Subject: Re: native peoples
Date: Nov 17 16:35:29 1995
From: David Wright - dwright at u.washington.edu


Didn't several Native American cultures switch from a hunter-gather
economy to agriculture (which supports higher pop density)? If so,
what drove that change? Was it population density exceeding capacity
of unmodified environment (i.e., change or suffer increased mortality),
change in religious belief, becoming bored with hunting and gathering,
or what? I would bet on population density, but confess to ignorance
here. I would also bet that changes in religion follow, not precede,
changes in lifestyle/economy. But at any rate, my previous assertion
was simply that when a human population reaches a critical density,
other organisms will become extinct, regardless of the "race, creed,
or color" of the humans involved.

Getting back *toward* birds, at least, this brings up a question
someone asked Dennis: what is the largest (body size) species of
vertebrate (was it terrestrial vert?) extant that equals or exceeds
that of Homo sapiens in number of individuals?

David Wright
dwright at u.washington.edu

On Fri, 17 Nov 1995, Eugene Hunn wrote:
> But perhaps there's a connection between their population densities and
> their religious beliefs? More likely, there's an indirect link via their
> economic systems. "Saturation" hunter-gatherer densities -- that is the
> "carrying capacity" of Homo sapiens under the constraints of that mode of
> production is in the range of .02 to 10/mi2, of agricultural systems
> typically 50-2000/mi2 depending on intensity, etc., with the highest
> densities limited to a few well situated areas such as river deltas...,
> alluvial plains. Global market economies push local densities in cities
> up to 50,000/mi2 (but drawing from a global hinterland). There are good
> examples of high density rural farming systems that coexist with high
> biodiversity, but a clear pattern showing a dramatic deterioration
> associated with the pressures of commercial production for world
> markets. Mexican Indian societies pre-Conquest achieved very high
> densities but the worst environmental deterioration in Mexico seem
> attributable to colonial and post-colonial land use patterns, driven by
> external demand. My point is that it's not simply density but the nature
> of the system: is it oriented toward competing in a global market or is
> it more locally or regionally contained.
>
> Gene Hunn.
>
> On Fri, 17 Nov 1995, David Wright wrote:
>
> > On Fri, 17 Nov 1995, Eugene Hunn wrote:
> > > Islands are special cases, as I believe the island biogeography
> > > literature shows.
> >
> > It may well be that critical human population densities are lower on
> > islands, but surely no one would suggest that humans cannot reach
> > critical densities on continents(?); the evidence would seem to argue
> > otherwise. My point was simply that when human populations exceed
> > the ability of unmodified habitat to sustain them, species will become
> > extinct. If only a small number of extinctions (or even "none") were
> > caused by Native Americans, this low impact is more directly attributable
> > to their low population densities than to their religious beliefs.
> >
> > David Wright
> > dwright at u.washington.edu
> >
>