Urban ecology is the study of humans and non-human organisms in urban areas, their interaction with their surroundings, and their reactions to environmental change. Anthropologists use theories, principles, or methods developed by ecologists to study how past cities arose, how current cities develop and change, and the effects of urban environments on people.
Ecological Theories of Urbanization
Archaeologists often use ecological theory to explain how relationships between humans and their environment have evolved, leading to urbanization. These theories are based on Thomas Malthus’ proposition that human population always tends to increase unless checked by some force. The British archaeologist V. Gordon Childe argued that the birth of agriculture led to surplus food and sedentism (people remaining in a fixed area). This allowed more people to specialize in crafts, arts, or political functions, and socioeconomic differences among people are more pronounced in ancient cities than in rural archaeological sites. In the 1950s, cultural evolutionists such as Leslie White used systems theory to argue that all cultures tend to become urban as they increase the energy they capture and use. Karl Wittfogel, Julian Steward, Marshall Sahlins, and Robert Carneiro portrayed urbanization as unique ecological adaptations to particular environments, such as the need for political organization to regulate agricultural irrigation in arid areas. Ecological explanations remain important, but currently are usually integrated with warfare, ideology, and individual agency as explanations for the emergence of cities.
Ecological concepts are also used to explain how contemporary cities grow and change. In the 1920s urban sociologists Robert E. Park and Ernest Burgess founded the “Chicago School” of theory by encouraging students to study cities as laboratories. They used ecological concepts to explain urban growth and change, proposing that cities are comprised of ecological niches arranged in concentric rings around a central core. These sociologists considered the city an ecosystem requiring energy to maintain segmented niches, which experienced residential succession much like patches of forest. Individual human expectations and aspirations depended on an inhabitant’s location within these niches. The Chicago School’s later focus on demographics and statistical analysis of census information was criticized for lack of attention to individuality. Their quantitative techniques continue to dominate urban planning and research.
Environmental Impacts and Sustainability
Cities produce pollution and their expansion reduces habitat for native species. Researchers are also interested in how these effects feed back to change cities.
For example, rain in coastal cities washes nitrogen from lawns and city streets into rivers, and eventually the estuary, where it can change the structure of shellfish communities. This can negatively impact shell-fishing economies and threaten a region’s sustainability. Archaeologists such as Charles L. Redman and Joseph Tainter argue that environmental deterioration often led to abandonment of urban areas in the past. In 1992 the Canadian ecologist William Rees introduced the concept of “ecological footprint” to describe the far-reaching environmental impacts of cities. Urban planners and activists interested in sustainable development attempt to quantify ecological footprints. It is also important to understand what people in cities “value.” The nascent field of ecological economics is an attempt to integrate concepts like ecological footprints with market-based analyses for decision making. Social ecologists such as Steven Kellert argue that concern about wildlife conservation is higher among urban residents, which suggests a positive environmental effect of urbanization.
Anthropologists George J. Armelagos and Mark N. Cohen, the historian Lewis Mumford, and biologist Jared Diamond have written about past tendencies for human health to deteriorate with urbanization because risk of disease increases and nutrition declines. Currently, urban pollution creates asthma epidemics, and mosquito-borne illnesses persist in many cities where the natural hydrology has been altered, among other problems. “Diseases of affluence” are also on the rise. A 2004 report by the RAND Corporation linked urban sprawl and reliance on automobiles to increased risk of asthma, high blood pressure, heart disease, and diabetes. Sustainability research is an attempt to identify why disadvantages begin to outweigh the benefits of urban life, and to correct problems through planning or social activism. Social scientists collaborate with geographers and ecologists using geographic information systems (computer mapping) that combine satellite imagery and aerial photography with census or questionnaire data to identify relationships between environmental quality and social conditions. When integrated with computer models of a city’s production of nitrogen, use of water, or energy budgets, such approaches can be used to analyze a city’s sustainability.
Urban Ecology and Social Movements
Low-income and minority populations are more likely to live in parts of cities identified by ecologists, toxicologists, and epidemiologists as unhealthful. “Environmental justice” refers to social activism and academic research focusing on this relationship. Environmental sociologists such as Dorceta Taylor, and anthropologists like Melissa Checker and Vivienne Bennett, argue that environmental injustice is often related to discrimination based on gender, race, or class. In the late 1800s, the landscape architect Frederick Law Olmstead advocated using nature in parks to break down barriers between social classes in American cities, an approach still advocated by urban social ecologists such as William R. Burch. Some restoration ecologists (who typically restore habitats for wildlife) are attempting to restore human relationships with natural processes in urban areas; for example, integrating resources like water-purifying wetlands or urban forests with community-based development (a process in which neighborhoods plan, finance, or otherwise implement their own development projects).
Future Directions
The United Nations estimates that the global population living in cities will exceed 50% for the first time in 2007 and continue to rise. Biologists are beginning to study biodiversity in urban areas, and how social forces shape landscapes. Archaeological debates about the extent to which ancient cities were more or less healthful than their hinterlands, and what ideological or organizational shifts lead to urban sustainability versus collapse, will gain relevance. Applied anthropologists are being challenged to integrate their knowledge of social dynamics with ecological data to promote sustainable social change. Technological advances in computer mapping will allow for more collaboration between ecologists, toxicologists and social scientists studying urban environmental justice and sustainability.
References:
- Cohen, M. N. (1989). Health and the rise of civilization. New Haven, CT: Yale University Press.
- Pickett, S. T. A., Cadenasso, M. L. Grove, J. M., Nilon, C. H., Pouyat, R. V., Zipperer, W. C., & Costanza, R. (2001). Urban ecological systems: Linking terrestrial ecological, physical, and socioeconomic components of metropolitan areas. Annual Review of Ecology and Systematics, 32, 127-157.
- Tanner, M. J., Hernandez, D., Mankiewicz, J. A., & Mankiewicz, P. S. (1992). The big apple: Restoration-based education on the Bronx River. Restoration and Management Notes, 10, 14-17.
