title: Non-metric tooth crown traits of the Thai, Aka and Yao tribes of northern Thailand.
abstract: A survey was made of Thai tribe members, who cultivate rice paddies in the flatlands of northern Thailand, and of the Aka and Yao tribes, who farm with the slash-and-burn method in a mountainous region of northern Thailand. Plaster casts of the upper and lower jaws of tribe members were taken. Seventeen non-metric traits of their tooth crowns were classified and compared with other Mongoloid populations in various regions and periods. It was observed that the Thai tribe had the Sundadont characteristics, typical of South-East Asians, but the Aka and Yao tribe had more Sinodont than Sundadont characteristics, typical of North-East Asians. The regional and temporal variations of crown morphology in South-East Asia suggest earlier setting of the Thai tribe than the Aka and Yao tribes in this region. Moreover, comparison of the tooth morphological and linguistic classifications contradicts the traditional theory of the genealogy of the Thai language family. On the subject of the origin of modern South-East Asians, it is suggested that there has not been a gene flow of Sinodonty into Sundadonty of the principal ethnic groups in Neolithic South-East Asia.
authors.affiliation: Department of Oral Anatomy, Nagasaki University, School of Dentistry, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Manabe
authors.forename: R
authors.initials: R
authors.lastname: Ito
authors.forename: Y
authors.initials: Y
authors.lastname: Kitagawa
authors.forename: J
authors.initials: J
authors.lastname: Oyamada
authors.forename: A
authors.initials: A
authors.lastname: Rokutanda
authors.forename: S
authors.initials: S
authors.lastname: Nagamoto
authors.forename: S
authors.initials: S
authors.lastname: Kobayashi
authors.forename: K
authors.initials: K
authors.lastname: Kato
mesh_terms: D044466:Asian People / Q000145:classification* / Q000235:genetics; D005260:Female; D014644:Genetic Variation; D006801:Humans; D008037:Linguistics; D008297:Male; D009811:Odontometry; D012016:Reference Values; D013785:Thailand; D019228:Tooth Crown / Q000033:anatomy & histology*