Population Growth

"Due to popular demand, here's a little more information on the population growth (and death) rates and maximum sizes, courtesy of Tom Hughes' economic model efforts."

1. Population Growth
2. Population Starvation
3. Maximum Population Size of a Region
4. Biospheres
5. Economics of Population Points

1.
Population growth occurs automatically and is calculated per population center (=a region that has any population on it at all). It's based on several factors:
Environment, Racial Tendencies, Growth Enhancing/Restricting Events and Technologies, etc.

The basic growth formula depends upon
A the current population of the region
B the race's base rate of growth in the region, and
C the maximum population of the region.

Population growth occurs most quickly when the region is neither too empty nor too full. There are two formulas that control growth - click here.

2.
When half or more of the food requirements are met, the population is merely "hungry" and their growth rate is reduced proportionally to the level of food shortfall. Thus, with exactly half the needed food coming in, there is a 0% growth rate on that region.

When less than half the food required arrives, then the folks are "starving". This gives that region a "death rate" to worry about instead of a "birth rate" because people are dying faster than they're being born. The death rate proportionally increases with the shortfall of food up to five times what the opposite of the maximum growth rate for that region would be.

That is, on a 1% to 5% scale, if people were growing at 1%, they'd starve at a five times 5% rate and vice-versa. -> The more people in a region, the faster they'll die off.

3.
The main factor that determines how many Population Points maximum a region can hold is the size of the planet.
It is also modified by the Habitability Zone that the planet resides in and the Ecosystem Density of that region.

Click here for details.

4.
When a planet isn’t habitable to a race, the population there must live in a controlled (or "enclosed") environment dubbed a "biosphere".
Every population group residing on a planet that is in that species’ Yellow 2 or Red Habitability Rings is considered living in a biosphere.

A The greatest drawback to biosphere living is that maintenance costs for that population group and any improvements in that region are exorbitant.

B The population group living in a region of the outer yellow or either red habitability ring must import all the food it eats. There are two Technology Achievements that ameliorate this situation.

1. "Bio-morphic Fungi" permits bioharvesting by one additional Habitability Ring.
2. "Mineral-morphic Fungi" permits bioharvesting two additional Habitability Rings.
   

When a civilization has both of these, therefore, it can bioharvest all the way into the outer Red Habitability Ring. In addition, Hydroponic Farms and Subterranean Farms are fully functional in biospheres. They add +½ and +1 unit of bioharvest unit each turn, respectively, even when placed in a Bioharvesting DEA that is built in a biosphere.

C No population will voluntarily move to a region where it will be living in a biosphere. That is, no migrants, immigrants, nor pioneers will settle there. If a civilization wishes to establish population groups in a biosphere living conditions, they must be brought over in outpost and colony ships and deposited there.

D Population living within a biosphere environment can grow naturally. Usually, such population groups grow at the rock-bottom (1%) population growth rate.

E On top of everything else, the maximum population limit for a region requiring biosphere living is only 1 Population Point. There are two Technology Achievements concerning the maximum population limit of a civilization’s biospheres.

1. Biosphere Housing Management (+0.33)
2. Biospheric Urbanization Module (+0.67)

5.
In addition to their primary role (=serving the labor needs of a planet’s economic capacity) each population point produces 3 Cement units and 1 Test Tube unit per turn. Click here for details (formulas for each population point).

Population points do not directly generate money. Instead, the value of all the goods they produce that do generate pre-tax income that is computed into that planet’s Gross Planetary Production.