考研阅读精选：快乐也是遗传

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『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

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  THE idea that the human personality is a blank slate, to be written  upon only by experience, prevailed for most of the second half of the  20th century. Over the past two decades, however, that notion has been  undermined. Studies comparing identical with non-identical twins have  helped to establish the heritability of many aspects of behavior, and  examination of DNA has uncovered some of the genes responsible. Recent  work on both these fronts suggests that happiness is highly heritable.
  As any human being knows, many factors govern whether people are happy  or unhappy. External circumstances are important: employed people are  happier than unemployed ones and better-off people than poor ones. Age  has a role, too: the young and the old are happier than the middle-aged.  But personality is the single biggest determinant: extroverts are  happier than introverts, and confident people happier than anxious ones.
  That personality, along with intelligence, is at least partly heritable  is becoming increasingly clear; so, presumably, the tendency to be  happy or miserable is, to some extent, passed on through DNA. To try to  establish just what that extent is, a group of scientists examined over  1,000 pairs of twins from a huge study on the health of American  adolescents. In “Genes, Economics and Happiness”, a working paper from  the University of Zurich’s Institute for Empirical Research in  Economics, they conclude that about a third of the variation in people’s  happiness is heritable. That is along the lines of, though a little  lower than, previous estimates on the subject.
But while twin  studies are useful for establishing the extent to which a  characteristic is heritable, they do not finger the particular genes at  work. One of the researchers, Jan-Emmanuel De Neve, has tried to do just  that, by picking a popular suspect—the gene that encodes the  serotonin-transporter protein, a molecule that shuffles a brain  messenger called serotonin through cell membranes—and examining how  variants of that gene affect levels of happiness.
Serotonin  is involved in mood regulation. Serotonin transporters are crucial to  this job. The serotonin-transporter gene comes in two functional  variants—long and short. The long one produces more transporter-protein  molecules than the short one. People have two versions (known as  alleles) of each gene, one from each parent. So some have two short  alleles, some have two long ones, and the rest have one of each.
  The adolescents in Dr De Neve’s study were asked to grade themselves  from very satisfied to very dissatisfied. Dr De Neve found that those  with one long allele were 8% more likely than those with none to  describe themselves as very satisfied; those with two long alleles were  17% more likely.
Which is interesting. Where the story could become  controversial is when the ethnic origins of the volunteers are taken  into account. All were Americans, but they were asked to classify  themselves by race as well. On average, the Asian Americans in the  sample had 0.69 long genes, the black Americans had 1.47 and the white  Americans had 1.12.
That result sits comfortably with other  studies showing that, on average, Asian countries report lower levels of  happiness than their GDP per head would suggest. African countries,  however, are all over the place, happinesswise. But that is not  surprising, either. Africa is the most genetically diverse continent,  because that is where humanity evolved. Black Americans, mostly the  descendants 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