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Oh, I wasn't even thinking of the granularity. I agree that some
continuous function might be appropriate, but to extrapolate beyond
even a few years is folly, and we need *much* more realistic functions
than a simple exponential growth model to have a shot at numbers
matching the actual data. Population dynamics are really, really,
really tough.
/snip/
------------------------------------------------------------------------
*From:* brian whatcott <betwys1@sbcglobal.net>
*To:* phys-l@carnot.physics.buffalo.edu
*Sent:* Wed, September 22, 2010 11:00:00 AM
*Subject:* Re: [Phys-l] H. Sapiens
I imagine the granularity of the poll count, gestation time and life
span underlying annual rates of increase of Human populations is so
comparatively tiny, that a continuous function is quite suited to the
purpose.
Brian W
On 9/22/2010 8:56 AM, curtis osterhoudt wrote:
If they say the population growth rate is "x% *per year*", then,yeah :) Hell,
for bacteria, it might easily be 1% per minute, given a richenvironment.
approximations. I gave
Of course you're right: each of the expressions are
the "70 rule-of thumb". 72 is also commonly used, because it has severalof 70, one
integral divisors. Once one starts quibbling about using 69 instead
might as well use the _proper_ expressions. Too, the errorintroduced with the
approximations is quite manageable, and is usually lost in the noiseof mutation
rates, environmental constraints, and so on (for "simple" populations ofmigrations and
bacteria or fish, say), and absolutely swamped by things like
societal changes (for humans, say).