Ancient human teeth tell a story of Europeans migrating to Eastern Asia during the Bronze Age, roughly 3,000 years ago, and mixing with local populations.

Human lower canines usually have only one root, but two-rooted canines occur in 5–8% of Europeans and occasionally in some Asian populations. Christine Lee at the Chinese Academy of Sciences in Beijing and Richard Scott at the University of Nevada in Reno examined the frequency of the dental trait in human skulls ranging between 60 and 6,000 years old from Spain and Eastern Asia. They found traces of two-rooted canines in up to 4% of skulls in regions of Mongolia and China. The researchers conclude that the rare trait was probably introduced into Eastern Asia by Indo-European groups crossing the western frontier of China and Mongolia.

Am. J. Phys. Anthropol. 10.1002/ajpa.21585 (2011)