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This isn’t anomalous or recency bias. You go back in history and everyone who makes predictions similar to Ehrlich about population crashes have been wrong. Malthus was saying the same things 150 years earlier and there were others before him and in between.

Every bacteria in the Petri dish doubles each generation, until it doesn’t.

It really doesn’t seem like a winning bet (other than fear mongering popularity), because you’re unlikely to be right, and when you are things seem to be falling apart. See also Peak Oil.

However, birth rates in most of the world (except Africa, SE Asia, and India by a bit) are falling below replacement. Many are looking at this as a good thing (exponentials can’t go on forever), and there are the contrarians, but being at the edge of a long term exponential transition is dangerous. There are many cultural and economic systems that have worked the way they do and grown to be dominant because of the exponential growth. People will continue to hope and believe long after things become obvious (see climate change). See also Moore’s Law.

> But a more data-oriented approach will still get people to the conclusion that we're on the clock until billions of people starve to death.

You’ve piqued my interest, where can I read about this data oriented approach that leads to this conclusion?

Most people live in cities [0] and requires ~2,000 k/cal a day. The systems required to feed people are complex and energy demanding. There are 8 billion humans which is a large number relative to the amount of food we can store.

It is a matter of time until we have a multi-billion person famine. Hopefully multiple centuries away if the transition away from oil to something else works out. Something like the year without summer [1] could be even more catastrophic, for example. Or wars, particularly of the nuclear variety.

[0] https://en.wikipedia.org/wiki/Urbanization

[1] https://en.wikipedia.org/wiki/Year_Without_a_Summer

The problem with such prediction is that it presumes that the population would grow at a accelerating pace, while the opposite is happening.

For me it's not about population growth so much as societal risk; our current population is only sustainable due to a complex web of interdependent systems.

How often do complex societies break down or decline in such a way that the complex systems which keep our urban populations alive are compromised?

The more people we have, also the more people we have available to keep these systems running and figure out new replacements. Assuming the caloric ‘profit margin’ stays positive anyway.

The Netherlands managed to dramatically raise crop yields after WWII by intensive farming methods like building a massive amount of greenhouses. The crop yield per hectare is insane as a result. It was as a response to WWII that this system of farming was adopted.

So if we reach a point of mass starvation many counties will adopt similar strategies and drastically raise crop yields.

https://news.ycombinator.com/item?id=33763087

It is a tradeoff though, crop yield is one thing, but most of the produce from the NL is bland, tasteless, full of chemicals, something that would have been considered unsuitable for human consumption earlier, and achieved at a cost of great environmental degradation.

That’s true, intensively farming in a small country will come with serious downsides. But if it’s a choice between starvation vs mass producing bland food and creating pollution, there is only one choice to make.

> most of the produce from the NL is bland

Credible Citation needed.

> full of chemicals

So what? You're also full of chemicals.

> something that would have been considered unsuitable for human consumption earlier

Actually our standards for consumption have gone up a lot. People used to eat all sorts of stuff when danger of starving was higher and population was poorer.

We seem to be so far past breakeven food/water/warmth that most of our efforts are spent getting all sorts of other stuff, though?

It's recent, I'll grant you that. I can't even think of when there was rationing in the west? Shortly after the war? At least the current grandparent generation seems to have childhood memories of that.

But to me, it looks like we've figured out those basic necessities to the point where at least ordinary variation in harvest won't be making us hungry. You could call that being noise proof.

The danger is that we systematically alter how the planet works, so that is not just bumps in annual crop yields, which we also seem to be doing, but it's not clear that we've messed up our basic necessities pipeline yet. It's also not clear that we'll inevitably do that.

One risk is that our systems are now extremely efficient, and one aspect of efficiency is that it tends to eliminate “unnecessary” buffers and stockpiles. Just-in-time manufacturing pulls supplies in response to demand. The global food supply chain still has buffers and stockpiles (e.g. grain bins) due to the seasonality of growing, but if hydroponics becomes the dominant method of agriculture (say, in a world with a more chaotic climate that needs to be kept at bay by greenhouses), then highly efficient farmers could optimize out all of their resiliency.

>I can't even think of when there was rationing in the west? Shortly after the war? At least the current grandparent generation seems to have childhood memories of that.

there was a pandemic a few years ago in which various western countries experienced shortages and in some cases rationing of some things.

There is rationing of water usage in many parts of the world, including parts of Western countries in which people live in water constrained areas, although that rationing is for garden usage - not drinking water.

I'm sure similar things can be thought of.

Obviously you don't mean those forms of rationing, you seem to mean large rationing of many different necessities and materials. But the fact that these rather minor forms of rationing exist in contrast to that in place during WWII does indicate that the system is not as able to handle all needs as well as you and a few other people in this thread seem to believe.

on edit: added word "exist"

All that is to say that the Malthusians are not just wrong, they are not even wrong.

I disagree that the prosperity we've experienced was truly "unexpected". Humans are self-regulating: fertility rates drop as resources become scarce (e.g. people are less likely to have children when struggling to meet basic needs), and markets innovate in response to scarcity (e.g. the Green Revolution). Technological progress, though unpredictable in its specifics, has consistently been a reliable force for adaptation. Ehrlich's predictions underestimated humanity's resilience, oversimplifying a highly complex system by reducing it to a linear regression.

This is that recency bias thing in action. Constant surprising technological progress of the sort we've seen for the last century or two is unprecedented and not at all the sort of thing that is suitable for long term planning. I usually wouldn't bother pointing that out, but there are two points I really want to emphasise as wildly optimistic:

> Humans are self-regulating: fertility rates drop as resources become scarce (e.g. people are less likely to have children when struggling to meet basic needs)

We didn't have birth control until the 20th century and it is mostly used by people who, historically speaking, are living with resources far in excess of their basic needs. Traditionally the self regulation was that people were born then the ones that couldn't eat enough to survive died.

And there is a pretty high risk of not finding stable equilibrium. The logistic map isn't a totally crazy model and displays some rather chaotic behaviour [0]. In practice that looks like a lot of famines.

> ... markets innovate in response to scarcity ...

Markets have existed forever, usually the innovative response to food scarcity was, once again, people starving to death. It is hard to underline just how weird the Green Revolution is. Obviously a great time to be alive but it is not a normal thing in the human experience.

[0] https://en.wikipedia.org/wiki/Logistic_map#Behavior_dependen...

I’m not sure why you keep invoking "recency bias." When forecasting the near future, as Ehrlich was doing, it’s entirely reasonable to use recent trends as a baseline. Are you suggesting progress might slow to the levels seen in prehistory, antiquity, or the medieval period? That seems highly implausible, barring a catastrophic event that disrupts modern civilization.

If anything, you might be underestimating the ongoing momentum of technological progress, which is not just sustaining its pace but accelerating across many fields. Some experts predict AGI is right on the corner - a development that could drastically amplify innovation and potentially eliminate the challenge of food scarcity.

Additionally, birth control will only keep becoming increasingly accessible worldwide, enabling more effective regulation of fertility rates in response to resource constraints.

> Humans are self-regulating: fertility rates drop as resources become scarce (e.g. people are less likely to have children when struggling to meet basic needs)

The exact opposite is what we are observing: people in poorer parts of the world, and poor people in richer parts of the world have way more children than people who have all their basic needs met and then some.

The best known predictor of average number of children is infant mortality rate: without fail, as infant mortality decreases, average number of children per family decreases as well.

I didn't claim the relationship was linear. People in poorer countries still have relatively abundant food by historical standards and aren't at risk of starvation. However, when food availability drops below a certain threshold, reproduction rates tend to decrease - this is basic ecology. Historically, the most populated regions were also resource-rich, like the fertile river valleys. But we're now living in an era of abundance where even the poorer regions have access to plenty of food.

> people are less likely to have children when struggling to meet basic needs

Completely disproven by the baby boom era where people were poor in many countries for years after the war but still made a lot of babies. Reality bites hard.

Ehrlich didn't just make this claim in the abstract. He proposed specific and brutal (I'd even say genocidal) policies that he claimed were the only ways of mitigating this inevitable mass starvation.

"Oh, he's wrong in all the details but maybe his general themes are right" is not acceptable when the outcome of listening to him is mass murder.

>> We're living through the most anomalously prosperous period

This. It's hard to make predictions precisely because the rate of change has been so rapid.

What is interesting to note though is the varied societal responses to the changes over the last 70 years or so. The US embraced materialism with some reluctant social movement (womens rights, civil rights etc). Europe embraced Socialism (in the sense of Social support, not Communism), the Middle East embraced materialism, but eschewed any form of social development (eg women's rights et al).

Right now we're in a bit of a rebound phase. Change has come too quickly (especially the last 40 years) so we're seeing pushback on rights (in the US) on social support (in Europe) and a general political swing to the right in lots of places.

There's a "looking back" element which seeks to slow found societal change even as technology accelerates.

Predicting what comes next is, well, tricky. But I expect in my lifetime to see global population maximum. I expect to see significant climate change. Both of those will be huge disruptions, and the knock-on effects could be anything

> The US embraced materialism with some reluctant social movement (womens rights, civil rights etc). Europe embraced Socialism (in the sense of Social support, not Communism), the Middle East embraced materialism, but eschewed any form of social development (eg women's rights et al).

The US is the most fundamentalist Christian country in the world. There is also a large degree of materialism, but still, only a fraction of the population of the USA even accepts the idea that atheism (a hallmark of materialism) is a legitimate religious position. What the USA has embraced more than anything is consumerism, not materialism.

What most of Europe has is called social democracy, socialism is a completely different ideology (workers having majority control of enterprises).

The Middle East embraced Islamic fundamentalism, not materialism. You could say that they also embraced consumerism, like the USA. But hardcore Islamic fundamentalism as we see it today in Iran, Saudi Arabia, or Afghanistan is a very recent phenomenon, born of the last fifty years or less (at any wide scale), and it is at a level that consumes entire societies. These Middle East countries didn't eschew progress on women's rights, they actively regressed women's rights to pre-medieval levels. Iran and Afghanistan had the right to vote for women before the USA: they lost it as fundamentalist forces gained power (actually, they still have it in Iran, but it's significantly affected by other lack of freedom).

> The US is the most fundamentalist Christian country in the world.

Due to a large population it leads as the country with the largest absolute number of Christians, sure.

In terms of percentage of Christians in the population as a whole, it doesn't even make the top ten list.

Vatican City, Timor Leste, American Samoa, Romania, Armenia, Grenada, Papua New Guinea, Greenland, Haiti, and Paraguay all have greater than 95% christian populations.

The US has perhaps a 65% Christian population albeit many of whom are in name without being particularly devout.

I remember reading about some people joining ISIS for economic reasons, I cannot find the article, but this one makes the same point (that among the other reasons, unemployment is also a factor):

https://carnegieendowment.org/posts/2014/11/the-ultimate-fat...

My point being: being a religious fundamentalist country doesn't require an almost totality of the population to be religious, but just the people who have power (weapons, money, etc.) to be fundamentalist... and the rest of the country to not violently oppose them.

I wasn't talking about percentages of the population, but about the impact that Christianity has in the public and legal spheres. Now, I may have exaggerated a little bit, as there are a few very small countries that are likely even more religious (the Vatican, Luxembourg), and perhaps one or two bigger ones (Poland does come to mind).

But overall, the prominence of Christianity in day to day American life and culture and the political sphere is off the charts. Things like saying Grace at family dinners as a common tradition, presidents and many other politicians ending their speeches with "God bless America", "In God we Trust" on dollar bills - these are virtually unheard of outside of the USA. Not to mention, the amount of times Biblical passages and teachings are brought up in political debates is staggering, even coming from a nominally "more Christian" country like Romania. Similarly, the amount of places and institutions named after religious figures or concepts is unprecedented.

But what about fundamentalist Christians? Watching from Europe I have a hard time picking the more fundamentalist country between the south of the US and the Vatican.

Does the proportion of Samoan fundamentalists exceed that of the US?

Tough question to answer, I suspect it might, Pacific Islanders hold tight to Jesus ...

* https://www.abc.net.au/news/2019-09-20/the-christian-convert...

The US wins by weight of numbers, of course, but having the most tongue talking snake handlers doesn't make the entire country the poster child for revival tents.

The Vatican doesn't interpret the Bible literally, and accepts the Theory of Evolution. Heck, the guy who first proposed the Big Bang theory was a Catholic priest! (Georges Lemaître)

We are seeing swingback to the right because the threat of left revolution (instignated or supported by nuclear state out there) is less credible now

> We're living through the most anomalously prosperous period in [History]

…on average - inequality has never been so high.

I think there’s a fairly reasonable argument to be made that the (super)majority people today are better off than they would have been 2-500 years ago, at least in most of the world.

Near as I can tell, folks have no idea (really) how bad it could be, since most of the really significant shifts have been in removing a lot of major problems.

For example, eradicating Smallpox. Controlling Measles, Polio, Tetanus. Synthetic fertilizers eliminating famines in all but the most dysfunctional areas, etc.

It used to be dying of disease or famine was a huge problem in much of the world. Now it is only in tiny, very broken areas, for relatively small portions of the population.

Then why average homeownership rate - at a same given age - is much lower for younger generations? Here's some actual data:

https://ifs.org.uk/data-items/average-homeownership-age-peop...

PS: Obviously my comment above was about contemporary generations: sure, we live better today than in the middle ages.

But how relevant is that?

True.

Just as the Industrial Revolution has reduced income inequalities within societies, it has increased them between societies. There lives now both the richest people who ever walked the earth, and the poorest. This divergence in regional and national fortunes since the Industrial Revolution has recently been labeled the Great Divergence.

Gregory Clark, A Farewell to Alms, (2006) pp 3--4.

<https://faculty.econ.ucdavis.edu/faculty/gclark/papers/FTA20...>

NB: Clark's book is from the Princeton University Press's "Economic History of the Western World" series edited by Joel Mokyr. It's an absolutely phenomenal treasury of books about economic history with a special focus on the immense transformation of the Industrial Revolution(s). Some may have heard of Robert J. Gordon's The Rise and Fall of American Growth, one of the 50+ books in the series. It's not all the books I'd recommend reading on the topic, but it's a dense treasury of quite good ones.

<https://press.princeton.edu/series/the-princeton-economic-hi...>

Never in history? Not in feudal Europe? Not in Egypt under the Pharaohs? Never?

I really doubt that...

People at every level of income are better off than their equivalent in the same country at every point in history. Once you get past 100 years or so it's not even close. Even the imperfect (to say the least) social safety nets in rich countries today are far above the level they were 100 years ago, and people are better off by almost every measure. Middle class people live like royalty a few hundreds years ago, when it comes to access to healthcare, food, travel, leisure (and that's before we talk about tech).