- A linguistic 'golden age' occurred 1,000 to 3,000 years ago with tens of thousands of languages spoken worldwide.
- The decline in linguistic diversity started with the rise of large states and empires, not just European colonialism 500 years ago.
- Today's roughly 7,600 languages are a historically biased sample of past languages due to selective survival.
- The study combined ethnographic data, prehistoric population estimates, and modeling to trace language diversity over 12,000 years.