In some Asian countries, notably China, rates of alcoholism are drastically lower than they are in other parts of the world. This phenomenon may be the result of a genetic mutation that causes Asian flush, a reddening of the face in some found in some drinkers.
Because of its unpleasant effects, those who develop Asian flush are much less likely to ingest or abuse alcohol. If non-drinkers are better able to promote their survival and propagation, might natural selection have favored this trait?
Red in the face
Under normal circumstances, alcohol is metabolized into acetaldehyde by the enzyme alcohol dehydrogenase. Acetaldehyde is in turn broken down into harmless acetic acid by the enzyme aldehyde dehydrogenase-2 (ALDH2). In those lacking this critical enzyme, acetaldehyde builds up much faster than normal.
When acetaldehyde is not rapidly converted to acetate the outcome is dramatic. There is an increase in blood flow to the skin of the face and neck, one’s heart beats more rapidly; headache, nausea and extreme drowsiness may ensue. Acetaldehyde is credited as the principal contributor to hangovers.
Dr. Ting-Kai Li, a professor of medicine and biochemistry at the Indiana University School of Medicine believes believes the mutant gene responsible for Asian flush may protect against heavy drinking and alcoholism, “[An] aversive reaction affects drinking behavior,” says Li. “It appears that the development of alcoholism is not a case of genetics versus the environment; it is one of genetics and the environment.”
Either or both parents can pass on the mutation, which is found in as many as 70% of Asians of Chinese or Japanese decent.
Source: SAMHSA, Office of Applied Studies, National Survey on Drug Use and Health, 2002. Koreans are less likely to carry the ALDH2 mutation.
The cost of abuse
While politicians decry the dangers of drugs, alcohol abuse and alcoholism is the greater contributor to our societal ills, costing the U.S. $148 billion each year. If we were drink-averse, the costs, monetary and otherwise, would be eliminated. According to the National Institute of Health,
“Two-thirds of the costs of alcohol abuse related to lost productivity, either due to alcohol-related illness (45%) or premature death (21%). Most of the remaining costs of alcohol abuse were in the form of health care expenditures to treat alcohol use disorders and the medical consequences of alcohol consumption.”
Booze can be especially deleterious to a developing child. Drinking alcohol during pregnancy can adversely affect the development of the fetus, resulting in lifelong medical consequences including impaired intelligence, motor skills and problem-solving ability. Those afflicted make less attractive partners.
And while there have been some studies which report benefits to moderate alcohol consumption, for alcoholics drinking moderately is not a realistic option. On average, an alcoholic who doesn’t stop drinking can expect to decrease his or her life expectancy by at least 15 years. When you’re dead you can’t mate.
Natural selection predicts the fittest will survive and pass on their genes. Might those who are genetically insulated from the deleterious effects of alcohol abuse stand a better chance?
4 comments ↓
There’s another way of looking at it: In a society where drinking is not merely socially acceptable but considered a manly attribute (of course this applies only to guys), being able to hold one’s liquor would *improve* one’s chances of finding a good mate. In Chinese society, in contrast, it could be that over thousands of years, frowning on excessive alcohol consumption would have the opposite effect: Guys with the “Asian flush” gene would tend to drink less and be more successful at finding good mates. In other words, this gene is an excellent example of social factors affecting genetic ones.
Everyone knows that this has more to do with water supply than anything else - Europeans drank beer all day whilst the Chinese drank tea. As a result white Europeans developed greater alcohol tolerance
Interesting thoughts, Rich. I feel social influence likely played a role as well. Your guess is as good as mine.
RE Anon: What do you think of the Americans who drink Cola constantly or the Russians who drink Vodka all day, or the Inuits who drink whale blubber?
Anon: Your argument doesn’t make sense. People do not learn to have genes - as in, a person who builds up his alcohol tolerance through his life doesn’t pass that on to his kids. We are talking about a genetic mutation which has influenced alcohol consumption. Lack of alcohol consumption cannot influence a genetic mutation to form.
The question is, why would this genetic mutation proliferate throughout an entire population of the world? Was it isolation? Was it more attractive in this culture, and therefore lent itself to finding a mate?
To say that it has to do with water supply confuses me the most, so maybe you can explain. It is my understanding that distilling and boiling basically result in the same thing - water that you can drink. But, one thing I know is that mead aided digestion of meat. Perhaps, because Europeans have always eaten a lot of meat, mead was necessary? While Asians have eaten more soy and fish? Genes that have adapted to society’s needs - maybe it’s the ability to digest alcohol that is the mutation, not the other way around? And those who could digest it fared best in Europe, where there was much more meat and grain consumption, which is a difficult diet for the body to digest?
And, has anyone thought of the relationship to the inability of most Asians to digest cow’s milk? Another tie in to my (very made-up) lack of meat theory.
Anyway, great post, Doug. It really got the ole juices flowin’.
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