The origin of the second-largest language family in the world is explored in Nature this week. The research sheds light on the movement of populations in ancient Asia.

The Sino-Tibetan language family is the most commonly spoken set of languages after the Indo-European language family. It incorporates more than 400 languages and dialects, including Chinese, Burmese and Tibetan, that are spoken collectively by about 1.5 billion people. Linguists debate where and when this group of languages emerged. The ‘northern-origin hypothesis’ places the onset in the Yellow River basin of northern China at around 4,000-6,000 years ago, and the ‘southwestern-origin hypothesis’ places it somewhere in the southwest of East Asia at least 9,000 years ago.

Li Jin and colleagues conducted a statistical analysis of root-meanings for words in a lexicon of 109 Sino-Tibetan languages. They conclude that these languages must have diverged around 5,900 years ago, which accords with the northern-origin hypothesis for the language family. It is thought that the languages split into two groups when one group of people migrated west into Tibet and south into Myanmar, and another group of people moved east- and southward, ultimately becoming the Han Chinese. The findings fit with the idea that languages spread along with agriculture, and the timing fits with archaeological evidence that reveals a southward dispersal of distinctive architectural forms and pottery types.