
We’ve predicted and broken human population limits for centuries - DiabloD3
http://nautil.us/issue/29/scaling/will-the-earth-ever-fill-up
======
shoo
> Humans don’t just extract from a fixed set of resources, but can create new
> resources through invention.

Perhaps I am being pedantic, but that sounds like nonsense. Sure, humans
invent stuff, but they don't invent the resources. They invent new ways to
access previously inaccessible resources, or extract accessible resources more
efficiently. But they don't magic more resources into being.

~~~
Confusion
Nothing is intrinsically a 'resource'. Something becomes a resource when it
can be used to further some human activity. Iron wasn't a resource until iron
forging was invented. Without humans, no resources exist.

~~~
jacquesm
But the iron was already there before we declared it something useful. Ants
use 'resources', so do bacteria so without humans resources definitely do
exist and are being used actively, whether we declare something to be a
resource to us or not does not change the fact that it was a resource _before_
our wandering eye fell on it.

Asteroids are a nice example. They're 'untapped resources', objects we one day
may use as resources but which for now just sit there because we haven't found
a way to make tapping that resource cost efficient.

~~~
Confusion
Fine: nothing is intrinsically a resource. Nutrients weren't a resource before
_some self replicating process_ started using it for some purpose, probably
fairly directly related to replication.

And iron ore still wasn't a resource until humans came along and invented
forging.

The term 'resource' does not describe the natural state of something. It
describes a relationship between things: something is a resource for some
goal(s), by some entity(ies). The relationship did not exist when the other
party was not in that relationship, for instance because the other party did
not exist. Thinking new resources cannot come into existence is making a
category mistake, thinking whether something is a resource is absolute,
intrinsic, independent of context.

------
facepalm
There are also cultures that vanished after thousands of years, and crisises
in which millions of people died. Human ingenuity and technological progress
didn't solve every problem. We just forgot about the dead (classic survivor
bias). Collapse by Jared Diamond has some examples of societies that failed -
by comparison, our current civilization is very young and hasn't really
"played out" yet.

Maybe the estimates of Malthus were wrong, but the underlying concern is still
correct. Our current food production is not sustainable because it relies on
non-renewable energy sources. I don't claim no solution can be found for that,
but there is also no reason to believe there will be a solution.

Another way to look at it makes it very plain: the surface area of earth
certainly is limited. So if population would grow forever, we would reach a
point where every person would only have one square foot of ground to live on.

Even that might be doable - we could live in a stacked way (skyscrapers), or
Matrix-Style in coffins with virtual environment. Nevertheless it doesn't seem
like a very desirable future.

------
wavefunction
My question is why do we need more people or want to encourage or allow it to
occur?

My immodest proposal is to introduce a natural decline in human populations to
more easily sustainable levels via the introduction of a reproductive "right":
every individual when born is entitled to one child.

A couple, then, could have a family with two children. Those who aren't
interested in having children could sell their "right" off on a market to
people who want to have more than their one child individually, so a couple
could buy the rights to more children and a larger family from those who don't
want to have children. The market could even fractionalize/derivatize those
rights so that individuals could sell "half" a childbirth right and two of
those individuals could have a family with one child.

The best part is, at two children per two parents, it's lower than the
replacement rate of "2.1" which means population levels would humanely
decrease with no need for wars or murder.

Our current societies are predicated on larger youth populations than parent
populations to support us in our old ages, but this strategy combined with
robotic technology for the elderly and post-scarcity economics would free us
from that pyramid scheme. This helps support a basic-income type scenario for
those people who assume that everyone (or 'THOSE PEOPLE') living in our
society will just have tons of kids due to boredom. Like the fears trotted out
about "welfare queens" having tons of kids because they supposedly get "free
stuff."

~~~
biztos
So the rich have large families, and the poor have forced sterilization?

~~~
wavefunction
It's voluntary. Perhaps you missed the part about the basic-income and right
to a child.

------
thaumasiotes
Population limits are certainly a well-documented phenomenon. Chinese history
shows excellent conformance to a "punctuated equilibrium" model -- the
population is stable nearly all the time, with two obvious sudden increases.
(From memory, I believe the increases correspond to (1) the local development
of a new, more productive strain of rice, and (2) the introduction of crops
from the new world.)

The inference is painfully obvious: for most of history, China has been
populated _at_ its own carrying capacity. The fact that the limit was broken
(really, raised) a few times doesn't mean the limit isn't a worthy concept.

------
danbruc
Why is this issue getting so much attention? It is a problem that will solve
itself, wherever the limit is. The only reason to worry about where the limit
is, is if you want to avoid it with birth control so that some nicer forces
than famines or resource wars keep the population stable. But even that seems
unnecessary, at least in the developed world, because the population growth
rates or even the populations are already declining. Which of course is a good
thing, why would you prefer a more densely populated world over the status
quo? Why would you want to raise child after child if two and a half are
enough to sustain the population?

~~~
facepalm
It will solve itself, but billions of people might die as part of the
solution. Mankind will survive, but for the individual some worrying might
make sense.

~~~
danbruc
The people that can prevent overpopulation don't suffer from it, the people
that suffer from it can't prevent it. So it's more of worrying for once
children's children.

------
qrendel
Yikes. I didn't realize the population density in Mumbai was near 53k people
per sq. mile. Apparently Manila is nearly twice that at 111k.[1]

Still, it surprises me overpopulation fears are so commonly expressed. Seems
like a greatly overblown meme that will end up doing more harm than good. Much
like Malthus opposing projects to feed the poor and hungry, I sometimes hear
people going as far as saying we (meaning relatively wealthy, white Americans)
should just "let them die" when it comes to impoverished people all over the
world. Despite the fact that, if energy consumption and environmental damage
is the fear, people in industrialized countries use as many resources as
dozens, hundreds, maybe thousands of lives in the "developing" world.

The world could likely support orders of magnitude more people than we give it
credit for. We haven't even started harnessing materials from space industry,
space-based solar power, or using the oceans and seabed as living space.
There's another 70% of the Earth's surface that hasn't even been touched yet,
and that percentage grows even more when you consider the vertical spaces
available within it. The overpopulation meme seems more dangerous to global
welfare than actual overpopulation has ever been thus far.

Kevin Kelly's edge.org response is a good read on the entire overpopulation
issue: [http://edge.org/response-detail/23722](http://edge.org/response-
detail/23722)

[1]
[https://en.wikipedia.org/wiki/List_of_cities_by_population_d...](https://en.wikipedia.org/wiki/List_of_cities_by_population_density)

~~~
jzwinck
The world probably could support lots more people than it has now. The
question is, why? If we believe 30 billion people is possible, should it be a
goal? What's better about 30 billion than 6?

~~~
qrendel
1) Reproduction is a natural right, and some people would consider having
children to be a great fulfillment. The evolutionary basis of this desire
would make it all the more powerful, and restricting it would only cause the
drive to grow stronger over time (as traits evolved to promote the
circumvention of the restrictions).

2) If there's no specific advantage to a lower or stable population, why is
any particular number preferable to another?

3) There are lots of advantages of large population: larger communities for
people with low-frequency deviations from social norms, a broader spectrum of
human social and psychological possibilities represented, increased production
and creative capacity, greater base of working-age citizens to support the
non-working portion (retired, children), more people at the top of the bell
curve to draw from for important positions (better leaders, more geniuses,
etc)... This is not an exhaustive list.

4) Likely other advantages as well, which would seem to counter the
disadvantages of larger population, judging from past human history (and
assuming no weird non-linear relationships). If the world is better with fewer
people, would you want to go back and live in a world with only 100,000?
1,000,000? Some other specific number?

~~~
danbruc
1\. Reproduction is not a natural right. If you reproduce beyond a sustainable
level your offsprings will pay for that with reduced life expectation and
being unable to reproduce in consequence. It's essentially the same thing that
happens in predator prey cycles. And you don't have to cease reproducing
altogether, just limit it to a sustainable level of about one child per human.

2\. There are of course advantages to stable population sizes, most
importantly resources will last longer and allow sustaining human society for
longer.

3.1. larger communities for people with low-frequency deviations from social
norms

It is not obvious to me why that is a good thing.

3.2. a broader spectrum of human social and psychological possibilities
represented, increased production and creative capacity

That seems to be the best argument for larger populations besides increased
production capacity because that is countered by an increased consumption.

3.3. greater base of working-age citizens to support the non-working portion
(retired, children)

That is not true for a larger population, the proportion is the same as for a
smaller one. It is only true while the population is growing and that is
either unsustainable or the effect is unimportant if the growth is marginal.

3.4. more people at the top of the bell curve to draw from for important
positions (better leaders, more geniuses, etc)

That is essentially the same argument as 3.2.

4\. Smaller populations are not necessarily better, you benefit from decision
of labor, scale effects, you are more resistant to disasters. The optimum is
definitely somewhere in the middle, it is neither one human that can no longer
reproduce and will easily go extinct, and it is also not ten to the hundred
for obvious reasons. The question is therefore definitely not whether or not
we should seek for a stable population, it is where the most desirable level
is.

And here I argue we should first bring the entire world population to the
levels of wealth, education and consumption of the middle class of leading
developed countries and then we can have a look at how much resources are
left, what happened to environment and climate, whether we need more smart
people.

~~~
qrendel
3.1 - A good thing because people with unusual interests and personality
traits will be able to form communities of people with similar interests. For
example, in a town of a thousand people, you might be the only one who enjoys
an odd hobby like underwater hockey (it's a real thing). In a city of ten
million, there may be hundreds or thousands of people to form an entire league
with. "Deviations" as used wasn't intended to have a pejorative connotation.

3.2. Contradicts the basic premise (no immediate resource limit) and the
original article. The world has become richer despite growing population,
because production has outrun consumption. No reason to think it will stop in
the immediate future, any more than it did in Malthus' time.

3.3. You're simultaneously saying the economic problems arise when population
stops growing and becomes stable, and supporting ending population growth in
favor of a stable population. If there's a limit where quality of life
decreases due to increasing population, we haven't hit it yet, given that
quality of life and per capita wealth is still improving globally, so there's
no reason to put the brakes on before we even know where it is.

> _it is also not ten to the hundred for obvious reasons._

We're assuming technology and productive capacity also improves to keep up.
We're also nowhere near 10^100. Nor do we know where this hypothetical optimum
is. Population controls should be a last resort to solving problems we are't
facing yet, not done just because a theoretical optimum for quality of life
may exist at some hypothetical large number.

~~~
danbruc
3.1. But that also means that all the bad minorities can form stronger groups
and be potentially more impactful. If you can not play underwater hockey you
might pick some other form of hockey instead. Maybe it makes you a bit less
happy but what is the effect of a less fragmented society? I am not dismissing
the idea that there might be a positive effect but I am not obviously
convinced.

3.2. I would argue that the increase in wealth is mostly due to increased
productivity and not due to population growth and therefore could continue
even without further population growth. Population growth is certainly not
totally irrelevant due to scale effects but I don't see that simply doubling
the population would lead to significantly increased wealth.

3.3. That is not what I am saying. Having a pyramid shaped age structure is an
easy way to have a lot of workforce available to support the elderly but that
structure is not the result of a large population but of an growing
population. And in order to be a significant effect you can not have just a
tiny bit of growth but a substantial amount of growth is definitely
unsustainable.

The limit definitely exists but I also think we will not hit it, we will not
need any (large scale) birth control policies because the birth rate will drop
enough with increasing wealth. Looking at developed nations it looks actually
more like we will have to incentivize having more children in order not to go
extinct.

------
jkot
I lived in Ireland and Greece. Many regions there had population peak
centuries ago and now are in decline for several decades.

~~~
wongarsu
Most developed nations currently have declining populations. For now it seems
like we can simply stop population growth by bringing the rest of the world to
our level of wealth. Then again there's the question whether earth has enough
resources to make that even possible.

~~~
eru
> Then again there's the question whether earth has enough resources to make
> that even possible.

In terms of energy: definitely. Nuclear or now solar suffices.

------
thomaslkjeldsen
According to Swedish professor Hans Rosling the fast population growth is
coming to an end and the population size is expected to stabilize at 11
billion people by the end of this century. His statistics and predictions are
based on data from the UN Population Division.

[http://www.gapminder.org/videos/dont-panic-the-facts-
about-p...](http://www.gapminder.org/videos/dont-panic-the-facts-about-
population/)

[http://www.gapminder.org/news/world-peak-number-of-
children-...](http://www.gapminder.org/news/world-peak-number-of-children-is-
now/)

------
x5n1
i think we need to define limits in terms of energy. there is a certain amount
of energy that comes in from the sun that life then uses to decrease entropy.
that energy can be used by any form of life to do work. we broke those limits
by in part by displacing a lot of other life. so yes we can probably push the
limits even more and displace yet much more life on the planet. at some point
however that fact will effect us unpredictably.

~~~
iofj
> i think we need to define limits in terms of energy

Ok. Let's do that. The earth receives about 10,000 exajoule per day (3850000
per year) [1]. Daily human caloric intake is 2500 calories [2]. Let's say
inefficiency and the fact that you actually need food, not pure energy, let's
say that means 20% efficiency, so 12500 calories per human daily. 12500
calories is about 50k joules. Things like running a tv/computer/... would be
peanuts on top of that so they "come free".

So divide one by the other. The earth, without space based power, can keep
about 1e18 humans alive on this planet using just earth-based solar power.

Plus you have to keep into account what humans actually do : they convert
chemical energy into heat. If we cover the planet in solar panels, why
couldn't we recover most of that human-generated heat ? Let's say we can
recover 99% of energy that we put into humans back out, that's another factor
of 100 right there.

We could use nuclear to increase that number to 1e30 or so for a millenium and
if you count fusion based power, the numbers become completely ridiculous.

To put that number in perspective, take it like this : when every human alive
today breeds into a population the size of today's entire human population,
then we'd be near the "pure solar" carrying capacity of just the planet
itself. If we were to beam power from space to the planet, we wouldn't run
into the next limit until 1e50 at least.

So we are very, very, very far away, even on an exponential population curve,
from the carrying capacity of the planet. When fitting an exponential curve to
some sample data (very inaccurate, but good enough for a ballpark figure), I
get that if the growth since WWII (1.36% per year, starting at 2000 with 6
billion people), then we'd get to 1e18 a little after the year 3400.

> we broke those limits by displacing a lot of other life

Only for a few measurements. There are a lot of problematic measurements of
life that are inaccurate and therefore full of noise, and can be outright
deceptive. Some of those measurements look bad : number of species, for
instance. But how relevant is that number ? Sure, if it keeps dropping our
zoos will become boring, but what will actually happen ? The truth is nobody
knows, and there doesn't seem to be a reason, aside from nostalgia, to assume
it's bad. One "real metric" that is at least measurable and I believe is
meaningful : the total amount of life is total biomass, and it is pretty well
known that humans have increased that by a lot.

> at some point however that fact will effect us unpredictably

It seems to me to be pretty much a given that lots of things can affect the
human race unpredictably, and given how many such factors there are, it seems
a safe bet that a few are indeed going to affect us (though the vast majority
won't). Malthusianism and global warming are such factors, malthusianism has
been proven false 3-4 times at least, and many limits to growth theories both
before and after have been (I like the economic "debt limit" ones, stating
that we can never have an economy larger than the value of all gold, then we
passed that, then money became "loaned gold", and the next theory was that
there was some factor that limits how big the economy can be n * total_gold, n
was to be 10, then 100, now it's at least 100 million, and they're still at
it), I wonder what the fate of global warming will be.

If you believe in Darwin and evolution, this is a positive. We will adapt to
whatever effect, predictable or unpredictable, starts affecting us.

[1]
[https://en.wikipedia.org/wiki/Solar_energy](https://en.wikipedia.org/wiki/Solar_energy)
[2] [http://www.webmd.com/diet/estimated-calorie-
requirement](http://www.webmd.com/diet/estimated-calorie-requirement)

~~~
x5n1
One question that I have if there is so much energy then why is life not using
more of it? I guess there are a bunch of other constraints on life other than
the sun's energy so my point is off.

~~~
jacquesm
Conversion inefficiency, maximum conversion limits (a black leaf would burn up
in full sunlight), consumption of energy by other bits and pieces of the
planet other than living creatures (the atmosphere, for instance is a huge
consumer, as is the planet itself, just to keep it above freezing, see also:
albedo).

------
weddpros
Population growth is exclusively cultural. See how it's declining in Europe,
still growing fast in Africa, etc.

Science could change that very fast: birth control isn't available to everyone
on earth... yet. But religion could change that fast too.

So I guess estimates for the earth population will depend on both science and
religion more than anything.

~~~
shoo
also helpful in reducing birth rates: education and the available economic
opportunities for young women

------
daniel-cussen
Same thinking as "housing never goes down." How did that one go?

~~~
daniel-cussen
Edit: also, remember Easter Island, where the population dropped by over 99%
after an ecological disaster last millennium.

------
hellofunk
I suspect that at 7 billion now, if the world population rose to even 100
billion, we'd find a way to survive. It would be a very different life
experience, but it would still be life.

~~~
jacquesm
I highly doubt we'd be able to feed and house 100 billion people.

~~~
pflanze
Able yes, but at very high risk of deadly instability through destroying most
of nature and accordingly higher dependence on technology, and smoothly
working social structures?

~~~
jacquesm
Unsustainable to me means 'unable'. If you can't sustain a model in the long
term that means that sooner or later there will be a crash. Whether the number
of people we can sustain long term is 10, 20 or 50 billion people is currently
not known but most people that have spent significant time on this problem put
the long-term sustainable number closer to 10 than to 20 billion. Now, as the
article states we've consistently under-estimated these numbers but even very
generous allowance for errors would cap the number that we could long term
sustain in any form well below 100 billion.

~~~
dennisgorelik
Are you that good in predicting the future hundreds of years ahead?

World population is not going to reach 100 billion in the next 200 years.

New technologies may allow:

1) Grow food in cold climate (Russia, Canada and even Antarctica).

2) Grow food in the ocean.

3) Grow food under ground.

4) 10x+ increase in food output from the same amount of land.

5) Industrial food synthesizing.

~~~
jacquesm
> Grow food in cold climate (Russia, Canada and even Antarctica).

Needs an energy source

> Grow food in the ocean.

We already do this and we call it fish. We're also _terribly_ bad at managing
this very important resource.

> Grow food under ground.

Needs an energy source

> 10x+ increase in food output from the same amount of land.

Needs wildly fantastic breakthrough in practice, currently at odds with the
theoretical maximum yield from acreage.

> Industrial food synthesizing.

We already do quite a bit of this but you'd have to come from an entirely
different angle (such as synthesizing protein from non-biological sources,
currently not a possibility).

So, with present technology and present knowledge about energy budgets and
support capabilities of arable land it's as far as I can see right out.

If there is some totally out-of-the-blue breakthrough (such as atomic
synthesis of arbitrary compounds combined with free energy) then sure,
anything is possible. But that's the same kind of bet the cryonists (sp?)
make, or even some religions, once you allow for miracles the future
possibilities are limitless.

I'll be more than happy to concede that there will be improvements in yield
but the amount of sunlight falling on an acre of land and the available
minerals and precipitation are limiting factors, even when you factor in
greenhouses, artificial lights, irrigation and so on. Hydroponics is probably
eventually one of the most efficient ways of doing all this and even that has
fairly hard limits in terms of energy required and amount of nutrients and
water required.

~~~
dennisgorelik
> Needs an energy source

Sun. Fission. Fusion.

> you'd have to come from an entirely different angle

Not me personally, but tens of billions of new people who would be born in the
next couple of hundred thousand years.

> If there is some totally out-of-the-blue breakthrough

If in 1900-2000 food production increased 5x then it is reasonable to expect
that in the next 100 years food production may increase 5x again (or more if
needed).

It looks like you want to have enough food now (in 2015) in order to be able
to feed world's population in 2215.

Why do you need to have that food 200 years ahead of the actual demand?

