Pop growth - what about decrease?

[The Boz]

So just resettle them. You can do it right now with both Authoritarian and Egalitarians.

Lategame you can just create a few Ecowhatsitcalledpolis. Or build artificial planets. Or conquer enemy territory.

If you are running out of planets you are either playing badly or intentionally don't want to win the game.

Both these work in theory, except for one detail. Which is two things:
1) do you want a habitat, or a useful megastructure?
ii) the constant clicking on manual resettlement is really annoying
c) high economic volatility of the entire setup

 

[Sarmatian]

Okay, let's consider a population where everyone reproduces at 20 years old, and dies at 80 years old. Assume an initial population of 100 20-yr. old people in the year 2000 - 50 men and 50 women. We will assume each couple has 1 or 2 children, perfectly balanced so the average fertility rate is 1.5. In case of decimal numbers we will round up.

Year 2000: 100 people initially
- 100 age 20.
- 75 children born.
Year 2020: 175 people initially
- 100 are 40.
- 75 are 20.
- 57 children are born.
Year 2040: 232 people initially
- 100 are 60.
- 75 are 40.
- 57 are 20.
- 43 children are born.
Year 2060: 275 people initially
- 100 are 80 - they die off.
- 75 are 60.
- 57 are 40.
- 43 are 20.
- 33 children are born.
Year 2080: 208 people initially
- 75 are 80 - they die off.
- 57 are 60.
- 43 are 40.
- 33 are 20.
- 25 children are born.
Year 2100: 158 people initially
- 57 are 80 - they die off.
- 43 are 80.
- 33 are 60.
- 25 are 20.
- 19 children are born.

Do you see what is happening? The initial population surges, but as the oldest generations die off it starts dropping again. You will find this same effect no matter when people start giving birth or how long they live - unless people are immortal, they will eventually die, and if they have left behind fewer offspring than is required to produce children, the population will decline. In a population with sexual reproduction, that number is 2, so a fertility rate below 2 cannot grow once older generations begin to die.

That works in a sealed system. Life doesn't work that way. Life expectancy rises, medical care becomes better. In a year 2100, life expectancy on average will be much higher. In Stellaris, techs increase life expectancy as well.

So, mathematically, in a hermetically sealed system that's set with same perpetual rules, over a long period of time, yes you would right. But life isn't a such system. And for the few hundred years the Stellaris games last, where life expectancy increases a lot (it can even close to triple, depending on your choices) we can safely assume that even with less than 2 children per couple, population would be consistently increasing, which was my point.

Add just 5 years more to each following generation, your cut off point will be much further out. And if you get to 200 years life expectancy, the population wouldn't start dropping for more than a thousand years.

 

[Delthor]

My approach to handling overpopulation is building a ringworld or two. You can easily support hundreds of pops per segment, and the whole thing can have ~1,000 pops living comfortably in a single system.

It does mean avoiding egalitarianism or at least being okay mildly upsetting them, since apparently funding emmigration for unemployed people so they can find jobs in a perfectly architectured paradise is somehow objectionable.

Edit: It makes me wished rogue servitors were more playable, but if they didn't make changes in the patch released today, I imagine machine empires are about where they're going to be for a few weeks at least so I'll be trying one this weekend.

 

[djvandebrake]

That works in a sealed system. Life doesn't work that way. Life expectancy rises, medical care becomes better. In a year 2100, life expectancy on average will be much higher. In Stellaris, techs increase life expectancy as well.

So, mathematically, in a hermetically sealed system that's set with same perpetual rules, over a long period of time, yes you would right. But life isn't a such system. And for the few hundred years the Stellaris games last, where life expectancy increases a lot (it can even close to triple, depending on your choices) we can safely assume that even with less than 2 children per couple, population would be consistently increasing, which was my point.

Add just 5 years more to each following generation, your cut off point will be much further out. And if you get to 200 years life expectancy, the population wouldn't start dropping for more than a thousand years.

It might take longer, but it *will* start falling, as surely as night follows day. Unless the people are *actually immortal* then eventually the oldest generations die, and if every person has less than 1 kid on average it is a mathematically inescapable fact that once people start to die the population will start to shrink. I don't honestly know how you cannot understand this. If you add 1.5 people and take away 2, you get .5 less people.

 

[Sarmatian]

It might take longer, but it *will* start falling, as surely as night follows day. Unless the people are *actually immortal* then eventually the oldest generations die, and if every person has less than 1 kid on average it is a mathematically inescapable fact that once people start to die the population will start to shrink. I don't honestly know how you cannot understand this. If you add 1.5 people and take away 2, you get .5 less people.

I do understand. I'm explaining that the population doesn't have to start dropping if life expectancy keeps going up.

It was a response to someone stating that population growth is too high in Stellaris since already in developed countries you have less than 2 children per couple. So, for the purpose of a Stellaris game, which lasts a few hundred years and life expectancy usually doubles, population would keep growing even with less than 2 children per couple.

I don't know what is so hard to understand there.

 

[Tisifoni12]

Even thinking of population 'growth' as representing spread as well as 'growth', e.g. more pops, but those pops may represent smaller numbers, the rate of growth seems kind of exponential. Population driving expansion rather than population as a finite resource in a galaxy offering vast, vast resources.