Biodiversity and the Fossil Record

From
Date
The thing that strikes me about the current "Are we in a mass extinction?"
debate is that no one seems to be paying much attention to the types of
organisms that are going extinct in the last few decades. The ones I keep
hearing about would have very little chance of being preserved in the
fossil record. Thus, there is a built-in scaling problem when people try to
compare the current biodiversity crisis to those of the past. However, if
we take a longer view and add in the Pleistocene extinctions as the first
of a series of waves of biodiversity reductions that have affected the
modern biota, then we do achieve at least a rough comparability.

As with the mess extinction debates in the fossil record, the real nub of
the problem is trying to figure out what proportion of extinctions were due
to "exogenous" causes (e.g., human activities) and what proportion would
have come about as a result of "normal" factors. I think it is somewhat
simplistic to attribute all extinctions that are currently taking place to
be the result of any one factor (e.g., human activity). Even more
dangerously, acceptance of the "humans must have done it" argument means
that no one needs to look for any other answer. To my mind this means that
many modern extinction events remain unexplained. I'm not saying that I
think human are blameless when it comes to causing modern extinctions, they
certainly are not as a number of very well documented studies have shown.
[Note my personal favorite is Peter Mathiessan's (name not spelled
correctly) book "Wildlife in America" which documents the decline and
extinction of the North American fauna/flora since colonial times.] Rather,
I am disturbed by the "knee-jerk" interpretation of all modern extinction
as man-related regardless of the quality of the evidence available. Going
back to the Pleistocene example, man may have had a hand in driving some of
the large Pleistocene mammals to extinction, but climate change was
certainly going on, large changes in many (if not most) animal ranges were
taking place, and I have a hard time picturing early man being responsible
for changes in vole biodiversity and/or distributional patterns (for
example).


Norm MacLeod



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Norman MacLeod
Senior Scientific Officer
N.MacLeod@nhm.ac.uk (Internet)
N.MacLeod@uk.ac.nhm (Janet)

Address: Dept. of Palaeontology, The Natural History Museum,
         Cromwell Road, London, SW7 5BD

Office Phone: 0171-938-9006
Dept. FAX:  0171-938-9277
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