Cladistic language concepts

[Isidore Dyen]

----------------------------Original message----------------------------
Can you segregate the slowly developing parts of the genome from the oth
ers, or more broadly, can you classify sections by their rates of
branching?
 
On Wed, 28 Oct 1998, Michael Ghiselin wrote:
 
>
>           Dear Dr. Dyen,
>                I must apologize to list members if something happened
>           when I tried to forward your message.
>                Also please forgive my delay in answering your
>           commentary.
>                Cladistics does run into problems where there is as you
>           say some kind of amalgamation of lineages.  Sometimes the
>           amalgamation is not so complete that lineages cannot be
>           detected.  An interesting example has been the origin of
>           mitochondria and chloroplasts from symbiotic bacteria.
>                As to DNA, it turns out that the techniques that we use
>           with it are pretty much the same sort of thing that we have
>           used all along in comparative anatomy.  I spent a lot of
>           time working with ribosomal RNA sequences and they worked
>           pretty well.  But they did not show the clearness of
>           resolution that we hoped for.  Some parts of the genome
>           change very slowly, others more rapidly.  What we try to do
>           for the very old relationships is find something that
>           evolves very slowly.  Linguists try to find that sort of
>           feature too.  The frustrating thing for us is that branching
>           can occur repeatedly within a very short period of time, and
>           the branches may not be evident in the slowly-evolving
>           molecules.  We get a sort of bush instead of a tree.  I
>           suspect that this has happened in linguistic evolution too.
>            What the DNA does for us is give a lot of additional
>           evidence and it often helps.  We will just have to keep
>           plugging away.
>           Sincerely,
>           Michael Ghiselin
>
>
>