We are given an overall impression from the literature that unusually high levels of density tend to have a deleterious influence in many animal and
human populations. It is also apparent, however,
that responses to high density vary considerably
between and within species. Human beings live and
multiply in settlements of extremely high density, and, although some detrimental consequences have been reported, it appears that in many communities today, high population density does not have serious
consequences for the health of individuals. This
conclusion applies particularly to Hong Kong, where we have gained the impression that the extreme
conditions of population density have remarkably little direct effect on biopsychic maladjustment or social disorder in the population (see Chapter III).
It was the situation in Hong Kong which prompted us to develop a conceptual model relating to the
responses in human beings to high population density. This model forms the basis of the present study, and it relates to the broader conceptual framework which
underlies the Hong Kong Human Ecology Programme. It
describes the sequence of processes and states
postulated to exist between high population density and the biopsychic state of individuals, and it aims
to assist us in filling some of the gaps in understanding which we have found to exist from our review of the
literature. At the same time, the usefulness of the model itself, as a basis for the study of human
responses to high density living is, of course, under scrutiny and will be tested through our study.
HYPOTHESES CONCERNING RELATIONSHIPS BETWEEN HIGH DENSITY AND BIOPSYCHIC STATE
A central theme of the conceptual model and of the underlying theoretical framework of the Hong Kong Human Ecology Programme is a concern with the
interrelationships between, on the one hand, environmental conditions and life styles, and, on the other, the state of health and well-being of individuals. In this
connection, and as we have discussed above, the
Hippocratic postulate is particularly pertinent; that is, the state of health of individuals, or the health
and disease pattern of a community, is taken to be largely a function of the quality of the environment and of
life-style. Furthermore, it is proposed that the state of health is less a function of the total environment
than of the actual experience of aspects of this environment; that is, of the individual's personal environment and
of his behaviour in that environment.
The Hippocratic postulate itself, including its refinement in terms of the importance of the personal environment, is not sufficient as a theoretical basis for the investigation or interrelationships between
71
environmental conditions and the state of health of individuals. When an evolutionary perspective is taken together with the Hippocratic postulate, we are provided with a valid and meaningful startina
point for the formulation of hypotheses (see Introduction, p. 9 ). This perspective is represented by the
principle of phylogenetic maladjustment , which states that if the conditions of life of an animal deviate significantly from those in which the species evolved, signs of maladjustment are likely to occur in the animal. Such conditions are termed 'evodeviations'. The principle of phylogenetic maladjustment applies,
as we have discussed, as much to human beings as it does to any other species, and it is very pertinent to the discussion of human responses to the condition of high population density, which is clearly an example of a deviation from the situation which prevailed in the 'evolutionary environment of Homo sapiens.
On the basis, then, of the principle of phylogenetic maladjustment, the hypothesis could be advanced that,
since high density is an evodeviation, it is likely to give rise to signs of maladjustment in a population. As we have discussed above, there is qood evidence
in the literature to support this hypothesis with respect to the infectious diseases. On the other
hand, the impressions which we have gained in Hong Kong call into question the validity of the hypothesis
with respect to other kinds of disorder (see Part R.l). In the context of our study, therefore, we have
restated the hypothesis as follows: there is likely to be a positive association between high population density and signs of biopsychic maladjustment in
human individuals, but this association is unlikely to be strong. V7e suggest, in fact, that the potential deleterious consequences of the particular evodeviation of high physical density in human beings are modified to a considerable extent by certain intervenina factors and by processes of adaptation, which are themselves of considerable interest and of great relevance to the situation in a modern urban community.
The simple hypothesis stated above is clearly not sufficient, then, as a basis for the study of
human responses to high density living. An expansion of the conceptual model is necessary in order to take into account possible intermediary states and processes in the sequence between high density and the health and well-being of individuals.
Figure 2 illustrates the first step in the develop ment of this model. It describes our fundamental
concern with an interaction between environmental factors and the biopsychic state of individuals , and it also shows the important distinction between high density in the total environment and high density as it is actually experienced in the personal
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Fig. 2: The relationship between the total environment, life conditions and biopsychic state.
total b i o p s y c h i c s t ate p e r s o n a l e n v i r o n m e n t e n v i r o n m e n t maladjustment density density filters
The total environment and the personal environment The distinction between the total environment and the personal environment of individuals has alreadv been discussed (see Introduction), and it is
particularly relevant in the understanding of human responses to high density livina. This distinction is especially important in relation to the refinement of Hippocratic postulate, which states that the health and well-being of individuals is largely a function of those aspects of the environment with which they actually come into contact. In terms of the initial hypothesis mentioned above, then, the influence of high density in the total environment on biopsychic
state in a human population is likely to be largely through the personal experience of individuals. Hence we might expect to find an interestincr variation in
the kinds of response to high density living which occur both between and within populations.
It is important, then, to take into account this relationship between personal experience and the total environment, which is determined by a series of inter vening factors referred to as 'filters’ (see Figure 1 and Introduction). The individual's experience of the total environment is determined to a large extent by cultural factors, and a filter influencing the
individual's experience of the total environment which is of particular concern in the present study is
economic status. Economic resources can provide an individual with the opportunity to live in a spacious home, to own a private car and so to avoid the discomfort
and congestion of public transport, and perhaps to 'escape' the urban concentration by living in a more 'exclusive' area of lower population density.
Economic and cultural filters are thus very important mediators in the relationship between high
physical density in the total environment and the responses of individuals. They are particularly important
aspects of the situation since they provide scope for potential processes of cultural adaptation to conditions of high physical density in the environment.
Physical density and 'crowding'
Another important distinction in the conceptual model is that between high physical density and the
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distinction is one which has increasingly been discussed in the literature, and it is perhaps the most important recent conceptual development in the study of the effect of high density living in human populations.
Physical density is usually measured in terms of the number of people per unit of space or area. There are different aspects of physical density: the
gross population density of a human settlement, for example, is defined as the number of persons per unit of area on
the ground. Residential physical density, on the other hand, has been defined in several ways - for example, as the number of persons per room in the home, and as the amount of floor space per person in the home.
Physical density is thus an objective state which can be measured with reasonable accuracy, both
on the level of the total environment and as an aspect of the individual's personal experience. 'Crowding' , on the other hand, is not so easily defined. The word 'crowd' is of Anglo Saxon origin^, and has been
described as:
'a number of persons or things collected or closely pressed together, a throng; a promiscuous medley; a
great multitude, concourse, swarm; a mob; the populace; the vulgar.' (Ogilvie, 1905)
1. Cruden (v): 'to press'; whence croda, gecrod: 'a press or throng'. (Ogilvie, 1905)
experience is essentially a subjective state which is usually assumed to be unpleasant. Clearly there is a relationship between physical density and browding', in the sense that the latter cannot usually exist without the former - a person is unlikely to feel 'crowded' when he is not in a situation of high density. Nevertheless, individuals differ considerably in the extent to which they feel 'crowded' under given conditions of density, and even the same individual may not always react in the same way on different occasions to the same high
physical density situation. This observation implies that the experience of 'crowding' is dependent upon a variety of factors in addition to high physical density per s e . That is to say that being 'crowded' is the result of an individual's perception of a high physical density situation.
For the purposes of the present study, the
subjective state of being 'crowded', which is associated with uneasiness and a sense of discomfort, will be
referred to as an 'affective density sta t e ' (Figure 3 ). More specifically, we define affective density as that state which develops when the individual feels
an urge to move away from the people around him. In other w o r d s , the individual who perceives the density in
his surroundings to be 'too high' would tend to avoid the situation, as long as the circumstances permitted such behaviour.
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Fig. 3: The relationship between the experience of high physical density and affective density.
pe rsonal e n v i r o n m e n t physical density other life conditions perception b i o p s y chic state l density
J
A transient state of affective density, when the behavioural response to which it leads is resolved
under appropriate conditions, is not necessarily
undesirable. Indeed, the behavioural tendency to avoid conditions of high physical density is likely to have been of survival value to human populations in the 'evolutionary' environment, and it may have a phylogenetic basis. In a time of acute food shortage, for example, a more
dispersed population would be better able to cope with the situation than one which is concentrated in a specific area (see Lee and DeVore, 1973).
avoidance behaviour cannot take place, so that his state of affective density persists. The question then arises of whether or not this chronic state of affective density has deleterious consequences for the biopsychic state of the individual.
Affective density and biopsychic maladjustment: frustration At this stage we can state the simple hypothesis that there will be a positive relationship between a state of chronic affective density and biopsychic
maladjustment, and that this relationship will be stronger than that which exists between high physical density per se and maladjustment. This is the second major hypothesis which underlies our conceptual model.
We have suggested that a state of affective density tends to lead to biopsychic maladjustment in human populations, but we do not, of course, imply that all people who experience affective density are inevitably in a poor state of health; clearly, there are intervening factors which allow some variability in this relationship. We have proposed, in fact, that an important intervening
factor between affective density and maladjustment is a state of frustration. This sequence of states is
4 .
Fig. 4: The relationship between the experience of high physical density and maladjustment:
affective density and frustration.
p e r s o n a l b i o p s y c h i c e n v i r o n m e n t s t a t e high physical density affective density frustration maladj ustment
When an individual finds himself in a situation in which he experiences affective density, and when conditions are such that he cannot resolve these
feelings by an avoidance of the situation, then he may well develop a feeling of frustration. The state of
frustration is itself, of course, a complex aspect
of biopsychic state - it is also an area which provides scope for variability in the relationship between
maladjustment and the experience of high physical density. Firstly, a state of frustration is less easily induced in some people than in others and,
this is not an aspect of the situation with which we intend to deal in detail here; frustration is
mentioned simply as an important intermediary between a state of affective density and a state of stress, which we postulate to be an immediate precursor of biopsychic maladjustment.
Affective density and biopsychic maladjustment: stress Stress has frequently been discussed in the literature as a reaction to high population density in animals (see Chapter I ) . Many mammalian species,
when 'crowded' together under artificial conditions, exhibit a range of physiological and behavioural
reactions which are commonly described as manifestations of a 'stress' response, and which have generally
deleterious consequences.
Although the responses of human beings to high population density are not necessarily comparable to those shown by most non-human species, it is reasonable to assume that some kind of stress reaction might be involved in human beings. We have made this assumption in our conceptual model, and propose that the perception of physical density which gives rise to affective
prolonged, to a state of frustration and to a state of stress. As we shall discuss below, chronic stress is likely to lead to biopsychic maladjustment, so that, through the sequence of states which we have postulated, an individual's health can be adversely affected by
the experience of high physical density in his personal environment. (Figure 5 )
Fig. 5 : The relationship between the experience of high physical density and maladjustment: affective density, frustration and stress.
pe rsonal e n v i r o n m e n t b i o p s y c h i c s t a t e high physical density
pertinent to our further discussion of responses to high density, it is worth digressing at this point
for a discussion of biopsychic stress in human beings.
Stress can be described as an aspect of the biopsychic state which lies at the extreme end of a continuum which is represented at its opposite
extreme by a state of homeostatic equilibrium^. (Figure 6)
Fig. 6: The ’stress-continuum'.
b i o p s y c h i c