Grammar analysis reveals ancient language tree
It's not the words, it's how you use them that counts.
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.
- Dunn AM, Terrill A., Reesink G., Foley R& Levinson S.C. Science, 309. 2072 - 2075 (2005).