What?s your favorite population size for an Earth-like planet???
Posted: Posted April 8th, 2019
Edited July 25th, 2019 by chiarizio
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Assuming inhabitants much like modern humans and a planet much like Holocene Earth, what’s your favorite global population for your built-worlds?
Number of digits, and first digit, please.
Anyone like it smaller than 100,000,000?
Anyone like it larger than 10,000,000,000?

As for me my current favorite is about 1,512,000,000.


How about your designed fictional or gaming cities?
Is 40,000 too small?
Is 8,000,000 too big?
Or do you use RL cities, with whatever their RL populations were whenever your story or game was set?


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Any idea where those multiple question-marks in my title come from? I only typed one!
I also don’t know where the multiple percent-signs come from in my replies to various threads.

Posted April 8th, 2019 by chiarizio
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500 000 000 so everyone can live relatively affluent wealthy lives in pristine clean cities with no poverty or bad neighborhoods. An abundance of resources and a rule of two children maximum per mother. I think 400 000 is a good size for large cities.

Edited April 8th, 2019 by I killed Mufasa
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A max of two children per mother will lead to declining population unless you can guarantee all children born will live long enough to have two children of their own.
Instead you want an average of two children per mother.
If the minimum is fewer than two per mother, then the maximum must be more than two, in order to pull the average up to two.
In the healthiest modern societies, the replacement rate is actually more like 2.1 per mother, because we don’t yet have perfect survival until parenthood of all children born.
In less healthy modern societies it may still be more like 4.
Pretty sure that already before the Renaissance it was less than 6 in the West.
But before vaccinations and antibiotics it was probably a lot more than 2, even in peacetime.

BTW about the time of the Renaissance, before the Scientific Revolution, I understand (if I remember right) it (the world population) was about 330 million, about a third of a billion, sort of closish to the half a billion you suggested.

Edited April 15th, 2019 by chiarizio
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If the population fell below say 400 000 000 then they'd have to temporarily allow 3 per mother. But it's unlikely it would fall that fast quickly, and as soon as it hit 500 000 000 again the law would revert back to 2 per mother.

Posted April 8th, 2019 by I killed Mufasa
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Technically speaking Earth's current population could live in an area the size of Alaska assuming all of the land was viable for farming and there was enough fresh water to sustain 7 000 000 000 people, but that would be exceedingly uncomfortable and you'd probably see a lot of sky scrapers and farming on top of those sky scrapers. Plus that civilization would need at least temporary access to the rest of the planet so they can build those sky scrapers and catch fish and other food.

My proposition of 500 000 000 for the entire globe would probably see at least one entire continent dedicated just to farming, one to mining, and one continent, probably North America if it were Earth, to living. Of course there would be some farming and a bit of mining on the living continent too just because it would be cheaper there.

Edited April 8th, 2019 by I killed Mufasa
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I also didn't take into consideration that some women won't want to have children at all, or might be incapable of having them. So the population may fluctuate between 400 000 000 and 500 000 000 more often than I thought. There are two remedies to this. One is to make the two children per mother a mandatory rule (Or at least raising two children birthed by a different woman, making the rule two children per woman whether they birthed them or not), or just keep raising it to 3 or 4 per women (optional) every time the population dips below 400 000 000.

Edited April 8th, 2019 by I killed Mufasa
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@IKM: it looks like you’re thinking about it!

Posted April 10th, 2019 by chiarizio
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I try. :P

Posted April 10th, 2019 by I killed Mufasa
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I imagine, in one of my built-worlds, that only 1/8 (ie 12.5%) of the planet’s surface is available for humans to inhabit, and an additional eighth (12.5%) is available for hunting/gathering/fishing/agriculture/aquaculture/forestry/mining/ranching etc. Then another 50% is available to travel through but not to stay in. Or maybe they can stay 12 to 36 hours in 25% but stop only for an hour in another 25%. The remaining 25% of the planet’s surface is no-go for humans.

Those fractions include water as well as land.
And if humans aren’t allowed to dwell on a part of the surface they also aren’t allowed to dwell above or below it; if they’re not allowed to extract or cultivate resources on a portion of surface they are also not allowed to do so below or above it; and if they’re not allowed to travel over a portion of surface they’re also not allowed to travel above or below it.

How far above or below does the prohibition extend? At a max, the radius of the planet; at a min, about a hundred miles or the thickness of the atmosphere.

The land-area and sea-area available and unavailable for each purpose would be distributed around the globe, rather than dedicating each continent and each ocean to one thing.
For instance, consider the following crude or crude-ish first approximation.
Assume the globe is 360 degrees of longitude in circumference at the Equator, and 180 degrees of latitude from pole to pole.
Assume each degree of latitude is divided into 60 minutes or nautical miles; and each degree of longitude is likewise divided into 60 minutes, which at the Equator are also a nautical mile.

Divide the planet’s surface into 2400 north-south strips each 9 minutes wide. Simultaneously divide it into 1200 east-west strips each 9 minutes wide.
Number the strips.
People can neither reside (dwell) in, nor exploit, any area in any odd-numbered strip.
If an area is in two odd-numbered strips, people aren’t even allowed to go there.
If it’s in an odd-numbered strip and an even-numbered strip, people are allowed to travel through it, but not to stay there.
If it’s in two even-numbered strips, people can either live in it or exploit it, but not both.
If the sum of the strips’ numbers is divisible by four (4), people can live in it.
Otherwise, if both strips’ numbers are even but only one is divisible by four, people can exploit it for resources, but not live there.

So 1200*600 = 720,000 of these areas will be unavailable for humans to even travel through.

360,000 will be available to live in but not to exploit; another 360,000 will be available to exploit but not to live in.

The remaining 1,440,000 of these areas will be available to travel through, but that’s all.

People who work in one of the exploitable zones will have to commute at least 9 but no more than 27 minutes (an average of 18 minutes if they don’t make any effort to make their residences as close to their jobsites as possible) between their homes and their workplaces. I’m just going to pretend that a minute is a nautical mile.

If someone wants to travel from their own home area to visit someone in a nearest non-adjacent other home area, they’ll probably have to go about 36 minutes or nautical miles, on the average, from town-center to town-center, if they travel strictly north-south and east-west and go through the center if the workzone.
However, if they travel northwest or southwest or northeast or southeast from town center to the corner of town, then skirt the edge if the no-go Zone by going 9 minutes north or south or east or west to the corner of the work zone then taking a right-angle turn to go east or west or north or south another 9 minutes along the edge of the no-go- “wild” zone to get to the corner of the next town, then go catty-corner again to get to the center of the nearest other town, they’ll have gone only 18 + squrt(2)*9 minutes or nautical miles. That’s closer to 30.6 than to 36.

Posted April 12th, 2019 by chiarizio
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Anyway; suppose there are about 35 births per year per thousand married women between the ages of 15 and 45. And suppose there are 60*60*60 = 216,000 classes/sections/skins of each sex. And suppose we want an average of 3500 (and a minimum of 350) people in each skin.
That’s about 2 sexes * 3500 people * 216,000 = 7000*216000 = 1,512,000,000 people in total, both sexes, all ages, all marital conditions.

The average inhabited area could have 1,512,000,000/360,000 = 151,200/36 = 4200 people living in it.
We should suppose that some inhabited areas have only 420 or even fewer inhabitants, while others have 42,000 or even more inhabitants.
Unusually sparsely-populated inhabited areas might have not many more than 42 inhabitants, while unusually heavily-populous areas might have almost 420,000 inhabitants.

I expect the oceanic or marine or aquatic zones could be exploited just as easily as the “dry”-land zones, but couldn’t be inhabited nearly as easily or as populously. So a lot of the watery habitable zones might have only 420 or only 42 inhabitants, while many of the dry-land habitable zones might have 42,000 or 420,000 inhabitants. Presumably the average dry-land community would be about 4 times as populous as the average “wet” community, or some such figure —— 3 or 4 or 9 or 16, I don’t know.

For purposes of government, divide the globe into twelve north-south strips 30 degrees of longitude wide, and simultaneously into twelve east-west strips 15 degrees of latitude wide. The globe will thus be divided into 144 not-really-“rectangles” measuring 30 degrees by 15 degrees, or, 200 9- minute units by 100 9-minute units. Each of these “rectangles” will contain 200*100 = 20,000 “zones”; of which 2,500 will be habitable, 2,500 will be exploitable, 5,000 will be reserved pristine wilderness, and 10,000 will be just-passing-through only.

They’ll be about big enough for medium-small nations or medium-large states or provinces or constituent republics or kingdoms of federations or unions.

If I further divide each such rectangle into twelve equally-populous north-south strips and simultaneously into twelve equally-populous east-west strips, it will be subdivided into 144 sub-“rectangles” averaging about 150 minutes of longitude east-to-West and about 75 minutes of latitude north-to-south. Each such “subrectangle” will average about 17 or 18 habitable zones.

They’ll be about big enough for medium-small states or provinces or constituent kingdoms or republics of unions or federations, or medium-large counties or parishes or what-have-you.

I don’t think I could go any further without making the topic drift even more than I’ve already made it.

Posted April 12th, 2019 by chiarizio
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