(单词翻译:单击)
Fighter pilots and astronauts have really intense jobs, and they put their bodies under extreme amounts of physiological stress.
战斗机飞行员和宇航员的工作非常紧张，他们将自己的身体置于极大的生理压力之下。
Just watch five minutes of Apollo 13 or Captain Marvel, and you will know exactly what I'm talking about.
只要看五分钟的《阿波罗13号》或者《惊奇队长》，你就能确切地知道我在说什么。
This kind of stress — especially the high gravitational forces — is so significant that some people believe it can affect their kids.
这种压力—尤其是地心引力—非常重大以至于一些人认为这会影响到他们的孩子。
More specifically, there's this common idea in flying communities that if someone who produces sperm wants to be a fighter pilot
更具体地说，在飞行界，大家普遍认为如果一个产生精子的人想成为一名战斗机飞行员
and an amazing parent, they should prepare for a household full of daughters.
也想成为一名了不起的家长，那么他们应该为一个都是女儿的家庭做准备。
The idea is that a sperm carrying a Y chromosome is smaller and more fragile than one carrying an X,
这种想法是，一个携带Y染色体的精子比携带一个X的染色体更小更脆弱
so it's more easily disrupted by things like high gravitational forces.
所以更容易被高引力之类的东西破坏。
But before you go start switching careers or anything, you might want to look at the research.
但在你转行之前，你或许想看看这个研究。
Typically, making a baby is pretty straightforward — at least, on a cellular level.
一般来说，生孩子相当简单—至少在细胞水平上是如此。
In most cases, you start with an egg cell carrying an X chromosome.
多数情况下，首先需要一个携带X染色体的卵细胞。
And then that egg combines with a sperm cell carrying either an X or a Y chromosome.
然后卵子和一个携带X或Y染色体的精细胞相结合。
And ultimately, you get an XX or XY kid. Although there is plenty of nuance, most females are XX, most males are XY.
最后，你可以得到一个XX或XY的孩子。虽然有很多细微差别，但大多数女性是XX，大多数男性是XY。
For most of the population, the odds of a sperm cell contributing an X or a Y is about 50/50.
对大多数人来说，精细胞产生X或Y的几率各占一半。
But if you look at certain studies, it seems like that might not hold true for pilots.
但是如果你看看某些研究，这种几率似乎并不适用于飞行员。
Take a 1987 study published in the journal Aviation, Space, and Environmental Medicine.
以发表于《Aviation, Space, and Environmental Medicine》期刊的一项1987年研究为例。
It looked at the number of sons and daughters of 62 male tactical pilots and astronauts.
该研究观察了62名男性战术飞行员和宇航员儿子和女儿的个数。
Then, it compared those numbers to those of 222 men who had regular day jobs
然后将这些数字与222名常规日常工作的男性
or were pilots with a lower exposure to gravitational forces.
或较少暴露于引力之下的男性飞行员的数字做对比。
The analysis found that the tactical pilots and astronauts tended to have more daughters than the average Joes they were compared to.
分析发现相比普通人，战术飞行员和宇航员更容易生女儿。
Now, to be clear, the researchers just pulled this data from biographies; it's not like they ran genetic tests or anything.
准确来说，研究人员只是从传记中提取了这一数据；他们并没有做基因测试之类的。
But it's likely that in this paper and in the others we mention, daughters were XX, and sons were XY.
但有可能是在这份论文和其他我们提到的论文中，女儿是XX，儿子是XY。
Still, one paper is rarely enough to prove anything.
然而，一篇论文不足以证明任何事情。
There might be more going on here, so it's important to look at other research.
或许还需进行更多研究，所以我们需要看看其他的研究。
There have been several other studies about this, but in 2009, an especially large one was published in the journal Military Medicine.
关于此还有一些其他的研究，但在2009年，《Military Medicine》上发表了一篇尤为重大研究。
It compared the families of more than 500 naval aviation officers to those of the general population.
该研究将500多名海军航空军官的家属与普通大众的相比较。
And on average, it found almost no difference in the kind of kids each group had.
平均而言，该研究发现两组孩子的类型几乎没有什么不同。
The one significant difference it did find was among pilots who flew in extreme environments about two months before they conceived.
研究发现的一个显著差异存在于她们怀孕前两个月左右在极端环境中飞行的飞行员中。
That group was more likely to have daughters. In human reproduction, timing is everything.
那组更有可能生女儿。在人类繁殖过程中，时间就是一切。
So maybe this was a sign that the stress of flight was damaging Y sperm right before conception.
所以这可能是一个信号—飞行的压力在破坏孕前的Y精子。
Still, it's hard to take that answer and run with it, because scientists can't actually explain why this would happen.
但还是很难接受这个答案，因为科学家不能确切解释为什么会发生这种情况。
Many people used to believe that Y sperm were smaller, which would make them more susceptible to damage.
过去很多人认为Y精子更小，所以它们更容易受到伤害。
But that was based on research from the 1960s, and today, we know that isn't true.
但这是基于20世纪60年代的研究，而现在我们知道事实并非如此。
As far as we can tell, there is actually no meaningful size difference between X and Y sperm.
据我们所知，X和Y精子之间并没有明显的大小差别。
So it's hard to figure out what's going on with those pilots.
所以很难弄清这些飞行员到底怎么了。
There are plenty of hypotheses floating around, but at this point, it's too soon to say anything for sure.
还有很多关于此的假说，但此时下结论为时过早。
At the end of the day, though, individual pilots probably shouldn't be worried.
但说到底，个别飞行员或许不应担忧。
As that 2009 paper pointed out, even if the odds are skewed toward XX kids on a population level,
正如2009年的论文所指出的，即便在人口水平上，这种几率偏向XX的孩子，
that doesn't mean they are for every individual. Ultimately, if you're a pilot, you probably can't predict
但这并不意味着每个人都会中招。最后，如果你是一名飞行员，你或许无法预测
what kind of kids you're gonna have any better than the rest of us here on the ground. So… welcome to the club.
哪样的孩子会比其余人的要更好。所以欢迎加入我们。
