Are species real?

Richard Pyle deepreef at BISHOPMUSEUM.ORG
Tue Apr 11 08:37:18 CDT 2006


> THAT precisely what I have always wondered about this question.  What does
> "real" mean?  Why is it important that they be so?   It smacks too much of
> metaphysics for my taste.

The important thing is that any two people engaged in a discussion about it
define it the same way.  I think the crux of the question is this: Does
evolution produce assemblages of individual organisms that cluster together
in objectively definable units; or do we *define* species to suit our
particular needs of communication.  So the meaning of "real" in these
conversations might best be represented as "natural" -- to be contrasted
with "artificial", which I would define more or less as "invented by
humans".  The only "test" I can see for examining whether species might be
natural, as opposed to artificial, is whether two separate human cultures,
with no interaction between them, come up with congurent nomenclature to
describe the organisms in their environments. If species are "natural" one
would expect a high degree of congruence.  But this test is weak, because
different cultures have different levels of technology and biological
insight, and the biological nomenclature is often biased towards cultural
interactions with various organisms.

> I suppose a species is as "real" as any ASSEMBLAGE can be.  Is a family
> real?  Is a flock real? Is a city real?  They are different from an
> individual, to be sure, but then, there is a lot of difference in what
> constitutes an "individual" in this world.

A good example of "natural" units are the chemical elements.  Although there
are variations (ions, isotopes), the distinction between, say, Nitrogen and
Oxygen is unambiguous and objective.

I think part (most?) of the problem underlying these conversations in
relation to organismal "species" is that different people see it from
different perspectives.  I don't know of anyone who would disagree that a
Palm tree and a human fall into separate objectively discernable units. In
fact, I'd wager that everyone who looked at the totality of living organisms
on Earth would find that any particular individual organism either
unambiguously does, or unambiguously does not, belong to the species Homo
sapiens.  So in this sense, it's easy to think of species as natural and
"real". But if you look at it from a broader perspective -- unconstrained by
any particular moment in time -- and consider all antecedents of every
living organism on Earth, would it be equally unambiguous for all individual
organisms as to whether or not they were, or were not, Homo sapiens?  In
this case, I'd wager not.

So, back to your comment about assemblages (families, flocks, cities,
etc.) -- I don't think "real" is an appropriate characterization of these
things.  Certainly it is *useful* for us communicating humans to *define*
units of assemblages to which we apply labels -- and I think this is VERY
true in the case of species (as one might expect, given that I am an alpha
taxonomist).  But there is a difference between "useful" and "real" (or
"natural") that goes beyond mere semantics. The difference is in how we, as
taxonomists, approach the question of assigning names to clusters of
organisms.  Do we try to answer the question, "Are these populations the
same or different species?" Or, do we instead focus on the question "Is it
useful or not useful to assign different names to these two populations?"
The distinction may seem unimportant -- but I believe it has led to a LOT of
time and energy expended on the various "wars" within our community
(cladistic vs. eclectic; Phylocode vs. Linnean nomenclature; holophyly vs.
monophyly/paraphyly; etc.)

> The simple fact that we can PERCEIVE species means that we can DESCRIBE
> them and USE them in our attempts to understand the world, and in the end,
> THAT is what matters, IMO.

On this point, I think we are in full agreement!

Aloha,
Rich

Richard L. Pyle, PhD
Ichthyology, Bishop Museum
1525 Bernice St., Honolulu, HI 96817
Ph: (808)848-4115, Fax: (808)847-8252
email: deepreef at bishopmuseum.org
http://hbs.bishopmuseum.org/staff/pylerichard.html




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