'Nothing in biology makes sense except in the light of evolution.'
Theodosius Dobzhansky, 1973.

Although originally meant as an explanation of how biological forms change with time, the scope of the theory of evolution has been found to be applicable to a wide range of biological phenomena. Perhaps the simplest definition of evolution, and one that has frequently been used, is 'descent with modification.' This definition is useful in its simplicity and its absence of ambiguity and directionality. 'Descent' simply refers to a progression from one generation to another and 'modification' refers to any form of change which then becomes available, under the appropriate circumstances, for descent to subsequent generations. There is no sense of a target form or function or any other quality at which an organism is aimed - it is a blind process.

An evolutionary approach to health and disease is one which views both equally and without preconceived value-judgements. The average individual will desire good health and wish to avoid disease as being a bad thing. From an evolutionary point of view, neither takes precedence over the other; they are both biological states. That which confers greater opportunity to produce viable descendants is that which is biologically advantageous. Thus, definitions of health and disease become relative and distinct from those which call upon some notion of 'quality of life.'

Such an approach is primarily mechanistic in character - with the term 'mechanistic' being used quite deliberately, for one is concerned with the machine that is the human being and how this functions. Although it might be argued that such an approach leaves humans incomplete, lacking their psychological, social and even spiritual dimensions, it is an approach which excludes these aspects so that factors in human experience, which would be otherwise overlooked by more 'qualitative' approaches, can be better understood.

The evolutionary approach is not taken because it is a prevailing biological dogma which should, therefore, be applied to the study of health and disease. Rather, it allows a distinct perspective on the relationships between human beings and the environments in which they live. No species exists in total isolation. Frequently, external factors are found to have subtle influences shaping them. The evolutionary approach, as applied to humans, is also one which questions constantly why they are as they are and seeks to explain current health problems in the light of how they have evolved. Whilst, for example, humans have evolved many unique capabilities which set them apart from other species, some characteristics have remained essentially unchanged, persisting, in effect, as remnants of a former mode of existence. At some stage in human history, when salt, fat and sweet foods were not as readily available as they are now, a physiological mechanism that produced a craving for these substances so that they were consumed whenever possible, was advantageous in ensuring the maintenance of necessary physiological stores. This mechanism has not been lost. Compared with the pace of biological evolution, there has been a rapid transition to a society where such foods are now in abundance, such that consumption of excess quantities of dietary salt, fat and sugar are now implicated in a number of modern health problems.

Having previously excluded non-mechanistic factors so as to understand human function and dysfunction, it then becomes possible to take a more informed approach to healthy living and to the prevention and cure of disease when the more 'qualitative' interpretations are reintroduced to form a pertinent synthesis.

'Never were so many facts explained by so few assumptions. Not only does the Darwinian theory command superabundant power to explain. Its economy in doing so has a sinewy elegance, a poetic beauty that outclasses even the most haunting of the world's origin myths.'
Richard Dawkins, 1995.

The duty of the physician, it has been suggested is 'to cure, sometimes; to help, often; to console, always' (on a statue to the physician E.L. Trudeau). To this, Darwinian Medicine can add a much broader level of understanding.

this great info was borrowed from: THE DARWINIAN MEDICINE WEBSITE http://www.chester.ac.uk/~sjlewis/DM
also was the thesis topic of an old friend.