Is a population of people with eternal youth sustainable?

Question

Alright so in my sci-fi setting, my space faring human civilisation has a widespread procedure that allows humans a very extended time period without any sort aging or its assorted issues (weakening immune systems, organ failure, etc) and basically the body is locked into a state of eternal youth . The procedure is widely available and affordable so there’s no rich/poor divide.

Now the problem is that since everyone is practically immortal and are constantly reproducing with the death rate drastically reduced (people still die from diseases and other causes). The civilisation they live in has FTL and is type 1 in the Kardashev scale and approaching type 2.

Note: they don’t have any mind uploading technology or the like.

What methods can be used to make the population growth manageable without dystopian methods like mass sterilisation or genocide or something like China’s one child policy ?

Edit: they cannot simply expand much further because most of the remaining space is inhabited other civilisation, ones who are truly type 2 civilisations and they don’t want to provoke them.

Edit 2 : there’s also fertility treatments for both males and females that allow their fertility to remain constant throughout their lives (if they choose to take them )

Answer 1

This idea that people with eternal youth would be constantly reproducing is not necessarily accurate; nor is the idea that producing any more than 2 children per couple going to result in population growth. Additionally, China's one child policy has had massive repercussions for the State that are only just now starting to bite.

In reality, population sizes in an enlightened immortal community would tend to police itself, but let's break down why this is the case...

Let's start with reproduction itself. Conceiving the child is fun; raising it for 20 years? Not so much. That's not to say that it's not a rewarding and fulfilling part of your life that you don't look back on with pride and satisfaction, it's just that raising children is hard work, especially in a developed society. It's also damned expensive in that same society.

So, couples who want to raise children will raise a few children, then when those children go off and live their own lives will use their eternal youth to pursue their own interests. Best of both worlds. In today's world, juggling a family, work and personal pursuits is very hard because we have a set amount of time in which to do all these things; that means we have to do them in parallel. Often people choose what they want to do by priority, and discard the lowest priority live choices because they want to focus on what they really care about. In many cases, this means people choose NOT to have children.

Of course, the other reason why some people choose to have children at a given time in their life is their biological clock. They don't know if they want to or not, but time is running out, so to speak. So they take the plunge, 'just in case'.

In an immortal society, the reverse in both cases would be true. Some people would choose to have kids because they can pursue interests largely in serial rather than parallel, and devote a certain amount of time to children, after/before which they pursue other interests. There would also be less impulse choices around children as eternal youth means that there is no 'biological clock' to force a decision at some point.

All that said, some people will still choose not to have children, or will be unable to have children. What that means is that those having children have to have more than 2 to maintain the population, let alone for it to grow. If only half of the population pairs up AND wants children AND can actually have them, then every breeding couple needs to produce 4 children in their lifetime to maintain the existing population size.

To use China as a case study, they told every couple that could and wanted to have kids that they could only produce 1 child. What was the result? Runaway ageing population. China has a serious health and aged care issue today and it's getting acutely worse, where it's predicted that in the next 10-20 years there could be one old person in need of care for every 3 working age people in the country. That's not a healthy ratio.

By comparison, the old age pension in Australia was enacted when there was 1 retiree for ~60 workers; that ratio is decreasing rapidly and as such even Australia is rethinking how we define retirement and social welfare for the elderly, not because of heartlessness, but because of sustainability.

Also, your question assumes that eternal youth doesn't impact a woman's fertility or that it perfectly restores her post-natal body to its pre-natal form. Neither of these assumptions are probable.

The concept of eternal youth is usually predicated on one of two approaches:

1. Slowing down metabolism and cell replication
2. Increasing the effectiveness of cell repair and replication

If you consider the first approach, this means that not only is a woman's body unlikely to recover quickly or well from a pregnancy, but the release of eggs for fertilisation is also likely to be slowed. This means that women would be less fertile in direct proportionality to the increased lifespan. There is also a chance that gestation would take proportionally as long - women who now live 800 years instead of 80 might take around 8 years to bring a baby to term. It also means that women would leave children to the end of their new lifespan because of the impact it would have on their body.

Option 2? Well, increased (even aggressive) cell repair may well impede the female body's ability to maintain a pregnancy as this generates many changes for the woman during the baby coming to term. It may well lead to many miscarriages and the metabolic requirements would mean a massive increase in food intake which would also put massive pressures on the body to process and supply to the baby as well as the mother.

Finally, we're also assuming that children will grow and leave the nest (so to speak) at the same rate in this environment. Assume children grow and mature physically at a normal rate until they're 'given the treatment'; they'll be physically mature by 20 like normal. The problem is, they won't be financially, intellectually or even emotionally mature enough to survive in this culture by themselves. They'll be competing with people who've been productive for centuries, building wealth, experience, skills; it's unlikely they'll be leaving home for decades to come. That alone could inhibit parents from wanting even more children.

Put simply, eternally young mothers would probably have a proportionally higher energy or time cost to reproduction in the first place, limiting childbearing to lifetime numbers similar to what we have now. They may well stay at home longer as well, meaning that people are less willing to take on such a commitment, and even if none of this is true, we still need a critical threshold of more than 2 children per breeding couple to replenish the ranks before we worry about runaway population growth.

Even if all that fails, the best possible thing you can do to limit population increase is education and gender equality. Take a look at the birth rate statistics in developed nations where there is a high degree of education and women participating in the workforce; it's close to zero. In the case of Japan, it's actually decreasing. Australia (for instance) is growing in population ONLY because of immigration. We're not having children at the rate we used do and are barely sustaining existing population counts via that method.

All things considered, while it's important to consider this issue before you release your treatment to the populace, I seriously doubt it's that big an issue for you, especially if your society promotes the value of education and equal opportunities for all. If it does, then your population is going to be too busy being great at what it does to be creating a runaway population size problem to solve.

Answer 2

You have FTL. Why do you need birth control? Space is huge. The majority of the population wouldn't live on Earth.

Between spaceships, space stations and terraformed planets, humanity would be out exploring the stars making new homes for themselves.

The only reason for birth/population control is a lack of resources/space and if you have a viable method of reaching out to the stars, you have no limit on resources.

Answer 3

Some great answers here – want to briefly add my two cents.

The TLDR version is: make contraception the norm (free IUDs for anyone who wants them!), give women full rights over their bodies, and create a more egalitarian society where anyone can have long, successful careers in fields that interest them.

It does depend on how you define 'manageable population growth,' but below are some knobs you might be able to turn without getting dystopian.

Having children is both expensive and dangerous. In fact, pregnancy has always been a leading cause of death for women, especially in poor countries. Combined with the fact that infant mortality has drastically declined with advances in medicine, having a baby in well off countries has become something people do less often simply because they don't need to have 12 kids just to make sure some survive until adulthood.

Moreover, with ubiquitous contraception and control over their bodies, women have more choice in when and how often they have children. In most countries these days, this leads to lower birthrates naturally.

And it makes sense: if you could make an expensive, large commitment with a (relatively) high risk of death anytime in your life, would it be the first thing did? Or would you get some lower risk, lower commitment things out of the way first? Given the profound nature of bringing life into the world, and having another being completely dependent on you, wouldn't you want to take the time to make sure you're ready and able to do it right? Would you want to take this risk often, or only once or twice?

As of 2015, the US birthrate has dropped to the lowest levels in decades, well below 'replacement.' With more access to the things that make that possible, I don't see any reason the downward trend wouldn't continue. Having babies is hard, but in the past, NOT having babies was even harder. Make it easy to not have babies and you're probably most of the way there (again, subject to your definition of 'manageable population growth').

Answer 4

The people who transition from mortal to immortal are the ones who will make kids, but the next generation could be vastly different. Education and upbringing would change as well, there is no 'need' anymore to further the blood line, and less pressure on 'settling'. After all, we have an eternal life now. This would lead to a lot of the newer generation not making kids.

Look to 20 something year olds nowadays. A lot of the people who start with kids do so because after 30 it becomes harder to do. And nearing 40 you get health complications as well. Throw in work life balance and you have a not so lenient time period in which you should have a kid if you want it to work out well.

That time constraint is removed now, there is less pressure and 'drive' to make kids early. People can take their time now, settle down, find the perfect partner.

The people who still make kids are no problem either. In fact, there might be a bigger issue of not having enough people rather than too many. You want to explore and expand the great human empire, and colonies are dangerous. Assuming people can still die by mines collapsing, domes breaking and such. Fatality rates will be high in new colonies, and you need fresh bodies to step in.

Throw in some wars here and there and disasters and I don't think you will have much of a problem.

Answer 5

I love all of these answers and in wishing to add to all the answers, I think in order to keep it from being dystopian is the fact that if as a natural process, you send generation-ships to other planets to explore and to make eco-friendly colonies, then assume that there is going to be accidents and attacks from the natural wildlife and the such as there are bound to be accidents in exploring space. In an utopian society, this would make such population decrease naturally without going with dystopian measures. There is also the increases of technology that needs testers. The rush to get a new invention out would be faster and probably harder not easier as the decades. So testing some prototypes out would not always follow safety guidelines and thus accidents as well will be made there as well.

Then there is the fact that there will be people that, due to being able to live forever, will create a number of lotus-eater type societies. Since time does not matter to people when they get the treatment, there will be groups of people that will not pay attention to time at all. Secluding themselves in their own cities to learn or to achieve personal enlightenment. With eternity at hand, who cares if I leave for a 500 year trip to find myself? Or if someone decides to lock themselves up in their room for a few decades, who really cares? Time in a way is very skewed for this society, what we use to keep time and what we task as important won't be for them. So the very concept of time will be slowly changed. Being considered mature at the age of 20 or 30 will seem like a far-gone idea, with people in their 50's behaving as if they were in their late teens-early 20's.

To sum it all up, time and exploration of space and ideas would cull the population in a natural way without the need for brutal rules to be in place.

Answer 6

Why would overpopulation be an issue for a type 2 civilisation? With the resources of one moderate earth-like planet you could easily support quadrillions of people. When that's all used up, just start mining the next planet. This is all considering the population keeps growing rapidly. Why would people keep getting children? I can imagine most people would get at most 3 children, because of it taking so much time.

Answer 7

I think the biggest question is how fast the average couple gets children vs how fast the society expands across the stars. As the population on a planet/space station/megastructure grows it will reach a point where it starts needing to move its population outwards. With enough encouragement you can get enough population to leave, and preferably relocate an older population that has had children and has less need to have more all to one planet/station/megastructure.

In the meantime, economy would need to be focused on expansion and construction to ensure enough livingspace and food for the evergrowing population.

You can have ways to reduce population and its growth. For example, you can increase the time it takes for people to want children as a part of the eternal youth process/program and/or education and/or deliberate anticonception. If it takes 200 years before people want children instead of 20 to 30 you heavily decellerate growth. You can have the population make the conscious decision to have a limited healthcare so that people have a higher chance to die from accidents or diseases (but with enough care that people dont suffer too much).

Then theres actively reducing the population. For example by fostering the forming of solarsystem nations that might disagree with one another and go to war. This could become a "natural" way to randomly select people to die and cull populations without it being too dystopian like a lottery or something. Other options could be designing the culture around dangerous extreme sports, hunting dangerous game with limited protection or even bloodsports with high prizes and social standing. The bloodsports dont necessarily need to be to the death, but have a relatively high chance of someone dying despite some limited precautions.

Answer 8

Taxes

Currently the United States promotes children by giving tax breaks to families with children. Stop doing that. Instead, families with children have to pay extra taxes. Or even just require that they provide for the children to a certain level. For example, certain educational options must be made available to children and the parent pays (possibly over time).

If a child is indigent, then the parent could be held responsible for upkeep, even after adulthood. Having children on the homeworld is risky. Much safer to have children on a colony. Colonies that are underpopulated would not have the same requirement that parents support indigent children. They don't want to discourage reproduction.

Emigration

The tax revenue can be used to encourage people to emigrate to colonies that need people. Or if that's not enough, it could be a requirement. You can have as many children as you want--if you emigrate to a place that needs population. Otherwise, you will be deported.

If two parents leave, that opens up two visa slots for immigrants. If living on the homeworld is desirable, then the government might auction them. The sale price for the visa might easily be enough to buy three tickets away in case there aren't enough taxes to do so.

No birthright citizenship

In our world, you can't just deport someone for having kids. The parents are citizens and by birth the children are too. So change those laws. If people have children without government sanction, they lose their citizenship and the children never have it.

This doesn't need to be a draconian policy. It's not required for armed soldiers to bust down doors in the middle of the night. It might even be common to give children visas for fifty years or so to allow them time for a decent education. The problem is not finite periods of time. The problem is eternity.

Chances are that most people that want to have children will leave early in this process. By the time of the story, the only people left on Earth are those who do not want children. Everyone else already found a colony.

Answer 9

I think the answer is much simpler, assuming they have total control on their reproduction (simple to achieve compared to eternal youth).

Raising a child is a lot of work, and thanks to eternal youth, can be delayed indefinitely without much risk. It also probably slowly became the norm. That is, if I had a life expectancy of 4 000 years, I might consider conceiving a child after 1 000 years, maybe, depending on the partner. My mother had me when she was 1 200 year old.

That in itself, drastically reduce the exponential explosion. That is, while people might still make as many children in average, if they do so on much bigger time scale, you have an effective birth rate that can match the effective death rate.

Answer 10

Real estate prices.

Unless people can afford to house their children, they'll quickly learn to use contraception to avoid having them as the price of housing will climb incredibly fast. As soon as this technology becomes remotely affordable, real estate prices will skyrocket as the number of homes vacated due to death will plummet.

Answer 11

ANSWER EDITED IN ACCORDANCE TO SPECIFICATIONS OF THE QUESTION

Biological immortality means, at least, that no sickness can get you, since your body already is in overdrive to keep itself in the best cellular and organs' conditions. ONLY a trauma can kill you, but hey, if it's not strong enough you can recover without even antibiotics, your body will work for you, hydrate and close wounds.

Other problem: Brain is not an infinite storage device and, contrarily to urban myths, it is NOT underused. At a certain point, it will begin overwriting memories. A person will not go dement like an Alzheimer's victim, it will just forget slices of life, just like we cannot remember all of our own experiences since we were babies. But no worry, informatics will remember wholesale for ya!

Anyway, since we're talking about a potential, disruptive demographic explosion like there was never before (let's not forget that, just by improving our lifespan of, what, 10%? and with better tech, we've grown to seven billion in a very short time), the only way to avoid turning the world into a barren wasteland is to devote every iota of the global economy to building generational ships.

Planetary colonies won't work: Considering the new rate the global population will be growing, there is simply no time to build stuff, say on Mars, give it time (and a lot of resources) to make it as self-sustainable as possible. Excess people must be sent away on huge spaceships to be built in orbit. If they have FTL propulsion, the Arks will have a chance to arrive to potentially inhabitable planets, but otherwise Earth just becomes a bottle that will fill rapidly to the point of explosion. Simply put, no matter of politics nor redistribution will make up for such a baby boom.

Unless you either start a State-sanctioned culling, or start forcing people not to have kids. Never. Because you can't count anymore on old age to get rid of the previous generations, nor sickness. The only birth tokens avalible to women would be allowed only after there's been a death by trauma (accident, homicide, suicide, etc). In this case, women should be put in a waiting list, much like we do today with transplants, until a slot is free and then she can be artificially inseminated. Such scenario would also offer narrative opportunites for assassinations-for-hire in order to allow a couple to reproduce, for example, but it wouldn't belong to a dystopian variant.

Also, unavoidably, as proven in history, the more people you pack up in a space, the more litigations you get. This could lead to a scenario not unlike John Brunner's "The Sheep Look up".

Answer 12

I didn't do any research on this topic but I thought about it a while, and I think that just not making kids until you are able to die or like 40 years away from death, this would probably stop the population growth especially when combined with the one child policy

Answer 13

People will still need to buy food (or the resources needed to make food). (Either individually, or as part of groups.) People who cannot afford to eat will be less attractive mates to people who want to have more grandchildren. And in difficult circumstances, people will starve.

If your answer to this is "the government will provide a guaranteed minimum income" or "food is a human right", then eventually "the government" will run into a limit for the amount of food it can afford. (At most, a government can afford a fraction of the resources of the group of people it controls.) For examples, consider the Ukraine during the 1930s or Venezuela during the 2010s.