Seven billion Earthlings: So what’s the problem?

Typically, I get uncomfortable when I’m in the presence of more than, say, five other people. Therefore, you might expect me to be particularly perturbed by reports that the world’s population reached seven billion people earlier today, 31 October 2011. Such reports do perturb me, but not because I’m worried about there being too many other people on Earth. No, they perturb me because they are usually either: (a) factually inaccurate; or (b) presented, without argument, as if there was some self-evident problem with having lots of Earthlings rather than just a few. There are two types of problem in play here, each of which betrays a different type of scientific illiteracy. And that’s the type of stuff I really do find depressing.

First of all, the accuracy issue. Today’s media splash arises from a United Nations publicity campaign designed to focus the world’s attention on the nature of population growth. That seems fair enough. However, as part of the occasion, the charity Plan International have chosen to anoint a specific baby born this morning in India’s Uttar Pradesh state as being the world’s seven billionth human being (alive today).

It’s probably obvious that deciding on who is going to be the seven billionth human is likely to be a tough call. For example, it is pretty impossible to keep track of the sheer torrent of human births and deaths, both of which need to be recorded with accuracy if the overall headcount is going to be correct. Whichever newborn you focus upon, it is inevitable that several other babies will be born at or about exactly the same time. For example, in India alone, 51 babies are born every minute, which is equivalent to one every 1.17 seconds. Now without getting into the whole blood-and-guts mechanics of childbirth (trust me, we don’t want to go there), let’s just say that such a rate lies well outside the margin-for-error for timing such things. For unless all the relevant midwives have stopwatches in hand at the required junctures, nobody will really know — to the second — when each baby is born. And yet that’s what’s needed in order to declare a particular baby to be Human Being No. 7 Billion.

It goes without saying that the rate of human deaths is just as torrential and chronologically immeasurable. Which just messes everything up entirely. Perhaps for this reason, various other organizations have been pointing out that the seven billionth person might already have long been born, or might not be born for a number of years.

Nonetheless, Plan International feel it reasonable to organize a publicity event surrounding one particular baby, Nargis Kumar, born in the village of Mall, India at 07:25 local time this morning. While acknowledging the purely symbolic nature of the publicity event (in other words, while acknowledging that Nargis Kumar is clearly not the world’s seven billionth human), Plan International say that their efforts are helping to “highlight its campaign against female foeticide“.

Not the world's seven billionth human, with her parents this morning. (Note: Unlike Plan International, I am choosing to pixelate the face of this unconsenting minor)

That is certainly a very honorable objective, but perhaps we should consider whether the idea of highlighting a baby born in India (as opposed to one born in New York, Paris, or, say, rural Sweden) might just be feeding a certain type of overpopulation-as-timebomb stereotype? After all, when it comes to publicly stated anxieties about overpopulation, people often seem more worried when it’s the world’s poor countries that are seen to be tipping the balance toward oblivion.

Even mainstream news agencies, such as CNN, seem concerned primarily with the damaging effects of population growth. Under the headline “With 7 billion on earth, a huge task before us“, they offer the following early verdict:

A rising population puts enormous pressures on a planet already plunging into environmental catastrophe. Providing food, clothing, shelter, and energy for 7 billion people is a task of startling complexity.

[Yes, it’s complex; and I wouldn’t like to be doing it on my own. Now, if only there were 7 billion or so other people around to help…]

CNN also appear to be somewhat obsessed with just how big the number “7 billion” is. In their supplementary coverage of today’s population landmark, they try to emphasize the size of the number by asking several rhetorical questions, such as the following:

And when was the last time you used 7 billion in everyday life? Have you ever eaten 7 billion of something? Have you ever owned 7 billion of anything?

Well, CNN, perhaps I haven’t consciously eaten 7 billion of something. But I am perfectly aware that, without being conscious of each individual one, I’ve consumed billions upon billions of different things throughout my life. As a result of this for example, I know that my digestive tract right now contains around 1,000 trillion exogenous micro-organisms (stuff like individual bacteria and fungi which entered my body from outside after I was born), which is around 10,000 times more micro-organisms than there have been human beings who have ever lived. I also know that, each time I go the toilet, I dump around a billion of them. So all in all, as numbers go, “seven billion” doesn’t bother me.

To help clarify what the number “7 billion” actually means, CNN call upon expert Klaus Volpert, a maths professor at Villanova University. “The number is just outside of our usual everyday scale of thinking,” he says. “We count to 10 on our fingers and that’s our scale, you know? Even counting to a million is already kind of outside of the everyday experience.

So what example from inside everyday experience does Klaus offer to help us to understand? Well here it is:

Let’s say the average human is about 5 feet tall, accounting for children. If you stack those 7 billion people end to end, they would reach about 1/14th of the way to the sun — or 27 times the distance to the moon. 

Oh yes, well that’s EXTREMELY clear. Glad to have that bench-marked in terms of my everyday experience, Professor!

That example reminds me of other illustrations of 7 billion people. Apparently, you can fit all the human beings alive today inside the Grand Canyon, if you were careful to stack them correctly. In a similar vein, it has been widely discussed that you could accommodate all of humanity in four-bedroom houses with 5,000-square-foot plots inside the state of Texas alone. If they lived in apartment blocks, it would required just 7% of Texas. Note that such arrangements would leave the entire rest of the world uninhabited by any humans at all. Hmmm. Suddenly the world doesn’t seem that over-populated…

Look! Even rich countries are over-populated...

Of course, the challenges of population growth are more to do with availability of resources (rather than of space) and with the growing impact on the environment created by increased human activity. But even then, the scientific debates appear conspicuously two-sided.

Firstly, the problem of diminishing resources appears a long way down the track. As might be suggested by the Texas example, it is unlikely that we are anywhere even close to exhausting the Earth’s food production capacity. Secondly, as regards our species’s collective carbon footprint, this is a well established minority-majority paradox: a tiny number of the world’s population account for the vast majority of its carbon emissions. What this means is that the relationship between population size and ecological damage is not straightforward, and population growth alone does not indicate risk in a transparent way. For example, an extra million Americans would be expected to produce more carbon emissions than an extra ten million Brazilians.

The point is that the number 7 billion in and of itself is not significant in any scientific, economic, sociological, or even environmental sense. It just happens to be a round number. And while it is large, it is only large in relative terms (relative to, say, the number of fingers on your hands). In another sense (such as compared to the number of bacteria in your stomach), it’s actually quite small.

The idea that there is a “problem” with human over-population is well established in our daily discourse, and is a staple concern among right-wing pressure groups. (As it happens, the Catholic Church would like to take this opportunity to announce that THEY ARE NOT TO BLAME for any looming catastrophes). But whether it is a real problem is very much open to debate.

On the one hand, several scientists believe that the world population is not really growing that much at all, but rather that the rate of population growth is slowing down dramatically. One conspicuous detail is that population growth has decreased most in areas where access to food supply (and other resources) has increased most. This is interesting because, in biology, no other species seems to drop its birth rate when its food supplies increase. Biologists suggest that humans are unique in seeking to maximize the quality-of-life of their offspring, rather than their sheer number.

Still other scientists argue for a more-is-merrier approach. For example, in economic terms, it can be shown that the growth in economic activity that inevitably accompanies population growth more often than not drives technological progress in ways that lead to the overall betterment of humankind (see economists such as Michael Kremer and Steven Landsburg). According to these views, the traditional Malthusian view — in which increases in population are believed to exponentially increase division of resources and thus escalate poverty and hardship — is flawed because it fails to account for the contribution of population growth to the production and development of new resources. If true, then such points would imply that having a large human population is not a really problem at all. Far from it, in fact.

Overall, the idea of sensationalizing the birth of a single baby in an impoverished area in India and claiming her to represent the 7 billionth human is far from scientific. This is despite the fact that its sheer specificity conveys the impression that it is computed on a scientific basis. But like many other statistical claims concerning population growth, this one is essentially political. While there are important matters at issue, promoting a factoid like this serves to detract from the underlying scientific complexities and the two-sided nature of the associated debates.

When it comes to politically spun science, small matters such as accuracy or relevance don’t seem to matter.

Now that’s a problem of apocalyptic proportions.

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  1. “Of course, the challenges of population growth are more to do with availability of resources (rather than of space) and with the growing impact on the environment created by increased human activity…. it is unlikely that we are anywhere even close to exhausting the Earth’s food production capacity”
    With the greatest respect, is this actually a ‘science’ blog, in the conventional sense of testable, reliable, verifiable knowledge about the world as it is? If so, the above statements have no place on such a blog.
    As for the more-is-merrier brigade, the only “scientists” calling for this are the ‘social scientists’ aka economists, who borrow the language of science and mathematics to make and support ideological positions, eg. “growth is good”, “resources will never run out”. Such reasoning belongs in the realm of politics, religion and economics, not science.

    “On the one hand, several scientists believe that the world population is not really growing that much at all, but rather that the rate of population growth is slowing down dramatically”.
    The worrying phrase in the above sentence is “several scientists believe”. The words “several” and “believe” are problematic. Several scientists also believe that global warming is a hoax, or that it has nothing to do with anthropogenic causes. They are, of course, entirely wrong. As are your scientists above, who appear not to understand the geometric function. Our last population doubling took 40 years. Repeat that and we hit 14 billion in 2051, 28 billion in 2091, 56 billion in 2131, 112 billion in 2171 and 224 billion in 2211.

    Curiously, the mere 7 billion of us to date have been sufficiently destructive to trigger the Sixth Extinction, with an estimate of between 30,000 and 50,000 species being driven to extinction annually. UN estimates are that up to 50% of major species will have become extinct by the end of the 21st century, and that is before taking into account a plant-wide extinction event triggered by a 6-9C average surface temperature rise, per the IPCC’s 2007 ‘A1F1’ projections (which we are, in fact, slightly ahead of at the end of 2011).

    “When it comes to politically spun science, small matters such as accuracy or relevance don’t seem to matter”. Indeed.
    For more on what 7 billion REALLY means, see below:

    • Brian Hughes

      Hi John – thank you for your remarks. I don’t disagree with much of what you are saying there, or with what your overall position represents. For example, I am not even remotely sceptical about anthropogenic global warming, and I fully endorse the view that our current patterns of consumption, if allowed to continue unabated, will have dire consequences for our planet and its inhabitants. However, you do make a couple of points that I would take issue with.

      1. The first extract you quote states: (a) “the challenges of population growth are more to do with availability of resources (rather than of space) and with the growing impact on the environment created by increased human activity” and (b) “it is unlikely that we are anywhere even close to exhausting the Earth’s food production capacity”. You then say that “these points” have “no place” in a science blog. I find this stance peculiar. The first point is simply a re-statement of the problem, while the latter point is explicitly framed as an opinion. Re-statements of problems and explicitly framed opinions are perfectly suitable for science communication. The biggest problem with science writing is when opinions are not sign-posted as opinions, but are presented as facts. I read your article in yesterday’s Irish Times ( and I would say that it also presents several re-statements of the problem and very many opinions, many of which are expressed as facts.

      2. You assert that “the only ‘scientists’” who endorse the more-is-merrier position are “‘social scientists’, aka economists”. As it happens, this is a nice example of an opinion stated as a fact. As it also happens, it is demonstrably inaccurate, on a few levels. Firstly, “social scientist” is not synonymous with “economist”. And secondly, such projections are not confined to the social sciences (or to economics) but are also presented in the biological sciences (you might wish to take a steer from Matt Ridley: You go on to assert that economists “borrow the language of science and mathematics to make and support ideological positions”. I’m sure that some economists do this. I am sure that some environmentalists do so as well. But are you claiming that all economists do so? You are certainly implying this. I would say that to make such an over-generalized claim is extravagantly unscientific. To use your own phrasing, this type of reasoning “belongs in the realm of politics, religion and economics, not science.

      3. You also take issue with my use of the phrase “several scientists believe”. Specifically you note that “the words ‘several’ and ‘believe’ are problematic” because – and this is the totality of your argument – “Several scientists also believe that global warming is a hoax” and are “of course, entirely wrong”. I’m sorry, but that’s just silly (and wholly unscientific). It’s not an argument of substance, it’s an argument by analogy; one with an ad hominem flavour to boot. Are you rejecting the point that “several scientists” hold the view as described? Or are you claiming that if “several scientists” believe something then it must be wrong? Either would be flawed.

      Several scientists” believe in the theory of gravity. Are you implying that they must be wrong? “Several scientists” believe in evolution. Are they automatically wrong? “Several scientists” believe that vaccination has no role in causing autism. Must these scientists be wrong simply because there are several of them and this is their belief?

      I agree with you that skepticism toward anthropogenic global warming is scientifically ridiculous. I agree with you that scientists who hold such a view are indeed entirely wrong (at least in my estimation). But this simply doesn’t have a bearing on the merits of any other beliefs that might be endorsed by “several scientists”.

      4. Your final argument appears to be based on the assumption that the geometric function that describes population growth in the past is destined to continue into the future and can be extrapolated without difficulty. Given the highly complex fluctuations in the growth – and decline – of populations in different parts of the world, the corresponding impacts on resources both locally and globally, and the feedback loops these create by way of influencing back on demographic shifts, I imagine that even geometric functions will over-simplify the true nature of events. I wonder if your view on this – that the world’s population will have reached 224 billion by the year 2211 – is empirically supported, or if in fact there are several competing theories as to how these demographic trends are governed?

      Overall, I think you missed the point of my post. My post dealt with the way that these issues are projected in the media, and how the nuances, complexities, and debates are typically over-simplified (notwithstanding some confetti-like sprinkling of statistics and technical claims). I think your article in the Irish Times is a good example of this.

      Personally, the views I hold are quite similar to your own. However, from an empirical perspective I cannot ignore the fact that the science here is incomplete and debated. I don’t think the problems of population growth will be solved by rhetoric, or by a dogmatic insistence on the inevitability of planetary catastrophe. What would be helpful would be a greater public appreciation of how the pertinent science positions are habitually represented (and misrepresented) in popular discourse.

  2. Hilarious. John rebukes Brian for using hand-wavy estimates, then repeats the goofy claim about 30-50,000 species being driven to extinction annually. Without evidence.
    (Hint: more species are removed than added to the “extinct” list every year).

    The always-accurate lower edge of the low band of the UN Population Survey indicates population will peak at under 8 bn. by about 2035. Then begin falling. Mostly because of the “wealth effect” on birth rates, of course.


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