Re: [GZG] Re: Gzg-l Digest, Vol 13, Issue 9

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.csua.berkeley.edu wrote on 08/05/2006 20:33:01:

> Beth muttered:
> >Laserlight's plausible story telling approach is fine
> 
> Let's say you start with 10,000 colonists, and add immigrants at the
> lesser of 60,000 immigrants or 10% of the base population per year. 
> After 100 years, with a 3% growth rate you get about 16 million; 
> with a 2% rate you get 9.5 million.

Many estimates of growth rates seem unreasonable to me.  If we take
Earth 
as an example, UN figures show that world population growth peaked in 
about 1970 at 2% per year.  Prior to 1950, it never rose about 1% and 
since 1970, population growth rate has been at a steady decline.  In
2000, 
annual growth was 1.39%.  UN forecasts: 2010 1.15%; 2020 0.98%; 2025 
0.86%.

Of course, growth rates vary considerably by country - but typically,
the 
better educated, richer, more technically advanced countries have lower 
growth rates.  In fact, if it were not for immigration, many western 
countries would see populations declining.

Therefore, I suspect that the above example growth rate is highly 
unlikely.  Let's take some extreme figures - lets say the population 
doubles every generation. (i.e. every person finds a partner and they
have 
4 children who all survive)  Lets have a new generation every 20 years. 
Starting with the 10000 colonists, mentioned above, that would mean that

after 20 years - you'd have 20000, after 40 years 40000, after 60 years 
80000 after 80 years 160000 and after 100 years 320000.  Now that's an 
astronomical rate of increase for a population - but it's nowhere near
16 
million.  Of course - there may have been massive immigration and for
any 
kind of 'population growth' model, it's the immigration that will be the

key growth driver - rather than natural growth.