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<APA page-header="Time Depth">
<tp>
  <tp-title>Review of “Time Depth in Historical Linguistics”, 
    edited by Colin Renfrew, April McMahon, and Larry Trask</tp-title>
  <bylines>
    <line>Brett Kessler</line>
    <line>Washington University in St. Louis</line>
  </bylines>
  <address>
    <line>Brett Kessler</line>
    <line>Psychology Department</line>
    <line>Washington University in St. Louis</line>
    <line>Campus Box 1125</line>
    <line>One Brookings Drive</line>
    <line>St. Louis MO 63130-4899 USA</line>
    <line>Email: bkessler@artsci.wustl.edu</line>
    <line>FAX: 1-314-935-7588</line>
  </address>
</tp>

<text>
<section>
<p>Time depth in historical linguistics.
Ed. by Colin Renfrew, April McMahon, and Larry Trask.
(Papers in the prehistory of languages.)
Cambridge, England: McDonald Institute for Archaeological Research, 2000.
Distributed by Oxbow Books.
2 vol. (xiv, 681 p.) paperback, 50 GBP.
http://www.mcdonald.cam.ac.uk/Publications/Time-depth.htm
</p>
</section>

<section>

<p>This is a collection of 27 papers, mostly presentations at a symposium
held at the McDonald Institute in 1999. Contributions focus on two
related issues: methods for establishing absolute chronology, and
linguistic knowledge about the remote past. Most papers are
restatements of the authors' well-known theories, but many contain
innovations, and some do describe new work. The ideological balance of
the collection feels just left of center. We do not find here wild
multilateral phantasms, reconstructions of Proto-World vocabulary, or
idylls about pre-Indo-European matriarchal society. Or not much. These
are mostly sober academics pushing the envelope in attempts to reason
under extreme uncertainty.</p>

<p>One of the recurrent themes was that the development of agriculture
may drive the expansion of language families and therefore imply a
date for the protolanguage. Colin Renfrew describes his idea that that
is what happened in the case of Indo-European (IE): PIE was introduced
into Europe at an early date, perhaps 8,000 BC.  Peter Bellwood does
the same for the Austronesian dispersal, where there is actually a
congruence of linguistic and archaeological evidence to support the
notion, then argues more boldly that agriculture was the motive force
for the breakup of language families throughout the world.</p>

<p>Another motif is that populations such as PIE speakers sat in place
for millennia, which gave them enough time to develop many
tree-confounding contact phenomena.  Such beliefs may explain why this
symposium had so many papers dealing with convergence. Renfrew writes
about convergence within a PIE that has not quite broken up. Kalevi
Wiik writes about a huge Uralic presence in prehistoric Europe, with
contact phenomena explaining the emergence of branches like Germanic
(Uralic substrate, Megalithic(?) superstrate). The rationale for these
conclusions does not strike me as obvious. Raimo Anttila expresses a
similar opinion about Wiik's theory as part of his own invaluable
contribution highlighting recent developments in Uralic
studies. Anttila's own contribution is on contact phenomena,
specifically PIE loans into Uralic ca. 4000 BC. Other papers on
convergence were perhaps less directly tied in to the theme of the
conference. Yaron Matras and Peter Bakker each presents a typology and
many fascinating examples of contact phenomena that can lead to highly
mixed, even intertwined, languages. Reading Bakker's paper, I was
struck by how fast languages can change in a contact situation;
thousands of years of stewing is not required.</p>

<p>Most of the remaining papers focus more directly on methodological
issues. This is the real strength of the collection, although I do not
wish to give the impression that it covers the range of methodologies
with any breadth or depth. Lyle Campbell gives a highly readable
overview of techniques traditionally used to align linguistic
developments with external events. T. V. Gamkrelidze's and Aharon
Dolgopolsky's papers also describe some traditional approaches to
dating, such as linguistic palaeontology and loanword analysis.  A
couple of papers simply show how difficult data can be for any
methodology. James Clackson claims that every single item ever adduced
for the linguistic palaeontology of PIE is susceptible to another
interpretation that provides no help at all in dating; for example,
the all-important ‘horse’ could simply have been the wild horse. Larry
Trask brings up some thorny chronological issues with examples from
Basque, and James Matisoff pretty much succeeds in frightening readers
away entirely from the very nearly intractable Southeast Asian
languages.  In general, the knowledgeable historical linguist will
find this set of papers useful to the extent that she is interested in
the excursus they take. For example, Campbell helpfully includes frank
analyses of the weaknesses in Johanna Nichols' methodology (see below)
as well as Dixon's (not Gould's) theory of punctuated equilibrium.</p>

<p>Several papers touched on the philosophy of science to varying
degrees, and I found these discussions surprisingly useful. Sheila
Embleton notes that historical linguists have traditionally had a bias
for stating only what is virtually certain. But there is also value in
different kinds of claims, such as identifying the most probable of
several alternatives, or in quantifying the likelihood of an uncertain
possibility. It is in this spirit that most modern users of
glottochronology work: They know it gives at best rough estimates, but
when such limitations are openly acknowledged, rough estimates are
arguably better than no estimate at all or estimates based on what
Marisa Lohr calls “intuitive glottochronology”.</p>

<p>And it is glottochronology, in one form or another, that most of the
methodological papers address.  Embleton begins this set of papers
with a condensed history of lexicostatistic methods that have been
used to establish dating. Several papers in this collection use a
fairly traditional approach to lexicostatistics. Ilia Peiros performs
a lexicostatistic subgrouping of seven Oceanic languages. Richard
J. Hayward even tries to adapt it to an analysis of sprachbund
convergence, with indifferent results.  Christopher Ehret reports on
23 test cases from several different parts of Africa where archaeology
and classical glottochronology give congruent results. Robert Blust,
on the other hand, shows that the classical lexicostatistical
subgrouping of Austronesian spectacularly fails to agree with the tree
that has been constructed in accordance with the comparative
method. He neatly demonstrates how lexicostatistics breaks down when
different branches replace their vocabulary at different rates.</p>

<p>April McMahon and Robert McMahon's paper implicitly criticizes
glottochronology from another direction. They discuss why dating can
be reasonably reliable in biology: biologists have learned to focus
not on phenotypes, whose rate of evolution is heavily constrained by
functionality, but on those molecules whose exact structure does not
make a big difference to the functioning of the organism. In such a
subsystem, changes are essentially random and average out to a
constant rate over long time spans. In linguistics, unfortunately,
essentially all changes are functional, like phenotypes, so all hopes
for constant rates of change are likely to be in vain.</p>

<p>Several papers suggest how glottochronology can be improved.  Lohr
reports the development of a new list of 128 concepts meant to replace
the Swadesh list. Furthermore, she uses Fitch and Margoliash's
least-squares method to derive “topologies” of languages from
lexicostatistic distances. An example with 18 IE languages suggests
that it gives more felicitous results than traditional clustering
methods. Lohr also illustrates that analyses using traditional word
cognacy work better than those using phonostatistics. Unfortunately,
as in most of these papers, details are sadly lacking: not even the
new word list is given.</p>

<p>In an old paper recently translated, Sergei Starostin presents several
modifications of his own, in addition to presenting a proposal for
what he calls root glottochronology. His first modification is to
square the time factor in Swadesh's formula, which would surely lead
to paradoxes. Under Swadesh, we might expect English to replace a
certain number of its basic words before this new millennium is
out. Under Starostin, that number would vary depending on whether
English is a Germanic language (with a small time factor) or an IE
language (with a large time factor). The second proposal, which is
more comprehensible, attempts to take into account that the less
stable words in a list will be replaced more quickly than the stable
ones. The formula gets quite complicated, but seems to fit known IE
dates better. Will this extend to other verifiable dates, or is it a
case of overfitting to a few data points?  Ehret reports the
modifications are unnecessary for his African languages. But
Alexander Militarev applied the revised formula to the Afroasiatic
languages. He reports an exact match with known Egyptian chronology
and reports coherent results when building a subgrouping tree for 25
Afroasiatic languages. Against the trend, these papers give full data
sets and details enabling replication.</p>

<p>Completely abandoning the mathematics of lexicostatistics, Mark Pagel
shows how maximum likelihood models can be used to subgroup languages,
an adaptation of cladistic methods used in biology. He illustrates the
technique with a set of seven IE languages, using 18 words, and
reasonable results are obtained.  Pagel's model is clearly a major
improvement over the classical Swadeshian mathematics, although
computation time is not mentioned.</p>

<p>Paul Heggarty describes a method for computing phonetic difference
between cognate words and thence entire cognate languages; he goes on,
with evident reluctance, to estimate the time of the IE breakup. This
is thoughtful, new work with the potential for being influential among
linguists of a mathematical or computational
inclination. Unfortunately, of the many conceivable applications for
whole-word phonetic comparison algorithms, determining the historical
distance between languages would seem to be the least appropriate. If
sound change is exceptionless, a single change should be treated as a
single historical event. But in Heggarty's method, the impact of two
different changes can vary by orders of magnitude, depending on how
many words meet the condition for the change and how dramatic the
effect is per word.</p>

<p>William H. Baxter and Alexis Manaster Ramer point out that historical
linguistics lacks any tradition for significance testing. With great
clarity and concision, they present a way to test whether words in two
languages—here, Hindi and English—are phonetically more similar
to each other than one would expect by chance, and therefore
historically connected. Most elements of their methodology
are due to Oswalt, but this is the first time that I have
seen a completely accurate explication of how Monte Carlo methods can
be used to determine significance in such analyses. The only omission
is of any discussion of the loanword problem, which could have been
introduced by discussing why it was deemed appropriate to include
Persian loans in the Hindi list and Scandinavian loans in the English
list. Otherwise this article can serve as a standalone cookbook for
how to do significance testing using phonological similarity metrics.
Computer code is even given, although the choice of programming
language—HyperTalk script—is bemusing.</p>

<p>The last section of the book is titled “Morphology, Spatial
Patterning, and Beyond”, by which is meant Nichols.  She uses a
combination of archaeological and linguistic evidence to argue for a
very early (pre-glacial) peopling of the Americas. But Daniel Nettle
neatly answers Nichols by showing how minor changes in her assumptions
radically change the conclusions her model predicts. Parameters that
are every bit as reasonable as Nichols' estimates can lead to the
conclusion that the Americas were first settled around 14,000 BC—the
communis opinio that Nichols attempts to overturn.</p>

<p>The book is published as two surprisingly heavy paperback volumes,
glue bindings. The design is attractive.  The footnotes, alas, are
endnotes. The typography is pretty good; phonetic symbols, Greek, and
Cyrillic (Russian) are all set competently. Consistent errors—using
ess-zet (ß) for IPA beta (β) and misaligning superior diacritics with
respect to slanted base characters—will not bother readers who are
better adjusted than I am. And hopefully others will not be as
credulous as I was in accepting that an awful lot of mixed languages
have retroflex approximants as syllable nuclei, before realizing that
every accented <ling>i</ling> in Bakker's contribution was
systematically replaced by <ling>ɻ</ling>.</p>

</section>
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