freeman (1) have also shown that electrical brain activity uses chaotic dynamics, which has revolutionized how we look at brain function. Chaotic models have also been used to help predict heart attacks (2)

It is not surprising, therefore, that investigators have been looking at chaotic properties in DNA structure (3) and even the evolutionary process itself (4). Though it is clear that mutation and natural selection are essential elements of evolution, the ever-increasing complexity of the genome raises questions in some mainstream scientific minds as to the adequacy of the evolutionary model to explain the larger picture.

Simon Conway Morris, Cambridge University Professor of evolutionary biology, and John Kearns, Harvard geneticist, have each doubted the standard evolutionary model in different ways. Evan Olsen (5) has even proposed a chaos model by which DNA is a fractal attractor, an essential element of chaos theory, which causes evolution to progress toward a defined goal.

This all raises the question of a purpose in evolution, or, at least, a defined direction. It is becoming more evident that the more we discover the complexity of the genome, and the multi-layered system of selective expression, the more we come to the realization that the simple random mutations and natural selection model is not powerful enough to explain all of evolution.

(1) Concepts in Neuroscience, Vol. 1, No. 2, 1990, 275-285
(2) Shu Dai, David G Schaeffer, Chaos: An Interdisciplinary Journal of Nonlinear Science, 2010; 20 (2)
(3) Ohno, S. 1988, Proceedings of the National Academy of Science USA 85: 4378-4386
(4) Wesson, 1981, Beyond Natural Selection
(5) E. Olsen, The Internet Journal of World Health and Societal Politics, 2006 Volume 3 Number 1