Reiji Yoshida's assertion in the June 17 article "How hard is it really to learn Japanese?" that Okinawan (Ryukyuan) is the only language "with a demonstrable connection to Japanese" is mistaken. While Okinawan is certainly the closest relative, the split occurring around 1,700 years ago, the affinity between Japanese and Korean, and to the wider Altaic family, can no longer be seriously disputed.
Evidence for this, first published by Roy Andrew Miller in the 1960s, has been amply substantiated since. We can now be fairly certain that proto-Japanese split from a Koguryo dialect of Korean something like 4,500 years ago. It is corroborated by DNA evidence showing beyond doubt that the Yayoi, who introduced proto-Japanese to the archipelago, migrated here from the Korean Peninsula. Other suppositions mentioned in the article -- affinities with Tibetan or Tamil -- are pie in the sky.
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