Strangled by Roots
根之牵绊
作者：Steven Pinker @ 2007-8-6
译者：沈沉（@你在何地-sxy）
校对：Drunkplane(@Drunkplane-zny)
来源：New Republic，
http://www.newrepublic.com/article/77729/strangled-roots
The genealogy craze in America.
美国的家谱热。
New technologies often have unforeseeable consequences. Michael Faraday could not have anticipated the rise of the electric guitar and its effects on our culture, nor did the inventors of the laser realize they had laid the ground for a thriving industry of tattoo removal. And it is safe to say that Watson and Crick could not have foreseen a day when an analysis of Oprah Winfrey's DNA would tell her that she was descended from the Kpelle people of the Liberian rainforest. "I feel empowered by this," she said upon hearing the news, overcoming her disappointment that her ancestors were not Zulu warriors.
新科技通常会带来一些意料之外的后果。迈克尔·法拉第不可能会预料到电吉他的兴起及其对我们文化的影响，激光的发明者也不会想到他们会为纹身消除业的繁荣打下基础。可以肯定地说，沃森和克里克【
译注：DNA双螺旋结构的发现者。】不可能预见到会有这么一天：对奥普拉·温弗里【
译注：美国脱口秀女王。】做个DNA分析，就能告诉她，她是利比里亚热带雨林中的Kpelle人的后代。“我感觉因此而充满力量”，听到这个消息后，她如是说，克服了此前因祖先不是祖鲁战士而产生的失望感。
A fascination with ancestry has long been part of the human condition, from the "begat's" of the Bible to the Roots miniseries and the restoration of Ellis Island. But with the advent of the Internet and genomic technology, genealogy has entered a new age. The past year has served up a series of high-profile revelations.
对家世的痴迷长久以来就是人类状态的一部分，从《圣经》中的“某某生某某”到电视连续剧《根》，再到埃利斯岛的重建【
译注：埃利斯岛为纽约一小岛，曾长期用作移民检查站】，皆是其表现。但随着互联网和基因组技术的到来，家系学已经迈入了新的时代。去年就涌现了一系列热度很高的现象。
The news that Barack Obama's ancestors owned slaves was a bit more surprising than the news that Strom Thurmond's did, but it was more surprising still to be told that among the Thurmond family's slaves were the ancestors of Al Sharpton.
比起Strom Thurmond【
译注：前美国参议员，支持种族隔离政策】的祖先曾经蓄奴这一消息来说，巴拉克·奥巴马的祖先也曾蓄奴更令人惊讶，但尤为令人惊讶的是，我们得知，Thurmond家族的奴隶中包括有Al Sharpton的祖先。
And Henry Louis Gates Jr., the host of the fascinating PBS series African American Lives, which explored the family trees of six prominent African Americans, was astounded to learn that half of his own ancestry was European, including Irish kinsmen on his father's side and two Jewish women on his mother's.
PBS有个非常好看的系列栏目《非裔美国人的生活》，曾探寻过六位杰出非裔美国人的家族树，其主持人Henry Louis Gates Jr.惊讶地发现，他的祖先中有一半是欧洲人，父系这边有爱尔兰亲戚，而母系那边则有两位犹太女性。
Few of us can expect that a search for ancestors will bring us an inheritance, a title, or a coat of arms: the rewards of genealogy are mostly psychological. As Winfrey put it, "Knowing your family history is knowing your worth." The sentiment, though, is dubious--not just on moral grounds but on biological ones.
极少有人会期待通过追寻祖先而获得一份遗产、一个头衔或者一枚盾徽。家谱学的回报主要在于心理方面。正如Winfrey所说的那样，“认识自己的家族史就是认识自己的价值。”然而，这种心理感情很难站住脚——不仅仅从道德层面看是如此，从生物层面看也是如此。
A closer look at the human drive to know one's family tree uncovers a number of tensions between our intuitions of kinship and the facts of kinship. Some of those facts show that the findings of the new genealogy should not have been surprising at all. And others, tacitly appreciated for millennia, have recently been neglected to our peril.
更加仔细地分析一下人类认识自己家族树的冲动，我们就能得知，在我们对于亲缘关系的直觉与事实上的亲缘关系之间存在诸多张力。其中部分事实表明，新家谱学的发现根本不应当令人感到惊奇。而历经千年被人心照不宣地领会的另一些事实，其最近遭遇的忽视则会陷我们于危险之中。
For all its fascination, kinship is a surprisingly neglected topic in the behavioral sciences. A Martian reading a textbook in psychology would get no inkling that human beings treated their relatives any differently from strangers. Many social scientists have gone so far as to claim that kinship is a social construction with no connection to biology.
尽管人们对它痴迷如狂，但令人惊讶的是，亲缘关系在行为科学中一直是个不受关注的题目。如果有个火星人来读读我们的心理学教科书，关于人类对待自己的亲属与对待陌生人会有何不同，他完全不会得到任何线索。许多社会科学家走得如此之远，乃至宣称亲缘关系是一种社会建构，与生物学没有任何关系。
But assuming the creationists are wrong and humans are products of evolution, it would be surprising if our species entirely escaped the powerful forces that shape organisms' behavior toward their kin. Genetics and evolutionary theory predict that the biology of kinship should have biased our thoughts and emotions about relatives in several ways.
但是，假设创世主义者是错的，人类是进化的产物，那么，要说我们这个物种彻底逃脱了那一塑造了有机体对待自己亲属的行为的强大力量，那会很让人意外的。遗传学和进化理论预言，亲缘关系的生物学应当会通过多种方式使得我们对亲属的想法和情感发生偏移。
The first is the simple fact that blood relatives are likely to share genes. To the extent that minds are shaped by genomes, relatives are likely to be of like minds. Close relatives, whether raised together or apart, have been found to be correlated in intelligence, personality, tastes, and vices. The discovery of an ancestor is thus felt to reflect on the descendant, who may feel he has an explanation for the kind of person he is, and who can claim to have a dose of the ancestor's praiseworthy traits.
首先就有一个简单的事实：血亲之间很可能共享基因。就心智由基因组塑造而言，亲属有可能具有相似的心智。我们已经发现，近亲属，无论是一起还是分开成长，会在智力、个性、品味和缺点方面相互关联。因此对祖先的观察，似乎就会反映在其后裔身上，其子孙可能会觉得他找到了他成为某种类型人物的理由，并且也可声称自己具有其祖先身上部分值得赞扬的特征。
A promotional spot for Coca-Cola in African American Lives juxtaposes footage of African Americans with images of traditional Africans and says, "She has her great-great-great-grandmother's eye for adornment. He is fit and agile, like his forefathers."
《非裔美国人的生活》插播过一个可口可乐的促销广告，里面把非裔美国人的镜头和传统非洲人的画面放在一块，说“她和她的曾曾曾祖母对装扮的品味一致。他健壮灵敏，跟他的祖先一样。”
The similarities among blood relatives mean that they are likely to share values, and shared values can lead to easy solidarity because of what ecologists call mutualism and economists call positive externalities. A pair of associates with the same interests can benefit each other just by being selfish--always the most painless route to altruism. If two roommates have similar tastes in music, each will benefit the other every time she brings home a new CD, and each has a reason to value the other's well-being. To identify a blood relative, then, is to identify a potential soul mate. Adoptees who track down their biological parents and siblings often report an instant solidarity as they quickly discover shared quirks and passions.
血亲之间的相似性意味着他们有可能共享价值观，而共享价值观使得相互团结更为容易，原因则在于生态学家所说的“互惠共生”和经济学家所称的“正外部性”。一对伙伴，如果利益相同，那么只需做到行为自利就能有益于彼此——而这总是实现利他的最不费力的办法。如果两位室友音乐品味相同，那么任何时候其中任何一位带回一张新CD，都会使另外一位受益，并且每个人都有理由珍视另外一个人的福祉。因此，确定血亲就是确定一位潜在的灵魂伴侣。被收养的人在搜寻到自己的生父生母和兄弟姐妹后，通常会提到一种立即出现的休戚与共之感，因为他们很快就会发觉彼此的癖好和喜爱相似。
A more direct tug of shared genes on family emotions comes from the phenomenon that biologists call inclusive fitness, kin selection, and nepotistic altruism. The overlap of genes among relatives does more than make them similar; it alters the dynamics of natural selection. Over evolutionary time, any gene that predisposed a person to be nice to a relative would have had some chance of helping out a copy of itself inside that relative, and the gene would have been favored by natural selection and entrenched in the genome (as long as the average benefit to the relative, discounted by the probability that the gene is shared, exceeds the average cost to the favor-doer).
共享基因对家族情感的更直接作用来自生物学家所称的“内含适应性”、“亲缘选择”和“亲缘利他”现象。亲属之间基因的重叠不仅仅使得他们相似，而且改变了自然选择的动力机制。在进化过程中，任何基因，如果它会使得一个人倾向于善待亲属，它就有可能帮助到那个亲属身上该基因的复制品，于是这个基因就会受到自然选择的偏爱，使自己在基因组中盘踞下来（只要该亲属的平均得益乘以两人共享该基因的概率后仍高于施以援手者的平均成本）。
A sharing of genes at the genetic level sets the evolutionary stage for feelings of solidarity and affection at the emotional level, and that in turn shapes much of human life. In traditional societies, genetic relatives are more likely to live together, work together, protect each other, and adopt each other's orphaned children, and are less likely to attack, feud with, and kill each other. Even in modern societies, which tend to weaken ties of kinship, studies have shown that the more closely two people are genetically related, the more inclined they are to come to each other's aid, especially in life-or-death situations.
遗传层面上共享基因，为情感层面上的团结感和偏爱感设定了进化平台，而这些情感现象又进一步塑造了人类生活的很大一部分。在传统社会中，血亲更有可能生活、工作在一起，保护彼此，收养彼此的孤儿，相互之间发生攻击、仇争、杀害的可能性更小。即便是在倾向于削弱亲缘关系的现代社会，也有研究表明，两个人在遗传上的关系更为接近，他们就更有可能帮助彼此，特别是在生死存亡之际。
Solidarity between pairs of relatives is further amplified by the fact that they have other relatives in common. My brother and I are close not just because each of us has copies of genes in the other, but because we share a mother, a father, a sister, and nieces and nephews, so our genetic interests are yoked together.
一对亲属之间的团结还会进一步被他们共同拥有其他亲戚这一事实放大。我和我哥哥亲近，这不仅仅是因为我们身上具有彼此部分基因的复制品，而且因为我们共同拥有一个母亲、一个父亲、一个妹妹，还有其他侄子侄女，所以我们的遗传利益是套在一起的。
This triangular altruism also explains why non-blood relatives can feel various degrees of affinity--most dramatically in the case of a husband and wife, whose long-term genetic interests are fused in their children, and to a lesser extent in the case of stepsiblings and in-laws, as long as they are not in zero-sum competition for the common relative's affections or resources.
这种三角利他也能解释为何非血亲也能感受到不同程度的亲和——特别突出表现在夫妻关系这一例子中，其长期遗传利益融于他们的子女身上，相对不那么明显的例子则是继亲和姻亲，只要他们并非处于一种争夺共有亲戚的喜爱或资源的零和竞争之中。
But now comes a crucial bit of arithmetic. In sexually reproducing species, every organism has two parents, and every organism makes up half the parentage of each of its offspring. The result is that as people are separated by more generations, they are related to an exponentially greater number of people, and their genetic relatedness to any of them plummets, also exponentially.
但现在要来点关键性的算术了。在有性繁殖生物中，每一个有机体都有一对父母，且每一个有机体都构成其任一后代之父母中的一半。结果就是，人们之间的代际隔离越远，他们之间存在亲属关系的人口数量以指数方式增加，而与其中任何一个的遗传相关性也以指数方式减少。
Going upward, you have two parents, with whom you share half your genes apiece; four grandparents, with whom you share one-quarter; eight great-grandparents; sixteen great-great-grandparents; and so on. Going downward, if you and your descendants have two children apiece, then you'll have four grandchildren, eight great-grandchildren, and so on. And going sideways, you share half your genes with your sibling, one-eighth with each of your first cousins, one-thirty-second with each of your second cousins, and so on.
向上，你有一对父母，你与之各自分享一半基因；4个祖父母，你与之分享1/4；8个曾祖父母；16个曾曾祖父母；如此等等。向下，如果你和你的后代各自都生两个小孩，你就会有4个孙儿女，8个曾孙儿女，如此等等。向两边，你和你的兄弟姐妹分享一半基因，与每个第一代堂表亲分享1/8基因，与每个第二代堂表亲分享1/32，如此等等。
Exponential functions quickly explode to unimaginable magnitudes or peter out to infinitesimal ones, and the inability of our intuition to keep track of them leads to many paradoxes of kinship. In an old Smothers Brothers routine, Tommy explained why the population explosion is a myth. We have two parents, he noted, and four grandparents, eight great-grandparents, sixteen great-great-grandparents, and so on. The further back you go, the more ancestors you have. So, he concluded, "The population isn't growing--it's tapering off!"
指数函数很快就会使量级得到不可想象的爆发，或者使之快速减少为无限之小，我们的直觉将无力掌握，而这会引发关于亲缘关系的许多悖论。在“斯马瑟兄弟”的一个保留老节目中，Tommy解释了为啥人口爆炸只是一个神话。他说，我们有一对父母，4个祖父母，8个曾祖父母，16个曾曾祖父母，如此等等。越往回数，你的祖先就越多。所以，他的结论是，“人口并没有增加，而是在逐渐减少！”
Like many of their jokes, this one depends on a subtle truth. If you assume twenty-five years per generation, you can calculate that you had around three billion ancestors at the time of the signing of the Magna Carta, one hundred billion during the Norman invasion, two quintillion at the fall of the Roman Empire, and around 1,200,000,000,000,000,000,000,000 at the birth of Jesus. Needless to say, the Earth did not contain a fraction of that many people in those eras.
跟他们讲的许多笑话一样，这个笑话底下也有一个微妙的真理。如果假定25年为一代，你就能算出，在《大宪章》签署的时候，你的祖先大概有30亿个，在诺曼征服的时候大概有1000亿，而在罗马帝国灭亡时大概有2万亿，而在耶稣诞生时有大概有1,200,000,000,000,000,000,000,000个。不用说，在那些年代，地球人口还达不到这些数量中的一小部分。
The paradox is resolved by the realization that our ancestors must have married their cousins of various distances and removes, so that vast numbers of the slots in one's family tree are filled by the same individuals. Imagine, in an extreme case, that your parents were first cousins. Then two of your great-grandparents on your mother's side would also be your great-grandparents on your father's side--you would have six great-grandparents instead of eight.
解决这一悖论，需要我们认识到，我们的祖先必定与其各类远房表亲结了婚，使得某人的家庭树上的许多空位是由同一人占据的。想象一个极端的例子，假定你的父母是第一代堂表亲。那么你在你母亲那边的两位曾祖同时也会是你在你父亲这边的曾祖——你的曾祖将是6个而非8个。
Genealogists call this "pedigree collapse": the necessity that as you trace your family tree backward, it will fan out for a number of generations until it begins to encompass most of the people in the available population, whereupon it falls back on itself, coinciding with the original growth of that population. The rate of collapse depends on the size of the pool of potential mates and the average rate and closeness of cousin marriages.
家谱学家称之为“谱系崩塌”，即存在一种必然：随着你向前追溯家庭树，它在数代人之间将呈扇形展开，直到它开始包括整个可及群体的绝大部分，这时它就不再展开，只与那一群体的增长保持一致。崩塌的速度取决于潜在配偶的可用规模以及堂表亲结婚的平均比例和亲缘度。
But the fact that our ancestors never covered the surface of the Earth ten deep shows that medium-distant-cousin marriages must have been the rule rather than the exception over most of human history. This chronic incest, by the way, did not turn our ancestors into the cast of Deliverance. The degree of relatedness, and hence the risk that a harmful recessive gene will meet a copy of itself in a child, falls off a cliff as you move from siblings to first cousins to more distant cousins.
但我们的祖先从未将整个地球表面满满铺上十层这一事实表明，中等亲缘度的堂表亲间婚姻必定曾是人类历史绝大部分时期中的常态而非例外。顺便要说，这种惯常性乱伦并未将我们的祖先变成电影《生死狂澜》中的角色【
译注：电影中的四个角色在广袤平和的大自然面前将人性中最丑陋的一面赤裸裸地暴露了出来】。随着通婚对象从兄弟姐妹到第一代堂表亲到更远距离的堂表亲，亲缘程度急剧下降，从而有害的隐形基因能在孩子身上碰到其复制品的风险也随之下降。
The same arithmetic that makes an individual's pedigree collapse onto itself also makes everyone's pedigree collapse into everyone else's. We are all related--not just in the obvious sense that we are all descended from the same population of the first humans, but also because everyone's ancestors mated with everyone else's at many points since that dawn of humanity. There aren't enough ancestors to go around for everyone to have a family tree of his or her own.
使得某个人的谱系崩塌的算术，同样也会使得其他每个人的谱系崩塌到别人的谱系上。我们都是亲戚——这不仅仅是因为，在很显白的意义上，我们都源自于同一初民种群，而且是因为，自人类出现以来的许多不同时点上，每个人的祖先都曾与另一个人的祖先结成配偶。世上就不存在那么多祖先，不足以让每个人都拥有只属于他/她自己的家族树。
So it is a mathematical necessity, not a surprise, that genealogy will turn up strange bedfellows. George W. Bush is a distant cousin of his electoral opponents Al Gore and John Kerry (as well as of Richard Nixon, Ernest Hemingway, Queen Elizabeth, and, through her, every European monarch). Gore, for his part, is a descendant of Charlemagne, and Kerry is a descendant of Mary, Queen of Scots--and presumably also (thanks to his recently-discovered-to-be-Jewish paternal grandfather) of rabbis, cantors, and medieval moneylenders.
所以家谱学会发现许多令人奇怪的关系，这是一种数学必然，而非意外。乔治·W·布什是其竞选对手阿尔·戈尔和约翰·克里（此外还有理查德·尼克松、欧内斯特·海明威、伊丽莎白女王，以及通过女王延伸到每一位欧洲君主）的远房堂表亲。而戈尔自己，则是查理曼大帝的后代，克里则是苏格兰玛丽女王的后代——同时可能还是犹太拉比、唱诗班领唱人和中世纪放债人的后代（因为我们新近发现他的祖先是犹太人）。
This brings up another corollary of the mathematics of kinship: a single mating between people from two ethnic groups results in all their descendants being related to both groups in perpetuity. So even occasional couplings across racial and ethnic lines can entangle family trees, explaining why humans, that peripatetic and sexually omnivorous species, are genetically fairly homogeneous, despite our worldwide distribution.
这就引出了亲缘关系数学的一个必然推论：两个种族群体之间的某一次联姻，就会导致他们的所有后代都永远与两个群体均有亲戚关系。所以，即使跨人种和跨种族边界的配对只是偶然出现，也能将各自的家族树缠到一块，从而能够解释，为什么人类这种四处迁徙、性开放的物种尽管遍布全球，但在基因上则大体上是同质的。
The genealogical ties connecting American presidents and European royalty are not a sign of some vast transatlantic ruling caste. Every noteworthy person is related to other noteworthy people (together, of course, with countless not-so-noteworthy people). One genealogist with too much time on his hands showed that the late Senator Alan Cranston was related to Emily Dickinson, George Plimpton, Margaret Mead, the actress Julie Harris, the Dow family of chemical fame, and Queen Geraldine of Albania.
美国总统与欧洲皇室之间的家谱关系并不表明存在某种庞大的跨大西洋统治阶级。每个名人都跟其他名人有亲戚关系（当然，也都跟无数的非名人有亲戚关系）。某位时间特别充裕的家谱学家曾表明，已故参议员Alan Cranston跟艾米丽·迪金森、George Plimpton、玛格丽特·米德、女演员Julie Harris、化学领域极富盛名的陶氏家族、阿尔巴尼亚的Geraldine王后都有亲戚关系。
Another discovered that Tom Hanks, the star of The Da Vinci Code, has blood ties with many of the historical figures mentioned in the film, including William the Conqueror, Shakespeare, and Henry VIII. Also recently revealed is the fact that Paris Hilton is related to fellow celebrity jailbirds Zsa Zsa Gabor and G. Gordon Liddy. Finding kinship ties among famous people is shooting ducks in a barrel.
另一个则发现，电影《达芬奇密码》的主演汤姆·汉克斯跟影片中提及的许多历史人物都有血缘联系，包括征服者威廉、莎士比亚、亨利八世等。另外，最近有人发现了另一个事实，帕里斯·希尔顿跟另外两位明星囚犯Zsa Zsa Gabor和G. Gordon Liddy有亲戚关系。在名人之间寻找亲缘关系就像是在橡木桶里面射鸭子一样容易。
And before you brag about the talent or courage you share with some illustrious kinsman, remember that the exponential mathematics of relatedness successively halves the number of genes shared by relatives with every link separating them. You share only 3 percent of your genes with your second cousin, and the same proportion with your great-great-great-grandmother.
在夸耀自己分享有某个著名族人的天赋或勇气之前，你最好能记住，亲戚之间每隔开一层关系，亲缘关系数学上的指数关系就会将他们的共有基因数量减半一次。你与你的第二堂表亲只共享3%的基因，跟你的曾曾曾祖母也是如此。
It is important to remember that psychological traits are nowhere near completely heritable in the first place, so the chances that you got your eye for adornment from that ancestor in the gorgeous dashiki are rather small. Do not expect genetically inspired largesse from the rich relative uncovered by your genealogy service, either. A gift from a second cousin would have to result in a thirty-two-fold increase in the number of your surviving descendants compared to his for a desire to bestow it upon you to have evolved.
记住这一条很重要：首先，心理特征是很难完全继承的，因此你得到你那穿着黑人花褂子的祖先所拥有的那种对于装扮的眼光，这样的几率相当小。也不要奢望通过家谱搜寻服务找到的那些富裕亲戚会因为受遗传关系激励而对你慷慨解囊。要使你的一位隔代表亲产生出馈赠于你的欲望，那将要求，送与你的礼物会让你增加的存活后代数目32倍于同一礼物用在他自己身上的效果。
The relentless decimation of resources (both genetic and financial) across generations is the rationale behind the feudal practice of primogeniture, in which all the family estate was bequeathed to the eldest son. And it is why in modern times family fortunes can dissipate so quickly--"three generations from shirtsleeves to shirtsleeves," as Nicholas Murray Butler put it.
资源（无论是遗传的还是财务的）在代际之间的持续分解正是长子继承制这种封建做法的背后道理所在，通过长子继承制，家族的财产被遗留给最年长的儿子。这也是为何现代家庭的财产会消散得如此之快——正如Nicholas Murray Butler所说，“富不过三代”。
The geometric decay of relatedness also takes some of the fun out of two of the main tools used by genetic-ancestry services: the analysis of mitochondrial DNA (which is passed from mother to daughter) and of Y-chromosomes (which are passed from father to son). Since they trace ancestry only through the all-female or all-male branch of your family tree, they can identify only one tendril, which diminishes exponentially the further back you go.
亲缘关系的几何衰减也会使得基因血统搜寻服务主要采用的两大工具——即线粒体DNA（从母亲传递给女儿）分析和Y染色体（从父亲传递给儿子）分析——不再那么好玩。因为这两种工具在你的家族树上搜寻血统时，要么是沿纯母系进行，要么是沿纯父系进行，因此它们找到的只是其中一脉，且会随着往回追溯以指数方式削减。
Winfrey's mitochondrial DNA does not show that she is a Kpelle, but rather that she is one-sixty-fourth (or perhaps even 1/128th or 1/256th) Kpelle. Many African Americans who seek their paternal ancestor, and therefore a sense of their African roots, via Y-chromosome analysis discover to their dismay that this root lies in Germany or Scotland.
Winfrey的线粒体DNA并没能说明她是Kpelle人，而只能说明她是1/64（或者甚至可能是1/128或1/256）个Kpelle人。许多非裔美国人通过Y染色体分析来寻找他们的父系祖先，从而想获得一种寻根非洲的感觉，但却失望地发现这一根脉位于德国或苏格兰。
If family ties are so biologically tenuous, why does kinship loom so large in the human psyche? One reason is that our intuitions about kinship evolved when we lived in villages and bands whose small size and limited mobility ensured that most marriages were between closer cousins, and hence the genetic overlap between relatives was close enough to be biologically significant. Today we project these feelings of affinity onto relatives who are far more distant--indeed, arbitrarily distant, thanks to the wonders of Internet and DNA genealogy.
如果家族纽带在生物学上如此单薄，为什么亲缘关系会如此巍然地耸立于人类心灵之中？一个原因在于，我们对于亲缘关系的直觉已在村庄和游团生活阶段得以进化，那种群体规模很小且流动性受限，使得多数婚姻都发生于较亲近的表亲之间，从而使得亲戚之间的基因重叠足够稠密，因而在生物学上很显著。今天，我们将这类亲密感投射到与我们血缘距离远得多的亲戚身上——实际上，由于神奇的互联网和DNA家系分析，这种距离可以无限远。
But the other reason is that our sense of kinship is triggered not by relatedness itself, but by the perception of relatedness. After all, when we encounter a possible relative, we generally do not demand a cheek swab and analyze its DNA. Instead we rely on cues that in the evolutionary past tended to correlate with relatedness.
但另一个原因在于，我们的亲缘感并不由亲缘关系本身引发，而是由对亲缘关系的感知引发。别忘了，如果我们碰到一个可能的亲戚，我们通常并不会要求做一个口腔拭子采集【
编注：即用棉签刮擦口腔内膜，这是采集个人DNA样本的常用简易方法】并分析其DNA。相反，我们依赖的是在过去的进化过程中指向亲缘关系的线索。
Recent experiments by Debra Lieberman, John Tooby, and Leda Cosmides have shown that two kinds of life experience are crucial in triggering family feelings toward siblings (such as doing them favors and being willing to donate a kidney to them). One consists of observing the sibling being cared for by one's mother when it was an infant. The other is having grown up in the same household as the sibling.
Debra Lieberman, John Tooby和Leda Cosmides最近所做的实验已经表明，在引发对于兄弟姐妹的家庭感情方面（比如给他们帮忙或者愿意捐赠一个肾给他们之类），有两类生活经历非常关键。一是观察到兄弟姐妹在婴儿时期被自己的母亲照顾。二是与该兄弟姐妹共同成长于同一个家庭。
That is why children adopted at birth can be emotionally close to their parents and siblings despite the lack of genetic overlap: the early close association sets off everyone's kinship detectors, a kind of benign illusion. And because these experiences also trigger repugnance at the thought of having sex with the relative, incest avoidance is not perfectly correlated with biological relatedness.
这就是为何出生时即被收养的儿童，尽管在基因上不存在重叠，但仍能与其父母及兄弟姐妹情感上很亲近的原因所在：早期的亲密关系触发了人们的亲缘关系探测器，这是一种良性的幻觉。并且由于这种经历也同样会引发对于与亲戚发生性关系的念头的恶心感，因此乱伦回避并不与生物亲缘关系完全对应。
Unrelated children who are brought up together (like nursery-mates in kibbutzim) tend to shun each other as sexual partners in adulthood, as if they were siblings. And children who meet a parent or sibling for the first time in adulthood can find him or her sexually attractive, as the novelist Kathryn Harrison recounted in The Kiss, her memoir of a four-year affair with her father.
没有亲缘关系的儿童，如果一起长大（如以色列集体农场中的托儿所同伴），长大后在选择性伴侣时也倾向于避开彼此，好像他们就是兄弟姐妹一样。而假如孩子们长大后才第一次看到父母或兄弟姐妹时，也可能觉得他或她具有性吸引力，这一点小说作家Kathryn Harrison在《罪之吻》这本关于她与其父4年私通经历的回忆录中有所叙述。
When it comes to individual people, then, kinship is in the mind of the beholder. That creates an opening through which manipulators can flood people's kinship sense with cues that mimic the signals of biological relatedness. This kind of mind control is a strong temptation to anyone who wants to foster cohesion among people who are not closely related.
论到个体，那么亲缘关系便取决于观察者的心思。这就为操控者使用模拟生物性亲属信号的线索来淹没冲击人们的亲属感提供了机会。这类精神控制，对于任何想要在并非近缘亲戚的人们之间塑造团结的人来说，是种巨大的诱惑。
Contrary to a shibboleth of the American right, family values do not uphold religion and country; they subvert them. An extended family is a rival coalition to any other group, held together not by an ideology or social contract or common purpose but by brute genetic relatedness. And it is a coalition with an unfair advantage: relatives care for one another more than comrades do.
与美国右派的某一陈腐观念相左，家庭价值观并不支撑宗教和国家；相反，它们起的是破坏作用。一个大家庭，通过直接的遗传相关性而非意识形态或社会契约或共同目标联合在一起，作为一种联合体，就是任何其他团体的竞争者。并且这种联合体具有一种难以平衡的优势：亲戚比同志更加关心彼此。
Religions and political movements thus have to undermine family loyalties. Marxist collectivization and Moonie programming are obvious recent examples, but millennia before them Jesus momentously declared, "A man's foes shall be they of his own household. He that loveth father or mother more than me is not worthy of me: and he that loveth son or daughter more than me is not worthy of me."
因此，宗教和政治运动必须破坏家庭忠诚。马克思主义的集体化和文鲜明统一教的计划都是近期的显例，但数千年前耶稣就郑重宣布过：“人的仇敌，就是自己家里的人。爱父母过于爱我的，不配作我的门徒；爱儿女过于爱我的，不配作我的门徒。”
Successful coalitions often try to co-opt family feelings by tricking the brain into perceiving the coalition as kin. Though the most potent technique--forcing people to grow up in a single household--is impractical, other kinds of kinship illusion have repeatedly been invented.
成功的联合体通常会尝试吸纳家庭感，方法是哄骗大脑将这种联合体认知为家族。尽管最为有效的技术——即强迫人们在单一家庭中长大——不具备可操作性，但其他许多种类的家族幻觉已被反复发明。
The anthropologist Alan Fiske notes that communal meals are one of the most common bonding rituals the world over, partly because they simulate family experiences, partly because people believe that you are what you eat, and so if you eat the same stuff you are the same stuff.
人类学家Alan Fiske提到，共餐是世界范围内最为常见的团结仪式之一，部分是因为它们能够模拟家庭经历，部分是因为人们相信“你是你所食”，所以如果你们吃的是同样的东西，那么你们就是同样的东西。
Many tribes and coalitions (such as the Mafia) cut their fingers and rub them together to allow their blood to mingle, hence the expression "blood brothers." People also disfigure their bodies--by scarring, tattooing, piercing, hairstyling, and circumcision and other forms of genital mutilation--as if to make the group look like a separate race or species, biologically distinct from other human groups.
许多部落和联合体（如黑手党）的成员会切破手指、相互摩擦以使血液混合，从而产生“歃血兄弟”这种表述。人们也会损毁自己的身体——如制造伤疤、纹身、穿刺、装扮发型、割包皮及以其他形式损毁生殖器，似乎以此来使得该群体看似一个单独的种族或物种，与其他人群具有生物学上的差别。
Language provides another way to co-opt the warm and fuzzy feelings people have toward their relatives. One common trick is the use of kinship metaphors: brethren, brotherhood, fraternity, sisterhood, sorority, the fatherland, the mother country, the family of man, and so on.
对于人们对其亲戚所具有的这种温暖而朦胧的感情，语言提供了另一种吸纳方式。常见的一种花招是使用亲戚暗喻：同胞、手足、兄弟会、姐妹感情、姐妹会、祖国、母国、人类大家庭等等。
These tactics are provably effective: experiments have shown that people are more convinced by a political speech if the speaker engages them with the language of kinship. Myths and ideologies are also commonly put to use. People are told that they are descended from a patriarch or a primeval couple, or that they are connected to a natal land, or that they came into being in the same act of creation, or that they are related to the same totemic animal.
这些策略经证明是有效的：实验已经表明，如果政治演说的演讲者用亲缘关系的语言来吸引听众，人们就会更为信服。神话和意识形态也经常被采用。人们被告知，他们都源自同一个族长或同一对原始夫妻，或者他们都与同一个出生地相联系，或者他们之存在是源于同一个创世行为，或者他们与同一个图腾动物相关。
In large part, the institutions of modernity depend on a dissolution of family ties. It is hard to run an effective organization if you cannot fire the knucklehead brother-in-law forced on you by your wife's family, nor can civil society function if the instruments of government are treated as the spoils of the most powerful local clan.
很大程度上，现代性的制度依赖于家庭纽带的瓦解。如果你没法开除由你老婆的娘家塞给你的笨蛋小舅子，那你就没法有效运营一个组织，或者，如果政府的诸多手段都被视为某个地方强势氏族的战利品，那么政治社会就没法运转。
Public safety is more effectively guaranteed by a disinterested police and court system than by a threat that your male relatives will avenge your murder, and national defense above all depends on the willingness of citizens to neglect the bonds of kinship.
比起血仇威胁（即你的男性亲戚会报复杀害你的凶手）来，一个无私的警察和法院体制能更为有效地保证公共安全，而国防则尤其依赖于公民们忽略亲缘关系纽带的意愿。
In The Godfather: Part II, Sonny Corleone upbraids Michael for his sympathy with the men who enlisted after Pearl Harbor: "They're saps because they risk their lives for strangers. Your country ain't your blood. Remember that."
在《教父2》中，麦克同情珍珠港事件爆发后从军的某人，杉尼·科里昂因而对其加以斥责。“他们都是蠢货，因为他们用自己的生命去冒险，为的却是些陌生人。你的国家不是你的血。记住这个。”
In the struggle between society and family, the exponential mathematics of kinship ordinarily works to the advantage of society. As time passes or groups get larger, family trees intertwine, dynasties dissipate, and nepotistic emotions get diluted.
在社会与家庭的厮打中，亲缘关系的指数衰减特性通常有利于社会。随着时间推移或群体扩大，家族树之间会相互缠扰，世家会烟消云散，而裙带感情会逐渐稀释。
But families can defend themselves with a potent tactic: they can graft the twig tips of the family tree together by cousin marriage. If you force your daughter to marry her first cousin, then your son-in-law is your nephew, her father-in-law is your brother, your parents' estate will be worth twice as much per grandchild, and the couple will never have to bicker about which side of the family to visit on holidays.
但家庭可以用一种强大的策略来捍卫自身：他们能够通过堂表亲婚姻来嫁接家族树上的小小树梢。如果你强迫你的女儿嫁给她的第一代堂表亲，那么你的女婿就是你的侄子，她的公公就是你的兄弟，且你父母相对于每个孙子而言的财产价值会翻倍，且这对夫妇永远无需为了假日应该回哪方家里而斗嘴。
For these reasons, clans and dynasties in many cultures encourage first-or second-cousin marriage, tolerating the slightly elevated risk of genetic disease. Not only does cousin marriage amplify the average degree of relatedness among members of the clan, but it enmeshes them in a network of triangular relationships, with kinsmen valuing each other because of their many mutual kin as well as their own relatedness.
出于这些理由，许多文化中的氏族和世家会鼓励第一代或第二代堂表亲婚姻，并容忍遗传病风险的些许提高。堂表亲婚姻不但会放大氏族成员之间的平均亲缘程度，而且还会将氏族成员网罗进一个三角亲戚关系的网络之中，其中的同族会因为他们之间的众多共同亲戚及自己的亲缘关系而彼此关心。
As a result, the extended family, clan, or tribe can emerge as a powerfully cohesive bloc--and one with little common cause with other families, clans, or tribes in the larger polity that comprises them. The anthropologist Nancy Thornhill has shown that the prohibitions against incestuous marriages in most societies are not public-health measures aimed at reducing birth defects but the society's way of fighting back against extended families.
结果，大型的家族、氏族或部落有可能以一种强大的凝聚集团的形式出现——与它们所属的更大政治体中的其他家族、氏族或部落没有什么共同目标。人类学家Nancy Thornhill已经向我们展示，绝大部分社会中的血亲结婚禁令并不是旨在减少生育缺陷的公共健康措施，而是用以压制大型家族的一种方式。
In January 2003, during the buildup to the war in Iraq, the journalist and blogger Steven Sailer published an article in The American Conservative in which he warned readers about a feature of that country that had been ignored in the ongoing debate. As in many traditional Middle Eastern societies, Iraqis tend to marry their cousins. About half of all marriages are consanguineous (including that of Saddam Hussein, who filled many government positions with his relatives from Tikrit).
2003年1月，在为伊拉克战争造势时期，新闻记者和博客作者Steven Sailer在《美国保守派》杂志上发表了一篇文章，提醒读者注意在当时的社会讨论中遭到忽视的一个伊拉克的特征。跟许多传统的中东社会一样，伊拉克人倾向于和堂表亲结婚。大约半数婚姻属于血亲结婚（包括萨达姆·侯赛因的婚姻，他在许多政府职位上塞进了他那些来自提克里特市的亲戚）。
The connection between Iraqis' strong family ties and their tribalism, corruption, and lack of commitment to an overarching nation had long been noted by those familiar with the country. In 1931, King Faisal described his subjects as "devoid of any patriotic idea … connected by no common tie, giving ear to evil; prone to anarchy, and perpetually ready to rise against any government whatsoever." Sailer presciently suggested that Iraqi family structure and its mismatch with the sensibilities of civil society would frustrate any attempt at democratic nation-building.
熟悉这个国家的人久已注意到，在伊拉克人的强大家庭纽带与他们的部落意识、腐败及他们对涵盖一切的国家缺乏忠诚等现象之间存在关联。1931年，费萨尔国王【
译注：即费萨尔一世，哈希姆家族成员，1921-1933年间任伊拉克国王】称其臣民“缺乏任何爱国观念……彼此之间没有共同纽带，响应邪恶；倾向无政府，永远准备着起来反对任何政府。”Sailer预见性地指出，伊拉克的家庭结构及其与公民社会情感不相匹配的现状，将会挫败任何构建民主国家的企图。
Outside a small family circle, the links of kinship are biologically trifling, vulnerable to manipulation, and inimical to modernity. For all that, the almost mystical bond that we feel with those whom we perceive as kin continues to be a potent force in human affairs. It is no small irony that in an age in which technology allows us to indulge these emotions as never before, our political culture systematically misunderstands them.
在小家庭圈子以外，亲缘关系的联系在生物学上极为微弱，易于被操控，并与现代性相抵触。尽管如此，我们对那些我们认为是亲戚的人的感情几乎是一种神秘主义的亲和，它将继续是人类事务中的一种强大力量。在技术已经允许我们旷古未有地纵情于这类感情的时代，我们的政治文化却系统性地对它们存有误会，这真是个相当大的反讽。
（编辑：辉格@whigzhou）
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——海德沙龙·翻译组，致力于将英文世界的好文章搬进中文世界——
如图所示，若每位家长控制一个十几二十人的扩展家庭，并且二三十位家长（他们是三重以内堂兄弟）组成合作联盟，那么群体规模便可达到三四百，而同时，群内每个成员需要长期交往密切合作的熟人数量仍处于邓巴数之下。这样，当分属两个支系的年轻人发生冲突时，纠纷便可由双方家长出面解决，或提交家长会议裁断，并迫使当事人接受裁决结果。
同样，当群体面临外部威胁，或谋求与其他群体结盟，或准备对外发动攻击等公共事务而需要集体行动时，家长联盟将充当决策与执行机构；也可以这样理解：通过强化父权，家长们把家族树最下面一两层排除出了维持群体团结所需要的那个关键合作圈子，从而避开了邓巴限制。
人类学材料显示，上述模式广泛存在于前国家定居社会，而且它正是在定居之后才出现的；游动性的狩猎采集社会大多是平等主义的，没有高度压制性的父权，长辈也很少向晚辈施加强制性规范，而一旦定居下来（或者游动性减弱），父权便出现了，并且在近代化之前的整个文明史上都占据主导地位；当今世界，凡国家权力所不及的定居社会，像阿富汗、索马里、中东和非洲的部落地区，父权仍非常强大，并且是维持基层社会秩序的主要力量。
父权的常见表现有：对家庭财产的控制，并尽可能的延迟分家，控制子女婚姻，社区内的老人政治；因定居而发展出的财产权，是家长执行父权的强大工具，爱尔兰传统社会的家长，会将财产牢牢控制在手里，即便子女都已成家也不分割家产；一些非洲部族的家长更夸张，当家庭财富增长时，优先用于为自己娶更多妻子，生更多孩子，而不是资助成年子女结婚成家（因而多妻往往与强父权相联系）。
这种做法发展到极致时，老男人们几乎垄断了娶妻机会，在非洲班图语民族（例如西非的约鲁巴人和豪萨人，肯尼亚的康巴人）的许多部落中，父权高度发达，多妻制盛行，男性在熬到40岁前很难娶到妻子，而十岁出头的年轻女孩常常被嫁给五六十岁的老男人；贾瑞德·戴蒙德在检查了大量人类学材料后发现，此类现象广泛存在于传统农牧业定居社会中。
其中原理，我们从进化生物学的亲子冲突（parent-offspring conflict）理论的角度可以看得更清楚：尽管父母和子女很大程度上有着共同利益，但两者利益仍有重大区别，父母希望在各子女间恰当分配家庭资源，以便总体上获得最佳繁衍成效，而每个子女都希望更多资源分给自己这一支，所以不希望父亲生太多孩子。
强大的父权改变了亲子冲突中的力量对比，压制了子女需求中偏离父亲愿望的部分，而且宗族组织的发展又强化了这一父权优势：原本，父代的多子策略高度受限于本人寿命，当预期寿命不够长时，继续生育意义就不大了，因为失去父亲保护的孤儿很可能活不到成年，但有了宗族组织，孤儿就有望被亡父的兄弟、堂兄弟和叔伯收养，甚至得到族内救济制度的帮助（救济制度最初就是伴随宗族组织的发达而出现的）。
将亲子冲突理论稍作扩展，可以让我们更好的理解家长制和部落老人政治：个人在家族树上所居层次（俗称辈份）越高，其个体利益和群体利益的重合度就越高，因而长辈总是比晚辈更多的代表群体利益，他们之间若能达成紧密合作，便有望维持群体和谐，并获得集体行动能力，而同时，因为长辈间亲缘更近，长期熟识的几率也更高，因而紧密合作也更容易达成。
父权和家长联盟为扩大父系群提供了组织手段，不过，若仅限于此，群体规模的扩张将十分有限，因为家长联盟的规模本身受限于邓巴数（还要减去每个支系的规模），若要继续扩张，要么让每位家长控制更多成员，要么让家长联盟发展出多个层级，无论哪种安排，高层联盟中的每位成员都将代表一个比扩展家庭更大的支系。
问题是：谁来代表这个支系？假如寿命足够长，一位曾祖父便可代表四世同堂的大家族（比扩展家庭多出一级），但活的曾祖父太少了；一种解决方案是选举，事实上，部落民主制确实存在于一些古代社会；不过，更自然的安排是让长支拥有优先权（说它“自然”是因为其优先权是自动产生的，无须为此精心安排程序机制），比如周代的宗法制，让长支（大宗）对幼支（小宗）拥有某些支配权，并作为族长代表包含二者的上一级支系。
于是就产生了一个三级宗族结构，理论上，这样的安排可以无限制的迭代，从而产生任意规模的宗族，而同时，每一层级的合作圈都限于几十人规模，因而每位家长或族长需要与之保持长期紧密合作关系的人数，也都限于邓巴数之下。
但实际上，组织能力总是受限于交通、通信和信息处理能力等技术性限制，还有更致命的是，委托代理关系和逐级控制关系的不可靠性，随着层级增加，上层族长越来越无法代表下层支系的利益，也越来越难以对后者施加控制，经验表明，具有某种集体行动能力的多级宗族组织，规模上限大约几千，最多上万。
在古代中国，每当蛮族大规模入侵、中原动荡、王朝崩溃、帝国权力瓦解之际，宗族组织便兴旺起来，聚族自保历来是人们应对乱世的最自然反应，古典时代以来的第一轮宗族运动，便兴起于东晋衣冠南渡之时；如果说第一轮运动主要限于士族大家的话，南宋开始的第二轮运动则吸引了所有阶层的兴趣，家族成员无论贫富贵贱都被编入族谱。
和聚居村落的结构布局一样，宗族组织的紧密程度和集体行动能力同样显著相关于所处环境的安全性，华南农耕拓殖前线，或者国家权力因交通不便而难以覆盖的地方，宗族组织便趋于发达和紧密；人类学家林耀华描述的福建义序黄氏宗族，血缘纽带历二十多代六百多年而不断，到1930年代已发展到15个房支，每房又分若干支系，各有祠堂，从核心家庭到宗族，共达七个组织层级，总人口近万。
类似规模的宗族在华南比比皆是，在宗族之间时而发生的大型械斗中，双方常能组织起上千人的参战队伍，可见其规模之大，行动能力之强；华南许多宗族部分的从福建迁入江西，又从江西迁入湖南，但许多迁出支系与留在原地的支系之间仍能保持定期联系。
共同祖先记忆、父权、家长制、族长会议、大型宗族组织，这些由扩大父系群的种种努力所发展出的文化元素，不仅为定居社会的最初大型化创造了组织基础，也为此后的国家起源提供了部分制度准备，父权和族长权，是早期国家创建者所倚赖的诸多政治权力来源之一。
当然，父系结构的扩展只是社会大型化的多条线索之一，要建立起数十上百万人的大型社会，还有很长的路要走，还要等待其他许多方面的文化进化，在后面的文章里，我会继续追寻人类文明的这段旅程。
（本系列文章首发于“大象公会”，纸媒转载请先征得公会同意。）
（摘自：林耀华《义序的宗族研究》）
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