A 2,500-mile radius in Asia contains half the world's population (2017)

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)

Waterluvian• 6 years ago

Can I cheat and use QGIS? Feel like if I got up off my butt and went to my PC it would take two mins.

I assume we are simplifying to an oblate spheroid and not worrying about topography and such.

Also I think this means technically its a Spheroidal Cap?

symplee2• 6 years ago

If we bring in topography, aren't we now running into a 3D version of the coastline paradox?

https://en.wikipedia.org/wiki/Coastline_paradox

So, yes, good point. Let's start with assuming a perfect sphere, then oblate spheroid, then topography, then only land (not water), and however crazy this thread gets with whatever else we haven't thought of :)

thaumasiotes10• 6 years ago

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.

thaumasiotes10• 6 years ago

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.

throwGuardian• 6 years ago

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).

emmelaich2• 6 years ago

.. 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.

ampdepolymerase• 6 years ago

Volcanoes are very fertile.

luhem7• 6 years ago

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.

contingencies• 6 years ago

Don't forget the Brahmaputra, Irrawaddy, Salween, Mekong, Red River, Pearl River, whatever dominates Java/Sumatra...

1014042• 6 years ago

Red River? Do you mean Yellow River (Huang He?)

cortesoft3• 6 years ago

I was wondering... they didn't mention reasons at all in the article.

blackrock2• 6 years ago

This must be why the Mongols dreamed of conquering China, and finally succeeded. To control access to this ancient agricultural production system.

And why the Chinese were so adamant on building the great walls as their perimeter defense system.

foobar_llc• 6 years ago

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

_-___________-_• 6 years ago

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

kissickas• 6 years ago

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

https://www.reddit.com/r/MapPorn/comments/1dqh7d/after_seein...

abbadadda• 6 years ago

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

cam_l• 6 years ago

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

http://www.radicalcartography.net/index.html?human-hemispher...

titzer• 6 years ago

Thank you for that rat hole. I spent > 30 mins looking at some really cool things!

divbzero2• 6 years ago

Awesome indeed. Thanks for the link.

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

gshdg• 6 years ago

It also omits Antarctica entirely

fizixer2• 6 years ago

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%).

thaumasiotes10• 6 years ago

It's about 10% of the world's entire area, ocean included. It's much more than that of the land area. (But as you note, it includes water too. Not sure how much.)

keanzu• 6 years ago

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...

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

fizixer2• 6 years ago

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.)

cortesoft3• 6 years ago

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• 6 years ago

Read the older comments in this thread...

dmix• 6 years ago

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://en.wikipedia.org/wiki/Influenza_A_virus_subtype_H7N9...

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.

andys627• 6 years ago

A 30 ft radius in Davos contains half the worlds wealth

yitchelle• 6 years ago

But only for a small percentage of the year.

quickthrower23• 6 years ago

Or a 2 ft radius in wherever bezos happens to be.

stickfigure• 6 years ago

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

divbzero2• 6 years ago

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.

quickthrower23• 6 years ago

Astronauts?

tim333• 6 years ago

There are quite a few in planes and up mountains.

speedgoose• 6 years ago

2500 miles ≈ 4000 km.

Guys, switch to metric units already. Thank you.

The rest of the world.

ikeyany• 6 years ago

I find it very interesting that a large portion of the UK uses yards to measure distances shorter than a few kilometers. I saw a sign that read "Exit - 500 yards" in London the other day.

ak393• 6 years ago

You think that’s bad? Half the folks in this 2,500 mile radius are “laughing in their crores and lakhs”. Mildly infuriating for someone not used to arbitrary multiple names.

bakery2k4• 6 years ago

That shouldn't be surprising. Distances longer than a few kilometers are measured in miles.

Jedd• 6 years ago

... the UK uses yards to measure distances shorter than a few kilometers.

For the record, in the UK, and indeed most metric / english-speaking countries, it'll be metres (and kilometres).

A metre is the ISO unit for distance.

A meter is a device to measure things (not just distances).

GordonS• 6 years ago

In the UK, yards are used almost exclusively for exit distance markers. I don't recall ever hearing/seeing them used for anything else in my entire life.

globular-toast2• 6 years ago

UK roads are in imperial: inches, feet, yards, and miles. Not many people use yards for anything else.

blackrock2• 6 years ago

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

renaudg2• 6 years ago

Why is it worse ?

VvR-Ox2• 6 years ago

Because the comma reaches below the baseline of the line and therefor better visually separates the two parts of the representation.

skrause• 6 years ago

I must admit, I find it baffling how the EU uses metric, but yet, they use the comma as the decimal point.

You make it sound that the EU is the odd one out here by not using the "normal" decimal point, but internationally both version are used just about as often: https://en.wikipedia.org/wiki/Decimal_separator#Arabic_numer...

Neither is better or worse, it's just convention.

jeroenhd4• 6 years ago

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.

wcoenen• 6 years ago

The history of this is that at some point, Arab mathematicians settled on a small pen stroke to separate decimals. When this got typeset, people found it convenient to just reuse the point or comma. Different countries made different choices, and now we have to deal with that.

The original arabic character now has a Unicode code point, so we could fix the mess by switching back to that ;-) https://www.fileformat.info/info/unicode/char/066b/index.htm

VvR-Ox2• 6 years ago

YMMD :D

I wonder when the day will come that humanity overcomes these issues without the need to convert values between several systems all the time.

867-5309• 6 years ago

YMMD :D

Your Mileage May Differ? :)

Keloo• 6 years ago

Your Measurements Might Disappoint?

jtolmar2• 6 years ago

YMMD

This is the worst date string format I've ever seen. Today is 0026, and February 26th will be too.

loco5niner• 6 years ago

YMMD

Your Measurements May Differ?

aldanor• 6 years ago

While I live in Europe and I do agree, imagine how nice would it be if the entire world used the duodecimal system today for everything, i.e. 100 was preceded by BB (143). Greeks and Shumers were smart guys - 12 has 4 divisors (excluding itself and 1) while 10 has only 2. Same story with 100 and 144, etc.

londons_explore2• 6 years ago

Having spent a lot of time recently digging around memory dumps, I'm getting pretty good at hexadecimal mental arithmetic, and it certainly seems like a superior system.

anonu• 6 years ago

Is there an imperative to do so? Don't get me wrong, I would love for everyone to use MKS.

But the cost of making that switch maybe far outweighs any gains.

Taniwha3• 6 years ago

The reason why you should do it is so that the rest of the world will understand what you are talking about, the cost is about 10 seconds with a calculator.

Tepix2• 6 years ago

But the cost of making that switch maybe far outweighs any gains.

Source?

The rest of the world has switched from its arcane units and is quite happy about it.

nojvek• 6 years ago

A litre of pure water weighs 1kg at sea level. A litre is 10cm x 10cm x 10cm. Water freezes at 0 and boils at 100. Volume, distance, temperature as wonderful easy to remember units.

Sincerely, metric system and friends.

ascar• 6 years ago

I like the metric system and would love to see the US switch to the metric system, but this comment is just wrong on so many levels.

One litre of water only approximately weighs 1kg and density is relative to temperature and pressure. Further, the "standard pressure" density is measured in isn't equivalent to average sea level pressure. Celsius is as much a SI derived unit as Fahrenheit is. The official unit is Kelvin and water freezes at 273.15K. Not such a beautiful number, but still based on the scientifically more significant definition of temperature.

wsxcde2• 6 years ago

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

b0rsuk• 6 years ago

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

marcthe12• 6 years ago

Actually the Sahara Savannah is cause my an increase in temperatures

k__• 6 years ago

Couldn't they build more green walls until the sahara is covered?

wsxcde2• 6 years ago

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.

BurningFrog2• 6 years ago

I also expect population prognoses to change many times before 2100.

archivist1• 6 years ago

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.

dntbnmpls2• 6 years ago

Total world landmass: 57,510,000 miles squared.

https://en.wikipedia.org/wiki/List_of_countries_and_dependen...

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.

empath75• 6 years ago

1/3rd of that circle is water. And a significant amount of it is also Siberia and Mongolia. Double check your math.

dntbnmpls2• 6 years ago

1/3rd of that circle is water.

Fine. Thrown in the saraha desert and a few other inhospitable areas and it'll make up that third.

And a significant amount of it is also Siberia and Mongolia.

Are we looking at the same map? Hardly any part of siberia is included ( maybe the a tiny portion of the russian far east ). Feel free to take out the mongolian landmass if you want.

Double check your math.

Did and my idea still holds.

scythe• 6 years ago

It's more than a third. Roughly half the circle is water. It also contains all of Tibet, the Hindu Kush and the Southeast Asian rainforest (except New Guinea). Furthermore it contains the highly mountainous islands of Japan, Taiwan, the Phillippines and Indonesia. Proclaiming that all or even most of this land is "habitable" is obviously silly if you just look at it:

https://media.cntraveler.com/photos/593eedf1f2125a2b5b9ed24d...

Any glance at a map of population density will reveal that all of the highest density areas (pink) are within the circle:

https://en.m.wikipedia.org/wiki/Population_density#/media/Fi...

This is definitely an interesting phenomenon and not just clickbait. The most likely explanation is that high rainfall in East Asia has allowed high-yield rice cultivation preceding the Green Revolution, allowing East Asia to support much higher population density in preindustrial times than any other region. Europe is too cold, Africa and West Asia too dry, and the Americas didn't have rice. (Although they did have the potato, but it didn't spread outside the Andes without European assistance.)

namarie• 6 years ago

There's also the Gobi Desert.

theredlion• 6 years ago

Myers was amazed to find that a circle roughly 2,500 miles in diameter, when placed over the right part of Asia, could hold more than half the world's population.

The above is from the article. It says radius in the title and diameter in the article

olalonde• 6 years ago

So that region is not more densely populated than the rest of the world? That makes me a bit skeptical of your math because it obviously is. For one, you are using habitable land mass for the rest of the world while the circled area is mostly sea water. I wonder how that comment got to the top.

nine_k2• 6 years ago

It's more densely populated because it has the highest concentration of habitable land.

Siberia to the north from there is not inhabited so densely because it has -50°C in the winter and +50°C in the summer.

Western Europe, US northeast, etc are also rather densely populated, but are smaller, with less-popuated areas, or with oceans.

code_sloth4• 6 years ago

52M km^2 of land on our planet is habitable, after forests, shrubs, rivers and lakes [0]. Total land mass is 149M km^2. So only 1/3 of the world's land is habitable. That's actually ~20M square miles. Your habitable land estimate is already nearly 50% off according to the source I found.

The circle covers 50.2M km^2 (4000^2 * pi). I'm going to assume the 2/3 land quotes are good enough an estimate. That makes the land mass inside the circle 33.5M km^2 (2/3 * 50.2). That means that the circle contains just 22.5% (33.5M/149M) of ALL land mass.

I couldn't find any quick data source on how much land inside the circle is actually habitable. So I'll apply a few ratios:

If X% of the land in the circle is habitable:

  X = 33% --> 33% * 33.5M / 52M = 21.5%  
  X = 50% --> 50% * 33.5M / 52M = 32.2%  
  X = 75% --> 75% * 33.5M / 52M = 48.3%

Your estimations would hold iff >75% of the land in the circle is habitable.

[0] https://ourworldindata.org/land-use

Merrill2• 6 years ago

A history of population within the circle would be interesting.

The population of China since 2000 years ago appears to have been a series of plateaus with brief periods of increase and a couple of brief decreases. The plateaus represent populations at the limit of agricultural systems. The increases are due to introduction of new systems, such as rice cultivation further north, double-cropping of rice and so forth. The decreases are periods of famine, disease and war. http://www.china-profile.com/data/fig_pop_0-2050.htm

Possibly other civilizations within the circle follow the same pattern of stability, innovation and crises.

lottin• 6 years ago

If I recall correctly, rice can sustain a much greater number of people per unit of land than any other crop, and this explains why East Asia is more densely populated than any other part of the world.

IIAOPSW• 6 years ago

Until the industrial revolution, the human population everywhere was in equilibrium with agricultural technology. Improvements to technology would lead to population growth until wealth per capita reached the same old level and people stopped having as many kids. Check out the book "A farewell to Alms" for a solid 10 chapters of historical records on this from around the world.

The first person to notice this universal truth about the human population was Malthus. He had the misfortune to make the observation right on the eve of era when it stopped being true.

rjkennedy98• 6 years ago

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.

alexilliamson• 6 years ago

Yeah this is the error in the parent calculation

swsieber• 6 years ago

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.

wongarsu• 6 years ago

This actually fits with the visual impression you get from the map. It's clearly far less than 50% of the inhabitable land mass

Abimelex• 6 years ago

you also need to map the circle firs to the surface, a circle on a world map is not the same as a circle on the globe.

Aperocky• 6 years ago

The circle contains 1/3 ocean and ocean is not landmass. You'll have to revise your calculation. Also, since the circle contains Tibet, desert in Xinjiang and Mongolia, your assumption that all of that is habitable land is even more wrong.

labawi• 6 years ago

The water is a fair point, but GP didn't exclude Sahara, middle east or other deserts, so it would not be proper to exclude Xinjiang or Mongolia.

jariel• 6 years ago

"So that area represents about (19.63 / 57.51 ) 34% of the total world landmass."

1/2 of said circle is ocean, not land. And some of said land is 'uninhabitable' i.e Gobi Desert.

And Canada is 3.8 miles squared, implying that 3.5 of those are uninhabitable is rather off. By that calculation, you'd be excluding most of Quebec and Ontario, which are 'inhabitable' just sparsely populated, in which case much of Tibet and China would be comparably 'uninhabitable' as well.

dilippkumar• 6 years ago

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.

I've been telling myself that I have to teach myself Non-Eucledian Geometry, but lacking any real motivation, I've successfully procrastinated for 6 years.

The unfortunate itch to be pedantic on the internet will hopefully drive me to learn how to correctly calculate the area of a circle on a sphere.

Anybody has a good textbook recommendation?

einpoklum• 6 years ago

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

lovemenot• 6 years ago

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

Ken Jennings: What is Valeriepieris circle?

billfruit• 6 years ago

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?

harikb• 6 years ago

Without artificial heating or cooling, it is far easier to survive India than many parts of say, US or Europe. So in terms of ancient civilization, India is the ideal climate

lotsofpulp• 6 years ago

It didn’t use to be so uncomfortable. Even just two generations ago, the weather was much milder and even when uncomfortable, only for a couple months.

Then everything got paved, all the trees were cut down so there’s no more shade, carbon emissions, population explosion, climate change etc. Even the cultural traditions which used to line up with seasons such as monsoons and spring don’t quite line up anymore.

odiroot• 6 years ago

Uncomfortable? They can farm and build for most of the year. As opposed to us in central Europe, where everything stops for nearly half a year.

joncrane• 6 years ago

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.

jtolmar2• 6 years ago

Mountains mean rivers, rivers mean agriculture, and agriculture means more people. The Himalayas are the largest mountains in the world, and the countries flanking them have always been the most populous.

Try an image search for "rivers of Asia" and you'll see a bunch of lines pointing near the center of that circle.

hacknat• 6 years ago

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

samatman4• 6 years ago

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.

est31• 6 years ago

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.

krtong• 6 years ago

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...

magicsmoke• 6 years ago

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.

iancmceachern• 6 years ago

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...

Someone3• 6 years ago

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.

tomq• 6 years ago

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.

supportlocal4h• 6 years ago

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

intpbro• 6 years ago

A 2500 mile radius is a huge area

A 2,500-mile radius in Asia contains half the world's population (2017)

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