人们的讨论往往聚焦于女性生育率的不断下降，但父亲的生育年龄似乎也很重要。有相当有力的证据表明，在40多岁或以上生育孩子的父亲，其子女患自闭症谱系障碍和精神分裂症的几率是通常水平的两到三倍。

Sir Mick Jagger embodies what one writer has called paleo-fatherhood, or the trend of becoming a dad in later life. He was 73 when Deveraux, his eighth child, was born to his 29-year-old partner, ballerina Melanie Hamrick.

米克•贾格尔爵士(Sir Mick Jagger)代表了一位作家所说的“大龄父亲”趋势。在他73岁时，他的29岁女友、芭蕾舞演员米兰妮•哈姆里克(Melanie Hamrick)为他生下了他的第8个孩子德沃罗(Deveraux)。

The Rolling Stone is an extreme example but there has been a shift to older parenthood in recent decades. In 2015, first-time dads in the UK were 33 and first-time mothers were 30, on average four years older than was the case 40 years ago.

这位滚石乐队(Rolling Stone)的摇滚巨星是一个极端的例子，但最近几十年，晚生育的趋势确实存在。2015年，英国男性首次当父亲的平均年龄是33岁，女性首次当母亲的平均年龄是30岁，比40年前的平均水平晚4年。

Discussion has tended to focus on women’s declining fertility, but paternal age seems to matter too.

人们的讨论往往聚焦于女性生育率的不断下降，但父亲的生育年龄似乎也很重要。

There is fairly robust evidence that fathers who conceive in their forties or older have children who run two to three times the usual risk of developing an autism spectrum disorder and schizophrenia. Other studies have implicated advanced paternal age (usually defined as over 40, though different studies use different thresholds) in low academic achievement. This matters: in 2015, 15 per cent of new fathers in the UK were aged 40 or over.

有相当有力的证据表明，在40多岁或以上生育孩子的父亲，其子女患自闭症谱系障碍和精神分裂症的几率是通常水平的两到三倍。其他研究表明，父亲生育年龄偏大（通常定义为超过40岁，不过不同研究使用的标准不同）会导致子女学校成绩较低。这很重要：2015年，英国15%的新爸爸年龄在40岁以上。

A paper out this month suggests that the children of both atypically young and old fathers are more likely to show unusual patterns of social development, and to end up more socially challenged than their peers.

本月发表的一篇论文显示，父亲生育年龄过小或过大，其子女更有可能出现异常的社交发展模式，与同龄人相比，他们最终在社交方面遇到的挑战更大。

The reasons for this are unclear but the findings highlight the emerging association between delayed fatherhood and higher health risks for offspring.

其中的原因尚不明确，但研究结果突显出，男性晚生育与子女健康风险更高之间是有相关性的。

The big question is whether this association stems from age-related genetic changes in sperm, or whether the men who become fathers later in life already have social difficulties that delay conception, and which then get passed on to the next generation.

关键问题是，这种相关性是来自精子中与年龄相关的基因变异，还是那些晚生育的男性本已存在社交障碍，由此耽搁了生育，而这种社交障碍又遗传到了下一代身上。

The new research was led by Dr Magdalena Janecka, from the Seaver Autism Center for Research and Treatment, at the Mount Sinai Hospital in New York. It looked at data collected on 15,000 pairs of twins between the ages of four and 16, including social development, conduct with peers, and hyperactivity, and ruled out those already diagnosed with autism.

这项新研究的带头人是纽约西奈山医学院(Mount Sinai Hospital)西维尔自闭症研究和治疗中心(Seaver Autism Center for Research and Treatment)的玛格达莱娜•亚内卡博士(Dr Magdalena Janecka)。研究分析了1.5万对年龄在4岁至16岁的双胞胎的数据，包括社交发展、与同龄人一起的表现、以及过度活跃表现，并排除了那些已被诊断为自闭症的孩子。

It found that children born to fathers aged either under 25 or over 51 were more socially skilled than their peers in their early development. By adolescence, however, the same children had fallen behind socially.

研究发现，在早期发育中，那些出生时父亲年龄在25岁以下或51岁以上的孩子的社交能力要高于同龄人。然而，到了青少年时期，这些孩子的社交能力则出现落后。

Their findings, published this month in the Journal of the American Academy of Child and Adolescent Psychiatry, were independent of the mother’s age.

这些研究结果发表在本月的《美国儿童和青少年精神病杂志》(Journal of the American Academy of Child and Adolescent Psychiatry)上。研究结果与母亲年龄无关。

Dr Janecka concludes that “social skills are a key domain affected by paternal age . . . in extreme cases, these effects may contribute to clinical disorders”.

亚内卡博士总结称，“社交能力是受父亲生育年龄影响的主要领域……在极端例子里，这些影响可能会引发临床疾病”。

The researchers theorise that paternal age influences how a child’s brain matures, with further study possibly shedding light on how autism and schizophrenia develop.

研究人员提出如下理论：父亲生育年龄会影响儿童大脑发育。进一步的研究可能会揭示自闭症和精神分裂症是如何发展的。

Scientists suggest that random genetic mutations during sperm production might explain the association. The precursors to sperm cells are continually dividing, with each division representing the opportunity for a genetic typo, or copying mistake.

科学家表示，在精子形成期间的随机基因突变或许可以解释这种相关性。精细胞的前体不断分裂，每次分裂都有可能出现基因错排或者复制错误。

The rate of these so-called de novo mutations has been estimated to double roughly every 16 years, meaning older men shoulder many more mutations than younger men.

据估计，所谓的新生突变率大约每16年增加一倍，这意味着年龄较大男性携带的突变基因要远远多于较年轻男性。

Others have suggested that the rate of such mutations is simply not high enough to account fully for the higher risk of psychiatric illness in the children of older fathers.

还有人提出，这种基因突变率还不够高，不足以完整解释为何大龄父亲的子女患精神疾病的风险更高。

A 2016 paper in Nature by scientists from the Queensland Brain Institute concluded that “genetic risk factors shared by older fathers and their offspring are a credible alternative explanation” to the mutated sperm theory.

《自然》杂志(Nature) 2016年一篇来自昆士兰脑神经科学研究所(Queensland Brain Institute)科学家的论文总结称，精子基因变异理论的“另一种可信解释是大龄父亲及其子女共有一些基因风险因素”。

In other words, men who are at greater risk of psychiatric illness tend to become fathers later in life — and their kids simply inherit that greater risk.

换句话说，患精神疾病风险较高的男性往往会推迟生育年龄，而他们的子女又会遗传这种较高的风险。

If this is the case, the biological clock does not tick as urgently for men as for women. But the science is by no means settled, partly because there are so many other factors aside from parental age — such as childhood neglect and drug use — that influence mental health.

要是这样的话，那么男性生物钟的转动并不像女性那样快。但科学并非一锤定音，部分原因是除了父母年龄，影响心理健康的还有很多其他因素，例如童年时期被忽视以及吸毒。

One major study, which supports the link between paternal age, psychiatric risk and academic outcome, involved combing the data of 2.6m Swedes. It was able to compare siblings born to the same father. If the siblings were simply inheriting risk, paternal age would be immaterial. In fact, as paternal age rises, so does the risk of psychiatric illness and lower school grades.

另一项重大研究分析了260万瑞典人的数据，研究结果证明，父亲生育年龄、精神疾病风险和学习成绩之间是存在关系的。该研究得以将同一位父亲的多位子女进行对比。如果子女都遗传了风险，那么父亲的生育年龄就不重要了。实际上，随着父亲生育年龄的提高，子女患上精神疾病和学习成绩较低的风险就越高。

“It would make sense that the effect lies in the integrity of the sperm line,” says Professor Frances Happé, an autism expert at the Institute of Psychiatry, King’s College London, and a co-author of the JAACAP paper.

伦敦国王学院(King’s College London)精神病学研究所(Institute of Psychiatry)自闭症专家弗朗西斯•哈佩(Frances Happé)教授表示：“问题有可能就出在完整的精子生产链上。”她是上述《美国儿童和青少年精神病杂志》那篇论文的联合作者。

Men, she adds, make sperm throughout life. The production process may be vulnerable to environmental effects as well as random mutations.

她补充称，男性终身都在制造精子。制造过程很容易受到环境以及随机基因突变的影响。

Professor Adam Balen, chair of the British Fertility Society, says the study “doesn’t give a definitive answer about the biological or social causes of autism in the children of older men”.

英国生育学会(British Fertility Society)主席亚当•巴伦(Adam Balen)教授表示，这项研究“没有就大龄父亲的子女患自闭症的生物学或社会学原因给出定论。”

He adds: “As people in more developed economies are choosing to have children later in life, we need to understand what that might mean for the overall health and wellbeing of future generations.”

他补充称：“经济越发达地区的人们生育年龄越晚，我们需要弄明白，这对于未来几代人的整体健康和幸福可能意味着什么。”

Prof Happé also warns that, since it is impossible to predict which men are affected, couples should not plan families around this research.

哈佩教授还警告称，现在还无法预测哪类男性会受到影响，因此夫妇不应根据这项研究来制定生育计划。

In the meantime, silver-haired dads are on the rise, thanks to a collision of social trends. Many men and women want to taste career success — and the financial stability that accompanies it — before procreating. Relatively high divorce rates are producing second broods, and reproductive science is extending the age limits to parenting that were previously set by nature. Celebrity fathers are removing the stigma of late parenthood: Sir Paul McCartney and Clint Eastwood became sixty something dads.

与此同时，由于社会趋势的碰撞，银发爸爸们正在增多。很多男女希望先品尝事业的成功以及伴随而来的经济稳定再生育。相对较高的离婚率带来了再婚再育，而生殖科学的发展也在不断提高以往由自然设定的生育年龄限制。名人父亲也正消除老来得子的耻辱感：保罗•麦卡特尼爵士(Sir Paul McCartney)和克林特•伊斯特伍德(Clint Eastwood)都是在60多岁当爸爸的。

There might even be advantages amid the (hypothetical) genetic gloom: work might not compete as much; finances might be less strained.

（假想的）基因低潮时期甚至可能还有好处：工作可能没有那么多竞争；经济状况可能没那么紧张。

Perhaps Sir Mick had thought it through, after all.

毕竟，米克爵士或许已经仔细考虑过了。