According to a study of types of earwax carried out by student teams, people living in Japan during the Jomon period (ca 10,000 B.C.-ca 300 B.C.) carried the gene for wet earwax. The study produced a map on which the darker shaded areas show the distribution of today’s populations with wet earwax. The study also showed the gene that was responsible for dry earwax is more common in western Japan and that it was introduced into Japan by people who came from the Asian continent during the Yayoi period (ca 300 B.C.-ca A.D. 300) or later.
Earwax map charts history of Japan A team of high school students has drawn up a map charting the prevalence of different earwax types–wet and dry–by prefecture. Presented at a recent conference of a scientific society, the map is expected to contribute to tracing the migration patterns of ancient people in Japan. Based on the theory that a specific gene determines human earwax type, the student team studied frequencies of the gene for dry earwax, which is said to be common in Japan. The map is the fruit of collaboration between students of 42 of the 101 so-called super science high schools (SSH) around the nation–institutions designated by the Education, Science and Technology Ministry as focused on mathematics and science education.
Sample nail clippings from 771 students in 32 prefectures–20-50 from each participating school–were collected. Students at Nagasaki Nishi High School extracted DNA from the nail samples, isolating the gene that determines earwax types, in cooperation with Nagasaki University. Using data from the samples, the student team found that the gene responsible for dry earwax is more common in western Japan. That tallies with an earlier study by Norio Niikawa, a professor at the Health Science University of Hokkaido, who found that people living in Japan during the Jomon period (ca 10,000 B.C.-ca 300 B.C.) carried the gene for wet earwax, while the gene for dry earwax was introduced into Japan by people who came from the Asian continent during the Yayoi period (ca 300 B.C.-ca A.D. 300) or later.
(Sep. 19, 2007) The Yomiuri Shimbun
Referencing a table on ethnic groups and the rate on earwax type, the students knew that the percentage of wet earwax occurence in the different ethnic populations was as follows:
Black people: 100%
Chinese Taipei: 40%
Tungusic: Hardly any
They also knew that ear wax type was determined by a specific gene and that about 85% of Japanese are genetically predisposed to have dry type ear wax.
The students then collected fingernail clippings from 771 students living in 32 provinces, extracted the DNA from each sample, and isolated the gene that determines ear wax type.
When they charted their results on a map, an odd pattern emerged showing that the gene responsible for dry earwax is more prevalent in western Japan. Experts conclude that the aboriginal population of Japan (called “Jomon” people) carried the gene for wet ear wax and that the Yayoi people who migrated to Japan from Asia about 2,000 years ago carried the gene for dry earwax gene for dry earwax. The distribution map of current earwax types in Japan created by the students reinforces the existing theory that Japan was invaded from the west from the Asian mainland and those invaders gradually spread to the rest of the country, moving east and north while displacing and/or absorbing the aboriginal population.
Sources and more on this topic:
The worldwide distribution of the wet earwax alleles:
A SNP in the ABCC11 gene is the determinant of human earwax type Nature Genetics 38, 324 – 330 (2006) doi:10.1038/ng1733
Japanese map of the earwax gene frequency: a nationwide collaborative study by Super Science High School Consortium. J Hum Genet. 2009 Sep;54(9):499-503. Epub 2009 Jul 31.
Ear Wax Reveals Mystery Feb 7, 2008
Japanese Scientists Identify Earwax Gene NY Times Jan 29, 2006