Re: mass extinctions and DDT

[Daniel Bensen <dbensen@gotnet.net>]

I think that the greatest evidence for humanity---the evidence that will stay
for the next 65 million years---is the alterations we make to the biosphere by
transporting animals around.  Because of humans, there are now (breeding
colonies of) Eucalyptus trees in California, mongooses in South America, Dogs on
every continent but Antarctica (and I'm not even sure about that), norway rats
everywhere, et cetera, ad infinitum.  Maybe some of these critters could have
gotten across the oceans by themselves, and probably some of them will go
extinct during the next 65 million years, but there will certainly be evidence
in the fossil record of (a) the sudden drop in large species diversity right at
the end of the Pleistocene and (b) the sudden expansion of range of just a few
species across the world that took place just a little later.  Some future
paleontologists might propose that these changes were caused by the formation of
a supercontinent (hmm, casts some doubts on Pangea :)) but the evidence will
point to humanity, even if we don't leave any of our artifacts.

There is, by the way, a funny book written on the subject.  It is called (I
think) Mystery Motel and tells about an archaeological expedition stumbling upon
the ruins of a 20th century motel (called the Toot 'n Come On) and the mistakes
they make.

Dan