How many people can the earth support?

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Andrew Lack takes issue with Colin Tudge’s suggestion that we, humanity, should be aiming for a world population of one billion rather than the 10 billion that now seems liable to come about 

Colin has suggested that a billion people on earth may be sustainable, requiring an eight-fold or even greater reduction from the situation at present. He is presenting this as a long-term solution over several generations. The problem with this, as I see it, is the shorter term: how to get there. You could argue that the long-term gain would be worth short-term pain, but firstly there would certainly be pain in the short term and secondly the differences that will almost certainly arise in the short term will affect the long-term profoundly.

The issue of human numbers raises totally different problems in different countries. In all the richer countries the current fertility rate is below replacement (usually seen as an average 2.1 children per woman), and for some it is well below, like Singapore at 0.72 per woman and South Korea, at 0.85 (actually a slight increase on recent years). The top 40 countries with highest fertility are all in Africa except for Afghanistan (no. 9) and Samoa (no. 32), and all with rates above 3.5 per woman. Britain stands at 1.4, USA 1.8. 

Some countries have already seen a population decline, like Japan and most eastern European countries including Russia. This leads to problems of an increasing proportion of old people needing pensions or care; the decline of businesses — especially small businesses – because their owners do not have adequate successors; ghost towns, abandoned dwellings and a dwindling of skills. Any country whose workforce declines will lose some of its influence in the world through lower economic activity. Western European countries would be in a similar position if it were not for immigration, which is the only potential panacea. Immigration does indeed solve the immediate problem of a declining workforce but it has become a mass movement and entire cities and districts in Britain and other countries have undergone a total change in character. The result is that it has developed into a ‘hot potato’ issue. To some, anti-immigration is seen as racist though that is, at best, an oversimplification. 

There has been what to me is a worrying trend in Europe of rejecting our values, based as they are solidly on Christianity (Tom Holland’s book, Dominion, lays this out brilliantly). Defending our values and our culture is not a race issue as such, it is what we have fought all our wars for, and most of us consider these values worth saving, from democracy to the welfare state and, yes, our anti-racist views. This, surely, is why several countries, like South Korea, Japan, Hungary, Russia and even France now have policies to try to increase the native birth rate, although this has had very limited success to date. This is one of the main reasons why immigration is such an issue. Overt Christianity has seen a huge decline in Europe over the last two centuries or more, and, with this, an inability to defend many of our values. This decline, coupled with the population decline and rapid immigration has markedly changed the nature of many European countries. 

A high population always represented power and, to an extent, still does – think of the contrast between Russia and Ukraine at present. If two countries with similar economic output show pronounced differences in fertility rate, the one with greater fertility has growing economic power. China is a fascinating case. Its great recent economic success is largely down to the population almost doubling between 1951 and 1979 when the one-child policy was introduced. This meant that the huge work force had few dependants – and economic growth was the outcome. But that is rapidly changing; with those born in the population boom now aging, they become dependent for pensions and medical care on a much smaller workforce. It remains to be seen what effect this has on the economy — but decline looks inevitable.

Ideas about respect for the natural world are simply not shared by all cultures. Although the natural non-human world has been decimated almost everywhere since the Second World War, the rise in environmental and conservation organisations has been most encouraging. I see signs of a turn-around in the fortunes of the natural world in many places across Europe. If we want the world to be as Colin has described it these have got to remain in place and increase in strength. And like Colin and, I trust, like everyone reading this I would like the human species to thrive, and to thrive alongside the natural world, a world that not only feeds us directly but is also so desperately needed for our emotional and spiritual lives. To get anywhere near this position, as far as I can see, a further population reduction in the richer countries of the world, especially Europe and the Americas, could be counter-productive as these are based on the western, fundamentally Christian, values that most of us would want to maintain whether we regard ourselves as Christian or not. Culture is changing, and though slow cultural changes are always happening, change can be difficult, especially if fast, and usually with unforeseen consequences.

I understand fully that what Colin is suggesting is a slow realignment, over several generations, not a rapid population reduction. But he made me think of the American ecologist H.T. Odum who stated in 1980 

“It is necessary that the United States cut its population by two-thirds in the next fifty years”. 

He did not say how, as far as I know, and fifty years is nearly up! There have been various attempts at direct population reduction, especially by promoting infertility as happened in one-child China. A similar idea was attempted in India by using bribes for vasectomies — but there was much resistance. It also was perpetrated by the United States when dealing with Puerto Rico in the early twentieth century. The whole business gets totally mixed up with eugenics as well. This was rife in the early twentieth century with the likes of Margaret Sanger and her ideas about birth control:

 “… Government should attempt to restrain, either by force or persuasion, the moron and the imbecile from producing his large family of feeble-minded offspring” 

— presumably with Ms Sanger as the judge. To this day abortion clinics in the USA are, shall we say, ‘strategically positioned’. There are several conspiracy theories around now about the mythical ‘Big State’ trying to decrease fertility, and some of these may even turn out to be true.

Current projections are that by 2050 48 countries will see their populations shrink. As almost all projections about populations and the problems of populations from Malthus onwards have been wrong, this may of course not happen. But we are certainly heading for a different world, and I have a strong suspicion that we may not like what we end up with if we continue along the line that the western world has taken of reducing our fertility in the way that we are doing. We may end up with fewer people to feed overall but will we end up with a better world as a result? Lowering our own fertility to help the future of the world looks to me like a kind of opt-out of our responsibilities.

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One response to “How many people can the earth support?”

  1. Colin Tudge avatar
    Colin Tudge

    Many thanks for this, Andrew. Points taken. However:

    More and more, it strikes me that the conventional approaches to the world’s problems — all the world’s problems; not just the issue of population – miss the point. Those who frame policy think predominantly in political and economic terms; yet truly to come to terms with the world’s problems they — we — need to think far more broadly than this. We need to incorporate ideas of a biological/ evolutionary/ecological nature; and also incorporate ideas that belong in the realms of moral philosophy and metaphysics (which in practice tend to be embedded in religion). To be sure, our immediate problems do seem to be primarily of a political and economic nature: the antics of Donald Trump; inflation; and so on. But all these considerations are embedded in far bigger issues to do with the nature of life, and the purpose of life, and what is good, and the other great metaphysical conundrums that have occupied humanity throughout history and doubtless long before. And the principal makers of policy do not discuss these grand issues, and for the most part are singularly ill-equipped to do so.

    Worse: for the most part, policy makers do not listen to the people who do think about the broader issues, who of course include clerics and philosophers of all stripes but also – very importantly! – people at large. Absolutely not does wisdom belong exclusively to the realm of intellectuals. (So it is that in the mid-20th century Left-leaning intellectuals were wont to suggest that the newly established USSR was a model society and that Stalin was some kind of prophet. But, said George Orwell, although of course he was a Leftie himself:
    “One has to belong to the intelligentsia to believe things like that: no ordinary man could be such a fool”.)

    A broader view
    We need of course to tackle our immediate problems but if we seriously care about the long-term future of humanity and of the natural world then we also need to broaden our horizons significantly and start to think in cosmic terms and on an evolutionary timescale. I suggest indeed that we should be thinking seriously about the next million years (for starters!).

    Like most “ordinary” human beings – all who are not psychopaths — I want the best possible outcome for humankind and for our fellow creatures. For all our flaws human beings are surely a good thing and Life a whole is altogether wondrous, a miracle, forever beyond our ken no matter how brilliant the science that we bring to bear on it.

    Science is telling us though that the whole caboodle – the universe and all the wonders within it — is finite. In particular, for cosmological reasons, the Earth will not be habitable forever. Big, complicated, and brainy creatures like us might reasonably hope to continue on this planet in a tolerable state for at least another billion years (which seems enough to be going along with), and various thermophilic or cryophilic or halophytic microbes might cling on for a few billion years after that, but it all must end eventually, as least in its present form.

    It seems to me though that the best we, humanity, can hope for is to continue to occupy this planet for as long as possible, as agreeably as possible, and in the company of as many of our fellow creatures as can be accommodated.

    To prolong our sojourn in the universe some have suggested that we (humanity) should be seeking to populate other planets and moons elsewhere. Various technophilic opportunists like Elon Musk have advocated such a course — and also some serious scientists who really should know better. More realistically, it seems to me that the best long-term hope for human beings (and our fellow mortals) is to strive to keep this planet in good heart for as long as possible so that it remains habitable for creatures like us, who are not thermophilic microbes, to continue enjoying life for as long as possible. Right now, with present policies and economic theories and the prevailing morality we seem to be doing the precise opposite. It almost seems as if the powers-that-be were actively seeking to anticipate the cosmological nemesis that seems inevitable and to bring the whole miraculous caboodle crashing down within a century or less, leaving our immediate descendants and our fellow creatures to scratch a living, or not, among the rubble and ashes. Donald Trump’s “Drill, baby, drill!” sounds like an invitation to a global suicide. The catastrophe of Gaza and the smouldering remains of wildfires worldwide might well be seen as a foretaste of what’s in store for all of us.

    So with all this in mind, and to be more specific, I suggest that the question we really need to ask is:
    “What is the maximum number of human beings who could continue to live on this Earth in a tolerable or indeed agreeable condition, and in harmony with our fellow species, before cosmological forces make the Earth uninhabitable?”

    To address this I suggest we need to invoke a new (though it is probably not new) unit of measurement, which might reasonably call a “person-year”. So the question becomes:

    “How many person-years could the Earth accommodate in an agreeable condition before it become uninhabitable?”
    It seems to me as a reasonable and partially-informed guess that as things are, with present policies and theories and ways of thinking, we would be lucky to keep 10 billion people in good heart for much more than 100 years. This means we could fit in 10 x 100 billion = 1000 billion person-years before Gaia collapses and our species comes to an untimely end. A hundred years is a very long time as far as most politicians are concerned, or economists, or engineers, but it is but a twinkling in the lifetime of the Earth.

    Yet if we reduced our total numbers to around 1 billion then provided we were content simply to live in reasonable comfort, and to eschew the excesses of Mar-a-Lago or of Putin’s gold-plated Kremlin (which most people surely would cheerfully forego), then our descendants should still be here and enjoying life in a million years’ time. This would mean we would be able to fit in 1 billion x 1 million = a million billion person years — a thousand times more than now seems possible with present technologies and ambitions and policies.

    Furthermore, all but the unluckiest in this reduced but long-lasting population would be far more fulfilled and at ease than most people are right now, or could hope to be in the foreseeable future.

    Still, though, on the evolutionary/cosmological timescale a million years is but a modest ambition. Some Earthly species of the kind that have been content to live within their own modest lights, including mosses and various clams and even sharks, have lived on this Earth more or less unchanged for 10s or even hundreds of millions of years. I see no convincing reasons why our own species should not do the same – although of course we should not simply stay the same. We could and surely should always be seeking to refine our ideas and understanding – spirituality and science. It’s this striving after insight that makes our species unique and special – not innately superior to the rest, but different.

    So, I suggest, we should be asking what would be humanity’s optimum population. We should not, as now (at best), simply be looking for ways to accommodate the numbers we finish up with — or seeking in fantasy mode to find new places in the galaxy and beyond to colonise, and doubtless to despoil.

    But no-one that I know about, and certainly no-one in a position of influence, is asking that very obvious question. It is indeed politically incorrect even to raise the issue. (If you do know of any scholars who are seriously and formally addressing this issue I would be very grateful to learn about them.)

    In all this, there is serendipity. For it transpires that all the effective means of reducing birthrate and hence of reducing population are benign, and desirable in their own right, including effective contraception and women’s lib.

    Malthus re-visited
    Finally, I do question Andrew’s comment that “almost all projections about populations and the problems of populations from Malthus onwards have been wrong”. Although Malthus (1766-1834) has at times been very popular and has been highly influential he has also been getting it in the neck and sometimes most notoriously abused ever since he published An Essay on the Principle of Population in 1798. Many who claim to be Marxists accuse him somewhat anachronistically of Fascist tendencies. One commented recently on this website that Malthus, perhaps unbeknown to himself, wasn’t really concerned primarily about human numbers at all, but was seeking to protect the capitalist hierarchy against the rising tide of revolution which began with the American Declaration of Independence in 1776, and continued spectacularly through the French Revolution of 1789 et seq, and culminated after his death in “the Year of Revolutions” in 1848. Well, Malthus was obviously very aware of these goings on but I can’t see why we should assume that his magnum opus on population that he worked on for several decades wasn’t about the matter he thought it was.

    For – surely? — Malthus’s basic point is one of biology, and seems irrefutable: that the human population (and indeed all populations of all creatures) have the potential to produce more offspring than can be supported in a finite habitat, indeed a finite world, and unless this potential is restrained then some kind of catastrophe will result. There are indeed reasons why Malthus’s gloomiest prognostications have not come about, and need not come about, if we play our cards sensibly. As the novelist, journalist, and political agitator and commentator William Godwin (1756-1736) pointed out from the outset, people can and typically do adjust their birthrate according to circumstance (and, it now transpires, so do many other animals). So we could indeed avoid Malthusian collapse if we set our minds to do so. But for various reasons governments the world over, and clerics too, undergo periodic bouts of pro-natalism, including of course the immediate problems posed by diminishing numbers as Andrew has argued, and encourage people to have bigger families rather than smaller. Some, like the Tory party’s present leader Kemi Badenoch, on the one hand urge the need to “clamp down” on immigration while encouraging native-born Brits to breed. (Governments in general are better at “clamping down” than they are at constructing something better.)

    Truly the world needs to re-think everything from first principles and make policies and shape our actions accordingly. And, I suggest, the first principles are those of ecology and the metaphysical concept of morality – and both point to the need to adjust human numbers to the ecological reality of the present, and the (albeit faint but nonetheless finite) possibility of a long and glorious future for us and all life on Earth. Ecological and cosmic reality, and moral principle, must outweigh mere ideology.

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