[Paleopsych] Reason: Make Mine Malthus!: Overpopulation panic's eternal return

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Make Mine Malthus!: Overpopulation panic's eternal return
[10]Ronald Bailey

    The world has never been overpopulated with humans in any meaningful
    sense. It seems, though, that it is overpopulated with theoretical
    fears of overpopulation.

    The appeal of the overpopulation myth is obvious--who doesn't love a
    simple, easily graspable idea that seems to explain a great deal? One
    such idea is the central biological insight that all animals aim to
    turn food into offspring. When a species' food increases, then its
    population grows as well; and when the food supply declines, so too do
    its numbers. This applies to everything from paramecia to parakeets.

    Since humans are also animals that reproduce, biologists have extended
    that insight to us as well. This is the source of the overpopulation
    fears that have haunted learned experts from [11]Thomas Robert Malthus
    200 years ago to [12]Paul Ehrlich today.

    An extensive literature [13]critiques the concept of human
    overpopulation. But it's apparently an idea whose time comes again,
    and again, and again, in all sorts of strange places. For instance,
    the 1990s saw a [14]bad novelization of the concept in Ishmael, in
    which a telepathic gorilla recycles Malthusianism.

    The latest iteration of this two-century-old idea comes from Duke
    University consultant Russell Hopfenberg, in an article called
    [15]"Human Carrying Capacity Is Determined by Food Availability", in
    the November 2003 issue of the journal Population and Environment.
    Hopfenberg writes, "[T]he problem of human population growth can be
    feasibly addressed only if it is recognized that increases in the
    population of the human species, like increases in the population of
    all other species, is a function of increases in food availability."

    Hopfenberg backs his argument by showing that global food supplies and
    human numbers both rise from 1960 to 2000. In 2001, Hopfenberg,
    writing with Cornell University ecologist David Pimentel in
    [16]Environment, Development and Sustainability, further asserts that
    "if food production continues to increase, the world population is
    projected to increase to 12 billion in the next 50 years (based on
    current growth rates)." Hopfenberg's solution to skyrocketing human
    numbers is simple: "Cap the increases in food production and thereby
    halt the increases in population by means of a reduced birth rate."

    So has the Malthusian case finally been proven? No. Hopfenberg's
    analysis makes the mistake of considering only global numbers. This
    hides a great deal of information. If we look on the regional level we
    see a very different picture than one of a relentlessly rising tide of
    human babies. Fertility does not correlate with food availability.

    The countries with greatest access to food are, in fact, the countries
    with the lowest fertility rates. As the United Nations reports, 14
    developed countries have fertility rates lower than 1.3 children per
    woman. (Replacement fertility is 2.1 children per woman.) The
    fertility rates in practically all developed countries are below the
    replacement rate. Clearly, food availability does not mean more
    children. More generally, as food security has increased around the
    world, instead of increasing as Hopfenberg's theory would suggest,
    global average fertility rates have dropped from 6 children per woman
    in 1960 to 2.6 today. And the rates continue to plummet. Sadly, in
    Africa, which has the highest current fertility rates, food production
    per capita has been declining for nearly 30 years.

    If food availability really determined human reproductive capacity,
    Illinois farmers should have the highest fertility rate in the world.
    Instead, they have one of the lowest. Hopfenberg would reply that
    excess food produced in North America and Europe fuels population
    growth in the rest of the world. In some sense that is trivially true,
    but the strictly biological model that he says applies to people does
    not account for such phenomena. For example, deer in Virginia don't
    sacrifice their chances to produce fawns and ship their food to deer
    in Arkansas, nor do sparrows in New York forego nesting in order to
    supply food to Floridian sparrows. Individuals, not populations,

    The notion that capping food supplies will halt population growth is
    also trivially true, but not by the gentle means which Hopfenberg and
    Pimentel suggest, e.g., reducing human birth rates. Food shortages no
    doubt reduce fertility, but they also shrink population much more
    quickly by simple starvation.

    Finally, Hopfenberg and Pimentel's projection that world population
    will reach 12 billion by 2050 is off. They simply extrapolate current
    levels of fertility, yet as we've seen, fertility rates are rapidly
    declining. The 2002 revision of the United Nations' [17]World
    Population Prospects' median variant trend projects a world population
    of 8.9 billion by 2050. Given the rapidly falling global fertility
    rates, the low variant trend is more likely--and that projects a world
    population topping out at 7.5 billion by 2040, then beginning to
    decline. Perhaps Malthusianism will finally decline along with
    fertility rates.
    Ronald Bailey is Reason's science correspondent. His new book,
    Liberation Biology: A Moral and Scientific Defense of the Biotech
    Revolution will be published in early 2005.


   10. mailto:rbailey at reason.com
   11. http://www.victorianweb.org/economics/malthus.html
   12. http://www.umsl.edu/~biology/icte/WEArecipients/ehrlich.html
   13. http://www.brothersjudd.com/index.cfm/fuseaction/reviews.detail/book_id/91
   14. http://www.reason.com/rb/rb072303.shtml
   16. http://www.oilcrash.com/articles/populatn.htm
   17. http://esa.un.org/unpp/p2k0data.asp

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