Earlier this month the UN Department of Economic and Social Affairs (you may have heard of it as “DESA”) received a new director for its Population Division, John R. Wilmoth.  Wilmoth was previously a professor at the University of California at Berkeley and has also worked at the DESA population division before. From 2005-2007 he was Chief of its Mortality Section. (Imagine having that as your job title? “Hello, I’m Chief of the Mortality Section”. I’m sure that that’s a conversation stopper at parties...)

 So what exactly does the Population Division of DESA actually do?  Luckily for all of us, Wilmoth has told us:

“The Population Division serves two key roles, both equally important and unique. First, we produce the “estimates of record” for monitoring world population patterns and trends, including projections of future trends. Our estimates of population size are a critical component of some of the most widely cited indicators used for monitoring social and economic development, including literacy rates and GDP per capita.... Second, the Population Division services the intergovernmental discussion of topics related to population trends and processes, by producing authoritative studies, in-depth data analyses, and thoughtful interpretations and commentaries.”

In essence then, the Population Division produces statistics and studies about the world’s population and its trends. As for those trends, Wilmoth identifies three that he sees as important for the world’s future:

“I think most people would agree that the three major trends are: population growth, population ageing, and migration (both within and between countries). Each of these presents important challenges to Member States and to the UN system, but we should not forget about the opportunities... A similar principle applies in the case of population growth or ageing. It is seldom true that a particular population trend is inherently good or bad.”

Wilmoth therefore has a somewhat more nuanced view on population growth than many others, which is good to see in someone at such a level in the UN.  What is also refreshing to see is his hesitation about the possibility of making cast-iron predictions about our demographic future:

“Demographers often make projections of future population trends and can be surprised when reality diverges from their forecasts – but that is the nature of this business. An earlier generation of demographers was surprised by the extremely rapid growth of populations in the decades after the Second World War, which was caused by the Baby Boom in industrialized countries and by very rapid reductions of mortality in the less developed regions. For my generation I suppose the two biggest surprises have been the phenomenal speed and depth of fertility decline, and the persistent increase of human longevity.”

As Wilmoth elaborates, these two surprises took earlier population experts by surprise (maybe they even took a certain Paul Erlich by surprise? Perhaps not, he seems quite oblivious). Anyway, back to Wilmoth:

Fertility levels have fallen substantially in most regions, far beyond what most observers expected 50 years ago...In many parts of Europe and East Asia, fertility is now well below two children per woman, and some populations have started to shrink in size. Such low fertility accelerates the process of population ageing, with substantial implications for government budgets given the high costs of old-age pensions and medical care. Mortality trends have offered surprises too. Fifty years ago many observers believed that human longevity was reaching an upper limit, since by then most deaths (at least in the more developed regions) were due to diseases of old age. Since around 1970, however, death rates at older ages in many countries have been falling at an unprecedented rate. Reductions have been rapid in particular for deaths due to heart disease and stroke.”

This is one of the reasons why we should be very reluctant to embark upon huge social change for the good of the future based upon future demographic projections. The inherent uncertainty in projecting what human beings will do in the future, (particularly in trying to project one of their most personal decisions: how many children they will have) is something that Wilmoth seems to be sensitive to:

"I expect that demographers will continue to be surprised by trends that do not follow our prior expectations. It is for this reason that the Population Division has worked hard in recent years to be more explicit and precise about the degree of uncertainty affecting projections of future population trends.”

Of course, whether policy makers choose to take heed of this uncertainty in formulating their plans remains to be seen.

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