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The Overpopulation Hubbub

by Steven Novella, Sep 28 2009

The question of human overpopulation of the earth is one of those empirical scientific questions that garners a strange amount of emotional opinion.  It is as if the sense of overcrowding and depleting resources triggers something primal in our monkey brains. On the other side, we resent being told to curb what is perhaps our strongest natural instinct – to make more versions of our genome.

Another feature of this debate that encourages or at least allows emotion to reign over data is that the core questions involve predicting the future. We are very bad at predicting the future. Predicting the future is really just an exercise in projecting our biases onto the future. The best we can do is extrapolate current trends forward, but there are often multiple overlapping trends that we can choose from, some trends are really cyclical, and the appropriate curve (linear, geometric, exponential) may not be obvious.

It is also important to identify in a controversy where there are value judgments that cannot be resolved objectively with facts. The abortion debate continues to rage because at its core is a personal choice of value – the mother’s biological freedom vs the life of a fetus. In the population debate there are value judgments regarding humanity’s rights and responsibilities toward the earth and all other life on it.

A recent issue of New Scientist explores various points of view regarding the population debate. For anyone interested in this topic this makes for good fodder. The basic facts are this – human population is now reaching 7 billion people. It is estimated that by 2050 we will exceed 9 billion. However it is also true that as our technology progresses we are able to sustain more people with fewer resources.

It often seems, therefore, that where one stands with regard to the population issue depends upon whether one is a pessimist or optimist. Although, even for the maximal optimist it must be acknowledged that there must be some upper limit to what population the earth can comfortably support, and that at some point (despite technological advances) increasing population becomes an increasing drag on the environment and other species – for reasons of physical space if nothing else (setting aside expanding the human population off planet and focusing just on the population of the earth).

Taking the pessimistic point of view is Paul and Anne Ehrlich, who write:

Somehow, cultural attitudes toward large families everywhere need to be changed. It should be considered immoral to have excessive numbers of children – an attitude that already exists in most industrialised nations with low birth rates. Nothing is more clearly a governmental responsibility than keeping a nation’s population size sustainable by benevolent measures.

As well as curbing population growth, we shouldn’t forget the pressing issue of excessive consumption by the rich.

Their argument amounts to a peak resources position – it will get more and more difficult to sustain an increasing population with fewer and fewer resources. Again, this is likely to be true at some point, but saying that we are essentially there now seems to ignore the role of technological advance.

Staking out the other end of the spectrum is Jesse Ausubel who points out that while the population has been increasing at a rate of about 1% per year, crop yields have been increasing at a rate of 2% per year, allowing us to grow more food on less land. In this interview he says:

Technology has liberated humans from the environment. Today we live about equally well in polar and tropical, arid and wet environments. The new question is whether humanity can use technology to liberate the environment itself. E-books, landless agriculture – farming that uses very little land because of high yields – and subterranean maglevs show the way.

It is important to note, however, that even a techno-optimist like Ausubel points out that we need to prioritize those technologies that do “free nature” by allowing us to do more with less. He is not saying that we should ignore the issues of population and resources – but that we can rely upon technological advances to give us solutions, if we choose to use them.


I admit I am more toward the Ausubel end of the spectrum than the Ehrlich end. Doom and gloom predictions over the last century about population increase and dwindling resources have not come true. Reading the Ehrlich’s warning about rising death rates sound a lot like the predictions of massive die offs that have been made and failed to manifest on a regular basis over the previous decades.

At this point I think we can conclude that it is not terribly useful to make predictions based upon current sustainability, because technology is constantly changing the equation. And technological advance has continued to surprise us. It seems likely that in 100 years the problems humanity will be facing are likely to be different than most of those causing current worry.

This does not mean, however, that we should just shrug and not worry. Thoughtfully contemplating the implications of our industry and population, and how to prioritize technological development and research is likely to have a huge impact on our future. I am optimistic that technology will give us potential solutions to the problems caused by a rising population within finite resources.

But we still need to develop and implement those solutions. Some of them will happen as a matter of course – people will use light bulbs that use less electricity and last longer simply because they will save money. But others may require more deliberate application, and we may need to bridge to “better” technologies through a cost-ineffective transition. For example, we may need to subsidize solar energy against the very cost effective fossil fuels before fossil fuel prices surge because of scarcity.

I say “may” because I personally don’t know – this is a specific technical question best left to appropriate experts. An approach I generally recommend over ideology.

44 Responses to “The Overpopulation Hubbub”

  1. teacherninja says:

    Thanks, Steve. It’s an interesting debate. Maybe you could find someone to interview on the podcast–there’s so much to talk about. I guess I’m somewhere in the middle of your two examples. I’m not so much worried about the doom and gloom because I know that natural selection will take it’s course if overpopulation becomes a problem, but I do worry about our environmental impact and agree that not having too many children is a good thing for all involved. People think that they should have two children to “replace themselves” but that would only be true if they died after having their children. When they have two kids there are now four people for a great many years. If everyone had one child instead, then the population would level off–not shrink but not get worse. Therefore I encourage realistic and science-based family planning and education at the very least.

    I also agree that we can’t foresee what technologies will develop to alleviate these problems and it’s always fascinating to watch how we deal with problems with new food growing technologies and cleaner energy sources. I do think, however, that there are certain walls we’ll hit (like land and water availability) that we’ll either have to deal with, nature will select for, or we’ll need to find a way to grow beyond this planet.

    Thanks again.

    • Max says:

      If everyone had one child instead, then the population would level off–not shrink but not get worse.

      I’m pretty sure it would shrink, based on math and on countries with shrinking populations.

      • Brian M says:

        In the short term (see, within one generation) it would stay the same. But yes, after 1 average lifetime, it would decline rather sharply.

      • teacherninja says:

        Sorry, my mistake. I just meant more people having one child and smaller families generally. Thanks.

  2. Max says:

    The Erlichs coauthored the 1978 book Ecoscience with John Holdren, who is now Obama’s “science czar”. In it, they discussed solutions like adding infertility drugs to the water supply, implanting infertility devices at puberty, taking babies away from single mothers, and having a “planetary regime” set population levels.
    I don’t know if they advocated these solutions, but they appeared to be more concerned about technical difficulties than about morality.

  3. SkepLit says:

    I see no downside to curbing population growth regardless of our technological capacity to support it. In fact, our propensity to throw technology at the problem may, in fact, be part of the problem. As Ausubel points out, our food production has increased at 2% and population at 1%. Had it increased at only 1/2% the rate of population growth would have been 1/2% since population is tightly bound by people’s ability to, you know, eat.

    Please don’t take that to mean that I am encouraging starvation as a means to population control. I’m merely pointing out the paradox that technology cited is not being employed to curb population but rather to allow it to expand.

    If technology is going to actually limit growth, it will be the technology we employ to change societal norms. It is my opinion that the lead times needed to create zero, one, or two child families as a universal norm will take so many generations that we had best get started on this now. As another Novella has repeatedly said on other topics, “we should be pouring billions into this”.

    • qbsmd says:

      “Had it increased at only 1/2% the rate of population growth would have been 1/2% since population is tightly bound by people’s ability to, you know, eat.”

      That is a great point that seems like it should have been obvious to me. I was thinking about how that 2% growth has resulted in things like global warming, decreases in biodiversity, etc. I’ve seen so much recently about how we’re overfishing the oceans, overusing water resulting in drying up rivers and emptying aquifers, shrinking natural habitats, and so on, that I was just stunned that someone could argue that there isn’t a serious overpopulation problem.

  4. Brian M says:

    Heres a thought. Why don’t we industrialize (or modernize) those countries that find it virtuous to have large families. As Ehrlich said, industrialized nations have less of a desire to have large families. I don’t think we are going to hit the maximum that we can sustain for a while, but it most certainly doesn’t hurt to help the people we have via industrialization, and as a side effect, slow the population growth so that even the most pessimistic predictions of technology growth have an even greater chance to feed everyone.

    Personally, I am on the side of technology. It has done wondrous things for us. People who say the space program and other science programs are wastes of money simply don’t understand that feeding the homeless comes directly from those science programs via the knowledge gained.

    Besides, if any government ever tries to stifle birth rates, you will either see a drastic increase in birth rates, or you will see some of the twisted things that you see in china (or is it japan that has a 1 child max?) where they kill off their child because it is a girl, and they want a boy. Try to ban religion, and the population gets 99.9% religious (see Shermer’s article from last week).

    If we put off overpopulation long enough, we will have space travel, and possibly even populate another planet. If that happens, suddenly, we will never worry about over population again, only finding new planets to put ourselves on. (Sometimes I wish I could live forever just to see that happen).

    • Thomas says:

      I agree, direct attempts to curb population by the government would prove to be disastrous.

      There are less intrusive ways of curbing population growth though. Worldwide gender equality would be the best way to achieve this. Women who have access to a quality education are less likely to have children at a younger age as well as less children overall. Only the most fundamentalist and patriarchal groups could sell this as an evil deed by the government.

    • teacherninja says:

      I agree that government is not the way to go. Promoting modernization and city-dwelling is a much better idea. People tend to have more sustainable numbers of children when they move into the cities and it’s better for the environment as well.

      • MadScientist says:

        Huh? Promoting modernization and city dwelling? How is that supposed to help? From a purely natural point of view, cities are parasites; they do not produce their own food, they take it from their hosts.

        Please give an example of a place which can reduce its population by being modernized. Everywhere I look modernization is accompanied by an increasing population – after many years the populations may slow in growth or even decline slightly, but that is *never* an immediate effect of modernization. When I look around the world I see nature controlling non-modernized populations; either through increased mortality due to lack of modern medicine or resource limitations. There are many places on the planet where modernization is not even possible – at least not without making the locals absolutely dependent on donated imports, whereas at the moment the locals live just fine. Talk about modernizing others to control their population is nothing but a bigoted desire to impose one’s own values on other societies.

        You also have things backwards; cities consume far more resources per capita than, say, tribal villages. How is that more sustainable? Though city folk can’t do without computers and World of Warcraft, it makes no sense at all to believe that others simply must have these wondrous things and that it somehow also makes those other communities sustainable.

      • Nexus says:

        100% Agreed. I’m finding that many of these comments regarding pro-tech, pro-industrialization etc are self-indulgent, and overtly idealistic. Saying that technology with save us is akin to saying that God will take care of us. The notion is absurd. There needs to a more comprehensive understanding of the multifaceted impacts that science and technology have had on our civilization over a long period of time. To assume that all technology has an ultimately positive impact on society is naivety, at its worst.

      • Brian M says:

        Well, I wasn’t specifically talking about cities. I was talking about _technology_. Technology isn’t a laptop. It isn’t a cell phone. Technology is the things that move us forward. For instance, better crop growing techniques, or genetically modified (read, selected for) crops, better medication for animals that are to be used as food (for example). Better medication for people, as well, is an example of modernization. Thinking people are better off by family farming is just ignorant when you consider the yield and market trading that can happen if modern farming techniques are employed.

        I’m starting to think you “technology haters” just don’t understand what is meant when technology is brought up. Overwhelmingly, technology has a positive impact. Trade and other commerce alone make the advances in technology worth it.

        Quite simply put, it is bigoted to think that other societies are better off struggling on their own. If offered, they would gladly take the many things that we have in order to make their own lives more secure.

      • MadScientist says:

        Sure, but as Nexus pointed out, saying “technology will save us” is like saying “god will save us”. Take the time to define what that technology is and how it will help, and more importantly how it will be exploitable ad infinitum – without stating such things you’re merely parroting something on fiat, not on fact.

        So far technology has allowed the human population to grow quite predictably; we haven’t hit the barriers which would force a natural cap on population growth (for example, the current classic Malthusian collapse in the Congo). However, what you see is quite deceptive; it is not sustainable, and if action is not taken for a humane and controlled decline, we will hit a limit and it will not be a pretty sight.

        In India the so-called “green revolution” has been a great boon (despite what weirdo groups like claim). More people had access to basic needs, but underlying societal problems are not being solved but pushed into the future instead. There are resources such as aquifers which are being depleted much faster than they can be recharged, and when those resources are depleted then a once productive region suddenly cannot support itself. The realistic view is that technology is buying us some time, not that technology will miraculously solve all problems which we can foresee.

        It will take many generations to reduce the human population to a level where people can live comfortably and in a sustainable fashion, but the general push of governments for larger populations all in the interest of economics is crazy; governments should be working on a scheme for an overall population reduction. Even now we’re telling future generations “you can’t have a car like I had”, and “we used to be able to go camping and cut trees to make temporary bridges”, “you can’t have a shower every day like we did in the good old days”. Overpopulation is already having a negative effect on the current generation.

      • Brian M says:


        I completely agree. But the statistics (and they’re just statistics) say that a higher technology level brings a lower birth rate (voluntarily). I think that actually kills 2 birds with 1 stone. It’s not a silver bullet, but I think its a pretty reasonable proposition for a large number of other reasons. Yes, more people live, but less people are born. Thats a good thing, IMHO. :)

  5. Cambias says:

    I’m always struck by the completely unexamined assumption that “overpopulation” is bad. What’s bad about people?

    It’s also significant that we still think of this as a problem, even though many of the world’s wealthier countries are facing the opposite problem: shrinking, aging populations. I believe Japan is already in a population decline, and several European countries are making up the difference only through immigration. Even China is going to be facing that problem in a few decades.

    So why do we still obsess about “overpopulation?” Is it just a way to wrap misanthropy or outright racism in a cloak of environmental concern? Paul Ehrlich seemed a lot more upset by “overpopulation” in India and Africa than in, say, Manhattan.

    • Thomas says:

      I would counter that accusations of racism are an attempt to marginalize genuine concerns about the environment.

      • Cambias says:

        No, they’re an attempt to point out the very, very ugly ideological underpinnings. Take away racism and the “fallacy of nature” and there isn’t much left of the overpopulation issue.

      • Thomas says:

        Should we compare quality of life between India, Africa, and Manhattan? This is why throwing around claims of racism is not contributing to the debate.

        For all I know I’m just projecting on Paul and Anne’s motives here because, when I promote gender equality and wider availability of birth control for poor countries, its to improve quality of life not prevent it. Then again, maybe they are just racists.

    • teacherninja says:

      Japan’s problems stem from their anti-immigration policies. The topic of the post was more about sustainability of the overall global population. Sure, we could have ten billion or more physical people on the planet, but I doubt they’d have a very pleasant quality of life.

  6. sidfaiwu says:

    “I’m always struck by the completely unexamined assumption that “overpopulation” is bad. What’s bad about people?”

    Oh, I’m sorry, I thought that would be obvious. Overpopulation means there are more people than the Earth can sustain. This leads to mass suffering and death – you know, bad things.

    I think what you mean is that there is undo obsessions about population (without the ‘over’). With this, I would agree. As you point out, as nations industrialize, the ‘problem’ seems to take care of itself.

    I found a nice graphic depiction of this phenomenon of decreasing birthrates as countries industrialize (note the ‘play’ button). I apologize in advance for the long URL.$majorMode=chart$is;shi=t;ly=2003;lb=f;il=t;fs=11;al=30;stl=t;st=t;nsl=t;se=t$wst;tts=C$ts;sp=6;ti=1950$zpv;v=0$inc_x;mmid=XCOORDS;iid=phAwcNAVuyj0TAlJeCEzcGQ;by=ind$inc_y;mmid=YCOORDS;iid=phAwcNAVuyj1jiMAkmq1iMg;by=ind$inc_s;uniValue=8.21;iid=phAwcNAVuyj0XOoBL_n5tAQ;by=ind$inc_c;uniValue=255;gid=CATID0;by=grp$map_x;scale=lin;dataMin=0.842;dataMax=8.7$map_y;scale=log;dataMin=240;dataMax=119849$map_s;sma=49;smi=2.65$cd;bd=0$inds=

    The trends suggest that loss of population may, indeed, become a concern in the future.

  7. MadScientist says:

    “we can rely upon technological advances to give us solutions”

    That’s a canard trotted out by the ignorant; we have absolute fundamental limits. For example you cannot make a ladder out of too thin a piece of material because it will not have the required mechanical strength for the job. Many resources are limited by our ability to mine ores near the surface; don’t imagine that supply can be maintained even if technology is developed to exploit deep deposits. People in the oil and gas industry imagine only a few decades more of somewhat extractable resources, and although no one can come up with absolutely reliable figures these people know their stuff well – so in no more than 100 years you can bet coal would be the only remaining fossil fuel. If you look at industry publications you will see charts on mineral production rates, expected growth, and estimated limits of currently known deposits; many proposed technological solutions are in fact probably not viable on the requisite scale due to the limitations of many resources. China is trying to acquire mining rights around the world to ensure its future supplies; if resources are so abundant, why would China waste money on such a venture?

    Even the increase in food production is heavily dependent on resource extraction; it is not entirely due to improvements in the crops. Add to that the fact that continued increases in productivity are not guaranteed simply because you imagine there is a nice trend line. Food supply did not magically increase. Put yourself in the Congo with the resources of the various tribes but your best variety of cultured crop. You may have significantly better yields, but nothing like what you’d get back home with the large machines for planting and harvesting, the water pumps, and the truckloads of fertilizers.

    In many places water is becoming scarce and larger populations simply cannot be supported without restricting water use. In other words, future generations are bound to live more frugally at best and why should the current generations doom the future generations to such conditions?

    Over all of course it doesn’t matter; we’ll all be long gone before the big problems really come up and the much maligned ‘Malthusian collapse’ will be a global crisis.

  8. Ken Baker says:

    It’s true that agricultural yields are increasing faster than population growth, but those yield improvement are enabled largely, and increasingly, by the use of fossil fuels. Oil is used not just to run the machinery to grow, process, and transport the food, but also to make fertilizer, herbices, and pesticides. This trend is clearly unsustainable.

    Also, agriculture is not the only constraint on human population growth. Fresh water, energy, and pollution management are some other variables in a complex equation. Considering the hundreds of millions of people who lack sufficient food and water, I tend toward the Ehrlich end of the spectrum.

  9. William Geoghegan says:

    Your article seems to be fairly simplistic and with very little data. It is strong on speculation and weak on comprehension. I suggest you read more on this very complicated topic. You might start with Lester Brown.

  10. Shayne O'Connor says:

    Um, you should probably watch this series of videos about the exponential function … you might start to worry a bit more and gain an understanding of how optimism or pessimism are no match for mathematical laws:

  11. sailor says:

    “I’m always struck by the completely unexamined assumption that “overpopulation” is bad. What’s bad about people?”

    Global warming, would be a good example I would have thought.

    • MadScientist says:

      Ah, but global warming doesn’t exist. I’d expound more, but I have to rush off; I’m late for a date with the tooth fairy.

    • Cambias says:

      Then why are you still alive?

      Seriously, if people = global warming = bad, your duty as a person concerned about the planet is to remove yourself from it. Otherwise you’re basically claiming that you are somehow of greater intrinsic value than these “overpopulating” hordes out there somewhere.

      If global warming is the problem, solve the problem. People aren’t the problem. People will solve the problem.

      • tmac57 says:

        People require resources. Resources are finite. Population is growing at an exponential rate. This is not mathematically sustainable. The problem might be solved rationally and humanely, or irrationally and cruelly. Either way, the problem will be solved, and it will necessarily involve the reduction of population growth to zero or negative growth.

      • sailor says:

        Well, when I was born the whole world’s population was way smaller. I did my bit by not having any kids, so I did not create those “overpopulating hordes”. I feel the answer to overpopulation is to scale back on breeding, not mass suicide.

  12. teacherninja says:

    Here’s a recent editorial claiming that it’s not really population, but overconsumption that is the real problem.


    • Max says:

      Starts off good, but then focuses narrowly on CO2 emissions. Nobody’s blaming Africa for CO2 emissions. The problems there are famine, disease, and violence, which are all related to overpopulation and a young median age.
      Democratization and industrialization can help solve those problems, but then it would contribute to fossil fuel consumption and CO2 emissions.

      • MadScientist says:

        Unfortunately many parts of Africa are a basket case; you can see exactly what Malthus was describing in his era (he was writing primarily about Africa then as well). Many people still live as they have for thousands of years and they are happy; many do not live long, but that’s how things have always been. Life is hard but it has always been that way, and for the most part these people are very peaceful and friendly. Most of the time they do just fine, but on occasion nature does screw them over badly. Do such people need to be ‘saved’ from anything? I don’t think so; it’s rather puzzling how people often think that others who are not like them somehow need saving.

        Now for the parts of Africa where you have strife – who knows what can be done. I think the best bet is to take some of these people and build up communities elsewhere. Over many generations you can establish successful communities that way. (Of course they can always be attacked by others, which screws things up.) I can’t imagine that there could be any simplistic solution in anyone’s lifetime though.

      • oldebabe says:

        Exactly. No one has found a way to abolish war.

      • Max says:

        The Democratic peace theory says that Democracies don’t go to war against each other.

    • MadScientist says:

      “If everyone shared there would be no problem” is a myth. Giving too much creates its own problems; Ethiopia has been in strife for decades now and even though the drought has eased ever so little, some locals say that many people have become too dependent on aid. Like all other animals, people can become lazy and yet aggressive and demand things without working for it.

  13. SkepLit says:

    To reiterate a point I made (perhaps too subtly) earlier: When we talk about technology solving the population problem by increasing the efficiency of food production or improving health care, that isn’t solving the problem at all. It is accomodating the problem by allowing population to increase. More food and better health care don’t decrease reproduction rates.

    That’s the wrong technology to be to be talking about. Technology may have a role to play in reversing the growth but it will be those technologies which can change human values and desires.

  14. Todd McInroy says:

    I am a little surprised by this post, did I somehow slip back in time to the seventies? The recent research I have seen says that the developed world has shrinking birth rates, and as soon as people have good medical care, so that most of their children live, family size drops. I expect the world to reach some peak population, and then drop. This will have ecomomic implications at some point because the world economic system requires constant growth.

  15. Prof Bob says:

    According to an article in Science Daily (April 20, 2009), a survey of the faculty at the State University of New York, which has a very strong environmental science department, the planet’s major environmental problem is overpopulation.. Climate change is second. This echoes the theme of the popular free ebook series “And Gulliver Returns” –In Search of Utopia—( As one professor at SUNY said “With ten million or even a hundred million people on the planet there would be no warming problem.” It is both the technology and the number of people using it that create so many of our planetary problems.
    There is no question that China’s one child policy has helped the world and the Chinese economy. Whenever a country attempts to reduce its population it can expect a two or three generation period of problems while deaths reduce to equal births. I hope that China will recognize this fact and keep its own population on the path to reduction–which should begin by 2050. China’s actual fertility rate is not 1.0 per woman, but 1.8–the same as Norway’s.
    China’s Platonic-like oligarchy is far more efficient than modern democracies. The self-centered desires of each of us to have as many children as we want; the pressure of some religions and most businesses for more converts and customers; and the need for more soldiers to defend each sovereign state– each fight the obvious solution to the problems of the world: warming, illegal immigration, the use of irreplaceable natural resources, waste disposal along with air and water pollution, starvation, and the lack of fresh water. But countries commonly encourage more births to enlarge the tax base and pay for the elderly. Then each generation will contain still more elderly.
    The earth is self correcting’ but the correction will cost billions of lives that could have been saved with intelligent action now.

  16. Gordon Cheyne says:

    Wouldn’t it be nice if we had a cheap technology that could reduce famine?
    And poverty?
    And environmental pollution?
    And maternal mortality?
    And infant mortality?
    And abortion rate?
    And AIDS?
    And overcrowding?
    But we DO.
    It’s called Family Planning.