The Science of Discworld Revised Edition

bizarre ancient ‘medicines’, their even more foolish customers, and some unreconstructed barbarians) seems to agree that the loss of magnificent creatures like the great whales, elephants, rhinos and of course plants like ginkgoes and sequoias would be a tragedy. Nevertheless, we persist in reducing the diversity of species in ecosystems all around the planet, losing many species of beetles and bacteria with hardly any regrets.
    From the point of view of the majority of humans, there are ‘good’ species, unimportant species, and ‘bad’ species like smallpox and mosquitoes, which we would clearly be better off without. Unless you take an extreme view on the ‘rights’ of
all
living creatures to a continued existence, you find yourself having to pass judgment about
which
species should be conserved. And if you do take such an extreme view, you’ve got a real problem trying to preserve the rights of cheetahs
and
those of their prey, such as gazelles. On the other hand, if you take the task of passing judgment seriously, you can’t just assume that, say, mosquitoes are bad and should be eliminated. Ecosystems are dynamic, and the loss of a species in one place may cause unexpected trouble elsewhere. You have to examine the unintended consequences of your methods as well as the intended ones. When worldwide efforts were made to eradicate mosquitoes, with the aim of getting rid of malaria, the preferred route was mass sprayings of the insecticide DDT. For a time this appeared to be working, but the result in the medium term was to destroy all manner of beneficial insects and other creatures,
and
to produce resistant strains of mosquitoes which if anything were worse than their predecessors. DDT is now banned worldwide – which unfortunately doesn’t stop some people continuing to use it.
    In the past, the environment was a context for us – we evolved to suit
it
. Now we’ve become a context for the environment – we change it to suit
us
. We need to learn how to do that, but going back to some imaginary golden age in which primitive humans allegedly lived in harmony with nature isn’t the answer. It may not be politically correct to say so, but most primitive humans did as much environmental damage as their puny technology would allow. When humans came to the Americas from Siberia, by way of Alaska, they slaughtered their way right down to the tip of South America in a few thousand years, wiping out dozens of species – giant tree sloths and mastodons (ancient elephants, like mammoths but different), for example.
    Some scientists have disagreed with this interpretation, claiming that humans could never have made that great an impact. In 2001, to test that claim, John Alroy simulated the effect of hunting in computer models of 41 North American species. It turned out that extinctions were virtually unavoidable, especially for the larger animals. Even highly incompetent hunters would have wiped them out. The simulations correctly ‘postdicted’ the fate of 32 of the 41 species, which adds credibility to their conclusions. ‘Whodunnit?’
New Scientist
asked, offering its own suggestion: ‘Mr Sapiens in the Americas with a large axe.’
    There have been many similar examples of ecological devastation wrought by ‘primitive’ humans. The Anasazi Indians in the southern part of today’s USA cut down forests to build their cliff dwellings, creating some of the most arid areas of the United States. The Maoris killed off the moas. Modern humans may be even more destructive, but there are more of us and technology can amplify our actions. Nevertheless, by the time humans were able to articulate the term ‘natural environment’, there wasn’t one. We had changed the face of continents, in ways big and small.
    To live in harmony with nature, we must know how to sing the same song as nature. To do that, we must
understand
nature. Good intentions aren’t enough. Science might be – if we use it wisely.
    1 Readers of the Discworld book
The Last Continent
will recall that, by an amazing coincidence, beetles were something of a passion for the God of Evolution.
    2 Rincewind would add some more:
    ‘Is it safe?’
    ‘Are you sure?’
    ‘Are you absolutely sure?’
    3 A worse case is what used to be called
Eohippus
, the Dawn Horse – a beautiful, poetic name for the animal that formed the main stem of the horse’s family tree. It is now called
Hyracotherium
, because somewhat earlier somebody had given