New Directions in Human Adaptability Research 10
received attention are still not adequately understood, and new vectors are found whenever studies go beyond what is already known. Many o: the health problems of the humid tropics are related to people creating habitats for the disease vectors-for example, standing water near roads. exposed trash and sewage, and defecation near water sources.
If necessary research tasks are to be carried out, the researcher wil. need improved training in botany, zoology, and in tropical ecology. Semi- nars exploring the advantages and disadvantages of various sampling techniques when applied to the tropical rain forest would be particularly valuable. Time spent at the Organization of Tropical Studies in Costa Rica and Panama-or similar institutes elsewhere that are dedicated to the study of lowland tropical regions-would also be very useful. The diver- sity of the tropical rain forest calls for a sizable team of experts from a variety of fields who are prepared to discuss the problems on a continu- ous basis.
Much of the impetus in the development of tropical rain forests comes from nationalistic governments wanting to make a claim to these territories that often hold significant reserves of raw materials. Any ecolo- gical effort in humid tropics will have to take into account these political forces and include them in the simulations of ecosystem management. Leaders of such nations will need clear proof that there are alternatives to the ways in which they are carrying out their development of the lowland tropics.
Urban Ecology Urban populations are not currently an important focus of human adapt- ability research. This situation reflects the traditional preoccupation of ecological scientists with “natural systems” and the avoidance of what is correctly perceived as a system too complex for precise analysis. The study of human adaptability to urban areas thus represents yet another new direc- tion for ecological and anthropological research. The field of urban ecology has attracted mainly sociologists, architects, environmental engineers, geographers, and psychologists. As one might expect, these disciplines have concentrated on problems best handled by their respective tools: the social structure of urban populations, the physical design of urban structures, the handling of urban material flows, the design of urban -transportation networks, and the psychological effects of crowding on small groups and individuals. What has been lacking is a broader and more holistic attempt at dealing with the interaction of cities with their supporting natural environment.
The City as Consumer Cities are human-created ecosystems that have a tendency to consume power produced by natural ecosystems and to allocate
308
power from a self-servini aas been so spectacular i1 :he dominant settleme 1969:15). Cities concenb consumed, as reflected cities vis-a-vis the rates E
Any society depenc extrasomatic. Somatic e chain. Extrasomatic ener energy found in fossil fut and heat from the sun an 1973:14). Preindustrial 1 limited power that coulc has radically changed ir rely on enormous inputs ize and in complexity.
The development o. logical record with the i thousand years ago (Sj economic centers of pm needs probably took pla mechanisms supported differ much from the p discussed in chapter 6. T in regional networks tha
In studying cities c significant characteristic illusion of self-sufficienc urban dwellers have act rural environments that was sometimes translate seriously threatening t results were soil exhau salinization and a break
The utilization of ex teristic and can lead to a food and energy needs f mental consequences o relied on the surroundin only the scale of urbaniz, led to a reconsideration not been clearly establi appear to be associated crowding pathologies, i Part of the problem is th
h 10
.d new vectors own. Many of eople creating iter near roads. ~s. researcher will ecology. Semi- ‘ious sampling be particularly in Costa Rica
-dicated to the -ful, The diver- experts from a , on a continu-
al rain forests claim to these als. Any ecolo- these political
: management. alternatives to of the lowland
· human adapt- eoccupation of snce of what is ysis. The study ther new direc- : urban ecology atal engineers, lisciplines have ools: the social . structures, the transportation tall groups and listic attempt at -orting natural
-ms that have a · and to allocate
Urban Ecology
power from a self-serving point of view (Michelson 1976:50). Urban growth has been so spectacular in this century that urban areas are rapidly becoming the dominant settlement pattern throughout the earth (McLaughlin 1969:15). Cities concentrate power and increase the rate at which energy is consumed, as reflected in the per capita energy consumption of modern cities vis-a-vis the rates estimated for earlier stages of cultural evolution.
Any society depends on two kinds of energy sources: somatic and extrasomatic. Somatic energy comes to human populations via the food chain. Extrasomatic energy, on the other hand, comes from harnessing the energy found in fossil fuels, wood, wind, water, tides, radioactive materials, and heat from the sun and the earth’s core (Man and the Biosphere/UNESCO 1973:14). Preindustrial cities relied primarily on somatic energy and the limited power that could be obtained from wind, water, and animals. This has radically changed in recent years and the industrial cities of our time rely on enormous inputs of extrasomatic energy to subsidize their growth in size and in complexity.
The development of urban society is clearly associated in the archaeo- logical record with the introduction of food production as recently as five thousand years ago (Sjoberg 1965). Before cities became political and economic centers of power controlled by elites, the provisioning of urban needs probably took place through interzonal exchange and redistributing mechanisms supported by patterns of marriage and kinship. These did not differ much from the patterns of exchange of rural Andean populations discussed in chapter 6. The earliest cities seem to have been more like nodes in regional networks than control centers (Adams 1968:42-48).
In studying cities one must keep in mind a number of ecologically significant characteristics that recur time and again. One characteristic is the illusion of self-sufficiency. From the earliest city to the largest megalopolis, urban dwellers have acted as if their existence were not dependent on the rural environments that provided them with somatic energy sources. This was sometimes translated into demands that could not be fulfilled without seriously threatening the natural environment. In numerous cases the results were soil exhaustion or overirrigation-the latter leading to soil salinization and a breakdown in the food production system (Ibid.: 54).
The utilization of extrasomatic energy sources is another urban charac- teristic and can lead to an even greater oversight. Because they import their food and energy needs from distant areas, urbanites fail to see the environ- mental consequences of their demands. Until very recently, cities have relied on the surrounding natural areas for the disposal of urban wastes. It is only the scale of urbanization and of the communications revolution that has led to a reconsideration of this policy. Although causal relationships have not been clearly established, the dimensions of modern industrial cities appear to be associated with a variety of forms of system disorganization, crowding pathologies, and pollution levels that threaten their existence. Part of the problem is the very complexity of urban ecosystems.
309
New Directions in Human Adaptability Research 10
C- 6 “‘-, ~ (“)o ? 0~
~% .,. ., Government <::’-· and cultural ~
centers
Manufacturing cities wholesaling and packaging
Meat-processing towns
Smelting cities Sawmill towns
Milling towns Canning towns
Grain-, tuber-, vegetable-, or fruit-growing towns
Ranching centers
Mining towns
Logging towns
Fishing villages
Figure 10.1 Urban Trophic Levels Source: Reprinted with permission of Macmillan Publishing Co., Inc. from The Urban Organism by Spencer Havlick. Copyright© 1974 Spencer W. Havlick.
Urban regions participate in food webs that reflect the upward flow of energy and materials from “producer communities” controlling cultural and administrative centers, or “third-order consumers.” Figure 10.1 illus- trates these trophic levels and reminds us of the danger of having consumer cities continually encroaching on the productive lands that support the whole urban ecosystem. The utility of this approach to urban analysis has not been fully demonstrated, but any effort at quantifying the flow of energy through urban ecosystems can benefit from this kind of trophic level approach (Havlick 1974:27).
Industrial urban settlements can also be viewed as a “climax” stage o human succession, similar in characteristics to the later stages of fore development (R. L. Smith 1974:284). The urban settlement begins as a small village or central core and grows outward-just as a forest invades aban- doned fields. Over time, the city undergoes a process of segregation of both social and functionalunits. In this segregation process, zones with specia- lized functions or dominant social groups are developed. The central core deteriorates in the middle stage and becomes less desirable, while the
310
younger outer zones b_ central area, if sufficie – ing ball” to bring it to similar to the positive et ecology books deal ,\i approach and are based
The Chicago Urban Eco formulating an urban ecc Robert Park and Roderic that sought correlations the Chicago sociologists atic theory. The theory w of competitive cooperatic ical research consisted o to the formation of coope 1925). As these change o play, dominance chang deteriorated areas. Parks, as a superstructure restin• the various symbols an achieve consensus. Onlv study for human ecology biological concepts of co were applicable to huma.r cepts seem to define real : or territories in the Amer.
Perhaps the best knov of the Chicago ecologist attempt at describing urb The model emphasized tl: :s, the oldest section) anc they improved their stat 1972:70). The model is ex zration of vice and gambli Burgess showed how the c val ues and how speculat, istrict in the hopes of the
do not improve the build home of recent migrants a “Michelson 1976:9). Altha
1The best account of the : 3urgess and Bogue (1964:2-14). :940).
~ … ~ ~· ~~ ~
. tura, _ illus- ~71.IIle- ~ the
·_· has energy ::: level
rtaze Of · forest ::. small _ aban- of both specia-
core · e the
Urban Ecology
younger outer zones become more attractive, expensive, and exclusive. The central area, if sufficiently deteriorated, must be ravaged by fire or “wreck- ing ball” to bring it to a younger, more productive stage of succession, similar to the positive effect of fire in a natural community (Ibid.: 285). Most ecology books deal with urban areas in terms of this “climax” stage approach and are based on the concepts of the Chicago human ecologists.
The Chicago Urban Ecology Approach The earliest systematic effort at formulating an urban ecology came from University of Chicago sociologists Robert Park and Roderick McKenzie. Although there had been earlier efforts that sought correlations between social variables and spatial distributions, the Chicago sociologists were the first to approach the topic with a system- atic theory. The theory was borrowed from biology-particularly the notion of competitive cooperation. According to Park the subject of human ecolog- ical research consisted of biotic relationships: competition for space leading to the formation of cooperative bonds or symbiotic relationships (Park et al. 1925). As these change over time and space, successional forces come into play, dominance changes, and groups invade either unoccupied or deteriorated areas. Park saw the other aspect of human society, the cultural, as a superstructure resting on the biotic forces. This superstructure included the various symbols and meanings used in human communication to achieve consensus. Only the biotic level was seen as the proper object of study for human ecology (Theodorson 1961:4). Thus Park believed that the biological concepts of competition, dominance, invasion, and succession were applicable to human organization and behavior in cities.1 These con- cepts seem to define real forces that govern and make sense of natural areas or territories in the American city (Michelson 1976:8).
Perhaps the best known of the spatial models is associated with Burgess of the Chicago ecologist school. His “concentric zones” model was an attempt at describing urban structure and development in North America . The model emphasized the dominance of the central business district (that is, the oldest section) and the gradual filtering outward of populations as they improved their status, income, and level of assimilation (Herbert 1972:70). The model is exemplified in Burgess’s explanation of the concen- tration of vice and gambling just outside of urban central business districts. Burgess showed how the central business district has the highest urban land values and how speculators purchase properties on the periphery of the district in the hopes of the city expanding. In the meantime, the speculators do not improve the buildings and this dilapidated housing becomes the home of recent migrants and deviants who cannot afford homes elsewhere (Michelson 1976:9). Although Burgess’s concentric zones model tends to be
1The best account of the foundation of the Chicago approach to human ecology is in Burgess and Bogue (1964:2-14). Useful, too, are the summaries by Robson (1969) and Quinn (1940).
311
New Directions in Human Adaptability Research 10
overly general, it is still a useful point of reference for testing hypotheses and for developing new models-particularly those that attempt to find spatial variation among interrelated social variables (Theodorson 1961:7).
Michelson (1976:17) has noted that the human ecologists had an incomplete conceptualization of the environment-that is, they viewed it as a social medium rather than as a variable. Because the urban ecologists were fixed on the use of aggregate data, they treated urban dwellers as undif- ferentiated masses ruled by economic forces. Again because of their need for aggregate data, they often turned to economic data for the development of indicators, which resulted in an all too frequent economic explanation of urban phenomena.2 The concentration of the Chicago group on the arrangement of social aggregates in space as a result of competition led to the erection of interdisciplinary barriers between these sociologists and biology and ecology that ultimately isolated them from the biological theories that had given birth to their approach.
An Ecosystem Approach to Urban Ecology The need for a holistic approach to urban ecology can hardly be argued, but some authors doubt whether such an approach can be applied to larger, more complex urban areas. (Stearns and Montag 1974:28). Forrester has pointed out that there are limits to the human capacity to manage complex systems. Complex systems, he says, are counterintuitive-that is, the evident control centers may not be the true ones, and efforts at control are likely to elicit ineffective, or even adverse, actions (1969:9). Simple systems rely on first-order negative feed- back loops (see figure 1.1). Such loops usually have only one important variable, and cause and effect relations are immediate in time and space. However, in complex systems cause and effect are not closely related in time and space. Instead, a multiplicity of interacting positive and negative feed- back loops are involved, and rates of flow are usually nonlinear functions.
Some urban analysts believe that simulation models can overcome the difficulties of applying a holistic approach to a complex system (Lapatra 1973; Stearns and Montag 1974), but Schwartz and Fain (1972) point out that some modeling approaches err in viewing human beings as rational-that is, as seeking and using all available information to achieve desired states. How often does a city council take into account all possible consequences of an industrial permit before granting it? More often than not, the decision is a simple matter of weighing the contribution of the industry to the city in terms of jobs, taxes, and political support, with some limited verbal assur- ances that the industry will try to comply with environmental pre- scriptions.
Despite the evidence of a growth crisis, few humans see the seriousness
2Firey (1945) showed how historical, cultural, symbolic, and sentimental aspects asso- ciated with Boston’s Beacon Hill district invalidated the mechanistic evolution of the central business district and the primacy of economic considerations in urban development.
of the threat. Human acz – , slow process. Yet, in ‘ e -_a: most of the petroleum the- previously unknown Yo: Harrison and Gibson (19;- the uncontrolled pace o we do not yet understand ::. to reverse the trend.
Dubas (1968a:235) re= shortsighted. Inhabitants adapt, even cheerfully, to — these pollutants by incrsa, responses that protect the – tating substances leads to c fibrosis, and other “aging masks the seriousness of = solution to the problem. r. individual.
Urban Health Stresses E accompanied by changes i.;:; probability of exposure c biomedical interactions the. lations have been made, b..: cal framework (Man and ;… complexity of the factors in demonstrating that urba: hazards. Urbanization has ::: some pathologies as norm noted in Europe and North shown that in other socie · (Harrison and Gibson 1976: and changes occur so rapid of physiological, biochemic
Significant changes in with urbanization or with e. diabetes, obesity, coronary adoption of urban lifestyles inally noticed in the Uni· income and urbanization, ar budget of individuals is c sugars. At the same time the ucts and other carbohydrate noted in total protein in1 increased (Ibid.: 130).
312
Urban Ecology
of the threat. Human adaptation to the environment traditionally has been a slow process. Yet, in the last fifty years human populations have consumed most of the petroleum that took millions of years to create and generated a previously unknown volume of waste products. It is for this reason that Harrison and Gibson (1976) speak of the danger of cities as being based on the uncontrolled pace of change. Population has increased so rapidly that we do not yet understand how it happened nor what we can realistically do to reverse the trend.
Dubas (1968a:235) reminds us that human adaptation is frequently shortsighted. Inhabitants of industrialized urban areas have been able to adapt, even cheerfully, to the polluted air. We know that the body adapts to these pollutants by increased mucous secretion and other inflammatory responses that protect the organism; but the constant exposure to the irri- tating substances leads to chronic pathological states, such as emphysema, fibrosis, and other “aging” phenomena (Ibid.: 236). In short, adaptation masks the seriousness of the problem, isolates the individual from seeking a solution to the problem, and lowers the long-term healthfulness of the individual.
Urban Health Stresses The change from a rural to an urban existence is accompanied by changes in eating habits, activity patterns, and increased probability of exposure to contagious diseases. Studies of the complex biomedical interactions that impinge upon the well-being of urban popu- lations have been made, but only occasionally have they had an ecologi- cal framework (Man and the Biosphere/UNESCO 1973:38). Because of the complexity of the factors that may be implicated, evidence has been slow in demonstrating that urban living involves biological and physiological hazards. Urbanization has been with us long enough to make one think of some pathologies as normal. The increase of blood pressure with age noted in Europe and North America was thought to be normal until it was shown that in other societies with different lifestyles, this did not occur (Harrison and Gibson 1976:3). Because the urban environment is so new and changes occur so rapidly, it is likely to impose unusually high levels of physiological, biochemical, and psychosocial stress.
Significant changes in the nutritional status of a population occur with urbanization or with exposure to an urban lifestyle. Diseases such as diabetes, obesity, coronary heart disease, and dental caries increase with adoption of urban lifestyles (Durnin 1976:129). A worldwide pattern, orig- inally noticed in the United Kingdom, seems to be that with rising income and urbanization, an increased proportion of the total food energy budget of individuals is derived from oils, fats, dairy products, and sugars. J\_t the same time there is a steady decline in the use of grain prod- ucts and other carbohydrates. Although no significant changes have been noted in total protein intake, the proportion of animal proteins is increased (Ibid.: 130).
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New Directions in Human Adaptability Research 10
These changes in diet are partly the result of work routines in which less time is spent on the buying, preparation, and eating of food than on its production. Consequently there is increased reliance on snacks, ready- processed foods, and alcohol for one’s calories. The brief lunches and breakfasts that result from participation in industrial labor and urban edu- cation routines lead to a pattern of one major meal per day, which is noted to lead to increased consumption of fattening items during that meal. When these eating patterns are combined with reliance on motor transportation and sedentary activities such as television watching, the urban individual shows a marked predisposition for obesity and heart diseases.
Obesity is one of the major disabilities connected with modern urban life. Unfortunately, we have very little knowledge of the varying distribu- tion of body fat at different sites of the body. Research has also overlooked the alterations in body fat that accompany aging and the differing body fat of different physique types. Although diet may have much to do with obe- sity, the whole context within which it occurs is virtually unknown: the role of social factors, psychological influences, eating and activity pat- terns, and economic circumstances (Ibid.:139).
The City and the Natural Ecosystem Urban systems share many impor- tant basic characteristics with natural ecosystems. Both are composed of interacting flows of energy, matter, and information. However, the dif- ferences between these systems are just as important as the similarities. Natural ecosystems are strongly influenced by the stabilizing role of nega- tive feedback. On the other hand, urban systems are controlled by the human population (Stearns and Montag 1974:29-31). In the urban system natural controls such as starvation and disease, are replaced by human controls whose effectiveness has been uneven-for example, human con- trols have resulted in the reduction of contagious diseases, but in an increase in the incidence of chronic and pollution-related illnesses. An understanding of urban ecosystems requires an understanding of the nat- ural limits of the environment, as well as of how values are formed, how goals are formulated, and how actions are implemented (lbid.:62).
Greenwood and Edwards (1973:226) have said that “from a strictly ecological point of view, the modern industrial city is a parasite upon the natural environment, taking resources from it and returning nothing but harmful refuse.”3 A look at a simplified model of the in and out flows of energy and matter suggests that such an evaluation may be largely correct (see figure 10.2). Today’s cities often rely on distant areas for their fuel and food needs. Primary production within cities is largely aimed at pro-
3The increasing volume of residuals (waste) makes it possible to postulate that their accumulation will be an important limiting factor to growth in the future (Man and the Bio- sphere/UNESCO 1973:74).
– Oysters; clanis, worms, ·crabs, b~rrtacles, r..c:-
Air and transportation currents of the city “‘- I V
314
Energy in food and fuels
·~ ft:~i-i People and machinery many occupations
Figure 10.2
center. Source: H. T. – Wiley-Intersciena:.
viding aesthetic areas of — o inhabitants. 4 Thus, the cor..s organism. Figure 10.2 also ~ living organism and a city.
The relations of cities -= locus of political power anc ~ areas. Power is today concez; – in the form of energy-demaz; – population densities and in – – – net result has been that 1.4:..= increasingly based on a nee priorities rather than on an – _ ecosystems. Wolman (1965). – cities, found that urban energ waste outputs put a serious b 10.2).
40ther roles of vegetation in c – to remove gaseous and particulate pc for small and migratory wildlife (Detw;
Urban Ecology
~:~:-bearing curren~s /) ~different times ~
,._.,,..,_,–.,D ,Heat and
57 kcal/(m2) (day)
Energy flow kcal/(m2) (day)
Air and transportation
clu::rr::en::ts::o=f=th::e::ci=ty====~>
Figure 10.2 (b)
Comparison of Two Consumers: An Oyster Reef and a City Both rely on concentrated inputs of energy. Figure (a) shows a reef of oysters in an estuary, and (b) an urban-industrial center. Source: H. T. Odum. 1971. Environment, Power and Society. New York: Wiley-Interscience.
viding aesthetic areas of greenery, not at providing food and fiber for its inhabitants.4 Thus, the contemporary city is best seen as a consumer organism. Figure 10.2 also illustrates the essential similarity between a living organism and a city.
The relations of cities to their surroundings have changed as the locus of political power and population has shifted from rural to urban areas. Power is today concentrated in a limited number of cities not only in the form of energy-demanding industrial parks, but also in growing population densities and in the concentration of nodal institutions. The net result has been that urban choices about resource utilization are increasingly based on a need to satisfy urban masses and institutional priorities rather than on an understanding of the regional basis of urban ecosystems. Wolman (1965), in a classic article on the metabolism of cities, found that urban energy requirements were high and that their waste outputs put a serious burden on the surrounding habitat (see figure 10.2).
4Other roles of vegetation in cities are(l) to ameliorate the “heat island” conditions; (2) to remove gaseous and particulate pollutants; (3) to baffle noise; and (4) to provide a habitat for small and migratory wildlife (Detwyler and Marcus 1972).
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New Directions in Human Adaptability Research 10
Because of the complex trade networks of modern cities and the inef- fectiveness of local habitat resistance, cities have grown without interrup- tion or inhibition. The more cities grow, the more they seem to attrac industry and rural populations rather than to discourage them. Rural pop- ulations come to cities with hopes of higher wage and employment opportunities, of better standards of living, better health facilities, or as a result of the displacement of small farmers by the large, mechanized oper- ators (Turner 1976).
The relations between rural and urban areas are systemic in nature. Improved communications make the city attractively visible to the rural dweller (that is, the “pull factor”). Per capita wages in Mexico City in 1970, for example, were $1,824, while they were only $622 in the country as a whole. In nearly any corner of the globe, public services are of higher quality and more accessible in the city than in the countryside. Health facilities, infrastructure, public utilities, entertainment, and schools tend to be concentrated in cities. Investment in rural areas, when it does occur. leads to further migration because the resulting education heightens expectations. Improved rural health conditions also tend to lead to popu- lations too large to be adequately supported by the traditional agriculture available to small farmers (that is, the “push factors”). Roads also facili- tate the migrants’ access to cities. Their dreams are seldom realizable. There are not enough jobs, schools, health facilities, and so forth to accommodate the onrush of migrants. These migrations also mean a shift of political influence from the countryside to the city and a homogeniza- tion of the rural population into urban ways.
The landscape, too, is changed. What were once prime lands for cul- tivation now are covered with suburban developments (for example, the Santa Clara Valley) or by the sprawl of separate urban centers into a mega- lopolis such as is seen in the Boston-Washington area (Borgstrom 1973:82). In 1949, 70 percent of the farmland in Santa Clara County was classified as prime agricultural land, but as the city of San Mateo grew, i saw the flat, deep soils of the Santa Clara Valley as ideal for reducing the costs of urban development. Price for land went high enough that farmers were induced to sell their land. This pattern has been repeated elsewhere in the United States where one-half of the best croplands have beer: urbanized (Wagner 1974:412).
The adaptability of our species to life in an increasingly urban world should indeed be a topic of research. The physiological adjustments required for coping with air pollution are no less complex than those observed in adapting to cold or altitude. Crowded and overstimulating life in cities elicits complex behavioral and cultural adjustments that have important long-term significance for our lives as social animals and gen- erators of symbols and meaning. The complexity of urban analysis has so far discouraged ecological scientists. This neglect must end, if for no
316
other reason than the -~:=- incorporation of the -. ·-…. and priorities.
Urban Ecology
other reason than the rapid disappearance of pristine situations and the incorporation of the whole earth under the influence of urban controls and priorities.
–=— :–
; –
::
“E – • :-
317
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