Un Population Projections As Underestimates? The World's Newest Numbers

Reference: The Wilson Quarterly and Martin Walker's article, The World's New Numbers (2009). www.wilsoncenter.org

Why current U.N. population projections (2009) may turn out to be serious underestimates This is to offer two observations concerning the revised U.N. population projections tions of 2008:

I. Medicine, Life Life-extension, and Underestimates The most recent U.N. population projections could, like so many demographic projections in the past, again turn out to be dramatic underestimates of the numbers that actually emerge. Why? Because in the past, decades of falling birth rates were expected to slow rates of population growth. The factor that has repeatedly confounded such projections, however, is that medical advances end up lowering death rates more dramatically than expected so that dramatic reductions in mortality end up canceling-out out tendencies otherwise suggested by falling birth rates.

Campbell, Mitchell, and Reese, 1997.

Result? In the past, real-world world populations with decades of falling birth birth rates (e.g., Sri Lanka 1938 1938-1984) routinely ended up not just growing larger, but growing faster-than-ever ever (see data below).

Year

Births per 10000

Deaths per 1000

Extra per 1000

1939 1940 1945 1947 1950 1955 1960 1965 1970 1975 1980 1984

35 34 38 36 39 35 32 33 30 28 25 27

21 20 20 19 11 09 08 09 08 06 06 06

.14 . 14 18 17 28 26 24 24 22 22 19 .21.

Birth rates

Death rates

Examining the data,, we notice that for every thousand residents of Sri Lanka in 1939,, there were 35 births and 21 deaths. Thus, by the end of the year,, each person who died had been replaced, physcially-speaking, and then - fourteen extra babies were born per 1000. By 1984, however, as a result of dramatic reductions in the death rate (due partly to the war on malaria) there were twenty-one extra babies born per thousand. Thus, not only was Sri Lanka's population almost a half-century half larger, but its rate of growth had actually increased by fifty percent.

This last fact is the lesson that Sri Lanka holds for the world today: Even if we succeed in lowering birth rates around the world, progress in medical research, life life-extension, extension, and biotechnologies may well end up lowering g death rates even more. Thus, while both trends each constitute one sort of good news, at the end of the day, when taken together, our populations could end up growing faster instead of more slowly.

If a similar set of events takes place worldwide and affects generations now living, world population by 2100 could end up closer to 13 billion than to the 9 or 10 billion imagined by current U.N. projections. And, if we are already close to or beyond earth's long-term limits (we are), each of these extra and unexpected billions increases the possibility and seriousness of overshoot (and the likelihood of collapse). Recent research studies, for example, have succeeded in multiplying lifespan in laboratory organisms sixfold. In a recent review article, for instance, Cynthia Kenyon (2005) reports on six-fold extensions of lifespans that have already been achieved in laboratory organisms, noting that in human terms, an equivalent extension would result in healthy, active 500-year-olds. (If what has already been accomplished, then, in actual laboratory organisms can ever be widely-achieved in human populations, some replacement-level fertility rates may, perhaps, have to fall to just 4/10ths of a child per woman - per century?) (And life-extensions of 500 years in human beings are not necessary in order to confound current U.N. population projections. If only twenty or thirty or forty-year extensions develop out of the research that is currently taking place, we will far overshoot the U.N.'s world population prospects as published this past spring.) Thus, the suppostions above may actually be surprisingly more realistic than they at first seem. For example, over the past one hundred years, our species has followed a repeated pattern following new discoveries and technical advances: First there is an initial achievement or discovery that is quickly followed by rapid advances, proliferation, and wide and novel applications. A good example of this is illustrated by the development of aeronautics. At Kitty Hawk, North Carolina in 1903, Orville and Wilbur Wright flew a heavier-than-air vehicle for twelve seconds and a distance of 120 feet. Less than seven decades later, U.S. astronauts traveled to the moon, landed on its surface, and returned safely to earth again in just over one week. Similar patterns have also characterized the development of computers, DNA technologies, communications, and molecular biology – each beginning with technical advances, followed by quick proliferation and progression to today's capabilities with breathtaking speed. All of the above examples thus suggest that today's advances in medicine, molecular genetics, and life-extension may have far-reaching impacts on death rates and demographics in the half-century just ahead.

II Problematic Aspects of Demographic Transition Theory Suppose that science and medical research bring about advances that result in relatively sudden and unexpected reductions in mortality. In this circumstance, current demographic theory envisions a period of “demographic transition” during which there is a time-delay before reductions in fertility occur to reflect the reduced mortality (and during this lag-time, populations skyrocket as births greatly exceed the lowered death rates). Finally, however, after one or more generations, current theory postulates a gradual decline in fertility rates that slowly reduces them to levels commensurate with mortality rates, and a population stabilizes. Thus, demographers commonly envision our time of soaring populations as a transition period during

which fertility rates have not yet caught up to our falling mortality rates. And they hope, imagine, and suppose that the transition will complete itself any decade now. One problem is, however, that such anticipations may well be subverted by a problematic aspect of transition theory. How? Why? Because science, medicine, and technology lower mortality rates not just once, but repeatedly - over and over and over again – so that we live in a perpetual state of transition. In other words, we repeatedly extend and perpetuate the period of demographic transition (with its skyrocketing populations) so that its completion never occurs or is repeatedly postponed. (In effect, each of our breakthroughs in medicine and life-extension re-initiate the transition period, delaying its completion and extending its duration more and more - so that our falling fertility rates are never allowed to catch up.) As fertility rates slowly and gradually adjust to an initial mortality reduction, today’s genetics, technologies, and medical advances institute a second, third, fourth, and fifth mortality reduction in increasingly quick succession. As a result, falling fertility never catches up to the multiple new reductions in mortality and the interim stage of the transition (with its period of soaring population) is never completed. (It will be completed eventually, of course, but with each delay in the transition, the completion is increasingly likely to occur as a collapse.) What current theory does not fully articulate, therefore, is the role of science, technology, and medicine that are currently making reductions in death rates so quickly and repeatedly that offsetting fertility reductions do not (or cannot) occur in the short times available. And finally, the coup de grace of all this is that the emerging advances in longevity seen in laboratory organisms (and compounds, perhaps, like resveratrol) seem set to perhaps amplify and worsen our current overshoot and carry us calamitously past natural thresholds and tipping points that should not be transgressed, so that our degree of overshoot becomes so great that complete collapse can no longer be avoided. As has been pointed out elsewhere, the earth's carrying capacity for an industrialized humanity is almost certainly somewhat less than two billion, and, considering the fact that we are on-track to add our seventh, eighth, and ninth billions between now and mid-century, a continuation of today's demographic tidal wave may constitute the greatest single risk that our species has ever undertaken. As a member of the natural science community, I concur entirely with one of the "asides" in Martin Walker's article, The World's New Numbers (2009): "Whether the biosphere can adapt to such increases in consumption remains a critical question."

Copyright 2009, R. Femmer. All rights reserved.

Anson, A. 2009. What Every Citizen Should Know About Our Planet, The Wecskaop Project, M. Arman Publishing, Florida. Kenyon, C., 2005. The plasticty of aging: insights from long-lived mutants. Cell 120 (25 Feb 2005): 449-460. Kenyon, C., et al. 1993. A C. elegans mutant that lives twice as long as wild type. Nature 366: 461-464. U.N. Department of Economic and Social Affairs, 2009. World Population Prospects Report, 2008 revision. Walker, M. 2009. The World's New Numbers. The Wilson Quarterly. http://wilsoncenter.org, accessed August 30, 2009.