Sinodonty and Sundadonty



Sinodonty and Sundadonty are two patterns, identified by anthropologist Christy Turner, for East Asia, within the "Mongoloid dental complex". The latter is regarded as having a more generalised, Australoid morphology and having a longer ancestry than its offspring, Sinodonty.

The combining forms Sino- and Sunda- refer to China and Sundaland, respectively, while '-dont' refers to teeth.

He found the Sundadont pattern in the Jōmon of Japan, Taiwanese aborigines, Filipinos, Indonesians, Thais, Borneans, Laotians, and Malaysians, and the Sinodont pattern in the inhabitants of China, Mongolia, eastern Siberia, Native Americans, and the Yayoi.

Sinodonty is a particular pattern of teeth common among Native Americans and some peoples in Asia, in particular the northern Han Chinese and some Japanese populations. The upper first two incisors are not aligned with the other teeth, but are rotated a few degrees inward and are shovel-shaped. The upper first premolar has one root (whereas the upper first premolar in Caucasians normally has two roots), and the lower first molar in Sinodonts has three roots (whereas it has two roots in Caucasians).

In the 1990s, Turner's dental morphological traits were frequently mentioned as one of three new tools for studying origins and migrations of human populations. The other two were linguistic methods like Joseph Greenberg's mass comparison of vocabulary or Johanna Nichols's statistical study of language typology and its evolution, and genetic studies pioneered by Cavalli-Sforza.

Today, the largest number of references on the web to Turner's work are from discussions of the origin of Paleo-Amerindians and modern Native Americans, including the Kennewick Man controversy. Turner found that the dental remains of both ancient and modern Amerindians are more similar to each other than they are to dental complexes from other continents, but that the Sinodont patterns of the Paleo-Amerindians identify their ancestral homeland as north-east Asia. Some later studies have questioned this and found Sundadont features in some American peoples.

For example, in 1996, Rebecca Haydenblit of the Hominid Evolutionary Biology Research Group at Cambridge University did a study on the dentition of four pre-Columbian Mesoamerican populations and compared their data to "other Mongoloid populations". She found that "Tlatilco", "Cuicuilco", "Monte Albán" and "Cholula" populations followed an overall "Sundadont" dental pattern "characteristic of Southeast Asia" rather than a "Sinodont" dental pattern "characteristic of Northeast Asia".