
A 2,500-mile radius in Asia contains half the world's population (2017) - elsewhen
https://www.cntraveler.com/story/more-than-half-the-worlds-population-lives-inside-this-circle
======
dntbnmpls
Total world landmass: 57,510,000 miles squared.

[https://en.wikipedia.org/wiki/List_of_countries_and_dependen...](https://en.wikipedia.org/wiki/List_of_countries_and_dependencies_by_area)

2500 miles * 2500 miles * pi = 19,630,000 miles squared

So that area represents about (19.63 / 57.51 ) 34% of the total world
landmass. So 50% of humans live in 34% of the landmass. But harsh and
relatively uninhabitable lands make up a large portion of the earth's landmass

( antarctica - 5,400,000, siberia - 5,100,000, canada - 3,511,023, australia -
2,947,336, , greenland - 836,330) = 17.8 million square miles.

So the habitable areas are 57.51 - 17.8 = 39.71 million miles squared.

So that circle represents ( 19.63 / 39.71 ) 49.4% of the habitable land.

So in the end, about 50% of the world population lives in about 50% of the
world's habitable land.

Astounding huh? It's amazing what some math and common sense and understanding
of geography takes away from a clickbait article based on a reddit post.

As others have noted, that area is also primed for human habitation due to
tons of fresh water rivers flowing from the tibetan plateau and rich fertile
land along with year-round planting seasons due to its proximity to the
equator.

~~~
rjkennedy98
It clearly says " 2,500 miles in diameter" which makes it 1,250 mile radius.

pi * 1250 *1250 = 4,908,738 square miles or ~5 million square miles.

That is < 10% of the earths land mass.

~~~
swsieber
It also clearly says "2500 radius circle" in the article title, and the
submission title. The article is fast and loose with diameter vs radius later
on as well. I can't blame the original commenter for using it as a radius when
that's in the title.

But I agree, it's actually the diameter and changes the math a lot.

~~~
humblebee
The distance from Mumbai India to Osaka Japan is ~4000 miles. Both of which
are clearly inside the circle.

What are you using to assert that the 2500 mile number is the diameter?

------
speedgoose
2500 miles ≈ 4000 km.

Guys, switch to metric units already. Thank you.

The rest of the world.

~~~
blackrock
I must admit, I find it baffling how the EU uses metric, but yet, they use the
comma as the decimal point. And the dot to separate thousandth units.

Like this:

1.000.000,52

Why is that better than this:

1,000,000.52

~~~
jeroenhd
It's because fewer countries actually use the period as decimal separators.
The English-speaking world (and its former colonies) and China use the period,
which is probably why it's so widespread to. Other countries, while countries
not originating in or heavily integrated into the English-speaking world use
the comma. By count of governments, the comma is clearly winning as a decimal
separator, though that doesn't say anything about usage in the global
population of course.

There's no real reason why one is better than the other. They're both somewhat
arbiratry and as far as separation goes, there's not even worldwide consensus
about the amount of zeroes that are in front of a separator. As a European, I
don't think I've ever been confused reading an English-style number because of
the different separator. The only problem i can imagine is a number with three
decimals (123.456) but with such many orders of magnitude in difference it
should not be a problem to understand the right number based on context.

The character was chosen based on either practical reasons (the French already
used a period for something else in maths) or because it made sense to use the
system of countries around you or countries you were trading with a lot.

You can ask the same question about why some countries drive on the left and
some on the right but in the end it's because you have to pick something and
at that point you just pick what's practical. Or, you can ask why the American
number system uses billion to mean 1e9 while in Europe it often means 1e12. It
all comes down to what people are used to. Or why America has its date format
unsorted (m/d/y vs d/m/y or y/m/d).

Furthermore, the whole world uses metric aside from three specific countries
versus the much larger split of comma versus period. It's not really something
that can go wrong much as long as you can understand some context (if you read
a theoretical numbering system like 10-000-000'00 you'd still understand what
the decimal point would be). Using two or four decimals clears up any
confusion regardless of system.

~~~
CydeWeys
> Or, you can ask why the American number system uses billion to mean 1e9
> while in Europe it often means 1e12.

I'm gonna stick up for the American system here, because if "billion" doesn't
mean 1e9 then the only way you can say that number is "thousand million",
which is terrible. The long scale just sucks.

~~~
jeroenhd
No, the way the UK used to say a thousand million is "milliard". You'll find
that same term in a lot of European languages. Same with billiard, trilliard,
etc.

The short scale is just another reason why European and American data sources
get confused every now and then. I find it kind of strange that the UK
switched to the American system despite having used the long scale themselves
for quite some time. I suppose it was just a consequence of the US media
getting influence in Europe after World War 2, but it couldn't have been an
easy switch.

~~~
TomMarius
Milion - 1 000 000

Miliarda - 1 000 000 000

Bilion - 1 000 000 000 000

Biliarda...

Trilion...

(Czech, it's very painful to read translated articles BTW)

------
throwGuardian
Part of the reason is the Ganges & YangTse river deltas are the most fertile
on Earth. While other regions typically yield 2 crops a year, these deltas
average 3 to 4.

Also, the climate is relatively moderate with no major high frequency
calamities (like earthquakes and hurricanes).

~~~
emmelaich
> .. _no major high frequency calamities (like earthquakes_ ..

And yet, it is one of the most geologically active areas on earth. The Ring of
Fire, Deccan Plateau, bunch of volcanoes.

I'm sure this has a lot do with it's fertility.

~~~
luhem7
The Deccan plateau is one of the world's most geologically inactive areas. The
ring of fire goes through the circle but isn't a major component of the
circle. There aren't even a remarkably high destiny of volcanoes.

What is active is the Himalayan mountain range.

~~~
emmelaich
True, I should have added _historically_.

Nonetheless, it's still close to geologically active areas.

e.g. the Indian Ocean 2004 Tsunami.

------
cam_l
Reminds me of an awesome map from a few years ago.

[http://www.radicalcartography.net/index.html?human-
hemispher...](http://www.radicalcartography.net/index.html?human-hemisphere)

~~~
divbzero
Awesome indeed. Thanks for the link.

The “other” hemisphere illustrates the strikingly vast expanse of the Pacific
Ocean.

~~~
gshdg
It also omits Antarctica entirely

~~~
Taniwha
it doesn't show any land masses at all, only the density of humans - you're
brain is likely filling in the familiar land borders

------
kissickas
The reddit thread (where it was originally posted) has some good discussion.

[https://www.reddit.com/r/MapPorn/comments/1dqh7d/after_seein...](https://www.reddit.com/r/MapPorn/comments/1dqh7d/after_seeing_a_recent_post_about_the_population/)

~~~
abbadadda
Interesting discussion there on climate and geography (in the vein of Guns,
Germs, and Steel). Thanks for linking.

------
stickfigure
A 3,958.8-mile radius around the center of the earth contains 100% of the
world's population.

~~~
divbzero
This noteworthy point can help our intuition.

    
    
         πr² = area of circle
        4πr² = surface area of sphere
    

Thus a 2,500 mile radius circle covers ~10% of Earth’s surface.

------
andys627
A 30 ft radius in Davos contains half the worlds wealth

~~~
yitchelle
But only for a small percentage of the year.

------
symplee
*Spherical cap

[https://en.wikipedia.org/wiki/Spherical_cap](https://en.wikipedia.org/wiki/Spherical_cap)

Bonus points for whoever calculates the ratio of the surface areas for the two
spherical caps that contain half of the human population. (The circle's radius
is ~4,000 km)

~~~
thaumasiotes
> Bonus points for whoever calculates the ratio of the surface areas for the
> two spherical caps

Hmpf, I went to all the trouble of deriving the surface area of a spherical
cap (it's really easy, as surface integrals go), and it's listed right there
in the wikipedia page. A = 2πrr(1 - cos φ), where φ is the angle between the
center of the cap and the edge (measured from the center of the sphere).

Assumptions:

1\. The "radius" of the cap is 4000 km.

2\. The "radius" of the cap is actually an arclength along a great circle of a
sphere (the earth).

3\. The radius (a real radius) of the earth is somewhere between 6300 and 6400
km.

The formula for arclength along a circle tells us that φ is somewhere between
40/63 and 40/64.

We can calculate the cap's percentage of the surface area of the entire sphere
as (1 - cos φ) / 2\. For an earth-radius of 6300km, this is 9.744%. For
6400km, this is 9.452%. For the smaller earth, the ratio of the cap's outside
to its inside is 9.26:1; for the larger earth, it is 9.58:1.

Rounding to two significant figures, like we used for the size of the earth,
the ratio should be between 9.3:1 and 9.6:1.

The ratio isn't really very informative, because the cap was drawn around
where a bunch of people live, and "everything else" wasn't. This has
artifactually put most of the ocean, where people _cannot_ live, into
"everything else". "Everything else" should probably be significantly deflated
to adjust for this. The article messes up a similar point:

> The population density of Greenland, for example, is just 0.1/sq. mi—that
> is, one person living on every ten square miles of rock and ice. But it's a
> lot easier to find company in Manila, which is literally one million times
> as crowded: 107,000 Filipinos per square mile.

The population density of Greenland is mostly zero with some spikes. There's
not a literal tenth of a person every square mile -- those people would all be
dead. The population density in areas where local population density is more
than zero is much higher. Manila is not actually one million times as dense.

~~~
thaumasiotes
It's more impressive to compare the area of the cap to the area of a flat
circle of the same radius. The curvature really adds up -- the cap is under
40% of the circle.

~~~
thaumasiotes
Ah, the reason this was so impressive is that I mixed up the radius of the cap
with the radius of the sphere on which it sits. In reality, this cap has 97%
of the area it would if it were a flat circle of the same radius.

------
dmix
Intestestingly in the original Reddit thread they were talking about epidemics
as around that time (2014 was the post date) the influenza H7N9 was hitting
China, which was also impacted heavily by Chinese new year travels. Smaller
rates than Corona but it still hit 1223 people and had a 30-40% mortality
rate:

[https://old.reddit.com/r/MapPorn/comments/1dqh7d/after_seein...](https://old.reddit.com/r/MapPorn/comments/1dqh7d/after_seeing_a_recent_post_about_the_population/c9sxqqt/)

[https://en.wikipedia.org/wiki/Influenza_A_virus_subtype_H7N9...](https://en.wikipedia.org/wiki/Influenza_A_virus_subtype_H7N9?oldformat=true#Reported_cases_in_2013)

From what I understand influenzas tend to be the scarier than Coronavirus
types of viruses in most projected pandemic scenarios.

This is one of the downsides of high density areas, although for more cost
effect for lower income people so density will only continue to grow in most
of the world.

------
billfruit
Beyond the factoid, the article unfortunately does not delve into why the
population is concentrated in such region. Especially India, Bangladesh,
Pakistan, that is most of the subcontinent has very uncomfortable weather, but
still is highly populated, I wonder why? Why didn't people in the early ages
decided to move to more temperate climes?

~~~
joncrane
Uncomfortable, but not fatal. A human being can relax and turn down its
metabolic needs when it's hot, find some shade, go for a swim. Also due to
both climate and fertile soil, there is abundant growable food so humans will
almost never starve (and even when food is low, metabolic needs are also low).
It's possible to simply exist without trying too hard in those types of areas.

Contrast with areas such as NYC or Moscow, where it's almost impossible to
simply exist for many months of the year.

------
OnlineGladiator
At first the article says it's a 2500 mile radius, and then it says it's a
2500 mile diameter. So which is it?

~~~
Kikawala
Radius.
[https://en.wikipedia.org/wiki/Valeriepieris_circle](https://en.wikipedia.org/wiki/Valeriepieris_circle)

~~~
newnewpdro
Strange for that wikipedia page to not contain a single graphic representation
of what's being described.

~~~
jacobwilliamroy
The DIAMETER of such an area is very roughly 12 percent of Earth's
CIRCUMFERENCE. So you could (probably) lay 8 of these areas around the
equator, give or take a a couple.

~~~
oefrha
The earth’s circumference is ~4E4 km; the diameter of this circle is ~8E3 km.
That’s 20%, not 2%. 2% would be utter madness.

~~~
jacobwilliamroy
Thanks for pointing that out. Its different now

------
iancmceachern
I was just reading this interesting article on the topic. I particularly like
the graph if population vs latitude.

[https://www.quora.com/Why-are-countries-like-India-and-
China...](https://www.quora.com/Why-are-countries-like-India-and-China-so-
densely-populated-What-are-the-circumstances-and-reasons)

~~~
Someone
That should have been scaled by, at least, length of the circle of latitude
(there are fewer people the nearer you go to the poles not only because it is
cold there, but also because there’s less area), preferably also by land area
on the circle of latitude.

Looking at the graph, I would guess that that combination explains quite a bit
of the shape of the graph.

------
est31
Note that the title is wrong. It's a circle on a map, not in real life and
thus it's not a "2 500-mile radius". A sphere in real life would be distorted
in the map. In fact, all the meridians and circles of latitude are circles in
real life but on the map they don't show up as circles.

------
cortesoft
They don't talk at all about why it is so. Is it particularly fertile
territory that can support this kind of density? Is there something about the
geography of the area or the geography of the globe that makes it have so many
more people than the rest of the world?

~~~
ta999999171
Read the older comments in this thread...

------
fizixer
2500 mile radius is no joke though.

It's 10% of world's land area.

edit: The circle in the article has plenty of water. I'm not counting that. So
maybe land area in that circle is 5% of world's total land area (not 10%).

~~~
keanzu
2500x2500xpi = 19.6M

World total area = 197M [0]

World land area = 57.5M [0]

Circle looks to me to be at least half water so it's about a sixth of the
world's land area.

Approximately 11% [1] of all land is arable worldwide. I suspect the
percentage is higher inside the circle.

[0]
[https://en.wikipedia.org/wiki/List_of_countries_and_dependen...](https://en.wikipedia.org/wiki/List_of_countries_and_dependencies_by_area)

[1]
[https://data.worldbank.org/indicator/AG.LND.ARBL.ZS](https://data.worldbank.org/indicator/AG.LND.ARBL.ZS)

~~~
fizixer
You're right. My bad.

I googled 'earth land area' and it showed ~196 million sq miles. And I used it
without double check. (Google incorrectly reported the full surface area of
earth.)

------
archivist1
It's centered on the island of Hainan. I want to know what the center of mass
is for that picture, since the humans are not uniformly distributed in that
circle.

------
tomq
A detailed follow-on study found a 4,000-mile radius sphere centered on the
earth’s core contains ~100% of earth’s population. Scientists stunned.

------
wsxcde
This will likely change once Africa becomes the most populous continent, which
is expected to happen somewhere around 2100.

~~~
b0rsuk
Not unless Sahara is going to become a green grassland again. With the way the
climate change is going, unlikely.

~~~
wsxcde
Three points are worth making here.

Nobody lives in the Sahara, the population centers in Africa are in the
tropical regions and the Mediterranean.

Africa will be the only continent experiencing population growth post-2050.
Africa's largest economy, Nigeria, is expected to become the third most
populous country in the world by 2050.

The effects of climate change on monsoon-dependent areas (the Mediterreanean
coast of Africa and the semi-arid regions bordering the southern parts of the
Sahara) are not well-understood and the effects are more complicated than
everything will become a desert. For example, the Indian monsoon is expected
to produce 10% more rainfall because higher temperatures allow the air to
collect more moisture. This is going to be a huge boon for certain semi-arid
regions of the country.

------
dehrmann
Guess that means more more than 2% of humans to have ever lived live in that
circle.

~~~
paulrouget
How many humans have ever lived? And how do we calculate that?

~~~
pesfandiar
One challenging aspect of the calculation would be defining "human".

~~~
herendin2
Hard to define, but not important for this stat, because the ancient global
population of proto-humans was so small that it's not even a rounding error in
107BN (the estimated total humans to ever have lived)

------
einpoklum
I would be interested to see how this circle looks on a Peters-projection map.

------
supportlocal4h
100% of the Earth's population lives within a 4000 mile radius.

------
hacknat
Probably close to 90% lives in Iran/Iraq 4000 years ago.

~~~
samatman
I'm curious how true that is.

Probably not very. The Nile, Yangtze, Yellow and Indus rivers were all
somewhat densely settled by 2000 BC.

------
intpbro
A 2500 mile radius is a huge area

------
lovemenot
>> A 2,500-mile radius in Asia containing half the world's population

Ken Jennings: What is Valeriepieris circle?

------
krtong
I enjoyed this post on reddit explaining why China has such a large population
[1]:

"You might be familiar with how the Nile River in Egypt works from school. If
you aren't - for 9 months out of the year the Nile has a moderate flow rate
that is sufficient to support human settlement and agriculture. For the
remaining 3 months the Nile's flow rate increases dramatically and it floods a
huge area around its river banks.

That flooding might sound bad but its not. Using soil for agricultural
purposes will deplete it's minerals within about 100 years. That's a long time
compared to a human life, but not compared to a civilization. When the soil
runs out of minerals you can't grow anything in it anymore, and it turns out
that this is the limiting factor for most civilizations. IE, a civilization
will begin intensively farming its soil, deplete the soil, then starve to
death.

In the modern world we're able to replenish the soil's minerals with
fertilizer. They were sort of able to do this in the ancient world as well,
but this involved transporting huge amounts of animal manure which is
difficult to do and, in practice, if an ancient civilization had to manually
fertilize the soil it would result in very low agricultural yields.

This is what makes the Nile's floods so good for the development of
civilization - every time the Nile would flood it deposits a huge amount of
new soil in the areas that got flooded. The source of that new soil was hills
and mountains in Central Africa, so it was filled with minerals. Or to put it
another way - every year the Nile naturally dumped a huge amount of fertilizer
on Egypt.

This natural fertilizing allowed Egypt to be by far the most productive
agricultural region West of India for thousands of years - everyone from the
Pharaohs to Alexander the Great to the Roman Empire fed themselves using the
food that the Nile was able to grow.

How does this relate to China? The Yellow River in China is the same type of
river as the Nile. It spends most of the year with a moderate flow rate, then
has massive floods for a few months that deposit a bunch of new soil along its
banks.

Where the Yellow River is different from the Nile is in its size. The Nile is
a single, small river with practically no tributaries or lakes. The Nile's
floods only cover a small geographic area located immediately adjacent to it.

The Yellow River, on the other hand, is a massive system with hundreds of
tributaries and lakes. When it floods, it covers almost the entirety of South
East China - which is an area thousands of times the size of that covered by
the Nile.

The Yellow River basin has been among for the most productive agricultural
areas on Earth for much of human history. Because the only limiting factor to
population size is a region's ability to produce food, this also means that
the Yellow River Basin (and by extension, China) has managed to maintain a
huge population for the entirety of human history."

1:
[https://www.reddit.com/r/explainlikeimfive/comments/exghji/e...](https://www.reddit.com/r/explainlikeimfive/comments/exghji/eli5_how_did_the_chinese_succeed_in_reaching_a/fg84swh?utm_source=share&utm_medium=web2x)

~~~
magicsmoke
Another point to add to this is that the Nile River is significantly easier to
manage for the Egyptians than the Yellow River was for the Chinese. Unlike the
Nile River that flows along the same path and floods the same areas every
year, the Yellow River has a nasty tendency to change its mind about where it
wants to flow into the sea, and it destroys all the farmland along its path
when it shifts its outflow from the north side of the Shandong peninsula to
the south and back again a few hundred years later. That widespread flooding
and shifting of the rivers path makes the entire North China plain very
fertile compared to a thin strip along the Nile, but it also causes widespread
damage and casualties whenever a bad flood year shifts the Yellow River's path
down the middle of a town.

------
foobar_llc
I guess that's why coronavirus blew up so fast.

~~~
_-___________-_
It didn't really, outside of China, and there are many more countries than
China in that circle.

------
toronto_tic
And most probably that's were everything started as well...!!!

~~~
knzhou
The continent that has contributed the most to global pandemics is Europe. By
far.

~~~
cortesoft
I think they mean where humanity started... which they are wrong about.

~~~
knzhou
Man, that makes even less sense...

