Demographic Transition and Minimalism

[NecronLord]

So, this comes up often enough on this board that it's worth having a dedicated discussion.

Complaints of Minimalism in the context of Star Wars makes sense, Star Wars is a massive Space Opera, inspired by EE Smith and Asimov, in the context of works that were being written before human geography really tended to predict any slow down in human reproduction rate; humans, and near humans, would spread out with ever increasing population because that's a sensible extrapolation from the boom of the industrial era. Or when discussing the warhammer setting, where cities are routinely dozens to a continent miles-high cindercones of industrial decay where people sleep in hab-rooms seven foot long. When you're trying to work out a population for Coruscant or Trantor or Hive Primus then often this implies that numbers of people must be very high indeed - these are settings where we have a lot of facts that indicate high populations should be the norm.

But it occasionally gets thrown around as a criticism of smaller populations in things like Star Trek, for instance we sometimes say it's silly or implausible that say, Centauri Prime has a population of only three billion or that the Federation only has a few hundred starships, or that all the Time Lords could live in a few domed cities. The thing is, these settings often have nothing in particular that indicates that they should be especially numerous.

There's no concrete fact that forces human population to expand, populations in the real world tend to grow or decline based on the ratio of children replacing each generation; throughout most of history we have had populations with a rate of children surviving to adulthood of greater than two per woman, but this is hasn't remained so; several real world populations have experienced a decline since the 60s and the introduction of reliable contraception, comparatively easy vasectomy old-age security programmes, and other factors that have reduced the number of children per family and increased the number of childless couples.

The Demographic Transition Model of human population, which predicts this, isn't necessarily universal and it doesn't mean that a far future population can't have a high population - some versions have a population that returns to a slow rise with a sufficiently high human development - e.g. when people have the time and resources to raise more children they tend to do so, and this can't account for major changes in population that aren't seen in the real world, e.g. immortality/resurrection, the use of cloning or something like that, but I'd contend it's worth considering.

With a reproduction rate anywhere below 1 child per person, after centuries - for Centauri Prime, for instance, or Romulus in ST Picard - billions of people might be expected, millions of years of a rate near to 1/per person and you end up with things like Stargate Atlantis' Ancients having had relatively few city-ships their civilization was based on, or the Time Lords living on one planet with a few cities, looking positively reasonable. These cultures might have no reason to build ringworlds or thousands of starships, especially if those ships aren't totally automated.

Is there any pressing reason that we should expect any space opera to have huge populations in the future?

[Jub]

I think we need to factor in the why of current slow growth rates in modern capitalist 1st world nations and see if they apply to sci-fi settings.

1) Career focused women. If having a child harms your career you're more likely to put off having a child until later in your life which may lead to fewer children being born.

2) Finances. My generation isn't having kids because we simly cannot afford to have them with how expensive basic costs are and how depressed wages are.

3) Environmental Concerns. Many people, especially in the west, have fears of overpopulation and seek to minimize their own impact by having fewer children.

4) Better sexual education. We're having fewer accidental pregnancies these days due to better access to contraceptives and better edcation about why using them is important.

I'm sure there are more I'm missing but you'd need to check this sort of list against your projected setting and see which pressures towards fewer children make sense and which ones may have been solved or otherwise made less impactful.

For example, the first issue might be solved with drastically increased healthy lives. If we managed to age two or three times more slowly it wouldn't be such a career hit for a woman to have a family between her 20's and 50's knowing she'll still have more time to focus on a career in her later years. We could even push a loss of fertility back indefinately and allow couples to have healthy children well into what we currently consider retirement where they have the time and resources to best care for them.

[chimericoncogene]

Mathematics suggests that at the same approximate technology level, larger, growing polities should outcompete negative-growth polities and swamp them into irrelevance. History suggests that if negative-growth polities try to assert negative-growth policies, the larger polity should win the ensuing wars (or force the other polities to grow).

Nonetheless, there are many reasons why this is not necessarily so. A vast number of reasons (convoluted, straightforward, or otherwise) can be used to explain away growth, just as we can always come up with more reasons to explain the Fermi Paradox. Likewise, a myriad of reasons can be used to justify supermaximalist positions for many settings. After all, at Chinese population growth rates, the human population will exceed the total mass of the galaxy (in grams, including dark matter) in 20,000 years, so there are no physical or logical objections to exceedingly large populations.

At the end of the day, most of the space operas and space fantasies above were not rigorously worldbuilt - they were thrown together to suit the story by persons who did not care too much about the details. Nor do we have sufficient hard data on astronomical phenomena, alien societies. or a long enough baseline of our own civilization to explain the Fermi Paradox.

With limited data to go on, headcanon and speculation are limitless, and hypotheses become unfalsifiable. Such is the corollary to Occam's Razor, especially when the issue at hand is not a matter of truth, but of preference.

As for future mass-consumption space opera, current cultural trends (particularly the devaluation of rapid economic growth and industrialization in popular culture) suggest that "small is beautiful" has won the memetic war for now (TBH, small imaginations meant that is always had the upper hand), and will probably dominate in the short and medium term. Not sure about how Asian, African, Middle Eastern, and Indian science fiction will go, though.

[NecronLord]

I'm sure there are more I'm missing but you'd need to check this sort of list against your projected setting and see which pressures towards fewer children make sense and which ones may have been solved or otherwise made less impactful.

For example, the first issue might be solved with drastically increased healthy lives. If we managed to age two or three times more slowly it wouldn't be such a career hit for a woman to have a family between her 20's and 50's knowing she'll still have more time to focus on a career in her later years. We could even push a loss of fertility back indefinately and allow couples to have healthy children well into what we currently consider retirement where they have the time and resources to best care for them.

This is true enough, though of course for live action settings it's quite rare to present a future without senseance broadly similar to our own, no matter how likely some kind of anti-agathic should be. Though you can get a high HDI with a positive and a negative growth rate, so there's certainly no need to have such things, social factors can put the numbers up after all, e.g. the USA vs Europe.

Mathematics suggests that at the same approximate technology level, larger, growing polities should outcompete negative-growth polities and swamp them into irrelevance. History suggests that if negative-growth polities try to assert negative-growth policies, the larger polity should win the ensuing wars (or force the other polities to grow).

It's a little myopic to focus on wars, but even the most "patriotic" or war-obsessed governments (hello Russia) aren't necessarily able to reliably coax their population to expand in the modern era.

Nonetheless, there are many reasons why this is not necessarily so. A vast number of reasons (convoluted, straightforward, or otherwise) can be used to explain away growth, just as we can always come up with more reasons to explain the Fermi Paradox. Likewise, a myriad of reasons can be used to justify supermaximalist positions for many settings. After all, at Chinese population growth rates, the human population will exceed the total mass of the galaxy (in grams, including dark matter) in 20,000 years, so there are no physical or logical objections to exceedingly large populations.

Is this the 80s? China is an example of a demograhpic transition country and China's next demographic problem is to cope with a major dip in its population.

For one discussion, or another - note that now the Chinese government is outright paying couples (at least from preferred ethnic groups!) to have second children to address the future population shrinkage and the attendant too-many-old-people problem.

At the end of the day, most of the space operas and space fantasies above were not rigorously worldbuilt - they were thrown together to suit the story by persons who did not care too much about the details. Nor do we have sufficient hard data on astronomical phenomena, alien societies. or a long enough baseline of our own civilization to explain the Fermi Paradox.

One thing I didn't mention was the suggestion that that might actually be a decent explanation for the Fermi Paradox; that information chatter and large scale industrial works might trend out of fashion in future societies.

Perhaps the spell of time in which a culture of biological origin has numbers in the teeming billions is typically only a few millennia long and after that they settle down into a long slow existence for millions of years with millions of people.

But it's a little off topic.

With limited data to go on, headcanon and speculation are limitless, and hypotheses become unfalsifiable. Such is the corollary to Occam's Razor, especially when the issue at hand is not a matter of truth, but of preference.

As for future mass-consumption space opera, current cultural trends (particularly the devaluation of rapid economic growth and industrialization in popular culture) suggest that "small is beautiful" has won the memetic war for now (TBH, small imaginations meant that is always had the upper hand), and will probably dominate in the short and medium term. Not sure about how Asian, African, Middle Eastern, and Indian science fiction will go, though.

It's not a matter of truth indeed, but you seem to operate on the assumption that the only possible futurism is endless population growth and that things like say, Star Trek are actually implausible because of this? There's no proof that Demographic Transition will become universal and that the real future will be small, but there's also no solid proof that it won't be.

To take a look at some UN figures...


Breakdown by continent

And that's the near future; in a thousand years we could end up with millions of humans total, there's no reason to assume that there must be vast populations, if the lower projections are correct we might end up far more like Stargate Atlantis than Coruscant.

[Starglider]

Over significant time spans natural selection will come into play. We're not talking millions of years either; transition of say apes into humans (say) took that long because the available selection pressure was spread out over a large number of complex traits that all had to progress down separate, but co-dependent incremental paths. When offspring survival is highly likely and the choice of whether to have kids (and how young / how many) is the primary determining factor in offspring count, then selection pressure is highly focused on any genetic traits that influence that choice. Extenting female fetility to older ages is also now seeing intense selection pressure. Thus in a sustained population decline (thousands of years; they may be measurable effects after only hundreds of years) we'd expect people with poor impulse control, excess affection for baby-like faces, higher likelihood to release multiple eggs resulting in twins etc etc to breed more and these traits to rapidly increase in prominence. Transhumanist technologies (up to and including exowombs and imortality treatments) will blunt the impact of this but not eliminate it, unless total control of the genome is achieved and applied to suppress selection of these traits.

[bilateralrope]

just as we can always come up with more reasons to explain the Fermi Paradox.

Not that we need new ones. Not when our current means of detecting extrasolar life need it to be pretty close to us.

[NecronLord]

Over significant time spans natural selection will come into play. We're not talking millions of years either; transition of say apes into humans (say) took that long because the available selection pressure was spread out over a large number of complex traits that all had to progress down separate, but co-dependent incremental paths. When offspring survival is highly likely and the choice of whether to have kids (and how young / how many) is the primary determining factor in offspring count, then selection pressure is highly focused on any genetic traits that influence that choice. Extenting female fetility to older ages is also now seeing intense selection pressure. Thus in a sustained population decline (thousands of years; they may be measurable effects after only hundreds of years) we'd expect people with poor impulse control, excess affection for baby-like faces, higher likelihood to release multiple eggs resulting in twins etc etc to breed more and these traits to rapidly increase in prominence. Transhumanist technologies (up to and including exowombs and imortality treatments) will blunt the impact of this but not eliminate it, unless total control of the genome is achieved and applied to suppress selection of these traits.

I'd grant that perforce, with things like the Ancients or Time Lords some kind of genetic control is clearly at play to stop them changing substantially in their physical forms over million-year timescales. The point about selection pressures eventually favouring people who have more offspring is actually a really good one, though of course not guaranteed, one only needs to look at giant pandas to prove that there won't necessarily be a high-fecundity gene lurking there to appear and save the population, so I think we can still say small future populations are realistic even beyond the medium term.

[chimericoncogene]

It's a little myopic to focus on wars, but even the most "patriotic" or war-obsessed governments (hello Russia) aren't necessarily able to reliably coax their population to expand in the modern era.

Is this the 80s? China is an example of a demograhpic transition country and China's next demographic problem is to cope with a major dip in its population.

For one discussion, or another - note that now the Chinese government is outright paying couples (at least from preferred ethnic groups!) to have second children to address the future population shrinkage and the attendant too-many-old-people problem.
One thing I didn't mention was the suggestion that that might actually be a decent explanation for the Fermi Paradox; that information chatter and large scale industrial works might trend out of fashion in future societies.

Perhaps the spell of time in which a culture of biological origin has numbers in the teeming billions is typically only a few millennia long and after that they settle down into a long slow existence for millions of years with millions of people.

But it's a little off topic.

It's not a matter of truth indeed, but you seem to operate on the assumption that the only possible futurism is endless population growth and that things like say, Star Trek are actually implausible because of this? There's no proof that Demographic Transition will become universal and that the real future will be small, but there's also no solid proof that it won't be.

To take a look at some UN figures...

[Don't quote pics ~ NL]
Breakdown by continent

And that's the near future; in a thousand years we could end up with millions of humans total, there's no reason to assume that there must be vast populations, if the lower projections are correct we might end up far more like Stargate Atlantis than Coruscant.

NecronLord;

Star Trek isn’t unrealistic because of its scale – five hundred years in the future, the world population is still in the billions. Population growth isn’t that fast.

Star Trek (and all of soft sci-fi) is unrealistic because it’s too human, too understandable. Weird technologies of which we only have an inkling of will advance faster than spaceflight, and enforce great changes to the human condition within a few short centuries (the transhumanists say less, they’re a bit silly). By the time we’re talking about manned missions to Pluto or interstellar missions or whatnot in two to five centuries, the crew will probably be very “weird” indeed – possibly even uploaded to software.

The Fermi Paradox is highly, highly relevant to this discussion. The reasons we are worried about the Fermi Paradox - the reason it was considered a logical paradox, a perplexing and unexpected phenomenon - are the exact same reasons for maximalism - the power of compound interest and natural selection.

Chinese population growth rates in 2017 were 0.5% pa. 1 billion x 1.005^10,000 = 4 nonillion, 4 x 10^30 (Star Wars had 20k years of history in canon for comparison, WH 40k has 40,000 years). I picked China because as you mentioned, this is not an impressive population growth rate. Of course, it's dropping yearly, but US population growth is also at 0.5% pa. If you divide the growth % by 5, the time to reach the same population rises by about the same factor – so at 0.1% pa, there will be 5 nonillion Chinese in the year 52,000.

The Solar System masses about two nonillion kilograms, so obviously there are limits to growth. Also, the "people" will probably no longer be modern humans, so whatever.

What is proposed here – demographic transitions, uploading to the cloud, etc, etc – are variations on the Great Filter theme; that is, many or most societies will change in a way that makes them invisible and/or small. We can only speculate (both for fiction and the Fermi Paradox) because we have bad data and tiny baselines.

The traditional counter to Great Filters (even in sequence) is this: If one critter gets past the filters, decides not to upload to the cloud, leaves its tech behind to run amok – and it’s not just evolution – you can have AI machines, paperclip maximizers, rogue factories whatever – the galaxy gets overrun with critters, paperclip maximizers, transhumans, or beserker-mutants in ten million years, even with slow interstellar travel. Why? Growth! See the calc above. In another 50,000 years, at 0.1%pa, the mass of Chinese people might exceed the mass of the observable universe. Back in the 80s, they were speculating about self-replicating factories with a doubling time of a year.

Thusly, because things that make more of themselves just dominate the numbers pool, the galaxy should be filled with aliens or their constructs.

The same logic that applies galactically applies within a species (and its constructs). If some subsegment grows, everyone else has to either stop them or they will grow out of control. If they need to stop them, at some point that’s war. And everyone has to expend resources and grow to wage war.

This is why I prefer light speed cages – too much population growth creates expansion fronts that exceed the speed of light, the civ implodes and kills everyone in a bunch of giant wars; the bubbles rise from the ashes, rinse and repeat. Live by growth, die by growth. Freeze growth and stay home... well, you're invisible. Heck, with paperclip maximizers, the bubble may be as small as a single solar system.

Obviously, the light-speed cage is well and truly broken by faster than light transport, which is why you would kinda expect FTL societies to be asymptotic (until the galaxy/universe burns in a giant war of population growth)…

Another reason I believe intergalactic FTL to be impossible. If it were possible, aliens would have conquered the universe and turned it into alien biomass ages ago.

[Starglider]

The point about selection pressures eventually favouring people who have more offspring is actually a really good one, though of course not guaranteed, one only needs to look at giant pandas to prove that there won't necessarily be a high-fecundity gene lurking there to appear and save the population,

Pandas are a special case; they're trying to act like herbivores without having a properly adapted reproductive system, which imposes a severe nutrient bottleneck. Panda reproduction is (most likely) well-optimised for their niche/habitat/protein uptake constraints, it's not like they don't have the genetic variety available for say larger litters (like other bears), it's that for pandas in particular that would actually reduce the total number of offspring surviving to adulthood. Also, mating drive being suppressed by captivity is essentially random chance / bad luck for any endangered species; there wasn't any significant selection pressure on this until extremely recently, and even then only for animals going through multiple generations of captive breeding.

The low rate of twins in humans is similarly due to human pregnancy being really draining and dangerous (compared to other mammals) due to large head size, high (relative) birth weight, bipedalism etc; technological intervention to reduce the risk moves the optimum upward, and natural selection will eventually adjust for that.

[NecronLord]

NecronLord;

Star Trek isn’t unrealistic because of its scale – five hundred years in the future, the world population is still in the billions. Population growth isn’t that fast.

[snip off-topic]

Chinese population growth rates in 2017 were 0.5% pa. 1 billion x 1.005^10,000 = 4 nonillion, 4 x 10^30 (Star Wars had 20k years of history in canon for comparison, WH 40k has 40,000 years). I picked China because as you mentioned, this is not an impressive population growth rate. Of course, it's dropping yearly, but US population growth is also at 0.5% pa. If you divide the growth % by 5, the time to reach the same population rises by about the same factor – so at 0.1% pa, there will be 5 nonillion Chinese in the year 52,000.
[...]

Another reason I believe intergalactic FTL to be impossible. If it were possible, aliens would have conquered the universe and turned it into alien biomass ages ago.

And this is exactly the thinking I'm critiquing; you said in short order that yes, these population growth rates can reduce, then continue to assume they'll be static for tens of thousands of years because... yeah, no reason.

[Broomstick]

Over significant time spans natural selection will come into play.

Yes, but I'm not sure the "natural selection" cheerleading section is really focusing on the right thing.

Natural selection isn't really about how many offspring YOU have, it's how many your kids have - your grand-offspring. This is why not everything is an r-selector. Humans are K selectors, although our population explosion over the last, oh, 12,000-20,000 years has somewhat obscured this.

Our hunter-gatherer ancestors, in addition to the constraints you already mentioned, also took steps to limit their population. They didn't sit down and think it out methodically, but infanticide was practiced to help space births out, as were customs such as nursing women being taboo for men to touch, even in a few cases polyandry. Hunter-gatherer women, to the extent we can study this, had fewer children than women in agricultural societies. There are other instances of humans limiting populations even with agriculture in the Pacific islands where, again, both infanticide and taboo came into play. Where that didn't happen you sometimes got populations that crashed hard (see Rapa Nui).

So, first, I question that population growth is the "natural state" of humanity. We are certainly capable of rapid expansion, but we are not obligated towards it. Unlike animals, we also use culture and intelligence to modify both our environment and our actions. When humans really comprehend they have limited resources (whether that is the limit of a nomadic woman in how many children she could carry, or an island with limited food and space) they act to control their reproductive rate. That is just as natural to humans as unrestrained reproduction.

I could certainly see humanity trending towards putting more resources into fewer children - many people are already choosing that which is why we seldom see families with more than 2-4 children in the Western world and in China there was a draconian mandate for a generation that was even more restrictive.

If there is no FTL and populations are largely limited to the planet they're born on I could see customs and policies that control population size. If FTL ever becomes cheap AND there are resources (either habitable planets or cheap-but-secure space habitats) then look for a population explosion as a species has the territory into which to expand rapidly. Rinse and repeat for various other factors.

Because humans, even at this point, have more conscious control over their reproduction than other organisms we also have more flexibility to choose the path we're on, and change that path when expedient.

[Guardsman Bass]

Even in poor countries with limited economic growth, we're seeing a downward trend in fertility rates (as best as we can tell - obviously our data gets poorer once you go back more than a few decades in a bunch of places). That makes me suspect that high birth rates in the past had more to do with limited access to effective contraception and high early childhood mortality rates than anything else, and as soon as that started no longer being as much the case in most places the fertility rate dropped.

That said, population will still go up over time if overall births exceed deaths, and you could get those massive SF populations if you're setting it in the Year 40,000 or the like. Other things could make it more likely, like people having more children because they're nearly immortal, or because you can grow humans in artificial wombs and raise them well with human-like robots for new branch societies off-world, or the like.

I'm not so convinced on the whole "faster breeding sub-societies eventually come out on top" factor. Amish birth rates are still high compared to overall US birth rates, but they've been going down as well. High fertility subcultures tend to converge on the fertility rates of the broader society the bigger they get.

Or when discussing the warhammer setting, where cities are routinely dozens to a continent miles-high cindercones of industrial decay where people sleep in hab-rooms seven foot long.

Not many people seem to live in space habitats in Warhammer 40K, although they've got the technology to build and maintain them if they're building and maintaining those massive hive cities. I just chalk it up to the relative age of the franchise.

[chimericoncogene]

And this is exactly the thinking I'm critiquing; you said in short order that yes, these population growth rates can reduce, then continue to assume they'll be static for tens of thousands of years because... yeah, no reason.

Necron, you're asking the wrong question (or maybe I'm answering a different one).

Of course population control is enforceable, given sufficient resources and willpower and political control. Of course there are a vast number of probable situations that cause terrestrial populations to slowly revert to stone age levels. It's probable even that most advanced civilizations across the universe suffer from economic and cultural factors that lead to demographic collapse, and that this partially accounts for the Fermi Paradox.

The question is whether populations MUST, in all cases including weird transhumanist ones with self replicating paperclip factories and copy pasting human uploads, stop growing. And that is a question of resource and expansion rate limits, not of desires and 21st century human specific cultural and economic phenomena. The light speed barrier is one possible hard limit to population growth (some have after all proposed disassembling the Sun and nearby stars to build habitats for zillions of uploaded humans). Without the light speed barrier, as in soft sci fi, the limits to growth are taken off.

There is no specific reason soft sci fi must succumb to demographic retarding pressures, but no specific reason it must grow exponentially either. Both are possible.

[chimericoncogene]

Is there any pressing reason that we should expect *any* space opera to have huge populations in the future?

To recheck the question.

No. Not all space operas must be expected to have huge populations in the future.

But some space operas can have huge populations in the future because the limits to growth including the light-speed cage are removed by faster-than-light travel.

The real future may have huge populations despite current demographic and economic trends because those pressures may change as you mentioned above, also weird transhumanist entities may emerge from humanity with different demographic and economic pressures over the next 100,000 years.

[Jub]

One factor that seems to have been missed is that it only takes a small fraction of your population to drive your growth rate through the roof. This assumes that you have a place to put them and that such a population is self sustaining, but those are requirements for any extra Sol colony so we're going to assume they're met. Extras like conquering aging, cloning, uploading, AI workers, etc. can all speed up this growth.

Let's start with an initial population 10 billion people in a system and say that all but 1 million of they have agreed to keep the population growth flat. The flat breeds buck the trend by doubling their population every 10 years and they have the industrial base and raw materials to build new habitats to match this growth rate. How long does it take them to match or exceed the initial starting population of the starting system?

Y: 1 million
Y+10: 2 million
Y+20: 4 million
Y+30: 8 million
Y+40: 16 million
Y+50: 32 million
Y+60: 64 million
Y+70: 128 million
Y+80: 256 million
Y+90: 512 million
Y+100: 1 billion
Y+110: 2 billion
Y+120: 4 billion
Y+130: 8 billion
Y+140: 16 billion

I think we can all agree that 140 years to increase to over 10 billion is achievable and it doesn't take much imagination to picture a system in which this can happen much more rapidly and where each new body is essential immortal. Thus, in works where populations are low we need an explanation for why no such splinter group ever formed and why they haven't dominated the other groups.

[Broomstick]

Thus, in works where populations are low we need an explanation for why no such splinter group ever formed and why they haven't dominated the other groups.

The first one that comes to mind is a religious-based war of extermination. Or politically based. Ideology of your choice.

Just because a species is advanced (however you define that) does not mean they are nice or tolerant.

[Jub]

The first one that comes to mind is a religious-based war of extermination. Or politically based. Ideology of your choice.

Just because a species is advanced (however you define that) does not mean they are nice or tolerant.

True, but does that still hold for settings where the first colonies were done via non-FTL means? I ask because in this case such a colony could outgrow the system that sent it before they can effectively police it. There's also the case where there is, for lack of a better term, dead space between 'interesting' systems. You may set up a few navigation beacons and a communications relay so stranded ships can call for help, but are most settings really going to station military personnel there so nobody can setup a colony? I ask because it doesn't take a lot of time and only a relatively small space to set off a population bomb.

EDIT: To be clear, it's not that you can't actively have population supression in a setting. I'm merely saying that such supression would probably need to be so integral to the setting that it would be obvious that it was ocuring and not something nerds like us would need to speculate on.