The Cancer Journal - Volume 6, Number 2 (March-April 1993)
From biology to medicine, and from medicine to biology
For the last two centuries, medicine and biology have been following paths which have sometimes converged, sometimes diverged and sometimes crossed. Each is based on a group of presuppositions which are no more common to the two disciplines than are their objectives and practices. Although pathological problems can inspire biologists and a better knowledge of the living organism can greatly benefit patients, biomedicine as such does not really exist except in the sense that all aspects of medicine will one day profit from progress in biology. This does not, of course, mean that psychiatry can be reduced to neuroscience, even if advances in this field should not be ignored.
We would like to take a critical look at the concepts behind the work of most present-day biologists. The wide range of living organisms are considered to be a hierarchy of structures going from the molecule to the organism, some would even say from the active sites of molecules to populations, with a parallel hierarchy of functions at each level; that is, an assembly of one-way structure-function relationships. In an analytical approach, biology describes in an exact and almost overdetailed way these structures, assuming that this knowledge leads, or will lead, to an understanding of the corresponding functions. This is a major theme of molecular biology and a strong argument in favour of what is called molecular medicine.
We invite our readers to cast some honest scientific doubt on two of these ideas:
Firstly, the idea of a hierarchy implies that information is preferentially passed in one direction, which seems to us to be at odds with the existence of a network of interactions, which is begining to be better understood. In this network, each structural level communicates not only with the levels immediately above and below, but also with all the other levels.
Secondly, the idea of a hierarchy of functions is difficult to reconcile with theory, nowadays quite well accepted, which defines functions as integrated processes. Of course, one could describe stacked levels of integration which would allow molecular, cellular and tissue-level functions to exist separately ending up with the functions of the organism as the medical community sees them; functions which when disturbed give rise to diseases and syndromes. This is all very well, apart from the fact that the transition from partial integration to total integration defies analysis, posing problems of continuity which are insurmountable, at least in human terms.
In contrast, we suggest that the term function should be restricted to the level of the organism, or to that of the biological system under study; avoiding all artificial syntheses which ignore discontinuities.
There is a serious drawback in this, it forces us to look again at the relationship structure-function. We refuse to accept that this relationship must always be of a purely mechanistic nature, even if this is so in elementary physiopathology. This type of mechanistic relationship, which was a great help in establishing the basis of anatomo-clinical medicine, cannot be transposed to the results obtained by modern biology. The abundance of these results and their level of complexity mean that the clock model no longer applies. It is not difficult to assign a function to each item of a clock mechanism, regardless of whether the clock is assembled or in pieces. This is no longer true for the living organism, and clinicians should tell biologists so. A dialogue between the two disciplines should continue the critical exercise which we have suggested here and give room for imagination to work. Starting from the basic concepts of each group, they should create one or more models for exploring function without neglecting any aspects of their complementary experience.
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