Questions about the definition of life, questions

The principle is of such evident importance to personality study that we find writers like Guthrie insisting that action occurs only when there is a threat to this inner stability, and writers like Raup who maintain that life consists essentially of efforts to restore this stability or complacency. Yet in the ebb and flow of life processes there must be as much digression from homeostasis as there is return to it, as much exploration as there is homecoming, as much "extravagance" as there is thrift. In fact, homeostasis is a useful concept not merely in showing the safety-maintaining systems of the body, but in suggesting that against a background of relatively constant factors there are factors which permit wide variability, "trial and error" in the execution of activities in contact with the outer world. Homeostasis means, moreover, more than relative constancy of separate features such as hydrogen-ion concentration or temperature. It appears to be very intimately related to the maintenance of the relative constancy of interrelations, such that variation in one aspect of the balanced living system induces compensating changes in other aspects, thus maintaining the integrity of the system.

But does the system as a system actually have this capacity to resist destruction, to preserve itself intact? Yes; this was classically demonstrated by Wilson's experiment on the tendency of living matter to preserve its form. He reduced a sponge to a pulp, squeezed and rolled it flat, and centrifuged it so that no trace of the creature's original outline remained. He then allowed the material to stand overnight. Slowly and in orderly fashion the material reconstituted itself into the organized sponge which it had been before. It is hardly necessary to refer here to a disembodied life goal or entelechy. The particles themselves demand one another in specific chemical and spatial relations. As far as we know, this maintenance of relations is of the essence of life, and therefore of personality. There are of course limits to the capacity for self-maintenance and self-restoration, but it is worth while to stress that homeostasis is not merely the maintenance of constancy in a single phase of inner existence; it implies the maintenance of the structural wholeness of the living individual.

Considerations such as these have raised in a new way questions about the definition of life, questions that are as old as the difference of opinion between Aristotle and his predecessor Democritus. The trouble with the atomism of Democritus lay not in the atoms themselves but in the neglect to consider those formal and systematic interrelations upon which their effectiveness as atoms depended--the presence, in highly organized matter, of organized patterns which are themselves more enduring than the individual particles which enter into them, just as a vortex (such as a cyclone) may maintain itself though old particles are dropping out and new ones being added constantly. (We are here not raising questions as to the difference between organization in the inorganic and in the organic worlds, but simply noting as an empirical generalization that life cannot be studied at all except in terms of organizational constants of this type, like those that appeared in the sponge or in the wounded man.)

Now if this be granted, the evolutionary significance of a tissue system may be largely independent of the particular particles of matter involved. During long eons of adaptation to different environments, wings may, for example, arise out of different organs, yet functionally achieve the same role. For the surviving organism, the important thing is that the function be performed, not the organs through which it is performed. Tissues will in time appear that permit the function necessary to the species to be carried out. The function is consequently not "explained by" the tissues. The tissues are chronologically and logically "explained by" the functions that must be performed if there is to be a living creature for us to talk about.

This was the point upon which nineteenth-century naïve materialism came to grief. The issue is not whether life involves physical and chemical principles similar to those found elsewhere; this is hardly worth arguing about. The real issue is whether the physical and chemical principles operating in their customary way accidentally produced life and the specific expressions of life under various environments, or whether the functional necessities and continuities of nature were such as to call upon specific chemical reagents and physical forces, pulling them into the ongoing system.

To explain personality from within, i.e., atomistically, step by step in terms of tissue changes, would be like saying that a man is five feet nine because he must fit clothes which are made to that specification. As the clothes are chosen and shaped to the individual, the functions of life (growth, repair, reproduction, and all the complex processes which mediate them) draw "clothing," as it were, from the physical and chemical forces outside, so of course they "fit."

This general principle was of course long ago recognized by evolutionists. They noted, however, an important apparent exception in the form of another principle known as orthogenesis, the tendency of living matter during evolution to move continuously in a given direction (through cumulative mutations, cf. page 29), whether this happens to serve a survival purpose or not. It was noted, for example, that the long canine tooth of the sabre-toothed tiger seemed to be getting too long to be useful. Contemporary paleontologists reject this example, and are skeptical of the general principle of a direction in evolution, aside from the requirements of adaptation. But long time trends, having an environmental origin, e.g., the successive impacts of cosmic rays, and a corresponding internal origin, e.g., the tendencies of some unstable molecules to break up in response to cosmic rays, seem nevertheless to need to be fitted into the picture.

It is quite likely that the tendency to extreme individuality among living tissues expresses one of these orthogenetic principles. Organisms need to vary, of course, if diversity is to exist so as to permit a rapid selection of the most fit. But the variation has admittedly become extreme in many higher forms, to a point where natural packs and flocks fail to maintain a biologically necessary unity of action, large numbers of individuals being unable to follow the modal tendency of the group. And even under conditions of stockbreeding, intended to reduce the variability in certain traits, an endless selective process is required. The tendency toward complexity is then probably an orthogenetic principle inherent in the ultimate biochemistry of life, and such complexity would be expected to give an extravagant degree of individuality, i.e., more variability than natural selection cans for.

Throughout all this discussion the chemical rather than the anatomical aspects of life have been stressed. Still, they have probably not been stressed enough. For a long period, psychology suffered from an emphasis upon the supposed primacy of the anatomical and physiological properties of nerve cells and muscles. The studies of physiologists and zoologists have made clear over the last half century that the existence of life is first of all a chemical fact, that the development of tissues depends first of all upon chemical laws, that recognizable fixed chemical structures appear only when the chemical problems have been solved, and that the structures and their interrelations are basically chemical systems. Nature, of course, ignores our overnice distinction between the physical and the chemical. What is meant is simply that the molecular and chemical processes require concentrated study if the molar physical processes are to be understood.

It is necessary, then, in personality study, to stress the maintenance of a stable complex individual system; this is a homeostatic problem and a broader biochemical problem. Secondarily arises another chemical problem, the interindividual variability in the chemical systems of life and the intra-individual variabilities day by day as the personality process changes. When this chemical context has been well defined, problems of anatomical, physical, behavioral response will yield more readily to analysis.