Human Ecology Theory

The application of systems theory is a basic tenet of human ecological theory. The family is seen as a system, with boundaries between it and other systems, such as the community and the economic system. Systems have inputs that drive various processes and actions, such as the finite amounts of money or time that families possess. They also have throughputs, which are the transformation processes that occur within the system, such as the exchange of money for the provision of an essential service, such as food, by eating in a restaurant. In addition, systems have outputs, which affect other systems, such the production of waste materials, which are byproducts of activity in the family, being returned to the larger environment. There are feedback loops from the end of the system back to the beginning, to provide both positive and negative comment back into the process and allow the system to adapt to change. In an ecosystem, the parts and the whole are interdependent.

Most theorists outline an ecosystem, most particularly a human ecosystem or a family ecosystem, as being composed of three organizing concepts: humans, their environment, and the interactions between them. The humans can be any group of individuals dependent on the environment for their subsistence. The environment includes the natural environment, which is made up of the atmosphere, climate, plants, and microorganisms that support life. Another environment is that built by humans, which includes roads, machines, shelter, and material goods. As Sontag and Bubolz (1996) discuss, embedded in the natural and human-built environments is the social-cultural environment, which includes other human beings; cultural constructs such as language, law, and values; and social and economic institutions such as our market economy and regulatory systems. The ecosystem interacts at the boundaries of these systems as they interface, but also can occur within any part of an ecosystem that causes a change in or acts upon any other part of the system. Change in any part of the system affects the system as a whole and its other subparts, creating the need for adaptation of the entire system, rather than minor attention to only one aspect of it.

There are also systems nested within systems, which delineate factors farther and farther from individual control, and that demonstrate the effects of an action occurring in one system affecting several others. Urie Bronfenbrenner's analysis of the systems such as the microsystem, mesosystem, exosystem, and macrosystem are an integral part of the theory. The microsystem is our most immediate context, and for most children, is represented by their family and their home. Young children usually interact with only one person until they develop and their world expands. The mesosystem is where a child experiences reality, such as at a school or childcare setting. Links between the institutions in the mesosystem and the child's family enhance the development of academic competence. The exosystem is one in which the child does not participate directly, but that affects the child's experiences. This may be a parent's workplace and the activities therein, or bureaucracies that affect children, such as decisions made by school boards about extracurricular activities. Our broadest cultural identities make up the macrosystem. This system includes our ideologies, our shared assumptions of what is right, and the general organization of the world. Children are affected by war, by religious activities, by racism and sexist values, and by the very culture in which they grow up. A child who is able to understand and deal with the ever-widening systems in his or her reality is the product of a healthy microsystem.

Bubolz and Sontag (1993) outline five broad questions that are best answered using this theory, which is helpful in deciding areas where the theory can make a useful contribution to our knowledge. These are:

1. To understand the processes by which families function and adapt—how do they ensure survival, improve their quality of life, and sustain their natural resources?
2. To determine in what ways families allocate and manage resources to meet needs and goals of individuals and families as a group. How do these decisions affect the quality of life and the quality of the environment? How are family decisions influenced by other systems?
3. How do various kinds and levels of environments and changes to them affect human development? How does the family system adapt when one or more of its members make transitions into other environmental settings, such as day care, schools, and nursing homes?
4. What can be done to create, manage, or enhance environments to improve both the quality of life for humans, and to conserve the environment and resources necessary for life?
5. What changes are necessary to improve humans' lives? How can families and family professionals contribute to the process of change?