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Published online: 22 September 2005; | doi:10.1038/news050919-10
Grammar analysis reveals ancient language tree
It's not the words, it's how you use them that counts.
Jennifer Wild
The languages used in Papua New Guinea have few common words,
making it hard to determine their origins.
© Punchstock
When it comes to working out the relationships between ancient
languages, grammar is more enlightening than vocabulary, scientists
say.
There are some 300 language families in the world today.
Researchers have long studied similarities between the words in
different languages to try to work out how they are related. But
the rate of change in languages means that this method really only
works back to 10,000 years ago.
Homo sapiens evolved more than a hundred thousand years ago and by
10,000 years ago had already settled around the globe. So
researchers are keen to peer further back in time to see how
language evolved and spread.
To do this, Michael Dunn and colleagues at the Max Planck Institute
for Psycholinguistics in Germany decided to look at grammar.
They took Papuan languages of people in the South Pacific as their
challenge. Radiocarbon dating shows humans lived more than 35,000
years ago in Melanesia, a group of islands including Papua New
Guinea. But the 23 languages that have evolved in this area share
few, if any, common words. So the standard techniques cannot reveal
much about the languages' histories.
The researchers made a database of 125 grammatical features in 15
Papuan languages. This included how word types, such as nouns and
verbs, are ordered in a sentence, and whether nouns have a gender,
as they do in languages such as German and French.
As a test case, the team did the same for 16 Austronesian languages
- the languages of the Philippines, Indonesia and Southeast Asia -
for which vocabulary analysis has already revealed evolutionary roots.
A computer program then analysed the data to determine ancestral
language links. This produced up to 10,000 possible family trees
and a 'consensus tree' that best fitted the data, the team reports
in Science1.
The consensus tree for the Austronesian languages closely fitted
the accepted lineage from previous study of vocabulary, which
demonstrated the validity of the method. The consensus tree for the
Papuan languages then revealed previously unknown relationships
between those languages. The people of the Solomon Islands and
Bougainville Island, for example, seem to be related in language.
Perhaps these people were living in one community on a common land
mass more than 10,000 years ago, the researchers suggest.
The tree will need further work before it can be validated, the
researchers say. The team's next step is to apply this method to
old languages in the Amazon.
References
Dunn AM, Terrill A., Reesink G., Foley R& Levinson S.C. Science,
309. 2072 - 2075 (2005). | Article |
http://www.nature.com/news/2005/050919/full/050919-10.html
