传递快乐的使者

　　Happiness is in your DNA; and different races may have different propensities for it

　　基因决定幸福；而不同种族的幸福倾向不尽相同

　　Born smiling?

　　天生会笑？

　　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 behaviour, and examination of DNA has uncovered some of the genes responsible. Recent work on both these fronts suggests that happiness is highly heritable.

　　人的性格有如一张白纸，唯有经历才能在上面挥毫泼墨——这个观点几乎在整个二十世纪下半叶都十分流行。然而近二十年来，此观点的说服力已逐渐减弱。同卵及异卵双胞胎的对比研究为证明行为的许多方面的遗传性带来了许多帮助，DNA检查也发现了与此相关的部分基因。最近，对这两个前沿问题的研究表明幸福感在很大程度上是遗传的。

　　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.

　　众所周知，决定一个人幸福与否的因素有很多。外部环境就十分重要：就业人群比失业人士更幸福，富裕阶层比家境贫寒的人更幸福。年龄也是一个因素：年轻人与老年人比中年人更幸福。但是，性格是唯一一个最大的决定性因素：性格外向的人比性格内向的人更幸福，自信的人比性格焦虑的人更幸福。

　　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 from University College, London; Harvard Medical School; the University of California, San Diego; and the University of Zurich 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.

　　性格与智力至少在某种程度上是遗传的，这个观点正变得越来越明确；所以，在某种程度上，一个人感到幸福还是悲伤的倾向可能是由基因传递的。为了确定基因到底在多大程度上决定幸福，来自伦敦大学学院、哈佛大学医学院、圣地亚哥的加利福尼亚大学及苏黎世大学的一组科学家在一个针对美国青少年的大型健康研究中对1000对双胞胎进行了测试。在苏黎世大学经济学实证研究院的一篇工作论文《基因、经济学与快乐》中，这些科学家们提出了以下结论：人的幸福感约有三分之一是遗传的。这个结论与之前的估计相一致，只是在程度上稍微低了一点。

　　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, of University College, London, and the London School of Economics, 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.

　　虽然关于双胞胎的研究有助于确定一个性格特征在多大程度上能被遗传，但是这项研究并未指出到底是哪个基因起到了遗传作用。伦敦大学学院及伦敦经济学院的一位研究人员简-以内马利·德·内弗已选出一个被认为最有可能起作用的基因，即编码血清素转运体蛋白质（这个蛋白质分子将名为血清素的大脑信使带入细胞膜中）的基因，并尝试检验这个基因的各种变异对幸福感的影响有多大。

　　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.

　　血清素与情绪调节有关，而血清素转运体在其中的作用至关重要。从功能角度上区分，血清素转运提基因有两种变体：长型和短型，长型能比短型制造出更多的转运体蛋白质分子。人类拥有分别来自父亲与母亲的两个血清素转运体基因，每个基因有两种版本（被称为等位基因）。所以，有些人拥有两个短型等位基因，有些人拥有两个长型等位基因，剩下的则长型短型各一个。

　　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.

　　德?内弗博士在研究中要求青少年在“非常满意”到“非常不满”之间对自己作出评价。德?内弗博士发现，拥有一个长型基因的人对自身评价“非常满意”的比例比没有长型基因的人多8%；而拥有两个长型基因的人则多17%。

　　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.

　　以上现象相当有趣。而研究有争议之处在于，志愿者的种族也被考虑了进去。所有志愿者都是美国人，但他们同样被要求区分自己属于哪个种族。在样本中，平均而言，亚裔美国人拥有0.69个长型基因，黑人美国人拥有1.47个，白人美国人有1.2个。

　　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 (Asians, Europeans, Aboriginal Australians and Amerindians are all descended from a few adventurers who left Africa about 60,000 years ago). Black Americans, mostly the descendants of slaves carried away from a few places in west Africa, cannot possibly be representative of the whole continent.

　　毫无疑问，以上结果与另一些研究的结果相符。这些研究表明，亚洲国家人民的平均幸福程度比其人均GDP所预示的要低。然而，在非洲，不论哪国的人民都感到很幸福。不过这也并不出乎意料。非洲是基因最多样化的大洲，因为那里是人类进化的地方（亚洲人、欧洲人、澳大利亚原住民以及美洲印第安人都是大约六万年前离开非洲的一些探险家们的后代）。美国黑人则大多是被人从非洲西部某些地区带来的奴隶的后代，因此他们不可能代表整个大洲。

　　That some populations have more of the long version of the serotonin-transporter gene has been noticed before, though the association has previously been made at a national, rather than a racial, level. In a paper in the Proceedings of the Royal Society, published in 2009, Joan Chiao and Katherine Blizinsky of Northwestern University, in Illinois, found a positive correlation between higher levels of the short version of the gene and mood disorders (China and Japan have lots of both) and with collectivist political systems. Their hypothesis is that cultures prone to anxiety tend towards systems that emphasise social harmony and away from ones that emphasise individuals’ independence of each other.

　　之前也有人注意到一些人拥有更多的长型血清素转运体基因，不过研究角度是国家而非种族。伊利诺斯州西北大学的约翰?乔和凯瑟林?Blizinsky于2009年在英国皇家学院学报发表了一篇论文，他们在文中指出，拥有短型基因及情绪障碍症（中国和日本的这两种人群都数目庞大）与实行集体主义的政治制度呈正相关关系。他们的假设是：有焦虑倾向的文化趋于实行强调社会和谐的制度，而远离强调个人独立的制度。

　　This latter study may be a few steps too far along the road to genetic determinism for some people. But there is growing interest in the study of happiness, not just among geneticists but also among economists and policymakers dissatisfied with current ways of measuring humanity’s achievements. Future work in this field will be read avidly in those circles.

　　对某些人而言，后一个研究可能在基因决定论这条路上走得有点远了。不过，不仅是遗传学家，就连经济学家、政治决策者也对研究幸福越来越感兴趣。因为政治决策者们对现在衡量人类成就的方式不甚满意。所以以上各界人士将会十分关注这个领域的未来研究成果。