Hi Jim,
Good to see you back.
>>There's nothing natural about species extinctions nowadays.
>
>It would be difficult to imagine that human kind had entirely supplanted
>a natural law of species extinction with a social one, at the best
>social laws modify natural laws. They do not replace them. But the point
>here is that you assume what you ought to explain, that bio-diversity is
>threatened by extinction, when plainly, extinction is how bio-diversity
>comes about.
Perhaps a quibble, but extinction, by definition, reduces bio-diversity. It doesn't enhance it.
Furthermore, there is a distinction to be made between extinctions caused by human agency and those which are not. We get to chose whether or not to allow certain extinctions to occur. Should we save the tiger, or rid the world of the beasts? We have the power to do either. If we want to save it, should we save part of its natural habitat so that it can continue to exist in the wild? That's a value judgement, and it is perfectly reasonable to argue that we should. They are magnificent animals.
>>Preserving species isn't an
>>absolute, of course; noone would want to preserve the smallpox virus, a
>>horrid life-form. But we're talking about the unnecessary destruction of
>>countless natural histories, of life-forms we don't know very much about,
>>who haven't done us any harm, and are the contingent, irreplaceable
>>product of millions of years of evolution. By preserving them, we're
doing
>>more than just preserving ourselves; we're also allowing those life-forms
>>to have a future, to evolve into other, perhaps more interesting species.
>
>Perhaps smallpox, too, was on the way to being a 'more interesting
>species'. But this is just sentimentalism. Why not deplore the waste of
>species under natural selection? You miss out of account the excellent
>species that man has brought into being, like domesticated animals, high
>grain yields etc.
Bio-diversity is a resource, just like coal or oil. People enjoy wild environments, and many people value maintaining species as an important goal in and of itself. That's why Save the Rainforest campaigns get so much sympathy and support. And extinction irretrievably destroys a portion of the genetic library, an immeasurably valuable resource to geneticists. Who knows how much useful genetic information is being lost?
It is also possible to drive an eco-system to failure, and we really don't understand what's involved in many cases, which argues to proceed with caution. I read of a recent study which looked at the viability of the Amazon rain forest. The authors thought that another 10-20 years or so of deforestation would doom the entire Amazon since the feedback mechanisms would be disrupted (too much runoff = not enough water retention to support the forest, something like that - I don't remember the details) and the forest would not be able to sustain itself. This would be a tragedy, not only because the Amazon is an irreplaceable treasure, but because many people rely on its abundance. A similar example would be the shrinkage of the Aral Sea. When the Aral Sea began to recede, it meant the end of all of the coastal towns whose economies in most cases relied on the Sea.
Brett