# Questions tagged [population]

For questions on population sizes, maximums and minimums, how they are affected by different events, etc.

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### What is a reasonable amount of population growth for 900 years?

Starting with about 500 humans and allowing for 900 years to pass, about how many people would there be at the end? (Just asking for a rough estimate, maybe a range.) Assuming: People are generally ...
26k views

### How can I kill every human on earth? [closed]

One day, "God" said to me: You need to eliminate the humans race! So, I was thinking at this problem: How can I kill every human on the planet (and then kill myself)? Some ideas: Nuclear Bomb - ...
3k views

### What's the highest population the Earth could possibly sustain?

Suppose that we pare down human consumption to a minimum survivable level across the Earth, and devote the entire surface of the planet (as well as the planet's interior, if needed) to support as many ...
12k views

### How many people are necessary to maintain modern civilisation?

Modern Earth; a series of connected events (natural disasters, mass migration, drug-resistant pandemic, collapse in biodiversity, armed conflict) have led to a significant reduction in human ...
16k views

### How long will it take human population to exceed one trillion?

Assuming that human civilization in the future will spread from earth into the galaxy, how long would it take for the human population to exceed one trillion (10¹²)? I doubt this is possible if humans ...
17k views

### How poor does Elven fertility need to be in order to keep the ratio of humans to elves constant?

I world-build for tabletop RPGs so I have Tolkien/DnD/Forgotten Realms like elves in mind. The assumptions are: The ratio of humans to elves in the world has been more or less constant. Humans live ~...
6k views

### How to calculate your kingdom’s population size?

How do I figure out the population numbers in my various kingdoms? I've seen the population growth tables for the entire world showing how the population grew and died off over time (yes Genghis, I'm ...
4k views

### How can I estimate how many people are living in a specific territory?

In my own medieval fantasy setting, I have different countries that all have different populations. I admit that I have no idea of how many people should live in X or Y. Just using the numbers for the ...
5k views

### I want a big city in the desert, what conditions make it possible?

Starting condition: I know how small cities form. It is mostly a trade center that requires an access to water and food. But some cities have more than 100 000+ people. Climate: It is in the desert, ...
1k views

### Minimum Population For a High Tech Society?

So I was thinking about minimum viable population levels for a colony and it hit me that there are two industries that probably can't be made to work at small population, but that you need to have a ...
3k views

### Which is initially more favorable; large or small settlements in a new planetary colony?

I have a question that concerns a story I am writing and I hope it is a valid one to ask. But in my story, several groups of colonists, each arriving on different ships at relatively the same time, ...
4k views

### Maximum relative size of a nation's military

As far as I can determine by my research, relative to the population, the largest (by measure of manpower) the US military ever reached was in 1945 at 12,209,238 military personnel (not limited to ...
720 views

### Land Requirement for Island City

What would be the land requirement (in acres) for both farming and housing to sustain a society in this scenario: Small city of 1000 humans living on an island Medieval setting Mostly self-sufficient ...
3k views

### How to increase the population growth of the human race

In my world (that takes place on an infinite plane), there exists an empire (let's call it Usotuhr) that is hell-bent on establishing human hegemony, or at the very least a human foothold, in the ...
413 views

### Population increase on a Colonized Mars [closed]

In my world, a second space race pushes humanity farther than it has ever gone before. Humanity has carved up to moon between superpowers (the U.S. and China) and second rate space powers (E.U., ...
625 views

### What's the minimum time that it would take for an advanced species to create an ecumenopolis?

In figuring out the rough timeline for my sci-fi, I've run into an interesting dilemma. As it stands right now, There are about 90 years in between one of my civilizations discovering space travel and ...
42k views

### If everyone in the world disappeared except 35 random people, how long would it take for one of them to realize they're not alone?

Everyone suddenly disappears from earth except 35 people randomly scattered wherever they were before everyone disappeared. How long would it take on average for 2 or more people to meet? What other ...
6k views

### How to build a self-sufficient town

Other questions have tried to address how big/small towns have to be in order to function, but I'm more interested in approaching it from a different angle: How big would a town have to be to support ...
2k views

### What computational resources would work for a 550-year climate forecast of our earth?

Folks, I'm in a bit of a jam. I am writing a fictional future history to support a series of post-collapse science fiction stories set ca. 2560 Gregorian. The first story, The Borax Road Affair, has ...
8k views

### In theory, could all mammals be wiped out by a single pathogen?

Pathogen Note: For the purpose of this question I define a pathogen to include viruses and/or bacteria. Edit: I don't exclude other biological agents such as fungi that might have the same effect. ...
4k views

### Lego world. How do they reproduce?

It is difficult to find statistics for the ratio of Lego men and women in the general population but from a non-scientific survey, I get the impression that Lego men vastly outnumber Lego women. Yet ...
510 views

### What is a good reference size for a settlement?

I have been sporadically building a particular world, mainly by developing its cultures with events (often paralleling Earth history) and individuals, rather than shaping the cultures beforehand. One ...
8k views

### What would be a logical reason to explain space based families having more children than an earth based one

In my yet to be named sci-fi universe humanity has begun to expand into space and has established large scale space stations near Earth and on places like Eros and Luna. I wanted the stereotypical "...
1k views

### Repopulating humans AND zombies

So most zombie apocalypse stories involve wiping out 99.9% of the human race and having a small minority survive to try and keep living. But, let's say I want society as we know it to collapse, but I ...
2k views

### Population Size of a Colony With a Large Gender Disparity

This is my first post on this site, so please bear with me. I am working on a series of stories about an interstellar colony with a large gender disparity. Namely the initial population was made up of ...
9k views

### Is it plausible that humanity goes extinct due to not making enough children? If not, what would make it more plausible?

With the increase in living standards, the number of children by women is decreasing in highly developed countries. Question: Is it conceivable (with the aggravating factors proposed below) to see ...
7k views

### How large would a mega structure have to be to host 1 billion people indefinitely?

Ruins of buildings, abandoned cities and suburbs dot the coasts of Earth's landmasses, inhabited by wild animals and the pieces of a once vibrant civilization. The oceans are relatively empty, the ...
3k views

### Population Range for a Booming/Dying Frontier Town

I'm designing a town in the Ozark mountain range circa 1871, and am unsure what population size to give it. River Bend is an isolated town in the Ozark highlands of Arkansas founded in 1845 on the ...
288 views

### Time duration for development of different physical attributes

On my fictional planet humanoid aliens have evolved on one continent, and have since spread around the entire planet, just like humans did on Earth. On Earth humans have since developed slightly ...
415 views

### Reasonable starting population?

Here is something a bit more rigorous related to my Kepler Bb Civilization I thought 100 humanoids transported with these criteria: 1:1 male:female ratio No children below 15 No ill or otherwise ...
8k views

### Why would people not settle an open plain?

My world consists of a relatively narrow strip of land with the sea on one side and the mountains on the other. However, to the north and south are simply grasslands, and maybe the occasionally forest....
467 views

### Maximum Earth population given biological shrinking

I want to create a world set on our Earth but with humans shrunk down as much as possible to allow a huge population. As the population increases they genetically modify their bodies to be as small ...
456 views

### I want a big city in a temperate area, what conditons make it possible?

Starting conditions: Climate: It is located in a temperate climate. In this classification, most C and D climates are temperate. Mostly: Cfb, Cfc, Dfa, Dfb, Dsa, Dsb, Dwa, Dwb. And also, Csa, and ...
325 views

### Maximum Earth population by wiping out biological life

I want to create a world set on our Earth but with humans converted entirely to machines, so the population can be larger than would be possible with biological humans. In contrast to biologically ...
557 views

### Megacity Shapes, Episode 1: Population Capacity

This scenario is based on three specific megastructures that are considered but never realized: Japan's Shimizu Mega-City Pyramid, 2004 meters tall and covering an area of eight square kilometers, ...
2k views

### Would the death of 50% of the human population drastically reduce carbon dioxide levels?

It is well known that in respiration, we produce carbon dioxide, while plants, via photosynthesis, absorb CO2. My question is, if 50% of all people die today, will the total amount of CO2 decrease ...
313 views

### Maintaining a constant population in a country

I am currently writing a short story about a world that is about to go into nuclear annihilation and ultimately destroy themselves through global thermonuclear war. Therefore, the government of one ...
849 views

### What is the difference of population density between the population of a nomadic and a sendentary territory?

Let's say that I have two places with the same climate and the same geography and everything. The only difference is that one civilization is nomadic and the other has settled cities on the land and ...
404 views

### How would an isolated world grow its population, then keep it stable?

The scenario In the scenario that I'm imagining, a small group of people (ideally 100 or less) travel to a parallel universe and begin a new society. The new planet that they land on has one land ...
4k views

### How small can a population be with regard to genetic diversity?

I'm working on creating a species that favours small families for a number of reasons, and have no interest in 'breeding as much as possible'. As a consequence, their population size is small. But how ...
460 views

### What is the result of a genetic mutation that disallows female offspring?

Premise: Assume that one man has a genetic mutation such that his gametes (sperm) never have an X-chromosome. Unlike most men (who have a roughly 50/50 chance to sire a male or a female child) this ...
723 views

### How many humans do you need to maintain a population indefinitely?

So this might be a slightly weird one, but I"ve seen answers to questions about minimum numbers for re-population and such, but what about a system where reproduction was controlled and coordinated, ...
582 views

### How to mitigate high infant mortality rates in a space colony

Judging by the majority of answers from this question: What would be a logical reason to explain space based families having more children than an earth based one the spacers are going to have lots of ...
358 views

### Gravitational Implications of a "Light Year City"

The "Light-Year City" Questions — What would be the gravitational implications of a city in the far, far distant future, with an area spanning one square light year (3.456 × 10^25 mi² area)? This ...
266 views

### Largest Population for Ancient World Migration/Encampment

What is a reasonable range of number of people that could participate in a cohesive and centrally organized migration/encampment? Assumptions: Ancient times, desert terrain. People include adults ...
8k views

### How much could a population of 100 grow in 1000 years? [duplicate]

My theoretical scenario has a isolated population of 100 placed in a temperate fertile environment, with little to no negative factors affecting growth such as war, radiation, predators, disease etc. ...