[Taxacom] Type of Homo sapiens (was: Are species real? Doesn't matter.)

[J. Kirk Fitzhugh]

To say that 'clades exist' can only be maintained if a clade is 
nothing more than the sum total of all relevant past reproductive 
events and population splittings that explain some set of shared 
similarities. But, in this way clades only exist in the sense of 
being a mental construct we infer relative to what we observe. Past 
events, and for the most part organisms, no longer exist. Clades have 
no boundaries as there is no 'thing' for which such a boundary could 
be perceived. The sum total of events among a group of objects does 
not translate into a boundary around those events and objects, unless 
there are emergent properties. What we assert to have existed in the 
past are organisms that engaged in all sorts of reproductive events. 
To such hypotheses we use the redundant label 'clade.'

Kirk
~~~~~~~~~~~~~~~~~~~~~~~~~~~
J. Kirk Fitzhugh, Ph.D.
Curator of Polychaetes
Invertebrate Zoology Section
Research & Collections Branch
Los Angeles County Museum of Natural History
900 Exposition Blvd
Los Angeles CA 90007

Phone:   213-763-3233
FAX:       213-746-2999
e-mail:   kfitzhug at nhm.org
http://www.nhm.org/research/annelida/staff.html
http://www.nhm.org/research/annelida/index.html
~~~~~~~~~~~~~~~~~~~~~~~~~~~
At 12:16 AM 6/3/2007, you wrote:

>Hi Dick,
>
>We have good scientific reason to believe that subatomic particles exist.
>We have good scientific reason to believe that atoms exist.  We have good
>scientific reason to believe that molecules exist.  We have good scientific
>reason to believe that living cells exist. We have good scientific reason to
>believe that multicellular organisms exist. We even have good scientific
>reason to believe that clades exist.  We do NOT have any reason to believe
>that "species" exist.  What separates the first six things from the last is
>that they all have definable and mostly unambiguous boundaries (in the case
>of clades, these are reproductive events -- as in the most recent
>reproductive event that is shared in the evolutionary histories of all
>extant organisms within a defined set).  Specifically, they have boundaries
>that exist whether or not human beings exist.  The boundaries that we define
>for species (i.e., the circumscription of all individual organims -- alive,
>dead, and yet-to-be-born) are simply that -- definitions that we create.
>Subatomic particles, atoms, molecules, cells, multicellular organisms and
>probably even clades are units that exist in nature whether or not humans
>are here to observe them.
>
>Aloha,
>Rich