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第3163节（第158101-158150行） (3163/3207)
humansare
inherently
bad
news
for
other
living
things.
the
sad
likelihood
is
that
we
may
well
be.
according
to
the
university
of
chicago
paleontologist
david
raup,
the
background
rate
ofextinction
on
earth
throughout
biological
history
has
been
one
species
lost
every
four
yearson
average.
according
to
one
recent
calculation,
human-caused