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Re: [Phys-l] H. Sapiens



Start of one or two people, and forward-march? Well, we suspect that after the
(purported) Toba event (BCE 70k yr), global population pretty much settled down
until agriculture, and then things took off again.


As a side note, one of my avocations is applying statistics and various
metrics to archaeology and anthropology. We're making good progress on tracking
stone tool "signatures" -- especially the shape of the notches used to haft
points to handles, arrows, and the like -- and being able to track (or so we
think) the migrations of these signatures around the Middle East around 20 - 10
k yr BCE.


/**************************************
"The four points of the compass be logic, knowledge, wisdom and the unknown.
Some do bow in that final direction. Others advance upon it. To bow before the
one is to lose sight of the three. I may submit to the unknown, but never to the
unknowable." ~~Roger Zelazny, in "Lord of Light"
***************************************/




________________________________
From: brian whatcott <betwys1@sbcglobal.net>
To: Forum for Physics Educators <phys-l@carnot.physics.buffalo.edu>
Sent: Wed, September 22, 2010 4:31:59 PM
Subject: Re: [Phys-l] H. Sapiens

Extrapolate?
Using a start of 1 or 2 at a distance of 100,000 years, and curve
matching an exponential to date
seems to show a population overestimate for most of human history, then
the rate is underestimated, as history becomes more recent.

Brian W

On 9/22/2010 12:03 PM, curtis osterhoudt wrote:
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 rich
environment.


Of course you're right: each of the expressions are
approximations. I gave
the "70 rule-of thumb". 72 is also commonly used, because it has several
integral divisors. Once one starts quibbling about using 69 instead
of 70, one
might as well use the _proper_ expressions. Too, the error
introduced with the
approximations is quite manageable, and is usually lost in the noise
of mutation
rates, environmental constraints, and so on (for "simple" populations of
bacteria or fish, say), and absolutely swamped by things like
migrations and
societal changes (for humans, say).



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