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Why God Doesn't Exist
The three
population
curves

    1.0        The Curve of Life: There are three possible population curves

    It is no secret to most people nowadays that the population of humans has expanded exponentially in the
    last 200 years. What is less well known is that, although the population of the world is still growing, it is
    doing so at a slower rate than in the past. 1963 was the glorious year in which we turned the corner. [1]
    The slope of the population curve went from convex to concave. Since then, the global rate of growth of
    humans has been steadily decreasing. I emphasize that I am referring to global population. I clarify this
    because most people have in the back of their minds that Africans breed like rabbits and will make up the
    shortages in no time. Not only is this untrue, but it has no bearing on what I just said. The global birth rate
    is what is decreasing and that includes Africans. If this rate drops to zero, we attain what is known as zero
    population growth (ZPG). For every person that is born somewhere, another one dies, and at the end of
    the year there is no net gain.

    Since 1990, U.N. demographers have consistently revised the date of ZPG downwards. [2] Two decades
    ago they predicted that our species would attain ZPG in the 22nd Century. The current revision predicts
    that it will happen in 2075. [3] Therefore, the experts seem to agree that we will attain ZPG within this
    century.

    These trends should alert you to the fact that we live in special times. The raw numbers presage that at
    some point the global population will begin to decline. We have never had this happen to us in our history.

    The demographer and the historian will protest. We had a population crash in the 14th Century, and we
    didn’t recover our numbers until a couple of centuries later.

    They are correct. There was a global crash, specifically in the population of Europe and due to the Black
    Death (1347 - 1352). [4] But here, I am not talking about a crash. I am talking about a sustained decline in
    the rate. This is a new phenomenon:

    " population growth is slowing down at this moment. However, that slowdown itself
       is a revolutionary event, which breaks a trend that has persisted over all of human
       history." [5]

    The discussion is not about an unexpected accident, a spike in an otherwise smooth trend. This time we
    can predict and guarantee that, whether sooner or later, the total population of the world will at some
    point reach a plateau, the maximum number of inhabitants we had at any one time (Fig. 1).

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    Since 1963, the rate of growth of global population has been steadily declining. Current projections sug-
    gest that the rate will drop to zero by 2075. The global population will have then reached a zenith (of about
    9.2 billion) and then is expected to drop a tad until it settles at a new plateau. This sustained decline is a
    new phenomenon in the demographic history of Man. We have had spikes in the curve before, but not
    smooth, prolonged, predictable negative slopes.

    Maybe not all demographers will agree with the historical trends I just proposed, but not one will
    challenge that the birth and fertility rates are steadily coming down. A sustained decline leads to ZPG.

    Once we attain ZPG, we can expect only one of three trends (Fig. 2). The population could:

    •        rebound and begin exponential growth again (more people are born than die)

    •        stabilize around an optimal level (births approximately equal to deaths)  

    •        continue to decline until we reach extinction (more people die than are born)

Fig. 1

Recent and predicted
population growth rate and
total population trends

    I repeat so that we don't miss the point: after we reach ZPG some time around the year 2075, there are
    only three possibilities. The population continues to increase, remains essentially constant, (oscillating
    up and down for the rest of eternity), or falls to zero (extinction). Which of these three trends will we
    follow? Will the Africans studs come to the rescue and multiply their seed biblically: like the sands of the
    desert? Will population recover to its former glory and continue oscillating up and down for the next
    billion years like some UN demographers predict? Or will our numbers continue to decline until there is
    no one left?

    In order to estimate what numbers the future may bring, it is helpful to review the population trends we
    had in the past. The strategy I have in mind is simple. If we can discover the factors that caused the
    population curve to deflect in the past, we can perhaps use them to speculate intelligently about future
    trends.

Fig.  2   The Curve of Life

The three possible demographic curves