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Two centuries of rapid global population growth will come to an end (ourworldindata.org)
107 points by sohkamyung 29 days ago | hide | past | web | favorite | 148 comments

A major point the article is missing is that after population peak comes population decline. The pattern of "demographic transition" is that as lifespans extend, infant mortality declines, and lifestyles change the birthrate drops. But it doesn't drop just to replacement rate, it drops much below replacement rate.

Most developed countries are in this state now where their population would be declining but for immigration.

When today's fast-growing countries reach the same point in their demographic transitions, the whole world's population will enter decline.

This could happen even earlier than around 2100 when the UN estimates; other demographers are forecasting a date more like 2065. [1]

What will the economics be of a world in population decline? How will culture and policies change to eventually stabilise the decline? Lots of questions...

[1] Lutz et al 2018 : https://ec.europa.eu/jrc/sites/jrcsh/files/lutz_et_al_2018_d...

Kevin Kelly talked about this issue a while ago. He points to the Amish as a counter example to general population decline.


A major point the article is missing is that after population peak comes population decline. The pattern of "demographic transition" is that as lifespans extend, infant mortality declines, and lifestyles change the birthrate drops. But it doesn't drop just to replacement rate, it drops much below replacement rate.

Great. Better to have it happen through declining birth rates than through natural disaster, pandemic, starvation, etc.

Those are not exclusive, you know that, right?

On the contrary, a shrinking population is much more likely not to be able to manage those issues.

Or an aging population.

When I was in college some of the profs offered extra credit if you wanted to go bag sand for major flooding about an hour away (a nice way to let people go home and help their family and friends).

Strong backs and enthusiasm are good for augmenting the experts in a disaster recovery situation.

Additionally the data points for the low-fertility countries are extremely reliable, while the data for the few countries with supposedely rapidly expanding population is only guesswork.

Most of the projected population increase in Africa is based upon a small number of countries like Nigeria, where most of the people live on the countryside, and there never have been reliable census to accurately predict the future population.

The only thing we know is that Africans moving to cities stop having many children, and that the fertlity rate in the richer African areas is rapidly decreasing. In Northern and Southern Africa the fertlity rate is already below 2.5, approaching sub-replacement levels. [1]

Which means it is definitely possible that the entire world will be entering sub-replacement level in the coming decades.

Unfortunately the African coutries with a high-fertility projection haven an interest in lying about their numbers, because it means more NGO money and political influence. [2]

The country with the lowest fertility rate in the world is South Korea, which has a fertility rate of <1. [3] South-Korea is facing extinction. [4]

Additionally there are hints that China is lying about their population numbers as well. [5]

India, which is the most populated country in the world, has already fallen to sub-replacement levels in almost all counties, and stands at a fertility rate of 2.2, as of 2017. [6]

[1] https://ourworldindata.org/fertility-rate

[2] https://qz.com/africa/1221472/the-story-of-how-nigerias-cens...

[3] https://www.theguardian.com/world/2018/sep/03/south-koreas-f...

[4] https://www.businessinsider.com/south-koreans-could-be-extin...

[5] https://timesofindia.indiatimes.com/world/china/china-has-be...

[6] https://en.wikipedia.org/wiki/List_of_states_and_union_terri...

With the current climate path we're on, catastrophic collapse of many ecosystems will likely accelerate the decline of the population.

I got a somewhat useful answer to this question over on economics stack exchange which could help people find related research.


It's always fun to answer multiple choice quizzes like this. Work out what point they're trying to make and go from 0/2 to 10/13.

I'm not informed, as the quiz result suggests, I just spotted the pattern.

Yep, I scored 12/13 and the only reason I missed one is because my pessimism briefly overrode the obviousness I’d the quiz’s bias.

More importantly, the numbers are rough and in a few cases I had an off by one issue. (E.g. I know global median life expectancy is around 65 years, quiz shows 60 and 70 and asks after an average. Or the question about educated women in low income countries where I know it's roughly about half and test showed 40% and 60%, or being out by half billion in map question between Asia and Africa. Duh.)

Do you feel the assumption that all countries will follow the same pattern may be incorrect? Would it be possible to achieve high GDP and yet still maintain a high birth rate?

Things aren't quite this simple because developed nations don't act as homogeneous wholes. The trends we see on the international level are followed within nations themselves and even down to the state, county, and city level. For instance this [1] is a graph of US income vs fertility. People who are earning substantial amounts of money are, like you said, simply not not reproducing enough to maintain their population. Yet people people who cannot even afford to feed themselves, let alone any children, are reproducing rapidly. The birth rate of those earning less than $10k is nearly 50% higher than those earning more than $200k per year. And the gradient between these two is somewhat disconcertingly smooth.

Religion is another factor that plays into birth rates. Muslims, for instance, have extremely high fertility rates and that stays true even once they migrate to developed nations. For instance the Muslim fertility rate in North America is about 2.7. It's also why the Muslim population is expected to increase 70% by 2060 whereas the number of unaffiliated is expected to increase by 3%, Buddhists decrease by 7%, and so on. [2] Those number increases are not affected by conversion which plays a roughly net zero role in Islam with about 25% of people leaving the religion, and 25% joining it.

So what you're looking at is more of a demographic switch than an economic one. People who are highly educated, secular, and high income will gradually die off, failing to replace themselves. At the same time individuals of lower income and those who place less value on education and more on religion will continue to increase in numbers well beyond replacement. Basically, so long as there is at least one group within a nation that consistently produces in excess of replacement, they will eventually replace any and every group that does not. And, in the longrun, that group will also guarantee that, over time, the population (local, nation, and world) will also continue to increase. So we'll see a population peak, a demographic swap paired with a population decline, and then a return to a growing population - likely with vastly different norms and values as a society than we have today.


Of course my analysis is also flawed because it assumes no revolutionary change in the norms of today. These range from the unpleasant to consider such as changes to welfare systems, to the highly pleasant to consider such as the possibility of expanding our populations outward with the colonization of new planets and space in general. But ultimately, I do not see longterm population decline as probable in any scenario.

Your article also affirms this hypothesis. For instance in their prediction graph they show that Sweden will now, even with 0 migration, see consistent population growth. Sweden is simply playing out this scenario in fast forward due to a very small population paired with high migration rates which did little than accelerate the rate of demographic replacement. E.g. in the 90s Sweden's population was less than 9 million and with negative fertility rates, they were starting to see population declines. Then enter the migrations and now their population is greater than 10 million and their population is now back to growing, even without any more migration.

[1] - https://www.statista.com/statistics/241530/birth-rate-by-fam...

[2] - https://www.pewresearch.org/fact-tank/2017/04/06/why-muslims...

Related to that, I highly recommend Factfulness[1]. You can try to answer 13 a/b/c questions here[2]. Most educated people score lower than if they would have just chosen answers randomly. It's really hard to discuss population and poverty if most people worldview is so skewed.

Btw, I've been wondering how population stabilization (it pretty much already stabilized in the US and EU) will influence real estate. Historically real estate have been a remarkably good investment. But historically population kept growing pretty fast. I'd love to hear some thoughts or recommended reading on that topic.

1. https://www.goodreads.com/book/show/34890015-factfulness

2. http://forms.gapminder.org/s3/test-2018

I can't imagine a factor of an economy, including property prices, that wouldn't be strongly effected by population stability.

What happens to wages? Inflation? Energy? Companies? The share market? ...aged care?

Absolutely fascinating stuff.

What currently happens is that wages start to follow the same sigmoid trend. So does energy use per capital.

Shares are too volatile to even predict in long term.

Aged care, not enough data for a conclusion.

Wow, I just took the quiz and it was rather enlightening. I ended up scoring reasonably well (9/13), but only because getting the first few wrong taught me to stop taking such a dismal view of the world. If I hadn't been shown the correct answers until the end, I probably would have done even worse. I might have to look into that book!

Oh, I didn't realize it shows answers right away. Previous version didn't do that. 9/13 would have been a great score.

edit: I've changed the link to a test that doesn't mark correct answers right away, previous link: http://factfulnessquiz.com/

The two versions of the quiz claim different correct answers for the population of the continents question.

Huh, indeed, factfulnessquiz.com seems to be selecting wrong answer as correct even though they list correct answer correctly on http://factfulnessquiz.com/answers

Pretty serious given that there are only 13 questions and that's what the whole website is about. They didn't even leave any contact. I'll send an email to gapminder.

Nice catch, and a really bad job from whoever made the quiz website. Triple checking those answers should be a priority.

Comparing to the answer I just looked up in the print version of the book (and double checking on google) the http://factfulnessquiz.com/ is incorrect on this point.

I scored 54% and all of the cases that I err'd were due to the reality being slightly better than I thought. That makes me think that to pass this test you do what I am not going to tell you now...

I scored 38% and I turned out to be pessimistic on all counts. Perhaps it is time to give Steven Pinker's Enlightenment Now a read.

Investment: I personally think about that. The area I live in is popular due to a good nearby university so I think population will grow at least for the next decade.

But in a time frame of 30-60 years... I'm not counting on getting the money back for my house.

I got 11/13. It helped that I recently did a study of education vs gender vs country development using Worldbank data for a data analytics course.

(Interesting result : in many regions women have high rates of post secondary education than men.)

There are massive issues with the calculation of poverty designed to give the illusion of progress under globalized production chains. In reality, the metric is completely disconnected from what people identify as poverty. The entire premise is flawed. See: Steve Pinker for an example of this technique in use.

Have you read Factfulness? He is very explicit about what he means with his different levels of income and changes in poverty - using examples of physical situation, not mere money. (Like at what point in the cycle do you own shoes? Can afford a bicycle? Have running water? What do these things mean for your income potential in the future, or that of your children?) Dr Rosling worked for much of his life as a health care provider in the poorest places on Earth, and was intimately familiar with what real poverty looks like, in all its details.

Yes, and I think it’s a boneheaded and disingenuous argument. Much, if not most, of the world is blatantly in poverty and cannot afford a quality standard of living. Comparing it to a world with equitable wealth distribution would be much better. This is how the western world justifies open exploitation.

That's the bias of privilege talking.

Going from $2/day to $8/day may not seem like much to you, but to someone at that level, their income has quadrupled. They might have access to a bicycle to get to a paying job now. Shoes. Clean water. School for their children, so the next generation has more opportunity. Go from $8 to $32 (using Rosling's quadruplings here), and you now have a car, potable hot and cold water from a tap, even the possibility of college for your kids. It's still "poverty" to us, but not all poverty is the same. Understanding this is a shift in perspective, and requires putting down our wealthy, western privilege for a moment.

Keep in mind, too, that a world of no health care, no clean water, no literacy, etc - the extreme poverty of the poorest nations - was the situation in much of Europe during the 19th century. It took Europe a long time to get to where it is today, and much of the progress happened in the post WWII, post colonial era. "Open exploitation" is not what you think it is, not anymore.

As I've pointed out elsewhere, much of the world has seen income increases from 20x-100x per capita in the past 50 years. That's the poor, "exploited" countries.

Economic change takes time. Generations. The fact that we wiped out two thirds of the world's extreme poverty isn't "boneheaded", it's incredible. But it will take several more generations to get the rest of the world up to the standards of our privilege.

As I said, marginal improvements are used to justify ruthless exploitation.

I have a hard time thinking of the 20x improvement in Egypt or the 100x improvement in China (or similar gains elsewhere) as "marginal improvements". We're talking orders of magnitude improvements in standard of living over the course of a couple of generations.

I don't know what you're expecting. Someone snaps their fingers and everything is magically "fair"?

> quality standard of living

How do you define this standard?

> equitable wealth distribution would be much better.

Let me present you with two scenarios, all else being equal, and you tell me in which one people are better off:

1: Every one makes the equivalent of $5,000 a year.

2: 90% of the population makes $20,000 a year and the remaining 10% make $100,000.

> This is how the western world justifies open exploitation.

Can you quantify this exploitation?

Except in Africa. The population is expected to double until 2050 and potentially double again by 2100.[1]

[1] https://uk.reuters.com/article/uk-health-global-gates/africa...

As Hans Rosling pointed out in Factfulness, the birth and literacy rates in Sweden in the 19th century were on par with the poorest of African countries today, resulting in fully 20% of the population becoming refugees in North America to escape famine. And today, 150 years later, it's... Sweden. The ideal of modern civilization. He said he was born in "Egypt", by which he meant the economy of Sweden in the late 1940s was similar to Egypt today.

With that in mind, is there any reason that the poor countries of Africa today can't be the Sweden of tomorrow? It's more irrational to say they'll stay poor and overpopulated than it is to say they'll become wealthy and modern with zero population growth.

Sweden has 10 million people, Egypt has 100 million.

Egypt doesn't have the resources or space to grow to a Swedish standard of living.

Egypt's per capita income grew over 20x from 1965 to 2015. And consider the population increase that happened over the same period. The overall GDP (constant US dollars) grew from $5B to around $335B.

Don't give me that "They can't do it" nonsense.

It's a water-scarce country that is the seventh largest food importer; much of the population lives in the Nile delta.

Swedes have a huge country and increased from a very small population to a relatively small population.

The resource constraints are different; you can't have infinite growth in every country.


Egypt is the cradle of civilization. The Nile hasn't gone anywhere. As soon as they get their heads out their asses and let farmers own farms rather than military cronies, they'll be able to feed themselves again.

cradle of civilization doesn't have much to do with resource constraints or the realities of Egypt's ability to reach a Swedish level of consumption.

No, see, "cradle of civilization" is exactly about resource constraints. They have water and sunlight and good soil, and those are the resources needed for agriculture. People living in Egypt and running short on grain is a temporary condition that condemns their government not a permanent one that condemns their land.

That's okay, because the population density of Africa is very low (it's comparable to that of the Americas, much less than Europe/Asia)[1], it's currently only 15% of the world's population[2], and Africa is an enormous continent[3] the fact of which the Mercator projection distorts[4].

[1][2] https://www.geolounge.com/continents-population-density/

[3] https://io9.gizmodo.com/africas-true-size-will-blow-you-away...

[4] http://www.petersmap.com/

It's an enormous continent, but a lot of it is covered by deserts and other inhospitable environments

You're right there, however I'm afraid the issue won't be density but a much different issue: Unemployment. [1] Reason this could be a worldwide issue is the opportunity cost. Can we afford not to have a billion or more minds on board to solve some of the worlds most pressing problems? China is trying its best to industrialize and capitalize on the growth. But many are claiming their tactics are almost neocolonialist. [2]

[1] https://mo.ibrahim.foundation/news/2018/african-governance-p... [2] https://www.nytimes.com/2017/05/02/magazine/is-china-the-wor...

Such long term predictions have relatively little value due to the sensitivity to the initial inputs. Any small deviation from reality will result in a huge deviation in the longer term and 80 years is much too long to predict with any accuracy.

Typically the only useful info you can get out of such long term studies is the sign of the change and the order of magnitude.

This is absolutely incorrect, and you have no idea what you are talking about. There is no sensitive chaotic model behind this, it's completely straightforward dynamics.

The fertility rate is about 2 kids per woman now. But the generation of 20 year olds is much larger than the generation of 40 year olds. So even though the generation of 0 year olds is the same size as that of 20 year olds, in 20 years time we will have replaced a small 40 year old generation by a large 20 year old generation.

There are only two factors here: Fertility rate per woman, and death rate. This prediction is not terribly sensitive to either, and both are easy to measure accurately and on quite stable long term trajectories:


> There is no sensitive chaotic model behind this, it's completely straightforward dynamics.

Sorry for the poor choice of words, no chaotic model was implied or intended.

> Fertility rate per woman, and death rate.

No, there is also technological development, wars and so on. So any prediction that looks 80 years out that only looks at fertility rate and death rate is going to be found wanting. It's a bit long for a long bet, but I'd be more than happy to take one for a 30% or more deviation from the prediction.

The degree to which people are willing to believe simplistic models without further qualification is astounding to me, given the past 80 years in development of medical technology, electronics and our ability to wage war any predictions about the next 80 years should come with huge error bars. And that's before we get into the consequences of Climate change.

> No, there is also technological development, wars and so on.

Which have an effect on fertility and death rate. There is literally nothing that matters to population dynamics other than fertility and death rate.

We have extensive experience on that now: Technological and social development drives fertility to at or below replacement levels rapidly. This is the main factor. Importantly though, _this is not a prediction_. This reduction has already happened. So the bulk of the prediction is just playing out the consequences of developments we've already seen.

Of course major events like climate change have the potential to invalidate this prediction. But that doesn't mean this prediction is useless. And this is would not be due to "sensitivity to initial inputs".

> Which have an effect on fertility and death rate.

Yes, but given that they are unknowns you can't just extrapolate from the presently available data and call it a day.

> But that doesn't mean this prediction is useless.

It's an open door that the world population will stabilize at some point, it is also an open door that the speed with which the world population is increasing itself is reducing. It has to, simply because more affluent people will have fewer children because they are not looking at their children as their source of income when they are themselves unable to generate any. Children as a pension scheme is a very common thing still, but that is fortunately changing.

> And this is would not be due to "sensitivity to initial inputs".

To a degree it is: any error in the predictions for the next couple of years will result in a much larger error in the future, simply because of the fact that population increase is a non-linear affair to begin with, and that any med-tech development that causes people to live longer will also cause a large increase in the number of people alive at any one moment.

Compounded those two could have an enormous effect.

For reference, the world, 80 years ago, so just before WWII had only 2.2 billion people.

> Children as a pension scheme is a very common thing still, but that is fortunately changing.

It is still the case, just on a larger scale.

Good point.

beat 28 days ago [flagged]

It's more likely the rate of birth rate decrease will increase, rather than decrease. The countries hitting birth rate decreases over the last 50 years are seeing birth rate drops in a generation that took a century in Europe - and remember, not that long ago, Europe once had birth rates, illiteracy rates, and poverty as high as the poorest countries in the world today.

Moreover, the major causes of birth rate decrease, like vaccination and refrigeration (which strongly impacts food supply), aren't going away. Look at a country with a high birth rate today, and you'll still find people walking for miles with buckets full of the day's water for their household. And anywhere that indoor plumbing and clean tap water is universal, the birth rate is down to replacement level. There are fundamental causes for birth rate decrease, and they're not going away.

Frankly, I think you're clinging emotionally to the Malthusian model, not rationally.

I would argue that the primary mechanism is cultural changes effecting the fertility rate. Japan suffers a declining population not because of its technology, but because of its culture. Population growth rate peaked in 1968. Up until 1968, lots of evidence social scientists had to work with indicated that technological and social advancement increased the fertility rate (notwithstanding life expectancy changes and rich vs poor countries). Just because cultural changes over the past 51 years have been toward lower birth rates, does not mean that this will continue.

You cannot predict the direction that culture will change. Any predictions I make about this are extremely speculative, but it is easily imaginable that 20 years from now the zeitgeist reacts against the corpus of current culture to be more family-oriented. Think about how much you hear people complain against "the machine." Whether it's on r/latestagecapitalism, or r/the_donald, everyone hates the piss out of broad society, and may find solace in tight-knit families.

There's nothing "cultural" about birth rates. Raising children is hard, sex feels good, given the option to have sex and not have children, most people choose to have sex and not raise children.

Atheist women choose not to have children, christian women choose not to, muslim women choose not to.

Give people the option not to have children, remove the stigma and maybe they have 1-2 children, but no more.

Given how many single people there are, how tight the fertility window is for women who have careers, how tight schedules are in big cities, how expensive it is to have children today, there's nothing we can reasonably do to increase birth rates.

You state that there is nothing cultural about birth rates and then list several cultural factors influencing birth rates. And then you state that there is nothing we can reasonably do to increase birth rates, even though most of the factors you mentioned are not set in stone.

I'm not even sure what you are trying to say.

I don't think the person being replied to necessarily meant that, but cultural is often used in this context as a racist term, as in: "Africans will always have many kids, it's their culture", where before the more overtly racist "nature" might have been used.

The implication being that the cultures of (some) people are unchanging and fixed. I think you'd agree with a statement like: Cultures and family values do change all the time, due to a variety of factors like better medical care, and economic empowerment, in reasonably predictable ways.

So it's not unchanging cultural differences between Africa and Europe that drive the different fertility rates, but rather different socio-economic factors that drive a different family culture. Changing the socio-economic factors will change the culture surrounding families, just as much in Africa as it did in Europe, the Middle East, Asia, etc... at various times in the last century and a half.

My argument was that all modern, technologically advanced civilizations will face these exact issues, so there is no point in calling those factors "cultural", because cultural facts are meant to distinguish between cultures.

I'm sure an alien species or a computer simulation having a few of the same basic drives as humans do (sex is very pleasurable, contraception exists, raising educated children is extremely expensive and hard, state provides pensions in old age, people are free to have or not to have children, child mortality is low, work provides money, money satisfies needs, quality work is abundant only in high density cities and a coupe of others) will arrive at same fertility problem we have arriven at.

My second point was that there is nothing we can reasonably do without a major overhaul of human traits or shutting down the technological advanced world we live in.

Look at the error bars for the U.N. estimates. 95% chance between 9 billion and 13 billion 80 years from now is not exactly a narrow band. https://population.un.org/wpp/Graphs/Probabilistic/POP/TOT/9...

One extreme unknown is global life expectancy. New diseases, or new cures for existing diseases can make a huge difference. Add in wars, economic growth, and a host of other factors making long term estimates are hard. Just consider how accurate past population estimates have been.


> Just consider how accurate past population estimates have been.

Uh, fairly accurate as far as I know? There were always bad extrapolations and naive papers and articles, but the state of the art predictions didn't do badly, especially after data quality improved.

Also, again, the major driver for the predicted dynamics is the collapse in fertility rate that has already happened, and no longer needs to be predicted. This is a vastly simpler question now than it was in the 70s.

Look at this graph:


Of course in 1970 it's almost impossible to predict how quickly Asia will experience the cultural, economic and technological changes that reduced the fertility in Europe dramatically over the previous century. Today the transition towards small family sizes has happened. We still have drift (as we see in Europe too) but the important major driver of going from roughly 6 children per woman to 2 children per woman has happened. So the biggest uncertainty factor in old forecasts is gone.

The 10 year forecast for U.N. population made in 1990 was off by 3.3%.

They have gotten fairly close with long term estimates a few times, but a poor track record for predicting deviations from existing trends.

Actually my reading is that the uncertainty here is driven entirely mostly the uncertainty in the fertility rate. People living longer has a relatively linear effect on population, fertility is much stronger. By eyeball this uncertainty projection for fertility seems extremely high, given the relatively smooth and predictable decline we've seen in the past [1]:


I spend a bit of time looking for the publications underlying this model right now, but couldn't find any.

But accepting the error bars doesn't change the story. Which is that this isn't that much of a prediction. The main driver behind the population dynamics of the next century is the decline in fertility that has already happened.

It's not a highly uncertain prediction that can turn out to be vastly different based on minor changes in the initial conditions.

But if we underestimate the decline of fertility in Africa (where it is changing the most at the moment [2]) over the next decade or two it could easily end up being off by 10% or more.

It's all fairly predictable.

[1] For example the 95th percentile prediction sees a sudden bump in Asia, taking it up to fertility levels not seen since the early 2000s by the mid 2020s, despite a perfectly smooth decline since: https://population.un.org/wpp/Graphs/Probabilistic/FERT/TOT/...

[2] https://population.un.org/wpp/Graphs/Probabilistic/FERT/TOT/...

On it’s own WWII killed off around 3% of the world population. The plague may have reduced the world population from an estimated 450 million to 350–375 million in the 14th century.

Long term estimates need to consider such black swans as a real possibility. Relative amounts of war and disease in Africa over the next 20 years will have a real impact.

Remember as the power dynamics shift, the action will too. In 30 years what’s left of Pax Americana will be done. Much of existing US Naval and Air power will have attritted away. Asia/Africa will be the battleground.

As those countries get more powerful and develop nuclear, the consequences of conflict get nastier. Things like restricting water supply bring back old style 20th century slaughter.

Less than 2 in most developed countries if you don’t count the newly minted citizens.

It could be that we are approaching a great filter: "when an intelligent species has the freedom to decouple the great incentive for reproduction (sexual pleasure) from the actual reproduction, it turns out individuals choose not to reproduce, which leads to the collapse of the whole civilization"

it might actually save our species to have lower population as it will slow resource depletion

From what I understand people are having less sex period.

I guess its some combination of women's lib (women more likely to say no to sex, relationships and children, wanting careers), people working more (side hustles are now a thing), and there now being more things to do (you can now socialise on the internet without actually meeting anyone).

Sperm counts in men are on decline as well. There might be some environmental factor.

Great sci fi novel here

Where is this from?

https://wikipedia.org/wiki/Great_Filter is a question intended to inspire a wide variety of possible answers like this one.

The fact that fertility is heritable makes an end to population growth unlikely.


That is interesting.

But I wonder how the model would be affected by, say, the mass availability of a significant longevity increase, brought about by some sort of medical breakthrough?

Since people would presumably not use that extra time to have more children (they aren’t time-limited now), the result would just be a linear increase in population. The important part here is the change from the exponential models of Malthus etc.

> they aren’t time-limited now

They mostly are actually. Barring the occasional exception there is a definite 20-40 or so age band where most females that have children will have them. This is in part because of society and custom and in part for very valid medical reasons, the chances of children having birth defects go up quite fast past the age of 35.

I think that 'IAmEveryone likely means that people aren't lifetime-limited. Most people aren't reproducing after 40, but expected lifespan is much more than that so even if it doubled there wouldn't be more children.

There are several factors here: the age at which people realistically will still want children and the fact that they themselves will simply be alive for a longer time.

Medical breakthroughs tend to affect the latter rather than the former more, though the fact that people live longer has an effect on the age at which they start with having children. In my grandparents generation it wasn't rare for 19 year olds to be married and to have their first child on the way, my parents generation had their children when approaching 30 (on average), and the present day generation has their first child later still. There is some correlation here with education levels and of course from country to country there are still huge differences but overall those seem to be the trends.

So a significant longevity increase brought about by a medical breakthrough will likely cause people to have their children at an even later age (with all the associated risks, possibly resulting in much more screening), somewhat offsetting the effect of those people themselves being alive for longer.

Social security would be a real problem, especially if the time that people could work productively would not increase at the same rate as the longevity.

That depends on the kind of longevity.

- If it's "stay old longer" then yeah, that's a problem (most of our present advances are this since they don't address ageing, just save people from its consequences).

- If it's "stay young longer (or indefinitely)" that will change a lot of assumptions. But it might also make people put off children until really late, like, "if you're less than 100 why are you even considering being a parent?"

Stay young longer is SF, stay old longer is already happening.

Stay young longer is near-future and clearly-approaching tech. It won't be one magical longevity treatment, it will be a number of closely linked medical breakthroughs and resulting therapies in stem cell replenishment, senescent cell clearing, amyloid clearing, etc. Many of which are in the pipeline, not clinical yet, but active research.

Google: the SENS research foundation.

"Stay young longer" is healthy lifestyle and a bit of personal responsibility.

Basically the problem of ageing is a gradual accumulation of "damage" of assorted kinds. An ideal regimen of exercise and diet and non-stressful life and so forth can reduce the rate but not to zero. Thus, even healthy people get old and die.

Actual therapies would go in and undo the damage, not stop it accumulating, but clean the existing damage down to a level where ageing symptoms would be reset back by decades. And could be repeated, leading to indefinite lifespans.

Yes, of course, I agree with you. However, the quote I was replying to had the word "longer", and not the word "forever" in it. And that's exactly what healthy lifestyle gives you - not miracles, but a definite increase in quality of life, and prolongation of the active part of it.

The downvotes to my comment above amused me, there are apparently people in denial here. :)

These predictions are laughable because they ignore the fact that fertility, like everything else, is heritable.

The people who aren't reproducing will die out. The people who are reproducing will do so, and their kids will keep reproducing too. These are separate sub-groups of the population.

As a very simple example, the Amish population doubles roughly every 20 years because of their high and early birth rates. It's not hard to calculate that there will be billions of them within a few centuries because of the power of exponential growth.

Any analysis which doesn't separate sub-groups by fertility, or handle the heritability of fertility, is meaningless.

All we're in now is a temporary state caused by rapid introduction of birth control and porn and other such technologies which suppress fertility. No different from hitting a bacterial colony with a drug that stops 90% of them from reproducing. It reverses growth for a few generations, but the logic of evolution and exponential growth always wins in the end and the population hits its carrying capacity once again. Which for humanity with modern tech, is going to be a very, very ugly situation.

It's far more likely that the Amish will have disappeared altogether in "a few centuries" than that they will number in the "billions". There is no Amish gene.

"rate of boiling off of young Amish each generation might act like truncation selection in favor being Amish, whatever that might be"



“[T]he difference in mean AQ [‘amishness’] between young Amish men and their non-Amish neighbors is about 2.8 standard deviations. In the IQ world this would correspond to a group different of 42 points. In the stature world this would correspond to a height difference of about 8 inches.”

You can just flatly assert that, but it'd be more interesting if you supported your assertion with some kind of argument. What exactly do you think is going to dissolve the Amish that didn't do so already? Do you not think fertility is heritable, and if not, how not?

Also, who said anything about genes? Sub-groups can be separated by culture, religion, genetics, or any combination of the above. Amish are separated by all 3.

Religiosity is also linked to genetics; this is scientifically established (though not totally proven yet).

Not the person you're replying to, but I'll give a hypothetical argument. The Amish have an extremely successful culture right now because their society positions them advantageously versus the predominant culture. Their practices are excellent for building strong communities and providing efficient, effective mutual aid in a form that is lacking in society at large; and unlike what most people think of the Amish, they do adopt some modern technology, but only that which strengthens the community.

As the Amish community grows, they will face the same challenges faced by all growing, successful "challenger" cultures: envy and resentment, followed by active undermining of their culture and attempts at assimilation through popular media, fashion, and a hostile legislative environment. (This presents itself as a sort of "embrace, extend, extinguish" effect, with the end product being ethnic restaurants and kitsch once the culture has been fully digested.)

The Amish may be able to adapt to face this challenge, but what often happens is that the process of adaptation ruins the good and unique things about the culture, and the assimilation happens anyway. Cultures that resist this effect stay small by necessity.

An example of a culture recently reaching this "breakout" point where pushback is encountered is the Hasidic community in New York. A good example of a culture that is left alone due to its small size is the Sikh-American community. An example of a fully digested culture is the Italian-American community, which no longer exists as a separate identity.

Well I'm not saying the Amish are "successful" in any sense of morality or human flourishing; I'm making no claim on that. I'm just saying they multiply fast. Not a judgment, just an observation.

I agree the pathway would definitely change. You'd see pushback. It's not like the Amish will be 300 million in their exact current format.

So let's say that does happen and the Amish start getting targeted for "embrace, extend, extinguish", or some variation of semi-forced immigration and assimilation.

Amish aren't homogenous. Some of them would be taken by this, assimilate, and drop birth rates. Some would not. Whatever characteristics made that last part not assimilate would then get replicated into a larger and larger population share. And the process continues.

We may see several phases of this, but at the conclusion of the process, the evolutionary logic leads to a certain result: A population who are absolutely, totally immune to any influence that would assimilate them into a negative-birthrate culture. And that population will rapidly expand until it hits physical limits.

The reason I think this is inevitable is because evolution is relentlessly adaptable, while the countermeasures are fairly static. It's like a new antibiotic. Even if it works really well, the bacteria's evolutionary process will just keep trying and trying until it finds a new replication pathway. The replicators can adapt forever while the force that is stopping them cannot.

A thoughtful response, and I think you are right in that not every Amish sub-community would be assimilated. This is already happening; there was a chapter in Kevin Kelly's "What Technology Wants" that describes the differing perspectives within the different Amish communities on things such as technology. There are some Amish communities that resist almost all modern tech; these communities are probably more likely to stay small over time (hard to attract and keep members), but I imagine they are also less likely to be absorbed into modern society than the rest of the Amish population. To me, it appears that some sub-subcultures manage to maintain their identities by putting up huge barriers to entry; the more costly they are (in terms of personal sacrifice), the more likely that the culture will maintain its identity, up to a certain point.

Robin Hanson has described this a fair amount as well. Some cultures have a "price of admission" that can't be easily faked (I forget his term for this) in order to protect their group resources against disloyal outsiders who may take advantage of the group. This explains a lot of the bizarre, contradictory, and otherwise illogical practices that you see in these insular cultures.

Exactly- they work well as a niche in a safe country providing police and guarded by a massive military.

But a country of Amish? They'd be conquered in a day.

I flatly assert that the Amish are like the thousands of other weird "traditionalist" isolationist minority subcultures who have existed throughout human history. None of those ever made it to "billions" either, and lots of them were even more pro-procreation than the Amish. If the Amish were a larger population, they'd have to mingle more with the rest of us. They make a big deal about their rumspringa, but their culture will not survive repeated mingling. Video games are fun. Tinder is fun. Air conditioning is comfortable. Let the robots pick the turnips.

>> This new equilibrium is different from the one in the past when it was the very high mortality that kept population growth in check. In the new balance it will be low fertility keeps population changes small.

What is the reason for low fertility prediction?

Poverty decrease: https://en.wikipedia.org/wiki/Income_and_fertility

Well it's a simplification. Better education also correlates with lower fertility.

And yes, I'm not showing causation. But anti-conception does require some basic money and education.

Culture. It's principally cultural not biological. It's perhaps clearer to say it is a decrease in fecundity rather than fertility.

Worldwide experience has been that increasingly developed nations have lower average fecundity. There are various likely reasons but the correlation seems to be quite robust. In most countries it seems that the causal link was from development to fertility. It is arguable that China reversed the causation, politically limiting fecundity.

This is a uniquely human dynamic. Pretty much every other species in the world drives its population to its Malthusian limit.

Higher standards of living?

Excessive taxes and expensive housing. In much of Europe it is simply impossible to buy a house on a single income, if you obey 100% of tax laws. These taxes are used to pay for the elderly, their welfare (pensions) and healthcare.

If you are in the US you may not appreciate how heavy the tax burden is in Europe. It varies by country but its normally something like: 30% payroll tax paid by employer. 30% income tax paid by you. 20% sales tax paid by you. Then, very expensive housing due to the high population densities and limited room to expand.

Additionally in Europe, many parents want their children to be educated in English, however the language of instruction is usually the local language. This is partly why the migrant stream into the Anglosphere is so high. The alternative are private international schools, which are hideously expensive.

Much of Europa has very cheap houses because populations are declining. It's just in large cities that real estate is becoming expensive.

And just like the US the jobs, education and culture are in the cities.

Housing in a second-tier Polish city is more expensive than Chicago!



Horribly wrong

The population decline projected follows a similar % drop versus time as the Black Plague.


This is one of the major cause of the destruction of the environment we're seeing globally.

All forecasts predict another 60% (!!) increase in global population before it stabilises.

Forget about banning plastic straws or flying less (which are feel-good measures more than anything else) with such numbers... We need to take dramatic and effective steps.

There are 80 years left until the end of the century. This increase is far from being inevitable! But, again, we prefer to ignore these key issues and focus on marginal, feel-good measures instead.

This increase is essentially unavoidable at this point in time. It happens despite the fact that fertile couples now only reproduce at replacement rate. But older smaller generations get replaced by larger younger generations. There is a multi decadal lag in population dynamics.

Why forget about the easiest steps if we need dramatic ones?

Why should rich people continue to fly around the world while you try implementing big restrictions on everyone? This makes no sense.

Perhaps you meant "In addition to bans on (...), we need dramatic measures"? Also, suggesting some steps would help understand how stronger your proposals are.

People are flying around the world trying to figure out how to supply people like you solar pannels, wind turbines and batteries. Enviomental solutions require a suppy chain, R & D and new factories.

roca 29 days ago [flagged]

Perhaps you didn't read the article, because its main point is that the official UN forecast is for world population to essentially flatten out at 10.9B around 2100, which is 40% more than today, not 60%.

11B from 7B is a 60% increase... But that's the usual sterile nitpicking. Do you want to argue about decimal points or address the actual point?

The important point is that this is a large increase when we already cannot manage now.

"we already cannot manage now."

Correction: we don't want to manage now. The world has far more than enough wealth and resources to hold climate change to 2 degrees and to stop clear cutting rain forests.

Point of order: 2 degrees of climate change will still be disastrous https://www.rifters.com/crawl/?p=8433

We can and do manage now, thank you very much. Poverty is decreasing at an incredible rate around the globe; education is increasing at an incredible rate. We've made the world's knowledge available to virtually everyone via in the internet just in the time I've been an adult. We've eradicated diseases that once killed millions every year.

Two thirds of the global extreme poverty (defined by the World Bank as about $1.80/day in current dollars) has been eradicated in just the past two decades.

We're doing awesome.

We also have about ten years of carbon budget left if we want to avoid the worst climate change yet our emission rate is still increasing. Permafrost is already melting much faster than the pessimistic models assumed, so it might already be too late to prevent the release of the absurd amount of carbon locked in the ice.

I was obviously not writing about poverty but about our impact on the planet and the environment...

I expect to see fossil fuel use as a major energy source eradicated within my lifetime. The planet is just fine; it's our own living environment we need to worry about. Earth has survived worse things than mere humans.

10.9/7.53 = 1.45, but that 10.9 has high error bars. The U.N. estimation is a 80% chance it’s between 10 and 12 Billion in 80 years. https://population.un.org/wpp/Graphs/Probabilistic/POP/TOT/9...

That’s quite a bit of uncertainty to make any real definitive statements beyond continuing growth expected.

As a point of comparison, the global population has almost quadrupled in the previous 80 years. So even in the worst case scenario, population growth is dropping spectacularly.

Absolutely, the trends seem very obvious. The global population is unlikely to double in the next 100 years.

I am mostly simply reacting to people trying to use specific estimates.


> These regions are marked by ideologies or interpretations of it that are hostile to women, and poor infrastructure.

> We need to shift 100% of our foreign aid to education, contraception and abortion for women.

You're essentially advocating for colonialism. Not every culture is the same and some do not want abortion, for example. It's not the west's role to forcibly import our culture into other countries just to lower their birth rate to that of our's (which is too low, not even replacement level).

They can do what they want, but the planet can't sustain large population growth anymore

I have no idea what metrics you're looking at to support that argument (Malthusianism has been debunked by the way) but the fact that their population keeps growing proves that you are incorrect.

Malthus wasn't debunked. The planet doesn't have the resources to both provide a high standard of living and continual population growth. There are physical limitations to how much food we can grow.

Saying growing populations disprove Malthus is like saying since smoking one cigarette didn't cause cancer, cancer from smoking is a myth.

> Saying growing populations disprove Malthus is like saying since smoking one cigarette didn't cause cancer, cancer from smoking is a myth.

No, because people who smoke do die from cancer. The earth has never hit a hard limit on how many people it can support. We are no where near the physical limit of how much food we can grow. Not even close (hence the actual population gain that only slows due to cultural changes and not resource limits).

That article doesn't say anything about the carrying capacity of the earth. Of course it can't, since no one knows what the actual carrying capacity is. All we know is that we've never hit it, that we can produce much more food (you'll see lack of food is not mentioned as a threat), that every time someone has predicted overpopulation they've been wrong and that technology keeps bumping the ceiling up.

Again, the population of third world countries keeps increasing rapidly. They have no problem with population growth. We in the first world have a population problem but that's because we're not reproducing at replacement rates.

How can you even argue that we can have infinite growth in a finite world?

I didn't say infinite growth. I said we're nowhere near the ceiling.

And you know this how...?

It's actually on the people who say that we're near the ceiling to prove that statement since it deviates from our current situation. I will say that the lack of growth in populations of 3rd world countries is proof enough. It's not like one day you wake up and millions of people get wiped out, a slowdown happens first. That hasn't happened.

Wow. So much wrong.

News items like these are then used as fodder for higher immigration limits so that the liberal parties keep getting elected further, even as they enjoy less and less support from their already existing citizens.

Actually, almost all of the democratic acts in the West lately (don't mistake the echo chambers which one of us is submitted to in social networks for the will of the majority), show a clear support for parties that - amongst other things - want higher immigration limits.

EU parliament elections, EU local elections, USA presidentials, Brazil, and the list goes on.

I should clarify, I meant: higher numerical intake limits for immigrants to developed countries.

Basically, most of the liberal parties have found this "hack" to win elections. Where they wouldn't be able to win elections normally, they simply keep importing more and more people, and these immigrants reliably vote for these parties. Eventually, these places end up becoming one party states. Consider the case of California as an example.

It's quite an indictment of the democratic processes.

The liberal parties that are suffering across the globe with the rise of "surprise" popularist right parties and politicians (and to a lesser extent increasing environmental awareness)?

It's how the democratic process is suppose to work, there is nothing "abnormal" about it. In the US at least, immigrants come here and eventually get to take part in the political system like everyone else. It's been happening for hundreds of years.

The only thing I could think that would make it seem abnormal to you is the demographic of the immigrants.

But, liberal parties have been loosing an awfull lot of elections lately, clearly this is no "hack" to win elections because it is not working as you state.

It's their ideology and it is up to the democratic process to judge it (favorably or unfavorably). And - although personally I favor controlled immigration only - it is perfectly healthy for a democracy to have parties that defend and present other perspectives.

> clearly this is no "hack" to win elections because it is not working as you state.

Like I just said, it's working extremely reliably. Look at California, the opposition is decimated there not by the merit of liberal parties work or argument but by the sheer number of immigrant votes. Granted there is a delay factor such that new immigrants can't vote but the mechanism of immigrants voting for liberal party is still at work.

This is just for state level, I predict something similar happening at Federal level elections in a 1-2 election cycle period. Trump election was an exception IMO.

I think GP meant with "higher immigration limits" : less restrictions on immigration.

There is always the doomsday argument: we should expect a significant population decline in the near future in order to justify the statistical typicality of our present day existence.

This data should mandatory in all school curricula throughout the world. One of the greatest impediments to understanding the social reality of the world around us is the general population's ignorance of this data.

We need people to (a) understand that the world's population is increasing but that the rate of increase will inexorably slow and that (b) this means that the population will plateau. We then need people to ask themselves can the Earth support that level of population of 11 billion. The answer is an incontrovertible "yes". Anybody who claims the Earth cannot support 11 billion people is factually incorrect. Is it going to cause environmental stress? Yes. Will it cause environmental collapse? No.

People also fail to understand this other simple fact. Even though there will be more mouths to feed, there will be more hands to make the food. And given economies of scale, it'll arguably be easier to feed 11 billion than 7 billion.

I would love to see a citation for 11 billion people not causing an environmental collapse.

At our current population 40% of insects could be extinct in the coming decades, and over the last 50 years 60% of animal populations have been wiped out: https://www.cnn.com/2019/02/22/health/food-biodiversity-repo...

Species extinction and animal population decline is not the same thing as environmental collapse.

edit: To clarify, people say that we have exceeded the carrying capacity of the Earth or that we'll exceed it as the population mushrooms. This data proves the population won't mushroom, and I assert that 11 billion is well within the carrying capacity of the Earth. Do I have any proof? No. But neither do the doomsayers who claim otherwise. That's the specific narrative I'm trying to push back against.

what do you think is the environment? we can't survive without biodiversity

We both know what the environment is.

What you meant to say is that we can't survive below some threshold of biodiversity. Nobody's talking about zero biodiversity. What do you think that threshold is? I think we can survive (and the environment will be okay with) less biodiversity. How much less that turns out to be I guess we're going to find out.

Citation that it will rather than the typical conjecture?

The accelerating rate of extinction outlined in the latest UN biodiversity report, out last month: https://www.ipbes.net/news/Media-Release-Global-Assessment

Again. I'm not talking about species extinction or even the rate of species extinction. I'm asking for a citation for environmental collapse.

Finding such a citation depends on what you call an ecological collapse. In 2019 we have an environment where global indicators of ecosystem extent have declined by 47% from baseline. If the stock market lost 47% of its value in 150 years, it would be in a state of ongoing collapse. 85% of wetlands were lost between 1700 and 2000- I would certainly say that is an ecological collapse.

A 50% increase in people means a 50% decrease in wildlife. (at least it has in the past).

Never seen that stat, but a decrease in wildlife is not the same thing as environmental collapse which is the doomsday narrative I'm trying to counter-signal.

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