Genetics researchers have uncovered the key gene behind the mystery of human earwax.

Finally.

The report in last week's Nature Genetics journal solves a long-running anthropologist's riddle — why many people in China and the Korean Peninsula, as well as elsewhere in Asia, have dry earwax while the rest of humanity enjoys the sticky variety.

The finding could represent the leading edge of some new reports about nondisease-related genes that are responsible for visible changes in human anatomy, population researchers say.

Geneticists had known the neighborhood of the earwax gene from previous work and decided to pin it down. It all comes down to a single gene, dubbed ABCC11, reports a Japanese team led by Kohichiro Yoshiura of the Nagasaki University Graduate School of Biomedical Sciences. The gene comes in two types, or alleles, corresponding to wet or dry earwax.

By examining 126 Japanese volunteers, the team determined that the dry-earwax gene is recessive, meaning both parents must pass a copy to their children for it to work. To chart a global earwax-gene map, the team next looked at volunteers from 33 populations worldwide, including Native Americans, Ashkenazi Jews and Polynesians. The dry-earwax allele probably originated in northeast Asia, the team concludes.

Biological anthropologist Mark Shriver of Pennsylvania State University said by e-mail that the finding points the way to future discoveries of disease-related genes specific to certain populations, as well as glimpses of how evolution changes genes.