by Richard Levins, Ph.D.

Richard Levins is the John Rock Professor of Population Sciences at the Harvard School of Public Health.

An examination of the changing health patterns in this century justifies both celebration and dismay. We can celebrate the increase in life expectancy at birth, the disappearance of smallpox, and the decline of other diseases. We can marvel at technical advances such as the development of reliable heart surgery, molecular methods for diagnosis, and sophisticated electronic imaging. But, we also have to recognize that diseases we thought were on their way out have returned with a vengeance (tuberculosis, cholera, malaria), and that apparently new diseases have arisen (AIDS, Legionnaire's disease, Ebola, hepatitis C), while microorganisms have shown remarkable flexibility in thwarting our therapies.

Agricultural productivity has risen greatly, but without eliminating hunger. The gap between rich and poor in life expectancy and morbidity has remained robust for more than a century despite changes in the details of class structure and substitutions of specific causes of death.

When we examine the pattern of success and failure, it seems as if the successes occur in the solution of narrow, highly specific problems amenable to molecular and technical solutions (smallpox), while the dramatic failures appear at the level of whole systems (wide disparities in health), where factors that were not taken in to account can overwhelm the expected results deduced from simple logic.

Solutions designed to solve isolated problems can exacerbate or give rise to new ones. Pesticides can increase pest problems and poison people, hospitals are a focus of infections, agricultural development can lead to hunger, and flood control can make us more vulnerable to floods. Therefore a public health community better prepared for surprise has to induce the perspective of evolution, biogeography, and ecology as well as social science, and deal not only with current problems but also with those that might arise.

When we move from a model that assigns relative weights to isolable influences, to a model of whole-system determination, we can see that:

• All theory is wrong that limits concern to just our species and pushes the rest of nature into the background;
• All theory is flawed which sees our species as an undifferentiated whole and ignores injustice that we inflict upon each other;
• All theory is too narrow which looks only at the individual confronting the environment and fails to see that individual as a unique "particle" formed in an eco-social field;
• All theory is wrong which separates mind from body;
• All methodology is wrong which pits quantitative against qualitative methods;
• Finally, all policy derived from theory is hopelessly biased if "policy" is seen as the allocation of resources and the drafting of regulations; if real conflict of interest is denied and the boundary conditions within which policy is formed are simply accepted as "life"; and, if researchers are not at the disposal of all affected parties.

When assessing health, then, our task is to integrate these insights and to confront health, society, and habitat as a whole, in its full complexity. Health is produced and eroded in a natural and social environment that varies in time, space, and according to the social locations of people in various hierarchical, cooperative and competitive relationships. External influences — chemical, physical and microbial — impinge on us in a pattern that depends on how we produce and consume goods and use our time. What happens next depends on the coping mechanisms that we develop in the course of a lifetime. The external becomes part of the internal; previous experience alters our body and mind and our behavior in ways that influence how we respond to the next encounter.

Our own physiological and psychological processes erase these impacts, some of them rapidly, some slowly, and some so slowly they have permanent effects on us. But the internal also becomes external, as our own activity selects, transforms, and even defines our environment. For the most part, this pattern was not constructed with health in mind. The health consequences are essentially random side effects of economic and social processes. But their consequences have become so powerful and pervasive that we now have to intervene in social development with health and well-being in mind.

Three principles for taking a more complex whole-system view of health problems are:

1. Challenge the false dichotomies that plague science. A particularly important dichotomy is that between individual responsibility and social determination of health. Consider these two propositions:

• We are each responsible for our own health, and
• Health is socially determined.

Both are claims about reality, and about the causes of disease. Both are also normative: each person should take responsibility for his or her own health, or our society should take collective responsibility for the health of all of us. The first blames the sick for being sick and justifies the denial of public resources for health improvement. The second, accepting social responsibility, would propose actions to improve health care, but it leaves the individual out of the equation or as a passive onlooker. Each proposition, taken separately, is false and harmful, but taken together they are jointly true and can be empowering.

2. Respect the spontaneous activity of nature. Infectious agents are organisms that evolve in response to their own circumstances and to our attempts to control them. They change when they encounter the new environments we create for them or our therapies make drug resistance an overwhelming survival requirement. How do other organisms confront uncertain environments? There are really only four response modalities available: detection and response, long- and short-range prediction, tolerance of a broad range of conditions, and prevention.

3. Respect the systemic nature of health-related phenomena. The variables that affect our health are linked in reciprocal feedback loops rather than by one-way causal chains separating independent from dependent variables. The causal pathways cross disciplinary boundaries and loop back and forth in positive and negative feedbacks. Therefore, in order to study the world, we must shift from the reductionist notion that it is sufficient to study its smallest pieces. Instead, we must adopt a holistic dynamic approach informed by philosophy and systems theory.

It is not easy to cross boundaries to adopt a whole-systems approach to health. It means leaving the areas we know well and venturing into fields where we have to depend on the expertise of others. It means learning unfamiliar concepts and mastering new tools to engage complexity. It means asking people to take health into account in making decisions that usually depend on other considerations. It may provoke controversy. It may make people we approach uneasy and even angry. It requires patience, imagination, courage, integrity, and a sense of humor.

Hegel warned that the truth is the whole. Of course we cannot really see "The Whole." But, we can recognize that a problem has to be posed big enough to accommodate an answer. If we fail to define the problem big enough, then many important impacts on a variable come from outside the domain of the problem and are treated as "random" or "error." Contrary to common sense, big problems are often more soluble than small ones.

Richard Levins is a mathematical biologist and John Rock Professor of Population Sciences at the Harvard School of Public Health. He is the recipient of a Robert Wood Johnson Foundation Investigator Award in Health Policy Research. He has worked as an ecologist in the field, advocating interdisciplinary collaboration. He is currently studying patterns of new infectious disease; the resurgence of diseases thought to be in decline in humans, plants, and animals; and the patterns of vulnerability in populations.

This essay is adapted from research Dr. Levins presented in 1998 as the first Robert H. Ebert Health of the Future lecture at the Kansas Health Foundation. The Kansas Health Foundation is a private philanthropic foundation, based in Wichita, with a mission to improve the health of all Kansans through grant-making in three program areas: public health, children's health, and leadership. Visit Kansas Health Foundation.

This essay is part of Thinking outside the Lunchbox, an ongoing series of essays connected to the Center for Ecoliteracy's Rethinking School Lunch program. Read all the essays at www.ecoliteracy.org

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