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Dialects as the key to Japanese prehistory

Japanese was not always the language spoken in Japan. Researchers link the arrival of the language in Japan with the migration of farmers around 400 BC. Linguist Elisabeth de Boer has been awarded an ERC Starting Grant to carry out research on the further spread of the language in Japan.

Wet rice cultivation

The words ’Ainu language’, written in Ainu
The words ’Ainu language’, written in Ainu

Japanese speakers started to leave present-day Korea for Japan in around 400 BC in order to start wet rice cultivation on the south-western island of Kyushu.

Ainu in the north-east

Archaeological finds show that they spread from there north-eastwards. As a linguistic remnant of this history, the almost extinct Ainu language – the last remnant of the many languages that must have been spoken in Japan – was preserved longest in the north-east.

Remarkable spread of tonal systems

But this is not the only remnant. The different tonal systems in Japanese dialects show a remarkable spread: as a result of her earlier research, De Boer had radically rewritten these tonal systems and demonstrated that tonal systems in a number of distant corners of Japan share all kinds of innovations. There are also other remarkable similarities between these dialects in other areas.

Migration could explain this

Tonal map of Japan. Japanese dialects have many different tonal systems. This map shows which types occur where.  The green areas are relevant for De Boer’s research.
Tonal map of Japan. Japanese dialects have many different tonal systems. This map shows which types occur where. The green areas are relevant for De Boer’s research.

This is the opposite of what one might expect: people who are a long way away from one another do not normally pass on to one another innovations in the language. In particular given the way the Japanese language came to Japan, migration could explain these developments. Another unexpected discovery is that the first signs of the spread of bronze culture can be found in a number of these areas.

Reconstruction of family tree of dialects

So far, no study has been made of how these dialects are related. Reconstructing a reliable family tree for the dialects is therefore the first aim of De Boer’s project. The complex tonal systems in particular are ideal material for research. De Boer will employ such research methods as fieldwork in the different dialect areas, linguistic analysis of these dialects and research on the documents that record the oldest form of this dialect type.

Better insights from linguistic research

Ainu ceremony in 1999
Ainu ceremony in 1999

To date researchers have tried to reconstruct the prehistoric migration movements in Japan purely on the basis of archaeological data. The findings from De Boer’s project will make it possible to chart – based on the study of the dialects – how the ancestors of present-day Japanese people came to Japan and spread over the islands.


De Boer: ‘This is a welcome sign of recognition, and I’m really pleased with it. My research on Japanese tonal systems caused quite a stir and it therefore took some time before my ideas were accepted. The fact that I have now received this enormous research grant means that I can study the implications of my work for Japanese prehistory, and that’s fantastic.’’

(18 November 2015)



ERC (European Research Council) Starting Grants are intended for researchers with 2-7 years of experience since completion of PhD, a scientific track record showing great promise, and an excellent research proposal. Funding per grant can be up to € 1.5 million.

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