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Darwin-L Message Log 5:113 (January 1994)

Academic Discussion on the History and Theory of the Historical Sciences

This is one message from the Archives of Darwin-L (1993–1997), a professional discussion group on the history and theory of the historical sciences.

Note: Additional publications on evolution and the historical sciences by the Darwin-L list owner are available on SSRN.


<5:113>From HOLSINGE@UCONNVM.BITNET  Thu Jan 20 07:04:30 1994

Date: Thu, 20 Jan 1994 07:56:29 -0500 (EST)
From: "Kent E. Holsinger" <HOLSINGE%UCONNVM.BITNET@KU9000.CC.UKANS.EDU>
Subject: Re: Systematics and linguistics
To: darwin-l@ukanaix.cc.ukans.edu

Just one minor comment on Scott DeLancey's idea of analogizing of morphemes
and molecular sequences.  This isn't quite accurate in biology.  With
molecular sequences we're faced with the problem that we *know* convergence
*will* happen at particular nucleotide positions, even though entire sequences
are extremely unlikely to converge.

Why can I say we *know* convergence *will* happen?  Because there are only
four distinct nucleotides in DNA.  Thus, at any position there is a good chance
that two sequences that share an A acquired that A independently.  Fortunately,
we have some ways of dealing with the problem.  Notice, however, that the A's
are chemically identical and indistinguishable in all observable properties
even if they were incorporated into the sequence in separate historical events.

With morphological traits, on the other hand, some cladists argue that "true"
convergence of the sort I have just described for molecular sequences is
impossible.  They would assert that if you look closely enough at those
characters "apparent" convergences will represent non-homologous character
states.

-- Kent

+--------------------------------------------------------------------+
|  Kent E. Holsinger            Internet: Holsinge@UConnVM.UConn.edu |
|  Dept. of Ecology &           BITNET:   Holsinge@UConnVM           |
|    Evolutionary Biology, U-43                                      |
|  University of Connecticut                                         |
|  Storrs, CT   06269-3043                                           |
+--------------------------------------------------------------------+

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