Most people aren't aware of this fact, but ear wax comes in two types wet and dry.

Now hold on, don't run off... this obscure factoid has repercussions beyond just grossing you out. For that we can thank the perceptive students of Japan's Nagasaki Nishi High School, one of 101 government-designated "super science high schools" that specialize in math & science.

According to a newly published report in the Daily Yomiuri Online , the kids at NNHS spearheaded a project that included students from 42 other super science high schools and gave us a map that charts the prevalence of wet and dry earwax types by province!


For now, we have this ear wax map, and what is IT good for? Well, the students knew that a specific gene determines ear wax type and were able to reference a table showing the rate of wet type ear wax among different ethnic groups:

Black people: 100%
European: 100%
Micronesian: 60%
Chinese Taipei: 40%
Japanese: 16%
Mongol: 12%
Korean: 8.5%
Chinese: 4%

As you can see, 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, and isolated the gene that determines ear wax type from each sample. When charted on a map, an odd pattern emerged: "the gene responsible for dry earwax is more common in western Japan."

Historians believe 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 ear wax.

The distribution map of current ear wax 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.

About Ear Wax Gene:

Earwax comes in two types, wet and dry. The wet form predominates in Africa and Europe, where 97 percent or more of the people have it, and the dry form among East Asians, while populations of Southern and Central Asia are roughly half and half. By comparing the DNA of Japanese with each type, the researchers were able to identify the gene that controls which type a person has, their report can be found on Nature Genetics magazine.

The Japanese researchers, led by Koh-ichiro Yoshiura of Nagasaki University, then studied the gene in 33 ethnic groups around the world. Since the wet form is so common in Africa and in Europe, this was likely to have been the ancestral form before modern humans left Africa 50,000 years ago.

The dry form, the researchers say, presumably arose later somewhere in northern Asia, because they detected it almost universally in their tests of northern Han Chinese and Koreans. The dry form becomes less common in southern Asia, probably because the northerners with the dry earwax gene intermarried with southern Asians carrying the default wet earwax gene. The dry form is quite common in Native Americans, confirming other genetic evidence that their ancestors migrated across the Bering straits from Siberia 15,000 years ago.

Japanese researchers believe that earwax type and armpit odor are correlated, since populations with dry earwax, such as those of East Asia, tend to sweat less and have little or no body odor, whereas the wet earwax populations of Africa and Europe sweat more and so may have greater body odor. Several Asian features, such as small nostrils and the fold of fat above the eyelid, are conjectured to be adaptations to the cold. Less sweating, the Japanese authors suggest, may be another adaptation to the cold climate in which the ancestors of East Asian peoples are thought to have lived.

Source: Inventorspot, NYTimes