考研阅读精选：快乐也是遗传
『快乐就在你的基因里；不同种族容易感到快乐的程度也不同。』The genetics of happiness：Transporter of delight
快乐也是遗传
Oct 15th 2011| from the Economist
THE idea that the human personality is a blank slate, to be writtenupon only by experience, prevailed for most of the second half of the20th century. Over the past two decades, however, that notion has beenundermined. Studies comparing identical with non-identical twins havehelped to establish the heritability of many aspects of behavior, andexamination of DNA has uncovered some of the genes responsible. Recentwork on both these fronts suggests that happiness is highly heritable.
As any human being knows, many factors govern whether people are happyor unhappy. External circumstances are important: employed people arehappier than unemployed ones and better-off people than poor ones. Agehas a role, too: the young and the old are happier than the middle-aged.But personality is the single biggest determinant: extroverts arehappier than introverts, and confident people happier than anxious ones.
That personality, along with intelligence, is at least partly heritableis becoming increasingly clear; so, presumably, the tendency to behappy or miserable is, to some extent, passed on through DNA. To try toestablish just what that extent is, a group of scientists examined over1,000 pairs of twins from a huge study on the health of Americanadolescents. In “Genes, Economics and Happiness”, a working paper fromthe University of Zurich’s Institute for Empirical Research inEconomics, they conclude that about a third of the variation in people’shappiness is heritable. That is along the lines of, though a littlelower than, previous estimates on the subject.
But while twinstudies are useful for establishing the extent to which acharacteristic is heritable, they do not finger the particular genes atwork. One of the researchers, Jan-Emmanuel De Neve, has tried to do justthat, by picking a popular suspect—the gene that encodes theserotonin-transporter protein, a molecule that shuffles a brainmessenger called serotonin through cell membranes—and examining howvariants of that gene affect levels of happiness.
Serotoninis involved in mood regulation. Serotonin transporters are crucial tothis job. The serotonin-transporter gene comes in two functionalvariants—long and short. The long one produces more transporter-proteinmolecules than the short one. People have two versions (known asalleles) of each gene, one from each parent. So some have two shortalleles, some have two long ones, and the rest have one of each.
The adolescents in Dr De Neve’s study were asked to grade themselvesfrom very satisfied to very dissatisfied. Dr De Neve found that thosewith one long allele were 8% more likely than those with none todescribe themselves as very satisfied; those with two long alleles were17% more likely.
Which is interesting. Where the story could becomecontroversial is when the ethnic origins of the volunteers are takeninto account. All were Americans, but they were asked to classifythemselves by race as well. On average, the Asian Americans in thesample had 0.69 long genes, the black Americans had 1.47 and the whiteAmericans had 1.12.
That result sits comfortably with otherstudies showing that, on average, Asian countries report lower levels ofhappiness than their GDP per head would suggest. African countries,however, are all over the place, happinesswise. But that is notsurprising, either. Africa is the most genetically diverse continent,because that is where humanity evolved. Black Americans, mostly thedescendants of slaves carried away from a few places in west Africa,cannot possibly be representative of the whole continent. (579 words)
文章地址：http://www.economist.com/node/21532247
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