yes but what and why of the environmenta

Fri, 30 Sep 1994 12:43:00 PDT

Foss writes:

" We are talking about possibly three topics I can discern at this time,
... (1) Pollution and contamination of the ecosphere as a byproduct of human
production and consumption. ...
(2) Exhaustion of natural resources due to surpassing of relative carrying
capacity or murderous working conditions. Carrying capacity refers to the
maximum population which can be supported off the resources available. The
actual population which is supported is always lower than this level, because
(a) Population limitation methods known to the peasants as transmitted in
the culture. These methods are ubiquitous, and include contraception,
marriage rules, birth-spacing by deferred weaning, and infanticide....
(3) Reversible or irreversible changes in an ecosystem by introduction of
new species or extermination of preexisting ones."

All three topics have in common a perturbation of a system beyond its
ability to recover and return to an initial value. What differs is the
nature of the perterbation (byproducts, exploitation, introduction). So from
the viewpoint of perturbation the three topics are closely linked, while from
the viewpoint of the source of the perturbation they are different.

Foss expresses a viewpoint in item (a) above that is commonly expressed,
namely that when people engage in activities such as marriage rules,
birth-spacing, etc. they are engaging in "population limitation methods known
to the peasants." The problem this poses is that it assumes the people in
question are acting out of a kind of group interest and are tracking their
current population size and then individually acting (even if it might be
against their own interest) to assure that population size is maintained
below carrying capacity. On the face of it this is not plausible and I do
not know of any data that shows that when individuals engage in methods to
reduce numbers of offspring it is done for reasons relating to
global/societal, rather than local/individual, issues. As I have
demonstrated with the !kung san, though, self-serving decision making can
lead to populatin stability as an emergent phenomenon. This particular
example is interesting because it has the counter-intuitive result that the
hunting/gathering groups (following the decision making used in the model) in
low resource density environments are likely to be much more below carrying
capacity than hunting/gathering groups in resource rich environments; i.e.,
the relationship between actual population density and carrying capacity
population density is a dynamic that needs to be worked out and not assumed
it is accounted for by reference to population limiting methods practised by
the persons involved. (This comment is not directed at Foss's argument, but
arguments similar to his that many others have also made.)

Unless the degree to which individuals engage in self-lmitation of
fertility increases with population size/density, such behavior neither
stabilizes population size nor maintains it below carrying capacity; e.g.,
the Netsilik eskimo before contact practised female infanticide, but the rate
at which it was practised (an adult ratio of 150/100 for males/females) still
allowed for a growing population which would crash when the population both
grew in size and there was a bad year when the caribou did not run where
expected. The reasons for the female infanticide seems clear enough:
pressure for increasing the proportion of male hunter/procureres to
number of consumers in the "extended" family. As such it resulted from
the individual family perspective so that pressure for practising female
infanticide does not change with population density, hence the rate of
female infanticide is not likely to vary with population density and so
female infanticide neither acts to stabilize the population nor to maintain
the population below carrying capacity.

D. Read