Re: [tied] Glottochronology (Was: "Celtic Found to Have Ancient Ro

 

Richard,

 

Hmmm...I think I must disagree with you. First, my point about the "core words" is based on my understanding (faulty as it may be) that Swadesh did not claim that all words change at a constant rate. Rather, if my memory serves me well here, Swadesh claimed that the "core words" changed at a constant rate. If so, it is upon a defender of such a view to show that such "core words" can be unproblematically identified. If not, the whole exercise becomes rather pointless as no non-arbitrary "lexical clocks" can be put together.

 

As for the "molecular clocks": there is a world of difference between evolution driven by natural selection and evolution driven by random accumulation of copying errors. I claim that only the latter give us some realistic hope of constructing meaningful "molecular clocks" and fail to understand what the compensating "error terms" could be here. Of course, certain bases are more prone to replacement than others, but this is not an obstacle in itself (although it makes more difficult the construction of molecular clocks as the rate of change must be studied case by case). What does count is the selective neutrality of the evolution. And unless you spell out how the "error termr" lay rest the (chronologywise) disturbing selective forces in (a) genetic evolution and (b) memetic evolution, I am still asking what might play the role of "junk genes" in memetic evolution.

 

And I did hope that my Keynesian joke would give some insight on my views: of course, if you take a very Olympian view of a river, you will "compensate away" the turbulences. But such an "Olympian clock" would permit margins of errors that are unacceptable for dating purposes.   

 

Best regards, Juha Savolainen 

 

Richard Wordingham <richard@...> wrote:

--- In cybalist@yahoogroups.com, Juha Savolainen <juhavs@...> wrote:
>
>
> Thanks for your comments and for pointing out the existence of
the "Continental Celtic" group. As nobody seems to have read the full
article, it is not possible to discuss properly the methodology of
Forster and Toth. However, if the NYT newspaper story got it
right, "Dr. Forster says he assumes that the rate of language change
can also be averaged over time". 
>
> Somehow I get the feeling that Forster, perhaps without knowing it,
is trying to resurrect Morris Swadesh�s "glottochronology" from its
scholarly grave. If I remember correctly, Swadesh argued that
the "core vocabularies" of various languages changed at a constant
rate. Too bad that it turned out to impossible to specify reliably
such "core vocabularies" and that the assumption of a constant rate
seemed to contradict the available evidence, not to speak about the
impossible dates Swadeshian approach suggested for many language
splits�

The variation of the rate of change from meaning to meaning is not
what invalidates glottochronology.

> Morover, if we take the "molecular clocks" (such as they exist in
their very imperfect state) as the point of comparison, we
immediately see a major difference between these clocks and lexical
items. The molecular clocks make use of "junk" DNA, precisely in
order to eliminate the workings of the natural selection. But what
items would play the role of "junk memes" here?

I presume that the implication here is that some words are ripe for
replacement.  The issue then is whether error bounds can compensatoe
for such effects.  If they can, then they are not a problem.  Some
mtDNA base positions are actually ripe for replacement, though it's
probably accurate to say that some base sequences are more prone to
mutation.  (Such tendencies can include a significant, and ultimately
lethal, tendency to insert bases.  No random walk here!)

The real killer for glottochronolgy is variations in the tempo of
change; I can't comment on how real they are, but Piotr believes they
are.

Richard.



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