Aurora Population Growth Rates

[gpt3 (OP)]

I was perusing some demographic data today and noticed something interesting.

A population's total fertility rate (TFR) is, roughly speaking, the number of children that the average woman can expect to give birth to over the course of her lifetime. High TFR generally results in a high population growth rate, although it can be counterbalanced by high death or emigration rates.

Country	Population Growth (%)	Total Fertility Rate
South Korea	0.1	0.9
United Kingdom	0.6	1.6
United States	0.4	1.7
France	0.2	1.9
Turkey	1.1	2.1
Israel	1.8	3.0
Kenya	2.3	3.4
Niger	3.8	6.8

Given that newly-established colonies have growth rates of 10% before accounting for migration, I can't help but wonder: how big is the average Aurora household? What are the side effects of Trans-Newtonian fertility drugs?

[TheTalkingMeowth]

What are the side effects of Trans-Newtonian fertility drugs?

Increased libido.

[nuclearslurpee]

If I had to venture some gobbledygook explanation, I'd probably say something like Earth presently has a lower growth rate due to high population so the data are not representative yada yada yada.

However I prefer the above explanation.

[Demonius]

At least we now know what important duty all these LTComs are fulfilling after retiring at 33...

[SevenOfCarina]

I always assumed that that was a consequence of their demographics being extremely skewed towards people in their twenties and thirties who immigrated with the intention of starting a family, with relatively few older people and almost no children.

The Aurora growth rates for small colonies appear to be mathematically impossible if we assume otherwise. For a population growing at a constant 10% per annum, the cohort aged n years must be 10% larger than the cohort aged n+1 years, and so on - we can construct a sample population pyramid using this, and determine the required fertility rate using the following approximation:

(1/(1 - imr)) * power[gr, anm] + power[gr, (anm - le)] = sum(n=1 to n=x) {cf x power[gr, (-tbp * (fr-1))] }

where imr = infant mortality rate ~ 0, gr = growth rate = 1.1 (10%pa), anm = age of new mothers, le = life expectancy ~ 90, cf = childbearing fraction ~ 0.5, tbp = time between pregancies, fr = fertility rate

If we assume that the colonists are having children one year apart (this is extremely short, realistically it'll be two years or more), then we end up with fr = 6.73 and nma = 7, i.e., the average age of new mothers is seven. Trying to bring nma up to 18 takes fr to 21 and tbp to 0.33, i.e., everyone is having triplets every year for seven years in a row.

[Droll]

I think population growth in aurora is balanced for game time and not realistic population dynamics lol. It always did seem quite fast, but now that the math is out there apparently we've turned into rabbits.

[RougeNPS]

Keep in mind this is assuming that 1: These are all couples doing it. 2: There its only 1 child per pregnancy. And 3: Generally people are getting pregnant when they are adults.

Good assumptions but not necessarily true under logical scrutiny.

[misanthropope]

for the 4x genre that is positively glacial.  off the top of my head, the later editions of starfire (with *slower* growth than the early eds) required females to be constantly pregnant with duodectuplets from age 16 til the end of time.

making the combat time scale sync with the civilization management is always gonna require some fudging.  anybody remember playing civ1 and your first catapult taking upwards of a thousand years to waddle to the front lines (*after* construction completed)?

[GodEmperor]

Its probably combination of drugs, medicine, fertility enchancments, wealth, cloning and all the other tech that would be available to TN society.

[misanthropope]

i mean if you're concerned about that sort of thing, you can maybe placate yourself with the argument that rapidly increasing technology and physical asset base means that the actual literal inventory of bug-eyed monsters increases quite a bit more slowly than GNP.

[Zap0]

Gal Civ tried to explain it by saying that these new people aren't all new births, but rather undocumented/unproductive/non-taxpaying people now becoming part of your state. Think peasants coming to the cities to find work.

[Paul M]

You could also explain it with the fact that the ratio of male to female is 1:7 and as was discovered in multi-wife situations the time between pregnancies will be reduced (it might actually drop below a year or at any rate get very close to that value).  So 7 couples will produce far fewer children than one man married to seven women.  There is also the 2525 solution where "you pick your son and daughter too (nice they were included) from the bottom of a long glass tube."  The whole polygamy thing though is likely to be the way you would work a new colony unless there is an eventual genetic diversity issue as the benefits to population growth are substantial.  If they come up to 10% I haven't checked though.

The starfire population growth rates were excessive beyond any reasonable scenario.  Basically economic activities were compressed by a factor of at least 10 to sync with military movement rates.  Attempting to bring the growth rate down to reasonable results in the sort of game Starslayer and I or Kurt are playing, which Marvin most certainly would never have enjoyed. 

[Froggiest1982]

Interesting.

It is still possible though to set the population growth in Aurora if you want something different. For instance, if you are playing a slow tech game, I find it useful to reduce it to 0.25. Playing around with the density modifier it is also nice to limit the planet's population capacity.

Combined with the NPRs standard generation, you may have more unique aliens that are able, for instance, to have double of the people on a planet and reproduce 3 times faster (insectoids?) than you do.

EDIT: On a side note I am recently using the same trick to actually reduce the Research speed in an attempt to have more challenging NPRs. My races have 0.1 research modifier while the game is still set at a normal research rate so that NPRs can grow faster and is generally more threatening by a technological superiority considering the IA general strategic thinking still need "some" work. If I decide to control the aliens though, I may set them only to 0.30.

[Steve Walmsley]

The pop growth for higher populations is modelled on Earth's population growth over the last few decades (slowing over time and headed for zero at about 12b - which is why 12b is Earth max pop). The 10% for tiny colonies is an arbitrary number for gameplay purposes and I interpolated the range between those two extremes.

[misanthropope]

Zap0:

i suspect an economist would say that your explanation and mine are exactly the same.  idk i found the thought humorous.