On the "Dryopithecns Pattern" in Recent Japanese
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概要
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The Dryopithecus pattern, as described by GREGORY in 1916, has been a subject of study by many anthropologists, and many treatises on the subject have been published, but only a few were studies on Japanese subjects.The authors observed the fissure pattern -in three form (Y, +, X) according to JφRGENSEN'S classification- and the number of cusps by the method of making a plaster cast of the crowns of the first and the second lower molars of 438 Japanese (214 males and 224 females).The results are summarized as follows:(1) The Y-pattern appeared in the first lower molar in 70.7 per cent of the total cases. This rate is extremely low compared with Caucasians and Negroids. The first molar had five cusps in 97.9 per cent of the cases, a very high rate compared to that for Caucasians.(2) The Y-pattern appeared in the second lower molar in 4.5 per cent of the total cases. The second molar had five cusps in 53.7 per cent of the cases, again a high rate compared to that for Caucasians.(3) In rate of appearance of both the Y-pattern and number of cusps no significant difference between male and female can be recognized.(4) The first molar has six cusps in 12.5 per cent and the second molar in 3.7 per cent of toral cases.(5) The Japanese seem to be highly specialized in the trend toward a reduction in the fissure pattern on the lower molars, but they seem to have a higher frequency of five cusps in the lower molars than other racial groups.
- 日本人類学会の論文
日本人類学会 | 論文
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