Darwin-L Message Log 3:106 (November 1993)

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.

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<3:106>From V187EF4Y@ubvms.cc.buffalo.edu  Mon Nov 29 19:13:00 1993

Date: Mon, 29 Nov 1993 20:19:13 -0500 (EST)
From: V187EF4Y@ubvms.cc.buffalo.edu
Subject: Re: cladistics et al
To: darwin-l@ukanaix.cc.ukans.edu
Organization: University at Buffalo

Bob O'Hara writes:

>Suppose we have three species, A, B, and C.  They may be related in any one
>of the following ways.  (It is important to understand that "relationship"
>in this context means historical, genealogical relationship: relative
>recency of common ancestry.  It is also important to understand that these
>trees are "trees of history"; that is, the root represents an ancestor that
>actually existed at sometime in the past.)

>            /------- C             /------- C             /------- B
>      /-----|                /-----|                /-----|
>     /      \------- B      /      \------- A      /      \------- A
> ----|                  ----|                  ----|
>     \                      \                      \
>      \------------- A       \------------- B       \------------- C

Actually, there's a fourth solution (if anyone's already pointed this out,
forgive me, I'm catching up on 3 weeks' mail):

         /------A
        /
  ------|-------B
        \
         \------C

The first three diagrams are usually the only ones used because it vastly
simplifies the algorithm, although there's nothing inherently more 'real'
about them.

-Pat Crowe, SUNY at Buffalo

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