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predominated numerically in the population. As industrial pollution darkened the trunks and branches of the trees on which they settled, however, the whiter moths became conspicuous to their predators and were picked off in proportionately larger numbers, until at the present time the populations of this species are predominantly of the darker colored variety (Kettlewell 1973). Should human antipollution endeavors now prevail, on the other hand, it is likely that the lightly speckled moths will again come into their own. Thus it will be seen clearly that, for this moth population as a whole, it is adaptive for it to carry, if recessively, in all generations a potential for alternative coloration that at any particular time is ill adapted—indeed, dangerous— for the individuals that carry it. Without this potential for alternative coloration, the destiny of aM the moths would be at the mercy of the vagaries of their habitat, and their species life would be very short.

Variation of color in the moths, of course, is an anatomical character. ln our own species from its earliest emergence, however, behavior has been as determinative of survival as morphology and a spectrum of behavioral traits therefore as important to the viability of our species as a whole as morphological variety. lt would seem reasonable to assume that a range of sensitivity to external stimuli and group pressures would have its place in this context and that those who take and become addicted to narcotics or stimulants in our present societies are among the more sensitive to such stimuli and pressures. ln other eras or in other circumstances, such hypersensitivity might well have been and may well yet become a species-saving characteristic. Yet in the universal ability of all groups of all species to reproduce a larger number of offspring than they can sustain and the tendency of all groups to do so lies the necessity that mechanisms must exist to ensure that at all times all populations are, so to speak, thinned out. lnevitably it is those individuals who are currently of the wrong color, too tall or too short, too slow or too fast, or too little or too acutely sensitive who are the ones who become sacrifices to the need of the group to adjust its density. Those individuals then, depending on their species, fall prey to predators; to reduced resistance to parasites; to elimination by others before birth, in the perinatal period, or later; or to self-elimination as a result of social pressures.

Within the context of the concept of the well-being of the larger entity, the whole society—its necessity to produce more recruits than it needs so that it may survive in case of calamity and therefore its equal necessity to eliminate its surplus—we discover an overall design into which several conditions that have proved puzzling to investigators may well fit. For example, no more than the potential addict does the schizophrenic show any organic impairment that could classify his condition as a disease state; and, like the addict, the schizophrenic is also hypersensitive to stimuli and to social signs—above all, to crowding. lt would appear probable that both the addict and the schizophrenic are heirs to genetically carried behavioral responses that were supremely adaptive in earlier phases of mankind's phyiogeny when human groups were small, when social stimuli were infinitely fewer, and when a creature's awareness had to be constantly alert and finely attuned to sensing danger from the environment in order to survive (Jonas and Jonas 1975).

A nervous system so exquisitely adapted to perceiving the minutest changes in environmental signals clearly becomes overwhelmed and produces dysphoria when its carrier must exist among the exponentially increased social stimuli of a modern environment. Those individuals

whose nervous systems are less sensitive and who would surely be at peril in, say, a forest habitat today are better adapted to our more crowded living conditions. The more sensitive can only attempt to ease their discomfort by blunting their perceptions with alcohol or depressive drugs or, alternatively, by using consciousness-altering drugs to transport their senses from the dysphoric world in which they live to private worlds of their own.

ln the conduct of group therapy among addicts in connection with the U.S. Army's detoxification and rehabilitation program, we have observed in practice that the members of these groups consistently show difficulty in relating to each other. They are plainly uncomfortable being together in a group, facing each other, and experiencing the social stimuli implicit in any close human gathering. Even with those who attempt to dissipate their discomfort in drunkenness, it is apparent that their conviviality or boisterousness does not lead them toward closer interactions with others but is, rather, a device that shields them from it. The alcoholics' own belief that they drink to relax their sense of tension is misleading. What they are doing is blunting their perceptions so that they no longer respond to those signals from others or from within themselves that cause them feelings of embarrassment, inadequacy, or shame when they are sober. ln doing so they eventually effect a general leveling of their mood, and then, paradoxically, the absence of affect itself produces an unhedonistic and dysphoric state.

Today addicts of whatever kind form a sizable segment of the broad spectrum of our population. As such they provide an available pool of individuals that is readily amenable to a reduction of population density by reason of their potential for reproductive failure. That is to say that, although the ability to reproduce may not be impaired in the individual case of any particular addict, nevertheless the addiction of itself renders successful mating less probable than for the nonaddictive person. Our clinical experience has been that, even where successful mating does occur among addicts, the problems which cause and are a result of their habit tend to make them less able to rear their children in a socially satisfactory manner. The children of addicted parents encounter more problems in social adjustment than most of their contemporaries, making subsequent successful mating difficult for them in their turn. Thus the potential for eventual reproductive impairment exists among addicts, even if perhaps extending over several generations. And in this vital social function they may have replaced that pool of children who in each generation in earlier times were eliminated by childhood diseases but who are now saved by medical intervention. (The semipermanent state of warfare which is characteristic of our species has not been an element in stabilizing populations because, until our own time, it has not reduced the female population. But in earlier times poor hygiene, productive as it was of plague diseases among adults as well as adding to the toll of child mortality, was also a factor in the automatic spacing of populations whenever they became too dense.) The large increase in stress diseases in modern times and of stress responses including anomie, accident proneness, a possible increase in homosexuality, addiction, and so on are today probably also aspects of the operation of this group mechanism.

This bioanthropological overview of the adaptive significance of selfeliminatory behaviors places these phenomena within the framework of a context wider than that to which we are accustomed in our professional concern for the well-being of the individual. ln the process, it forces upon us the necessity of contemplating ethicomoral issues—of making a decision as to whether our primary duty is to an individual or to our society. To offer an analogy, it is as though a surgeon were obliged to decide whether to rescue an organ to the possible detriment of the whole organism. lt is a quandary that is currently becoming apparent to widening circles of responsible scientists. Our comparatively recent awareness of the limited nature of our biosphere and of the closely interlocked necessities both of inanimate material and of all forms of life that sustain and are sustained by it enforces a reevaluation of many, perhaps most, of our existing values. This awareness has produced a growing number of people committed to such concerns as environmental quality, the preservation of endangered species, the control of population, the wider effects of pesticides, birth control, and so on.1

ln the present-day liberal political and philosophical climate, the interest of the individual reigns supreme. The idea that a society might sacrifice certain of its individuals for the greater good of the whole is anathema, and we cannot dissociate ourselves from the reality of the prevailing morality. We are of our times, and it is our deepest desire to improve the lot of each and every human being. This does not ,preclude the possibility that at some future time other moralities may supervene.

Addiction and similarly dysfunctional social behavior, then, constitute pathways along which certain individuals move toward an exit from the gene pools of their populations, and the attempt to halt their departure and to encourage them to reverse their course fosters a biological paradox.

We have seen that the phylogenetic preservation of variety within a population, whether of anatomy or behavior, does not only permit a group to survive changes in its environment. lt also provides a group with a certain proportion of individuals that it may safely discard whenever its density exceeds an optimum. Thus we recognize that those who become addictive do not nave within themselves the behavioral repertoire that will enable them to move successfully into the mainstream of the life of their group. They are, so to speak, biologically designed to fulfill a different role.

1We might note that, while it is reasonable to assume that conditions involving hypersensitivity to the environment may in the past have had and may yet have adaptive elements, there are genetically determined physiological variations (such as juvenile diabetes mellitus, among numerous other genetic abnormalities) that would seem to be nonadaptive in any circumstances. Such variations as these would be eliminated from a population in a natural state simply by the death before reaching reproductive age of the individuals carrying them. Given the orientation of our Western societies, however, we search for remedies that will allow so-afflicted individuals to live out their lives and perhaps to procreate. The heritable element of their disability may be masked through several subsequent generations, depending upon several factors, including the genetic endowment of those with whom succeeding generations mate. lt is therefore usually extremely difficult, if not impossible, to determine precisely the stage at which maladaptive traits carried genetically are finally eliminated from the gene pool of a human population, although, by their nature, this must eventually occur if the society is to continue in existence.

ln our individual-oriented, liberal society, such a concept, however, is unacceptable. Humanitarian principles impel concerned professionals to devote all available resources to the task of rehabilitation. As humanitarians we ourselves (the authors) are also involved in such an endeavor. As biologists, however, we have to see that a remedy for addiction does not lie in the realm of treatment for the individual but, rather, in a broader understanding of the ecological needs of the society as a whole. Unless we see to it that steps are taken to prevent overpopulation, if not addiction then other social mechanisms will emerge that will have the effect of eliminating individuals, and a new set of problems will then have to be faced.

Emerging Concepts
Concerning Drug Abuse

William R. Martin, M.D.

PHARMACOLOGIC REDUNDANCY

When l first arrived at the Addiction Research Center in the fall of 1957, l knew little about problems of drug abuse and of the pharmacology of abused drugs. l came to the Addiction Research Center with some knowledge of neuropharmacology and neurotransmitters, and a high level of interest in drug receptor interactions. l also had an interest in the limbic cortex and its interactions with the autonomic nervous system and the EEG. l was particularly interested at that time in the role of both descending and ascending catecholaminergic and cholinergic paths in EEG activation and vasomotor responses, and in characterizing alterations of physiologic responses with both stimulus response and dose response parameters.

Results that l obtained with these studies of atropine led me to conceive of the principle of pharmacologic redundancy as a mechanism of both tolerance and dependence (Martin and Eades 1960). Subsequently, l generalized my thoughts concerning redundant processes in the central nervous system (Martin 1970) and entertained the possibility that presynaptic elements might contain more than one transmitter and that the postsynaptic neuron might have more than one type of receptor. Further, our data on the effects of atropine on EEG activation and vasomotor responses suggested that parallel pathways contained a variety of synaptic mechanisms and that when one synaptic process was impaired, another parallel process using different synaptic mechanisms could assume the function of the impaired synaptic system. Subsequently data were obtained for the cotransmitters by others.

HOMEOSTASIS

Himmelsbach's (1943) concept of compensatory homeostatic mechanisms as an explanation for both tolerance and dependence was the basis of several experiments, and we were able to show that indeed homeostatic mechanisms played a role in both acute and chronic tolerance and

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