February 07, 2006
BehindTheMedspeak: Got Earwax? And if you do, well, is it wet or dry?
Finally I address something important, something that might actually make a difference in how you live your life.
From a team of Japanese researchers led by Kohichiro Yoshiura at Nagasaki University comes sensational news: the gene that controls whether you have wet or dry earwax has, at long last, been identified.
Now admit it: haven't you been losing sleep for years, wondering when they'd finally pin it down?
Nicholas Wade of the New York Times reported on the findings, published in the journal Nature Genetics on January 30.
Should you prefer the USA Today take on the discovery, here you go.
Here's the Times story.
- Scientists Find Gene That Controls Type of Earwax in People
Earwax may not play a prominent part in human history but at least a small role for it has now been found by a team of Japanese researchers.
Earwax comes in two types, wet and dry.
The wet form predominates in Africa and Europe, where 97 percent or more of people have it, and the dry form among East Asians.
The populations of South 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, they report in today's issue of Nature Genetics.
They then found that the switch of a single DNA unit in the gene determines whether a person has wet or dry earwax.
The gene's role seems to be to export substances out of the cells that secrete earwax.
The single DNA change deactivates the gene and, without its contribution, a person has dry earwax.
The Japanese researchers, led by Kohichiro 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 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 Strait from Siberia 15,000 years ago.
The Japanese team says that the gene that affects earwax, known to geneticists as the ATP-binding cassette C11 gene, lies with three other genes in a long stretch of DNA that has very little variation from one person to another.
Lack of variation in a sequence of DNA units is often the signature of a new gene so important for survival that it has swept through the population, erasing all the previous variation that had accumulated in the course of evolution.
But earwax seems to have the very humble role of being no more than biological flypaper, preventing dust and insects from entering the ear.
Since it seems unlikely that having wet or dry earwax could have made much difference to an individual's fitness, the earwax gene may have some other, more important function.
Dr. Yoshiura and his colleagues suggest that the gene would have been favored because of its role in sweating.
They write 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, while the wet earwax populations of Africa and Europe sweat more and so may have more body odor.
Several Asian features, like small nostrils, are conjectured to be adaptations to the cold.
Less sweating, the Japanese authors suggest, may be another adaptation to the cold in which the ancestors of East Asian peoples are thought to have lived.
But now you're just getting warmed up, isn't that right?
I know you so well.
But I digress.
Here's a link to the abstract of the Nature Genetics paper.
And now I'm really gonna put a bee in your bonnet.
Because tomorrow, at 12:01 p.m., precisely 24 hours from now, bookofjoe is going to run an unprecedented (if it happened before I sure as heck can't remember it and my crack research team is, as usual, asleep at the switch so there's no help from that peanut gallery) Episode 2 of "BehindTheMedspeak: Got Earwax?," featuring a revolutionary new tool to enable 21st–century earwax management — in the privacy of your own home.
Don't miss it.
February 7, 2006 at 12:01 PM | Permalink
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Why focus on the earwax and not the body odor? It doesn't bother me if your earwax is dry but it sure will bug me if you stink and I have to breathe it. If it's true that wet earwax=more body odor, then shouldn't the practical application of this not be that you should try to sit/stand close to the chinese people on the subway/airplane?
I chaulk this up to it being a japanese study but being promoted in the West. You can't promote this kind of study as saying that 99% of Americans of European descent stink while 99% of Chinese don't.
Posted by: Chris | Feb 7, 2006 11:59:09 PM
I still say that somebody needs to produce a pair of reading glasses with ear-pieces that have screw-on cotton-tipped applicator ends for hygienic ear-cleaning.
Posted by: Flutist | Feb 7, 2006 1:31:38 PM
I think that's gross.
What's even more disgusting is seeing someone stick a bobby pin or something in their ear, wiggle it around, then stick it in their mouth afterwards to clean it off. Dry or wet. UGH.
Posted by: Three Layer Cake | Feb 7, 2006 12:51:30 PM
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