Following the issues raised in the question How to limit population growth in a utopia? I'd like to ask a related question. In a stable utopia, would the population be old-aged, compared to less-than-utopian societies?

I define "utopia" as a society where all traditional ills are kept at the minimum possible: hunger, poverty, diseases, substance abuse, violence, crime, wars etc. The society achieves that (somehow) without relying on magic or futuristic technology. Also, this utopia is stable - it occupies a fixed land, its use of non-renewable resources is negligible and its population size is fixed (somehow). There is no immigration or emigration in or out of the utopia.

After considering these conditions, it looks like average life expectancy (and consequently, the age) of utopian citizens should be higher than in any of the real world countries.

Thus, would the "real" utopia be a society more aged than any real world country?

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    $\begingroup$ The movie Logan's Run (1976) offers an alternative of utopia for the young only. As you approach age 30, it becomes a dystopia. It's stable, with a young population...until they destroy it. $\endgroup$
    – user535733
    Nov 25, 2020 at 22:24
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    $\begingroup$ In a stable population, in the long run the average age will tend to be half the average lifespan. Average lifespan 90, average age 45 -- lower than in Germany or Japan, about the same as in Italy or Greece. (And are we really supposed to do arithmetic on this site?) $\endgroup$
    – AlexP
    Nov 25, 2020 at 23:05
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    $\begingroup$ In a true utopia people wouldn't age. $\endgroup$
    – Hot Licks
    Nov 26, 2020 at 1:18

5 Answers 5


Yes. Your average age depends on life expectancy and is $L\over2$

For your society to have 0 growth, and everyone dies of old age, you need to have a child born every time someone dies of old age. This would lead to a perfectly flat population distribution.

If everyone lives to 100 due to your excellent medical system, at any time half the people will be under 50, half will be over 50. So the average will be exactly 50. It's half your life expectancy.

Japan's average age is 48, Australia's is 37. Your country would be the oldest average age.

However that 100 was chosen arbitrarily. If everyone dies at 60, your average age would be 30, but dying at 60 doesn't sound very utopian to me.

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    $\begingroup$ When you run the math, it doesn’t quite work out so simple — it depends on the structure of the life expectancy distribution. Taking an unrealistically extreme example: if half of babies born die at age 10, and half live to exactly 100, then the life expectancy will be 55, but at any given point, long-lived individuals will make up 10/11 of the population not just half, so the mean age will be around 46 and the median age will be 45 (rather than both being 55/2 = 27.5). In a more realistic distribution, though, I guess the discrepancy would be smaller, and “L/2” a good approximation. $\endgroup$ Nov 26, 2020 at 9:52
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    $\begingroup$ Your link doesn't support your theory. 1) Median isn't the same as average, 2) The median age in Japan is 48 but the average lifespan is 84, so the median age is > L/2. $\endgroup$ Nov 26, 2020 at 14:25
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    $\begingroup$ @PeterLeFanuLumsdaine That's true in the real world, but here we are talking about a utopia where any causes of death except old age are so rare that they are negligible. $\endgroup$
    – Philipp
    Nov 26, 2020 at 14:47
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    $\begingroup$ If people die of old age in a distribution around the life expectancy then at the very least you’ll see a long tail on the upper end of the age range, surely? $\endgroup$
    – Joe Bloggs
    Nov 27, 2020 at 13:58

Real world countries could be older, because they are not in population equilibrium.

In your utopia, each woman would have two children, to replace herself and the father. Add in one extra child occasionally to account for circumstances where a child dies before reproducing.

In some first world countries that is not happening. On average, women have less than 2 children. Japan is an example.


The main cause of Japan’s population decline is the rapidly decreasing number of births, which is currently at the lowest it has been since data started being collected in 1899. In 2019, only 864,000 babies were born in Japan – 54,000 less than the number from 2018. The fertility rate in Japan is 1.4 births per woman – far below the population replacement of 2.1.

Your country would have lots of old people but percentagewise not as many as Japan - especially the predicted Japan for 2060.

  • $\begingroup$ Not that japan has a problem a utopia will not have which is high cost of children. High cost combines with low mortality pushes the population even further into K strategy. $\endgroup$
    – John
    Nov 27, 2020 at 5:50

TL:DR: If the society were perfectly utopian and perfectly disciplined/controlled, yes there would be children and young people equally in proportion with very old people.

A few assumptions are in order.

The fundamental assumption is that there is procreation. That is, there is a continual supply of babies. Otherwise, your question is moot - with no babies, either everyone stops aging at, say 30, and so everyoe in the population will be 30 years old, or the population will just keep getting older and older, with zero young people.

So, given procreation, the society may be utopian in the sense of health, but there still must be death at the end of life. Otherwise, the population keeps increasig to infinity. It is not a stable population, which violates one of your criteria.

Let's pick some arbitrary age, say 150, that everyone lives to, on average. More than likely, there will still be accidental deaths. No utopia can get around the zap/splat factor, there will always be lightning, for instance, or rocks falling from cliffs. But lets limit this to just a few exceptions here and there.

Given these conditions, for a stable population, there will not be a population pyramid, there will be a population cylindar. Every decade will have the same number of people. Say 100,000 from 0 to 9, 100,000 from 10 to 19, 100,000 from 20 to 29, 100,000 from 30 to 39, all the way up. A total stable population of 1,500,000. (feel free to scale the numbers by any factor to get the population size you want). It might tapper off towards the top, say 90,000 from 140 to 149, and then a steep drop-off. Perhaps 10,000 from 150 to 159. People stay perfectly healthy, until they aren't. Death comes suddenly, maybe in their sleep. They just don't wake up. All body systems shut down at once. No more telomeres, everything unravels. (As a bananas-cuckoo-crazzy side bar, google 'telomeres' and right at the top of the list, you will be pleased to know that you can buy them on ebay.)

If essentially everyone lives to reproduction age, say 30, then for a stable population each person can reproduce only one child. If the society is a binary split 50 males to 50 females, then one female can have two children - one for the mother, one for the father. If the people are asexual, then each person can have only one baby. This would be on average, of course, because some might decide to have no children, so their ration would have to be assigned to someone else.

Assuming 20 years from birth to maturity, then most people would spend only 20 years of their 150 raising a child. Perhaps 40, if they reproduced their two children (perfectly binary population) serially instead of in parallel. Perhaps 100 years would be spent either in child-free boredom, or bliss, who knows which. It does beg another question be asked, exactly what would be the puropse of living, if it was not reproducing? Would it become a completely hedonistic society? The up-side is that in a binary society the typical 140 year old would have two children, four grand children, eight great-grand children, and sixteen great-great grandchildren, given 30 years to a generation, if my math is correct. Note that there would be an initial population pyramid until the population stabilized into a cylindar, after one 150 year cycle. That is, the singular baby would go throug 150 years of children and grand children until they died at 150, then each person who died would roughly be replaced by one child who was born.

But exactly what would one DO, for the last 50 years, being able to plan how long they had left to live, almost to the year?

  • $\begingroup$ each person would need to produce TWO children, it take two to tango. $\endgroup$
    – John
    Nov 27, 2020 at 5:39

No, a society cannot be stable without growth

No society can be stable without growth. An aged society is a ticking time bomb because a time will come when there's too few replacement workers in the queue, causing all kinds of problems when there's work to be done.

It's theoretically possible, but impossible from a practical perspective (due to random issues like disease, accident, etc. that brings about the need for redundancy) to have a society that's so balanced that the replacements exactly balance the aging. However, avoiding those random problems requires such high technology that you might as well invoke magic and simply keep everyone from aging at all.

From a very practical perspective, no matter how high your technology, entropy exists. Buildings, tools, and infrastructure ages requiring renewal that an older or aging population cannot perform efficiently (if at all). People need things to do to feel useful and satisfied (meaning new adults need jobs currently held by the older generations). Etc., Etc. What this means is that you always need growth. Perhaps not a lot of growth, but growth, nonetheless.

Which means your society cannot be aged. By definition, it cannot be a utopia unless it is preparing for the workload of future maintenance.

If you want some hard-core insight into the issue of stable societies, check out "The Concept of a Stable Population" from the United Nations.

  • $\begingroup$ Here’s a better link for the UN report you cite, with date (1968), full publication info, and other important context: un.org/en/development/desa/population/publications/manual/model/… The whole topic is a much less settled question than your answer suggests — while plenty of authors (like that UN report) have argued a stable population is impossible or very difficult to achieve, many other serious researchers have argued that it’s achievable with reasonable technology, the right social organisation, and so on. $\endgroup$ Nov 26, 2020 at 9:59
  • $\begingroup$ "It's theoretically possible, but impossible from a practical perspective (due to random issues like disease, accident, etc. that brings about the need for redundancy) to have a society that's so balanced that the replacements exactly balance the aging. " It is only a consideration if those events occur BEFORE the person has reproduced. After reproduction, they are irrelevant to the equation in the long run. $\endgroup$ Nov 26, 2020 at 14:45
  • $\begingroup$ @JustinThymetheSecond Huh? If I die from a random accident, I must be replaced in a perfectly balanced society. If no child is available to replace me due to lack of redundancy.... Your comment doesn't make sense to me. One of the fundamental problems with people trying to (literarily) create stable, non-growing societies is that they ignore a simple reality: people die, often at inconvenient times. Planning for random death without redundancy is, IMO, impossible. $\endgroup$
    – JBH
    Nov 26, 2020 at 16:43
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    $\begingroup$ The population does not have to be expanding only CAPABLE of expanding which any large human population is. the population is not static its being continually replaced at the same rate it is lost, If there is a war mortality rises and people have more children in response. Humans already do this naturally. $\endgroup$
    – John
    Nov 27, 2020 at 5:35
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    $\begingroup$ I had opted to exclude "futuristic technologies" from this utopia, so, at least for this particular question, dementia is still present. All diseases that are treatalbe today would be treated, and all preventable diseases should be prevented as much as it's possible. The question of productivity is much more up to discussion. Any modern society can carry a number of healthy retirees as well as a number of people who need long term medical care. But how high this number can be? $\endgroup$
    – Alexander
    Nov 30, 2020 at 3:08

The answer varies along with the country's ethics. In The Giver, the elderly are usually sent to the House of the Old, which is basically a nursing home. The actual ages are not disclosed, but most of the elderly are treated as children, while the actual responsibilities are given to the presiding rulers. After the elderly become no longer useful, they are killed. In this sense, The Giver is a dystopian, authoritarian ruler. The elderly are not given a chance to continue living and contributing to society.

So it depends, yes there are aged people in the advanced society, but they are often removed or killed, making the average population middle-aged.


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