As biologists we are trained to recognize that extinction is
a natural phenomenon—that ~99% of the life that has evolved on Earth has passed
away to leave either no trace, or if we are lucky, a commemoration of their
existence in the fossil record. As
conservation biologists, we are aware that the current extinction rate is
100-1000X the background extinction rate—and a central goal of conservation
biology is to conserve the biodiversity that remains—but what Kolbert (2014)
has made me consider is how many extinctions we should expect to see in our
lifetime. Kolbert says “From Darwin’s
premises, an important prediction followed.
If extinction was driven by natural selection and only by natural selection, the two processes had to proceed at
roughly the same rate. If anything, extinction had to occur more gradually” (p.
55). We shouldn’t expect to see, perhaps, even one extinction in our lifetime,
yet the reports abound. (And to think that two centuries ago, the very notion
of extinction barely existed!) Of course, the background extinction rate goes
out the window in mass extinction events.
Kolbert opens the door and welcomes everyone to the
Anthropocene just on the edge of the sixth extinction event, an event that has
already began to unfold. Come on in.
Have a seat and watch the consequences unfold. Humans, despite our frontal
lobe development, seem to show limited capacity for foresight, leading to extinctions
through both direct and indirect means, although both routes may be
unintentional. What leads me down the path of despair, if only briefly since
there is no time for despair, is our past record for driving once common
species to extinction. In “The Original
Penguin,” Kolbert points out that the Great Auk had a wide distribution in the
Northern Hemisphere ranging “from Norway over to Newfoundland and from Italy to
Florida, and its population probably numbered in the millions” (p. 57-58). We
hunted without foresight that millions could turn into a small remnant
population, left to the vagaries of small populations until they were a single
nesting pair and then collected for a “gentleman” who wanted it for his
collection in 1844 (p. 62). (Why does she not call him a fool [edited for
polite blogging]??) Are we more enlightened today with better technology and
knowledge of what is happening beyond our own home range? Theoretically,
although this knowledge barely helps the elephants and black rhinos. The enlightened many who may wish to protect
species that are rare is undermined by the cheaters—the poachers who will come
in to take what is rare and, therefore, valuable—although their measure of value
is limited to a price tag and the risk of poaching is often not great enough to
impede this activity.
If our direct actions that lead to small populations (if not
outright extinction) cannot be adequately curbed—this should be the low hanging
fruit—then how can we hope to manage our actions that indirectly put
biodiversity at risk—actions that increase greenhouse gases that warm the
climate and increase the acidity of the oceans?
Ugh. Bleh. No idea.
What Kolbert does brilliantly in this book, it seems to me, is to 1) establish
a framework of how life has changed on earth over millions of years—with each
mass extinction event appearing to be a result of different phenomenon; 2) lay out
our historical understanding of species loss; and 3) clarify how humans have
set the stage for another dramatic shift, all by ourselves—no asteroids needed. Maybe a human-mediated mass extinction event
won’t lead to the worst day on earth, the way the asteroid hit at the end of
the Cretaceous period did—but it seems less than ideal and currently
unavoidable (although we can avoid the worst outcomes). Kolbert’s writing is
beautiful, even as she horrifies—I’m waiting to see if she offers a path
through the mess we’ve created and I’m wondering how many people we need on the
path to reach the best possible future.
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