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[this is mainly for Mike, but comments from anyone else on the deep-ecology
list are invited. When I try this sort of thing in most conversations and
on most lists, there is a deafening silence!]
>>At 21:33 9/03/99 -0800, Mike Vandeman wrote:
>>> ... Killing organisms can destroy biodiversity, and hence can create a
>>>permanent loss. That is not sustainable.
>>
>At 07:48 AM 3/17/99 +1300, David wrote:
>>Mike,
>> You ... explain[ed] your views on the importance of the survival of
>>individuals (rather than just species) for maintaining biodiversity.
>> My response is that the probability of any one individual contributing a
>>potentially valuable gene (or more) to the gene pool is so slight as to be
>>essentially negligible.
>
At 19:01 16/03/99 -0800, Mike wrote:
>I agree that the probability is low. However, all existing species,
>including humans, are here just because of such a mutation that began in a
>single individual. If you killed that one individual, that mutation wouldn't
>re-occur for millions of years, IF EVER!
>
** Mike, I've put the above in time order, but I seem to see a break in
logic or at least an extremely tenuous thread here. I'm not as good at
following a logical sequence as I used to be, or as my wife and some of my
children are, and certainly not as good as my father-in-law and you -
mathematicians. But ...
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
** I believe this summarises what you've been saying: "If you killed that
one individual, [that] can destroy biodiversity, and hence can create a
permanent loss. That is not sustainable."
You have (presumably) a string of statements linked by if-then, which start
with:
(i) "One individual, for at least part of its lifetime, contained each of
the genes that have contributed to that species'
survival/evolutionary-success in the past and/or contribute now and in the
future", and finish with:
(ii) "destroying biodiversity is not sustainable".
** Could you go through the complete string, for me?
I'll try my hand at it below, but first I'll describe/define some concepts
that I use certain words as labels for.
- biodiversity - it is a size, an amount. I don't know, but a measure may
be the total number of different genes currently in living things. It
therefore can be increased or reduced, but your use of the word "destroy"
must be as an emotive code-word for a particular very small reduction that
has the possibility of ending up with the extinction of a species.
- species - I'm on shaky ground here (my training is in Physics), but I
currently believe species are labelled as such on the basis of inability to
viably interbreed, and that a single gene-difference is by no means likely
to be essential to the creation of a new species. The various races that
eventually become clades (branches from a common ancestor) in almost all
cases contain several genetic differences by the time they become separate
species, as I understand it. For this reason, and also because of the
common-ness of parallel evolution, I don't see the development of a species
as typically or even often dependent on a single (mutation-created) gene.
- sustainable - (Here I think your mathematical background is causing you
trouble!) I regard a certain time-scale as an intrinsic part of the idea
of sustainable. On this basis, the "true or constant for all time" idea
isn't applicable to ecology, whether of the world, a continent or the seas,
or a smaller region.
I use the word to apply to all these examples:
(i) the hundreds of millions of years when the saurians (and even the
dinosaurs) were the family that had the major effect on the earth's living
things;
(ii) the several hundred thousand years when the homo group were
hunter-gatherers;
(iii) the several thousand years, about 36,000 to 40,000 years ago, just
after the Australian Aborigines arrived in what is now Australia, when they
hadn't yet over-used fire. After that was a non-sustainable transition
period, followed by perhaps 10-20,000 years of sustainable living
controlled by cultural taboos, climate etc., that meant that the remaining
species fluctuated in size (no. of individuals) but stayed nearly constant
in number (of species);
(iv) the thousand years or more at about 4-5000 BP when agriculture-based
"civilization" was centred on the Nile, Tigris-Euphrates, Indus and Yangtse
rivers (but the human population there hadn't yet increased to an
unsustainable level), and most other humans were practising
slash-burn-plant-harvest-move-on agriculture and/or fishing; _and_ (knowing
this and the next to be debatable)
(v) the several hundred years at around 900 AD when plagues (& other common
illnesses), wars in China, the Arab world and the Americas, and lack of
food, meant the death rate nearly balanced the birth rate and the human
population hardly changed, so its impact on other living things was again
about constant; and lastly (though I'm now having doubts:)
(vi) a period spanning my birth-date (1936), from when my father was born
to about 1950, where people had the Great Depression to focus the mind on
what is essential in life, and the range of consumption was (I think)
tolerable, so if the human population and its consumption had been kept
stable no further inroads into the living-space of the rest of the world's
species need have occurred.
** As you can see at the end of (iii), I regard the occasional loss of a
species as normal for world ecology, so long as, over a few million years,
the number of new species about balances the lost species. Yes, the world
is a little different at the end of those million years, but that is part
of sustainable life on earth.
** Now; my attempt to reconstruct your logic-chain, Mike.
(1) One individual, for at least part of its lifetime, contained each of
the genes that have contributed to that species'
survival/evolutionary-success in the past and/or contribute now and in the
future;
if this, then:
(2) the death (killing) of that individual will have, as a necessary
consequence, the extinction of that species some long time in the future
when an environmental stressor causes the death of all members of the
species without that gene;
if this, then:
(3) biodiversity is reduced, i.e. both: there is an unfilled niche in the
ecology of that region, and the total number of genes in all living things
is reduced by those unique to that species;
if this, then:
(4) since long-term stability of an ecology is strongly dependent on how
diverse it is (geography, niches, species, genes - all of it), that
region's ecology is now more fragile, more likely to be reduced further by
the next stressor;
if this, then:
(5) after sufficient stressor-impact (number and degree), that region and
the world lose a large number of species and their genes, and become
unstable;
and in this way:
(6) destroying biodiversity is not sustainable.
** I started out expecting to point out holes in the chain, but I seem to
have set up a "straw man", so I now think I should wait for the real thing
before I say whether I see faults in the statements and their apparent
connections.
(** I'm glad to have the chance to put my mind to work! Better than
playing Caesar III !)
David.
** http://www.geocities.com/RainForest/6783/index.html#top
David MacClement <davd@geocities.com> , or davd@tao.ca for secure mail
http://www.geocities.com/Athens/Delphi/3142/index.html#top