One particular trait that came into the news a few years ago (2006) is related to sweat and ear wax. (That there was the layperson’s link, but if you want the hard science and have access to Nature, look here.) Which one’s grosser? Ear wax? Okay. Well, there are two kinds of ear wax in humans: brown, wet, waxy stuff, and yellowish-white, drier, flaky stuff. If you’re a Northeast East Asian, or of Native American ancestry, chances are that your ear wax is the latter type. (Though bear in mind, this is for pre-Contact gene pools; if your great-great-grandparent was one quarter Cree, I have no clue what type your ear wax will be.) If you’re from an African or European gene pool, chances are your ear wax is the former type, darker and wetter. Central Asia is mostly a mix, and Southeast Asia is something of a mix too.
Why the adaptation? It seems not because of earwax itself, but rather because the gene that causes the wax to be drier and flakier also seems to control perspiration — people with the drier earwax sweat less. Which one can imagine would be handy in certain conditions. (The researchers who reported it theorized cold weather, given other adaptations like East Asian nostril size.)
So, yes, there’s a genetic link between why, in Korean, ear wax is called 귀밥 (gui-bap, ie. “ear rice” — because it comes out pale and flakey and dry) and why it used to be so darned hard to find deodorant in stores.
(If I could “buy” this adaptation, I suspect I would. The humidity these days drives me nuts, making me sweat much more than I’d like!)
Another trait that came up in a recent discussion about drug control on a mailing list I’m on, about drug controls, drinking cultures, and the Prohibition. I made an example of drinking culture in Korea, and discussed how he main drinking style here is drinking to get drunk, even though a number of people here seem also to have trouble breaking down alcohol; I also discussed what I’ve noticed about how people react socially to the effects of that condition.
(Men I’ve met affected with this condition usually sort of grin and bear it, but women especially are very self-conscious of it. I’ve heard a lot of women say they feel that they look stupid, foolish, or dumb when their face reddens from drink. I haven’t heard nearly as many men say this. The men seem less embarrassed than the women, in my experience, but that’s limited experience, remember, and even the guys seem somewhar embarrassed by it.)
The condition, in any case, apparently is called in technical terms “acetaldehyde dehydrogenase deficiency,” but don’t let that scare you. The way regular people talk about it is, “Ah, yeah, some Asian people don’t produce a lot of that enzyme that breaks down alcohol so they get red-faced and sick when they drink!” This is known colloquially by a multitude of names in English: Asian Flush, Asian Glow, Asian Red, and so on.
The question, of course, is why some people (people bandy around numbers like 40% or 50% of East Asians) would come to have that condition. And the answer suggested in an article titled ” Why can’t Chinese Han drink alcohol? Hepatitis B virus infection and the evolution of acetaldehyde dehydrogenase deficiency” is interesting. Basically, the idea is that the populations in which this mutation are common all live in places where Hepatitis B is also endemic. Hepatitis B and heavy alcohol consumption kill your liver way faster than Hepatitis B alone, or heavy drinking alone. If you aren’t able to drink heavily — because you have this mutation — then you’re unlikely to die from heavy drinking — but you’re also unlikely to accelerate your own death by unknowingly combining hepatitis B and heavy drinking. So people with this mutation would have tend to be better at surviving a (common in these areas) infection of hepatitis B, possibly to the degree that it would be selected for.
So one reason some of your (probably Asian) friends turn red in the face when they drink and can’t drink much is because this was an evolutionary advantage to their ancestors, thanks to the prevalence of hepatitis B where their ancestors lived at some point… or so the theory goes. Well, that or maybe the alcoholics all died faster, and that would be why the rate of alcoholism is lower in places where this is common — 10-20% lower, according to this article.
Which may not be much consolation, but the neatness of knowing has got to be worth something… it might at least save some people from wasting money on this sort of thing. While a drug simulating this condition seems to have been developed for the treatment of alcoholism, there doesn’t seem to be a “cure” for the “Asian Glow” beyond, maybe, dosing with antacids or fructose/glucose — and even those, according to doctors quoted in the article linked in the paragraph above, might only facilitate such individuals to drink more only to bring on all kids of awful cancers or liver conditions, to which they’re more susceptible to begin with, or an early death from alcohol poisoning.
What seems curious, though, is how alcohol would be such a big part of social life in Korea despite all of this. According to Dong-Kwon Lim, a folklorist, drinking has always been a distinctly important part of Korean social life — one that differentiated it from China’s or Japan’s. Indeed, Lim claims that “inns” were considered, by Koreans, “drinking places” (as opposed to “eating places” in China and “sleeping places” in Japan — I have no idea what the older terms are, though, since he doesn’t give them). As he writes in In Search of Korean Folklore:
In the Korea of the past, a person was often called heroic or manly if he could drink well, while those who could not were considered unmanly. So a man was judged by how much he could drink and the size of a drinking party was also used as a barometer when people evaluated a family’s generosity. The party could not be judged a success if all of the participants returned home without some incident. Id some of the guests happened to fall down into a ditch, the family was said to have thrown a good party. While this may be unimaginable in other countries, Koreans had their own standard of evaluation using alcohol as a criterion.
I’m not so sure that these standards are unthinkable in other countries, of course — especially not historically speaking. I would wager that some Northern European societies — why am I thinking of cartoonlike Vikings like those featured in How To Train Your Dragon? — had similar standards, and that indeed even today, if you but visit a fraternity house at any American university (or a “student ghetto” like McGill Ghetto in Montreal, or wherever one can find a large concentration of students in Britain), I’d wager the same essential criterion exists… though absent, of course, as high a concentration of the Asian Flush.
And that’s what is particularly intriguing to me: why would a drinking culture of that kind develop in a place where so many people just cannot drink? Quite curious.