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Childrearing, Culture and Mental Health

Health and an Evolutionary Perspective: Some Theoretical Considerations

Boyden[8] has emphasized that the insights provided by the study of human biology can contribute substantially to understanding and overcoming health problems. The medical approach traditionally consists of recognizing an undesirable form of ill-health and attempting to find the cause, or at least a cure, whereas the biological approach works in the other direction. It involves viewing modern humans in an evolutionary perspective, noting the biologically significant environmental and behavioural changes imposed on them by their culture, and inquiring into their biologically determined reactions to these changes.

Humans, who have evolved over millions of years from other primates, have lived for most of their history as hunter-gatherers. About 10,000 years ago some humans began to adopt a different way of life. This period (about 400 generations) is too short for any substantial changes to have occurred in the human phylogenetically-determined characteristics: that is, the genetic characteristics of Homo sapiens which result from the evolutionary history (or phylogenesis) of the species.

Boyden[8] proposed the term "phylogenetically-determined maladjustment" (or simply "phylogenetic maladjustment") for that particular kind of disturbance in an organism or population which is due to the fact that the environmental conditions have deviated significantly from those to which the species has become genetically adapted through evolution. He pointed out that this principle is of great importance in understanding patterns of health and disease in humans and other species. It appears relevant to psychiatry both for understanding psychological disturbance and for promoting mental health.

Boyden and his co-workers[9,10] have acknowledged that this term is unsatisfactory since it is not the phylogenesis but the environment which is at fault in not matching those biological requirements which have been determined during the phylogenesis or evolutionary history of the species[11]. Unfortunately a satisfactory term embodying both the phylogenetic and the environmental components of the concept has not yet been devised. Hence, the term "ecologically-determined maladjustment" is used here instead*, bearing in mind that an evolutionary perspective is implicit in the word "ecology".

* [Footnote: For a discussion of this problem see McClelland et al [10]and Boyden et al [9].In these publications the concept is termed "the principle of evodeviance" based on the term "evodeviation" . This appears a useful term, but the maladjustment arising from it is still called "phylogenetic maladjustment," because it is due fundamentally to the fact that the phylogenetically determined characteristics of the species are not suited to the new environment. This does not fully resolve the original objection and for the purposes of this paper the term "ecologically-determined maladjustment" seems less open to misunderstanding.]

Despite problems of terminology the principle itself is a corollary of the Darwinian theory of evolution which states that species become, through natural selection, increasingly well adapted to the environment in which they are evolving. If environmental conditions change the species is likely to be less well adapted to the new conditions, and physiological or behavioural maladjustment may occur. In nature, if environmental changes persist, maladjustment leads in the long run to a fall in population, and eventually to extinction, or through natural selection to genetic adaptation to the new conditions. In the human species exposed to the new conditions of civilization, however, neither of these solutions has resulted, because the changes have occurred too rapidly for appreciable genetic adaptation and also because the human species has recourse to a further adaptive process known as cultural adaptation.

1. Cultural Adaptation

In cultural adaptation society introduces measures aimed to counteract or eliminate the signs of "ecologically-determined maladjustment". These measures may be either corrective or antidotal (that is, symptomatic). Corrective measures aim to reverse the unsatisfactory biological conditions ultimately responsible for the state of "ecologically-determined maladjustment". In antidotal measures these underlying causes are ignored, and adaptation is simply directed at a symptom or at an immediate cause of the disorder. For example, dental cavities arising from an excess of carbohydrates in the diet may be approached by appropriate changes in the diet (corrective adaptation) or by developing a profession skilled in filling cavities (antidotal cultural adaptation). One of the disadvantages of antidotal adaptation is that by merely treating the symptoms of a disorder which is due to deteriorating environmental conditions we may be allowing the conditions to continue to deteriorate. Boyden points out that doctors and policemen are usually agents of antidotal, rather than corrective, responses to "ecologically-determined maladjustments".

Clearly the urban environment of modern humans deviates extensively from that to which they have been biologically adapted through evolution. Many advantages of civilization appear obvious, and few people would forego them. Nevertheless, a deeper understanding of biological processes demonstrates that it may be difficult to determine the full extent of the benefits and the disadvantages which will arise from any given deviation from the evolutionary environment. If we review our cultural environment in a biological perspective, areas of deviation appear which involve a significant and unnecessary risk of "ecologically-determined maladjustment" without adequate compensatory benefit.

2. "Ecologically-Determined Maladjustment'' and Childrearing

Important comparisons have been made between the hunter-gatherer way of life and that of modern urban humans [8] but unfortunately little attention has been given to those differences which particularly affect the child from birth onwards. Since childhood, especially infancy, is the formative and most vulnerable period of life, "ecologically-determined maladjustment' is likely to be particularly significant then. The general principle of "ecologically-determined maladjustment" may be applied to psychological maladjustment in childhood in the following way.[12]

It is increasingly recognized that Homo sapiens, as well as other animal species, is genetically biased to behave in ways that promote individual and /or population survival in the environment to which the species was originally adapted through natural selection.[6 13-18] Psychopathology may arise from a mismatch between the genetic influences and biases underlying the needs and behaviour of the developing human being on the one hand and the provisions and demands of the environment on the other. In childhood, disturbances of development are likely to occur in proportion to the extent to which the rearing environment differs in significant ways from the original environment of evolutionary adaptedness, and especially when the rearing environment cuts across the grain of behavioural tendencies which are deeply rooted in the species because of their important survival functions [12]. These findings are contrary to an assumption that is commonly held: that our species is infinitely modifiable. Of course, other factors, including individual vulnerability, affect the outcome in any particular case.

Liedloff [19] discussed some of the above issues in terms of the "inherent expectations" with which the human infant confronts life, the design of a species being a reflection of the environmental conditions to which it has become adapted or has come to "expect" through the ' continuum" of its evolutionary history. If an infant is exposed to a stressful situation for which it has not been prepared by its evolutionary history the limits of its adaptive capacity may be strained or exceeded.

In relation to the genesis of psychopathology this appears to accord with the formulations and research reports of Janov [20,21,22] and Holden [23] which suggest that neurotic and psychosomatic disorders arise from an overload of physical and psychological pain which cannot be integrated by infants and young children. Janov terms this "primal pain", and Holden reports that there are a number of physiological correlates of neurosis which are measurable, and, conversely, physiological changes which occur, as neurosis is reversed in primal therapy.

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