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MOTHERHOOD begins as a tempestuously physical experience but quickly becomes a political one. Once a woman’s pregnancy goes public, the storm moves outside. Don’t pile on the pounds! Your child will be obese. Don’t eat too little, or your baby will be born too small. For heaven’s sake, don’t drink alcohol. Oh, please: you can sip some wine now and again. And no matter how many contradictory things the experts say, don’t panic. Stress hormones wreak havoc on a baby’s budding nervous system.
男方的健康和福祉，对他未来孩子的健康和幸福的有着明显的影响，这一点在生物学中已经很明确了。这不仅仅是因为，一个身体强壮富有韧性的男人，更有可能成为一名出色的爸爸，或者因为他很可能有良好的基因。不论这个男人的基因是好是坏（不管在这种语境里“好”和“坏”意味着什么），他这些年选择的生活方式，即使是那些在他背上BabyBj"orn牌抱婴袋多年之前作出的选择，都将在他孩子的身体和思想上反映出来。 Doctors have been telling men for years that smoking, drinking and recreational drugs can lower the quality of their sperm. What doctors should probably add is that the health of unborn children can be affected by what and how much men eat; the toxins they absorb; the traumas they endure; their poverty or powerlessness; and their age at the time of conception. In other words, what a man needs to know is that his life experience leaves biological traces on his children. Even more astonishingly, those children may pass those traces along to their children. 多年以来，医生们已经告诉男人们，吸烟、酗酒和软性毒品会降低精子的质量。或许医生们应当补充的是，父亲们能在多方面影响到未出生孩子们的健康，这包括他们的饮食种类和饭量；他们吸收的毒素、所忍受的创伤、贫穷与无力，乃至怀孕时他们的年龄。换句话说，一个男人应当了解，他的生活经历，将为他的孩子留下生物学上的痕迹。更令人吃惊的是，孩子们可能会把这些痕迹再传给下一代。 Before I began reading up on fathers and their influence on future generations, I had a high-school-biology-level understanding of how a man passes his traits on to his child. His sperm and the mother’s egg smash into each other, his sperm tosses in one set of chromosomes, the egg tosses in another, and a child’s genetic future is set for life. Physical features: check. Character: check. Cognitive style: check. But the pathways of inheritance, I’ve learned, are subtler and more varied than that. Genes matter, and culture matters, and how fathers behave matters, too. 在我开始阅读有关父亲们及他们对下一代影响的文章时，我对于男人如何将其特质传给孩子的认识，仅停留在中学生物课的水平。父亲的精子和母亲的卵子撞在一起，精子决定了染色体中的一组，卵子则决定了另一组，孩子未来生命的基因就这样被决定下来。身体特征：确定；性格：确定；认知方式：确定。但现在我已学到，遗传所经历的精妙路线，远比上述的要复杂多样。基因有影响，文化有影响，父亲的表现行为也有影响。 Lately scientists have become obsessed with a means of inheritance that isn’t genetic but isn’t nongenetic either. It’s epigenetic. “Epi,” in Greek, means “above” or “beyond.” Think of epigenetics as the way our bodies modify their genetic makeup. Epigenetics describes how genes are turned on or off, in part through compounds that hitch on top of DNA — or else jump off it — determining whether it makes the proteins that tell our bodies what to do. 最近，科学家们已经痴迷于这种既不是基因，也不是非基因的遗传方式。这就是表基因(Epigenetic)遗传。“Epi”这个词头源于希腊语，其含义是“高于”或者“超越”。表观遗传学(Epigenetics) 关注于我们的身体如何修正其基因构成，它描述基因如何开启或关闭，在一定程度上通过物质依附在在DNA上面，或脱离下来，来决定是否会制作出告诉我们的身体该做什么的蛋白质。 In the past decade or so, the study of epigenetics has become so popular it’s practically a fad. Psychologists and sociologists particularly like it because gene expression or suppression is to some degree dictated by the environment and plays at least as large a role as genes do in the development of a person’s temperament, body shape and predisposition to disease. I’ve become obsessed with epigenetics because it strikes me as both game-changing and terrifying. Our genes can be switched on or off by three environmental factors, among other things: what we ingest (food, drink, air, toxins); what we experience (stress, trauma); and how long we live. 在过去大约十年里，表观遗传学的研究变得如此受欢迎，几乎成为一种时尚。心理学家和社会学家特别喜欢它，因为基因的表现或抑制，在某种程度上取决于环境，并且至少扮演着一个与基因本身同样重要的角色，决定着一个人的个性、体型和容易得病的体质。我也为表观遗传学着迷了，因为它既改变了我的所知道的游戏规则，又给我带来了恐惧。在众多事物中，我们的基因会因为三个环境因素而开启或关闭：其一是我们摄取的，包括食品、饮料、空气、毒素等；其二是我们经历的，包括压力、创伤等；其三是我们能活多久。 Epigenetics means that our physical and mental tendencies were not set in stone during the Pleistocene age, as evolutionary psychology sometimes seems to claim. Rather, they’re shaped by the life we lead and the world we live in right now. Epigenetics proves that we are the products of history, public as well as private, in parts of us that are so intimately ours that few people ever imagined that history could reach them. (One person who did imagine it is the French 18th-century naturalist Jean-Baptiste Lamarck, who believed that acquired traits could be inherited. Twentieth-century Darwinian genetics dismissed Lamarckism as laughable, but because of epigenetics, Lamarckism is staging a comeback.) 表观遗传学认为，我们的生理及心理倾向并非成型于石器时代。进化心理学似乎有时也这么认为。相反，是我们过往的生活及当下的环境塑造了这些。表观遗传学证明了，我们是历史、公众及个体作用的产物。我们的一部分是如此的“自我”，以至于很少有人想象得到这些部分会受历史影响。（有个人的确想到了这一点，他是18世纪法国自然学家让-巴蒂斯特·拉马克[Jean-Baptiste Lamarck]。他认为习得特点可以遗传。在20世纪，达尔文遗传学否认了拉马克学说，称其可笑。而现在因为表观遗传学，拉马克学说卷土重来。） The best-known example of the power of nutrition to affect the genes of fathers and sons comes from a corner of northern Sweden called Overkalix. Until the 20th century, Overkalix was cut off from the rest of the world, unreachable by road, train or even, in wintertime, boat, because the frozen Baltic Sea could not be crossed. Thus, when there were bad harvests in Overkalix, the children starved, and when there were good harvests, they stuffed themselves. 营养物质会影响到父亲和儿子的基因。这一论点的最著名的例子，出现在位于瑞典北部一角的上卡里克斯。20世纪以前，上卡里克斯一直与世隔绝，不通公路、铁路。在冬季，波罗的海结冰，连船都无法通过。于是，上卡里克斯收成不好时，孩子们会饿肚子；而到了大丰收时，孩子们又会吃的撑撑的。 More than a decade ago, three Swedish researchers dug up records from Overkalix going back to 1799 in order to correlate its children’s health data with records of regional harvests and other documents showing when food was and wasn’t available. What the researchers learned was extremely odd. They found that when boys ate badly during the years right before puberty, between the ages of 9 and 12, their sons, as adults, had lower than normal rates of heart disease. When boys ate all too well during that period, their grandsons had higher rates of diabetes. 十多年前，在上卡里克斯，三名瑞典研究者寻找到了从 1799年开始的记录，他们搜集了研究儿童健康的数据，当地收成记录及记录食物充足或匮乏的文件，以寻找这些材料之间的对应关系。结果极其奇怪。研究者们发现，如果男孩子在青春前期，即9至12岁，吃的不好，他们的儿子成年后患心脏病的几率低于正常水平。当男孩子在那个年龄段吃的太好了，他们的孙子患糖尿病的几率更高。 When the study appeared in 2002, a British geneticist published an essay speculating that how much a boy ate in prepuberty could permanently reprogram the epigenetic switches that would govern the manufacture of sperm a few years later. And then, in a process so intricate that no one agrees yet how it happens but probably has something to do with the germline (the reproductive cells that are handed down to children, and to children’s children), those reprogrammed switches are transferred to his sons and his sons’ sons. 当这个研究在2002年出现时，一位英国基因学家发表了一篇论文，推测道，一个男孩在青春前期的饮食状况，可能会永远重组其表基因开关，而这些开关会控制几年后其精子的形成。于是，在一个如此复杂的，无人确定如何发生的，可能与基因系（传给子辈孙辈的生殖细胞）相关的过程中，这些改变了的基因开关就遗传给了他的子子孙孙。 A decade later, animal studies confirm that a male mammal’s nutritional past has a surprisingly strong effect on his offspring. Male rats that are starved before they’re mated produce offspring with less blood sugar and altered levels of corticosterone (which protects against stress) and insulin-like growth factor 1 (which helps babies develop). 十年后，动物研究证明，雄性哺乳动物过去的营养状况会影响到其后代，影响之大令人吃惊。在交配前挨过饿的雄鼠，其后代的血糖会低一些，肾上腺酮（抗压力）及类似胰岛素的一号生长素（帮助宝宝发育）水平会改变。 Southeast Asian men who chew betel nuts, a snack that contains a chemical affecting metabolic functioning, are more likely to have children with weight problems and heart disease. Animal studies have shown that the effects of betel nut consumption by a male may extend to his grandchildren. 有些东南亚男子咀嚼槟榔。他们的后代更可能有体重问题或者得上心脏病。槟榔含有影响影响新陈代谢的化学物质。动物研究显示，雄性食用槟榔，其影响可能会持续到其孙辈身上。 Environmental toxins leave even more florid traces on grandchildren and great-grandchildren. Vinclozin, a fungicide that used to be sprayed all over America (it’s less common now), is what’s known as an endocrine disrupter; it blocks the production of testosterone. Male rats whose mothers receive a fat dose of vinclozin late in their pregnancy are highly likely to be born with defective testicles and reduced fertility. These problems seem to reappear in up to four generations of male rats after the mother is poisoned. 环境中的毒素对孙辈及曾孙辈的影响更是特色鲜明。全美都曾喷洒Vinclozin杀虫剂（现在没那么常见了）。那其实会影响内分泌，阻碍睾丸激素的分泌。给怀孕晚期的母鼠使用大量vinclozin，它们生出来的雄鼠极可能有睾丸缺陷或生殖力低下。在母鼠中毒后，这种问题会在4代雄鼠身上出现。 THAT food and poison change us is not all that surprising, even if it is surprising how far down the change goes. What is unexpected are the psychological dimensions of epigenetics. To learn more about these, I visited the Mount Sinai Medical Center laboratory of Dr. Eric Nestler, a psychiatrist who did a discomfiting study on male mice and what he calls “social defeat.” His researchers put small normal field mice in cages with big, nasty retired breeders, and let the big mice attack the smaller mice for about five minutes a day. If a mean mouse and a little mouse were pried apart by means of a screen, the torturer would claw at the screen, trying to get at his victim. All this subjected the field mouse to “a horrendous level of stress,” Dr. Nestler told me. This process was repeated for 10 days, with a different tormentor placed in each cage every day. By the time the torture stopped, about two-thirds of the field mice exhibited permanent and quantifiable symptoms of the mouse equivalents of depression, anxiety and post-traumatic stress disorder. The researchers then bred these unhappy mice with normal females. When their pups grew up, they tended to overreact to social stress, becoming so anxious and depressed that they wouldn’t even drink sugar water. They avoided other mice as much as they could. 食品与毒物会改变我们这一点本身一点也不让人吃惊，即便我们会对改变的持续效应感到吃惊。出人意料的是表观遗传学的心理学部分。为了了解的更多，我拜访了艾瑞克·内斯特勒博士(Dr. Eric Nestler)的西奈山医学中心实验室(Mount Sinai Medical Center laboratory)。内斯特勒是一个心理学家，他曾使用田鼠进行了一项有关“社交失败”的令人不安的研究。他的研究员把正常的小田鼠跟暴躁的大型种鼠一起放进笼子里，让大鼠每天攻击小鼠五分钟。如果用屏幕把攻击中的大鼠和小鼠分开，大鼠会抓挠屏幕，试着抓住小鼠。内斯特勒告诉我说：“这让小田鼠‘紧张到极点’。”这样的事反复上演了十天，每天每个笼子里都放一只不同的大鼠。到这种折磨结束的时候，大约三分之二小田鼠表现出了永久性的或者明显的鼠类抑郁症、焦虑及创伤后压力心理障碍症。研究者们然后让这些不快乐的小老鼠跟正常母鼠交配。它们的幼仔长大后，倾向于对社会压力过度反应。它们会变得过度紧张、过度抑郁，以至于连糖水都不敢喝。而且，它们会尽量避开其他同类。 Dr. Nestler is not sure exactly how the mouse fathers’ trauma communicates itself to their offspring. It may be via sperm, or it may be through some more complicated dance of nature and nurture that involves sperm but also other factors. When instead of letting the “defeated” mice mate, Dr. Nestler’s researchers killed them, harvested their sperm and impregnated the female mice through artificial means, the offspring were largely normal. Perhaps the sperm was harvested at the wrong stage in the process, says Dr. Nestler. Or maybe the female mouse picked up some signal when she had sex with the dysfunctional male mouse, some telltale pheromone or squeak, that made her body withhold nutrition and care from his pups. Females have been known to not invest in the spawn of non-optimal males, an outcome that makes perfect evolutionary sense — why waste resources on a loser? 内斯特勒不确定老鼠爸爸的创伤是如何遗传给孩子的。可能是通过精子，也可能是通过其他更加复杂的自然或者哺育过程。这些过程包含精子及其他因素。有时，内斯特勒的研究者们不让那些“失败”的雄鼠交配，而是杀掉他们，抽取精子，并且对母鼠进行人工授精。这种情况下，它们的后代大部分是正常的。内斯特勒说，可能是在过程中的一个错误阶段抽取了精子。或者是母鼠在交配中，收到了一些不正常的雄鼠信号，一些泄密的信息素或者声音，使得母鼠没能给幼仔足够的营养和关爱。根据现有知识，一些雌性不会在非最佳雄性的后代上下工夫，这在进化角度完全讲的通——凭什么将浪费资源在失败者身上？ When it comes to the epigenetics of aging, however, there is little question that the chemical insults and social setbacks of everyday life distill themselves in sperm. A woman is born with all the eggs she’ll ever carry. By the time a man turns 40, on the other hand, his gonad cells will have divided 610 times to make spermatozoa. By the time he’s in his 50s, that number goes up to 840. Each time those cells copy themselves, mistakes may appear in the DNA chain. Some researchers now think that a percentage of those mistakes reflects not just random mutations but experience-based epigenetic markings that insinuate themselves from sperm to fetus and influence brain development. Another theory holds that aging gonad cells are more error-prone because the parts of the DNA that should have spotted and repaired any mistakes have been epigenetically tamped down. In any case, we now know that the children of older fathers show more signs of schizophrenia, autism and bipolar disorder than children of younger ones. 当涉及到衰老方面的表观遗传学时，毫无疑问的是，在每天的生活中，化学物质对身体的损害和社会生活上的挫折，都会被提炼并存留在精子中。在一个女人出生时，她这一辈子所能产生的卵子数量是固定的。随着一个男人长到40岁，他的性腺细胞已经过了610次分裂以制造精子。在他50岁的时候，这项数据上升到840次。每次这些细胞进行自我复制时，错误都可能会在DNA链上出现。一些研究人员目前认为，这些错误中的一部分反映的不仅仅是随机的基因变异，同时也包括经历带来的表基因标记，这些潜藏在精子中的表基因标记将被传给胎儿，并影响大脑的发育。 另一种理论认为，衰老的性腺细胞更容易出错，因为那些应当发现和修复错误的DNA部分，已经在表基因的层面上被明显压低了。我们现在知道，大龄父亲的孩子，比起更年轻的父亲的孩子，将显示出更多患精神分裂症、自闭症和双相情感障碍的迹象。 In a meta-analysis of a population study of more than a million people published last year, Christina Hultman of the Karolinska Institute of Sweden concluded that children of men older than 50 were 2.2 times as likely to have autism as children of 29-year-olds, even after the study had factored out mothers’ ages and known risk factors for autism. By the time the men passed 55, the risk doubled to 4.4 times that of 29-year-olds. Can the aging of the parent population explain the apparent spike in autism cases? A study published last month in Nature that used whole-genome sequencing on 78 Icelandic families made the strongest case to date that as fathers age, mutations in their sperm spike dramatically. Some of the mutations found by the researchers in Reykjavik have been linked to autism and schizophrenia in children. 在去年发表的，一个对象超过一百万人的种群研究中， 瑞典卡罗林斯卡研究院(Karolinska Institute)的克里斯蒂娜·胡尔特曼(Christina Hultman)在一个荟萃分析中得出结论说，做父亲者的年龄超过50岁时，他们的孩子患有自闭症的几率，是29岁男性的孩子的2.2倍，这还是在该研究剔除了母亲的年龄因素，和其他已知的自闭症患病风险因素之后。当做父亲者的年龄超过55时，风险就又翻了一倍，是29岁父亲的4.4倍。父亲种群的老龄化能否解释自闭症病例的明显飙升？上个月《自然》(Nature)杂志发布了一项研究成果，对78个冰岛家庭使用全基因组测序，对于以下观点做出了迄今为止最有力的证明，即随着做父亲时年龄的增长，他们的精子变异会发生戏剧性的激增。这些雷克雅未克的研究人员发现，上述变异中的一部分与儿童自闭症和精神分裂症有关。 In his Washington Heights laboratory at the New York State Psychiatric Institute, Jay Gingrich, a professor of psychobiology, compares the pups of young male mice (3 months old or so) to those of old male mice (12 to 14 months old). The differences between the pups, he told me, weren’t “earth-shattering” — they weighed about the same and there weren’t big gaps in their early development. But discrepancies appeared when the mice grew up. The adult offspring of the older fathers had less adventuresome personalities; they also reacted to loud noises in unusual ways that paralleled reactions evinced by schizophrenics who heard similar sounds. 在位于华盛顿高地的纽约州精神病研究院里，精神生物学教授杰伊·金里奇(JayGingrich) 在自己的实验室比较了三个月大的年轻雄鼠的幼崽，以及十二至十四个月大的年长雄鼠的幼崽。他告诉我，这两类幼崽之间，并没有“惊天动地”的差异。他们的体重大致相当，在他们的早期发育中也没有大的不同。但当这些老鼠长大时，差异出现了。年长雄鼠的后代们缺乏喜欢冒险的性格；它们对于高声噪音的反应也很不寻常，与那些精神分裂症患者听到类似声音时的反应相接近。 Still, Dr. Gingrich said, “the differences were subtle” until he decided to pool the data on their behavior and graph it on a bell curve. A “vast majority” of the children of the older mice were “completely normal,” he said, which meant their score fell under the upside-down parabola of the curve. The real differences came at the tails or skinny ends of the bell curve. There was about a sixfold increase in likelihood that one of the “abnormal outliers,” mice with cognitive or behavioral handicaps, “would come from an older father.” Conversely, the super-high-performing mice were about six times more likely to come from a younger father. “I’m an inherently skeptical person,” Dr. Gingrich told me, but he was impressed by these results. 不过金里奇博士曾认为，“这些差异是细微的”，直到他决定把它们行为的数据集中起来，并绘成钟形曲线图。他说“绝大多数”年长老鼠的孩子们是“完全正常的”，这可以通过他们的数值分布于曲线图上下颠倒的抛物线之下来看出来。真正的差异，出现在钟形曲线两端的尾部，或说细小的结束端。在这里，“异常的离群值”老鼠，即那些有着认知和行为有障碍的后代老鼠，有着六倍于正常水平的可能性来自“那些年长的老鼠父亲”。与之相对于，超强表现的后代老鼠有着六倍于正常水平的可能性来自来自那些更年轻的老鼠父亲。“我是一个天生持怀疑态度的人。”金里奇博士告诉我，但这些结果给他留下了深刻印象。 One unanswered question about autism and schizophrenia is how they crop up in generation after generation; after all, wildly dysfunctional individuals don’t usually flourish romantically. “I think we’re going to have to consider that advanced paternal age, with its epigenetic effects, may be a way of explaining the mysteries of schizophrenia and autism, insofar as the rates of these disorders have maintained themselves — and autism may be going up,” Dr. Gingrich said. “From a cruel Darwinian perspective, it’s not clear how much success these folks have at procreating, or how else these genes maintain themselves in the population.” 关于自闭症和精神分裂症，一个悬而未决的问题是，它们如何会在一代又一代中突然出现。毕竟，机能严重失调的人并不受异性欢迎。“我认为，我们将不得不考虑增高的做父亲的年龄，及这种现象的表基因效应，或许可作为对精神分裂症和自闭症秘密的一种解释。因为目前这些心理病症的发病率一直稳定存在，自闭症甚至有上升趋势。” 金里奇博士说道，“以一个残酷的达尔文主义者的眼光来看，目前还不清楚这些人在生育时会有多大几率成功，以及这些基因怎么还能把它们自己保存在种群中。” When you’re an older mother, you get used to the sidelong glances of sonogram technicians, the extra battery of medical tests, the fear that your baby has Down syndrome, the real or imagined hints from younger mothers that you’re having children so late because you care more about professional advancement than family. But as the research on paternal inheritance piles up, the needle of doubt may swing at least partway to fathers. “We’re living through a paradigm shift,” said Dolores Malaspina, a professor of psychiatry at New York University who has done pioneering work on older fathers and schizophrenia. Older mothers no longer need to shoulder all the blame: “It’s the aging man who damages the offspring.” 当你成为一位大龄母亲时，你将会习惯于那些超声波扫描技术人员的白眼，一遍又一遍的医疗测试，并为你的宝宝是否会患上唐氏综合症而担心。此外你还得忍受那些来自年轻母亲的真实或想象中的暗示——因为你更关心自己事业的发展而不是家庭，才使自己这么晚才怀孩子。但随着对父亲一方遗传研究的积累，疑问的指针开始向父亲们滑动。“我们正在经历一次思维模式的转换。”纽约大学精神病学教授多洛雷斯·马拉斯皮纳(Dolores Malaspina)说。他已经在大龄父亲和精神分裂症上做了开创性的工作。大龄母亲无需再承担所有的责任，“这是大龄父亲们在损害后代。” Aging, though, is only one of the vicissitudes of life that assault a man’s reproductive vitality. Think of epigenetics as having ushered in a new age of sexual equality, in which both sexes have to worry about threats to which women once felt uniquely exposed. Dr. Malaspina remembers that before she went to medical school, she worked in a chemical plant making radioactive drugs. The women who worked there came under constant, invasive scrutiny, lest the toxic workplace contaminate their eggs. But maybe, Dr. Malaspina points out, the plant managers should have spared some concern for the men, whose germlines were just as susceptible to poisoning as the women’s, and maybe even more so. The well-being of the children used to be the sole responsibility of their mothers. Now fathers have to be held accountable, too. Having twice endured the self-scrutiny and second-guessing that goes along with being pregnant, I wish them luck. 不过，在那些损害人类生殖活力的各种因素中，衰老只不过是其中的一个。对于表观遗传学的考虑，已经开辟了一个性别平等的新时代；那些对大龄的担忧，曾一度不平等地压在女性的心上，而现在男女双方都将有所分担。马拉斯皮纳博士记得，在她去上医学院之前，曾在一家化工厂制作放射性药品。在那里工作的妇女，会受到定期的严密检查，以免这个有毒场所污染她们的卵子。但是马拉斯皮纳博士指出，或许工厂的经理们也应该分一些关注给男性，因为他们的生殖种系也像女性的卵子一样容易中毒，甚至可能更容易中毒。孩子的幸福曾只是母亲们的责任。现在父亲们的责任也应该被追究。在经历了两次对怀孕的自我审视和事后思索之后，我祝愿天下所有的父亲母亲们好运。 本文最初发表于2012年9月8日。 朱迪思·舒利瓦茨(Judith Shulevitz)是《新共和》(The New Republic)杂志的科技编辑。 翻译：林蒙克 |
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