Demography and Health

In earlier posts I've made reference to Thomas Malthus, the English economist born in 1766.  He is most known for his ideas regarding the balance between population growth and food.  The logic goes something like this.  Humans have offspring in geometric proportions (1 to 2 to 4 to 8 to 16 to 32....) while food can increase only arithmetically(1 acre of farm yield to 2 acres to 3 acres to 4 acres, and so forth).  With these calculations, it would be inevitable that in time there would be hunger, because the need for food would surpass the supply.  Coming to bear on this balance would be disease (Malthus might use the word "pestilance") and war.  The end result of Malthus' projections was that population would inevitably be in check because a growing population would always be limited by starvation, illness, and violent conflicts.  Economics is called the "dismal science" for a reason.

Malthus died in 1834, just prior to the beginning of dramatic population growth in the West.  He never knew about effective methods of birth control.  He could not imagine the technologies of agricultural science, enabling stunning growth in crop yields and new ways and places for food production. All the advances of public health and health promotion would come mostly after the century of his death.  Shame on us, the regular frequency of war hasn't changed, but the population death rate due to war has improved: remember that the U.S. Civil War was our most deadly on a population basis.  We now have the expertise to treat battle wounds that in the past would have most certainly been fatal, and our weapons, though more deadly, are also more precise.

We now know that Malthus' original idea is too simplistic, and that there are many more ways that ingenious humans can intervene collectively to support and sustain population health and growth.  It is not inevitable that a growing population will be smacked back down by a roaring  epidemic or a deadly conflict.  Nevertheless, our health status and health promotion methods are and will continue to be effected by population patterns and demographic change.  So, what are some things likely to happen in the future which will influence health in the population?

It will be a while until the results of the 2010 U.S. census are released; statistics will be disseminated incrementally as parts of the data analysis are completed.  Nevertheless, there are some things we know now about the U.S. population, based on recent demographic analysis.  Many of the trends in the U.S. are paralleled in other developed nations.

One dramatic change that will continue into the future: our population is looking more and more like an inverted triangle.  The size of the population in childhood and adolescence is smaller and smaller, while the population over 50 is getting larger and larger.  Fertility in the U.S. and most developed countries is not great enough to grow the population; the average couple is having too few babies to make a second generation larger or even equal to the first.  All of our population growth in the U.S. is from immigration and from people living longer lives. 

There is a market place of ideas on all sides of the current immigration debate.  However, there is one immovable fact.  Unless we permit immigration to continue, population will shrink, and there will be fewer and fewer young workers to support more and more older citizens needing medical and social services.  By the way, we are one of the few developed nations in the world with growth.  Immigration is a logistical problem in terms of integrating new arrivals into our economy and communities, but it is a huge advantage we have compared to Europe or Japan. 

In addition, health promotion services will shift in focus to older clients and target groups.  In the past, not much attention was given to designing health promotion interventions for people in their 60s or older, because the cost benefit ratio was too small, and seniors themselves had little expectation that they would live long enough to benefit from lifestyle change.  Because the horizon of age-related disability is being pushed back to the 80s, 90s and beyond, there will be new attention to understanding the health promotion needs of this segment of the population.

The other major demographic shift is coming like a slow-motion tsunami.  Just before mid century, it is projected that there will be no racial or ethnic majority in the U.S.   People "of color" will increasingly make up our population, but no single group will dominate, at least in numbers.  To the extent that the different racial and ethnic groups have a unique culture, this will certainly present challenges to make health promotion programming relevant to varying communities.  Changes in minority vs majority will bring about political power shifts that will change the way we think about and act on health disparities.

I believe these population pressures, aging and diversity, are important factors driving much of the political rancor going on in our nation right now.  People feel bludgeoned by changes that they don't understand and can't really change, but which are substantially driven by demographic trends.  Unless we learn to get along better, these fights will intensify in the future.  The train of these population changes has left the station.  However, interesting challenges lay ahead for trying to address the health needs of a quickly evolving nation.