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Being a teenager is hard. And so is living with one, I'm told.
我被告知作为一个青少年不容易，和青春期的人在一起生活也不容易
No human gets to escape this moody, angsty, confusing phase.
没有人能逃避开这段情绪化的、焦虑的、迷茫的时期。
And interestingly, such an extended adolescence is unique to humans.
有趣的是，这样一段延长的青春期是人类独有的。
Other animals grow up a lot faster than we do.
其他的动物成长速度比我们快得多。
And you may think our teen years are just about streamlining bodies for baby making,
你也许认为我们的青少年期只是在长身体以繁衍后代，
but as it turns out, the storm of sex hormones that we associate with the teenage years,
但事实证明，青春期时性荷尔蒙的大爆发
are only a small part of what's really going on in the teenage body.
只占那时身体变化的一小部分。
Most of the action, it turns out, is happening in the brain.
大部分的变化发生在大脑。
Until fairly recently, we thought that the brain finished the nuts and bolts of its development,
直到最近，我们还认为大脑已基本发育完全
by the time we started kindergarten. But really,
在我们开始上幼儿园的时候，但事实上，
when puberty starts, it undergoes massive remodeling.
当进入青春期大脑会开始大规模地重塑。
This amounts to several years of neural growing pains,
这意味着长达数年的神经成长的烦恼
as well as the other more visible growth that's going on all over your body.So take heart!
以及其它你身体上下更易见的成长变化。所以振作起来！
Whether you're going through it now, or about to go through it,
不管你是正在经历青春期还是正要经历
or count yourself among the veterans of that turbulent decade,
或是认为自己在那混乱的十年里已是个老手
know that the result of the teen years is a stronger, faster, more sophisticated brain.
你要知道最后你将有一个更强壮、更快速、更精密的大脑。
If there were someone that told me twenty years ago...
如果二十年前有人这样告诉我就好了……
Let's start with that obvious scapegoat of adolescent anguish, hormones.
让我们从看上去是导致青春期烦恼的罪魁祸首，但其实是“替罪羊”的荷尔蒙说起。
That word itself, is kind of a lazy shorthand
这个单词本身即是一种偷懒的简易表达
that people use to describe the chemicals that some glands secrete, that can affect our behavior.
是人们用来描述从一些腺体分泌的、可以影响我们行为的化学物质。
But the fact is, hormones have all kinds of jobs that have nothing to do with where you grow hair,
但事实是，荷尔蒙有诸多作用，但不能决定你在哪里长毛发，
or what turns you on, or whether you feel glum for no apparent reason
不能使你“性奋”，也不会让你不明原因地觉得沮丧
Hormones keep your heart beating, and your body hydrated, and they make your organs grow,
荷尔蒙使你的心脏保持跳动，保持身体水分，使器官生长，
and make you grow bone, and muscle, and skin!
使你生出骨头、肌肉与皮肤。
What people actually mean when they talk about 'teenage hormones', are sex hormones.
当人们谈论“青春期荷尔蒙”时，他们实际上指的是性荷尔蒙。
And yes, puberty involves a whole series of sex hormones storms,
是的，青春期包含一整个系列的性荷尔蒙爆发，
the first of which actually kicks in before you're outta Primary School.
最早的性荷尔蒙分泌实际上在你小学毕业前就已开始。
That's when the Adrenal glands start secreting androgens, which triggers the growth
那时肾上腺开始分泌雄激素，从而引起
in activity of the skin's sebaceous glands, making skin more oily.
皮脂腺的生长加速，使皮肤变得油腻。
Soon enough, more apocrine or sweat glands get activated increasing body odor.
很快，更多的分泌腺或汗腺活跃使得身体气味增加。
Then comes the waves of hormonal agents that start activating the gonads.
然后大量的荷尔蒙开始促进生殖器官的发育。
For boys, this influx of luteinizing hormones from the pituitary gland, get testosterone from the testes,
对于男孩，从脑垂体大量涌入的促黄体生成素，促进睾丸大量分泌睾丸素，
and suddenly, that guy has up to fifty times more testosterone than he did before puberty.
一下子，那家伙获得了比青春期前最多50倍的睾丸素。
This also changes the shape of the male body, promoting hair growth,and building up lean muscle mass,
这也改变了雄性的身体，促进毛发生长，塑造肌肉线条，
just as the increased presence of estrogen in girls rearranges the deposition of their fats, stimulating the growth of breasts.
就像女孩们体内增加的雌激素会重新安排脂肪的位置，促进胸部的增长。
Humans are actually lucky to experience the craziness of puberty only once,
人类很幸运，只用经历一次青春期的疯狂，
many other animals undergo multiple similarly intense hormonal rodeos as they enter sexually active periods,
很多动物在进入发情期时要经历数次类似的紧张的荷尔蒙起伏变化，
sometimes called the rot or heat, every new breeding season.
有时可称为“堕落或疯狂”。
Some male species completely stop eating during their breeding period, because they're just that sex crazed.
在繁殖期一些雄性品种会完全停止进食，它们只是为性疯狂。
And yet all that said, teen are far less ruled in their hormones than you might think. There are other factors that play here.
然而说了那么多，青春期对荷尔蒙的控制并没有你想的那么大。还有其它的因素在影响。
For example, your favorite moody teen may be by turns punchy, angry, depressed, or in a zombie like fog,
比如，你那处于青春期的情绪化的宝贝，也许变得寡言、愤怒、沮丧或像僵尸一样无神，
because of their chronic lack of sleep.
只是因为长期的缺少睡眠
Sleep is vital to everyone, but it's specially important for kids and teens,
睡眠对每个人都很重要，对小孩和青少年尤其重要，
because it's during sleep that your pituitary gland releases an essential growth hormone, necessary for development.
因为在睡眠中，脑垂体会释放一种重要的生长激素，这对于成长很重要。
A normal sleep cycle driven by circadian rhythm, is regulated by the daytime release of cortisol,
一个遵循24小时节律的正常的睡眠循环，由人体白天释放的皮质醇
which helps you wake up, and melatonin, which helps you wind down when it gets dark.
和晚上释放的褪黑激素调节皮质醇使人保持清醒，褪黑激素使人保持平静。
But this biology of sleep timing changes as we age and as puberty begins, teens' sleep clocks get pushed back.
但是这个生物钟会随年龄变化，当进入青春期，睡点会推后。
Most adults start producing melatonin 10 p.m. ish,
大多数的成年人晚上10点开始分泌褪黑激素，
but one study showed that teenagers don't start producing melatonin until closer to 1am!
但一项研究显示青少年直到凌晨1点才开始分泌褪黑激素！
This may be because puberty's hormonal frenzy is stalling the release of melatonin,
这也许是因为青少年疯狂的荷尔蒙推迟了褪黑激素的释放。
and could partly explain why so many teens stay up late, energized by the night,
这也可以一定程度上解释为什么那么多的青少年熬夜，晚上精力旺盛，
but had a really hard time rolling outta bed with the alarm.
闹钟响了却起不来床。
Of course it's a bit of a chicken and egg deal, since watching reruns of The Simpsons,
当然这有点像先有鸡还是先有蛋的问题了，因为看《辛普森一家》的重播
and playing Call o' Duty late at night continues to stimulate the brain, which may further delay the release of melatonin.
或者玩《使命召唤》到很晚，这些都在刺激大脑，也许会更一步推迟褪黑激素的释放，
Still, some researchers are starting to advocate for pushing back high school start times in the morning,
所以，有些研究者开始提倡将高校的早晨开始上课时间往后调，
in the hopes of having more focused students.
希望这样有更多集中精力的学生。
So we've got sex hormones changing the bodies, and a lack o' sleep to contend with,
那么我们知道了性荷尔蒙会改变身体，以及缺少睡眠对人的影响，
but increasing evidences suggest that, there is something much bigger at work that's making teenagers so 'teenager-ry'. Their brains!
但是越来越多的证据表明，有些事有更大的影响使得青少年如此的与众不同。即他们的大脑！
It turns out that brains actually take longer than we thought, to fully mature.
事实表明，大脑确实需要比我们想象的更长的时间来发育成熟。
I don't mean physical size - our brains are already about 95% full-sized by the time we're just six
我不是指物理大小--在我们只有6岁时，我们的大脑就已经有成年人95%大小了
but more in the sense of the connections inside the brain.
我指的是大脑内部的神经连接。
Adults - for the most part - know how to make decisions by evaluating choices, and weighting consequences.
大部分成年人知道如何做决定--通过对比选择，权衡结果
They do this with their prefrontal cortex, which is responsible for controlling impulses and emotions, and forming judgments.
通过他们的前叶额皮质层，这负责控制冲动和情绪来做出决定。
Its neurons chat with the neurons in other regions of the brain, responsible for - say it - memory or movement, through synapses.
它的神经元与大脑其它的区域的神经元进行交流，比如说，负责记忆和行动的神经元，这种交流通过突触进行。
The thing is, teenage brains don't quite work like this yet.
真实情况是，青少年的大脑还没有像这样运作。
The prefrontal cortex may not be fully developed until you're mid-twenties,
他们的前叶额皮质层也许无法发育完全，直到25岁左右，
and teen synapses - those "lines" of communication - are still growing, and specializing. They're also - slow.
青少年的突触（即脑内神经的交流线路）还在成长中、细化中。它们同时也非常缓慢。
As an adolescent brain keeps developing, its axons - the long "tail-like" parts of the neurons that transmits signals to other neurons
在一个青少年的大脑成长过程中
become more and more insulated by a fatty layer called the 'Myelin Sheath'.
轴突变得越来越不易受影响，因为被一层厚的称为髓鞘保护膜所包裹。
This padding greatly increases the cell's transmission speed,
这层包裹大大提升了细胞的传输速度
and while it helps adults make faster decisions, it isn't fully formed in teens.
这使得成年人做决定时更迅速，却在青少年时期无法完全发育完成。
These changes occur slowly, beginning at the back o' the brain, where the oldest and most fundamental brain parts reside,
这些变化发生得十分缓慢，开始于大脑的后部，即大脑最古老和最基础的部分
and slowly working its way forward to the more advanced and complicated brain bits.
然后逐渐地往更先进和复杂的部分发展。
The prefrontal cortex is the last to be hooked up and shaped.
前叶额皮质层是最后被连接和塑造的，
So it's important to keep in mind, that just because your favorite teenager stayed up until sunrise
因此这很重要你要记住，你的宝贝在考试的前一天晚上
binge-watching 'The Walking Dead' the night before an exam, it doesn't mean they're dumb or lazy,
无节制地看《行尸走肉》直到天亮并不意味着他们又蠢又懒
their brain are just literally finishing being built.
只是因为他们的大脑还在塑造中。
But at the same time, because all o' this brain building's just starting to peak,
同时，因为他们的大脑塑造开始达到顶点，
this is also, when the brain starts getting thinned out.
这也是大脑开始清理多余连接的时候。
You actually start losing connections that you don't use enough, in a process called synaptic pruning -
那些你用得不频繁的连接会消失，这一进程称为突触修剪
which has led to a theory that this is kind of a 'use it or lose it' phase.
由此引出一种“用进废退”的理论。
Meaning, adolescence could be an specially important time to use your brain
这意味着青少年时期对大脑的使用特别重要
play an instrument; engage in sports; write poetry; learn language!
演奏一种乐器、参加一项体育活动、写诗、学习新语言！
Because by doing these things, you're helping hardwire those synapses, and giving your brain topiary a lovely lasting shape.
通过做这些事，这些突触连接会巩固，你的大脑会被修剪成一个可爱又持久的形状。
Whereas if you're sitting around all day playing Candy Crush,
而如果你整天都坐着玩《糖果粉碎传奇》
those will be the connections that survive, which you don't need...
这些有关的连接就会留存下来，尽管你并不需要……
This shaping of the teen brain manifests itself in other ways too, like in teenage attitudes.
这种对青少年大脑形状的塑造也通过其它方式表达出来，比如他们对外界的看法。
A group of scientist at the McLean Hospital of Massachusetts, once hooked up a group of adults and a group of teens,
美国马萨诸塞州麦克莱恩医院的一队科学家，通过核磁共振设备进行观察，曾组织一组成年人和一组青少年
to MRI devices and then asked them to identify a series of expressions on photographs of adults faces.
让他们鉴别照片上的成年人脸上的系列表情。
Interestingly, while adults correctly identified one expression as fear,
有趣的是，当成年人正确地指出一个表情是害怕时，
the teenagers thought the faces showed anger, surprise, or shock. They weren't registering subtleties well.
青少年认为那是表示害怕、惊讶或震惊。他们无法识别这些微妙的差异。
Not only that, but the MRI images showed that adults and teens responded with different parts of their brains.
不仅如此，核磁共振图像显示成年人和青少年是用大脑的不同的部分回应的。
Adults, use the reasonable prefrontal cortex, while the teens mostly use the gut reaction, emotional amigdala,
成年人理所当然地使用前叶额皮质层而青少年主要使用直觉反应，即主管情绪的杏仁体，
located farther back in the brain.
杏仁体位于大脑的更后面。
Results like these might help explain why teenagers seem to experience frequent mood swings.
这样的试验结果也许可以帮助解释为什么青少年们看起来更易情绪波动。
For one, they tend to react quickly from the emotional part of their brain,
首先，他们倾向于从大脑的情绪部分快速反应
without running those reactions by the more rational frontal cortex,
而不是用更理智的前叶额皮质层，
and two, it could be that they're just misreading expressions, and therefore the intentions behind them.
其次，有可能他们只是误解了试验的表情及其后的意图。
The frontal cortex also helps people relate to, and understand each other,
前叶额皮质层也可以帮助人们建立联系，理解彼此
and you can imagine what happens when concern is misjudged as anger; or worry, as disappointment.
所以你可以想象当关心被误解为生气或担心被误解为失望时会发生什么。
The Fresh Prince has an entire song about it.
Fresh Prince就有一整首歌是关于这个的。
But the truth is, as much as parents just don't understand, teens don't always understand either.
但事实是，父母常常无法理解他们的小孩，少年自己也常常无法理解。
When the emotional amigdala, and the more rational cortex aren't fully hooked up yet,
当负责情绪的杏仁体与更理智的前叶额皮质层还没有完全连结好，
that can make it hard for teenagers to productively work through emotions.
青少年们就很难控制好情绪。
This kind of reactionary, impulsive behavior may also lead to more risk taking.
这种叛逆和冲动行为也许会导致更危险的行为。
Adolescence is the time when we're most likely to experiment with whatever booze, or drugs is available,
青少年时期我们最容易体验酒精或毒品，
and unfortunately, it's also the time our developing brains are most vulnerable to lasting effects
不幸的是，那也是我们塑造中的大脑最脆弱、会受到永久影响的时期。
Studies have shown that teens are more likely to become addicted to drugs and alcohol, than adults
研究已经表明，青少年比成年人更容易沉迷于毒品或酒精，
partly because their brains are more attuned to their reward centers.
一部分原因是他们的大脑对脑内的奖赏区域更熟悉，
While the teenage prefrontal cortex is still developing, their 'Nucleus Accumbens',
因为他们的前叶额皮质层还在发育中，他们的“伏隔核”
or 'pleasure and reward zone', forms early on.
或“愉悦和奖赏区域”成型更早。
Neuroimaging studies have shown that when presented with a big potential reward,
神经影像研究表明当有大的潜在的奖赏时，
teen brains light up way more than kids or adults brains, but if the reward was small,
青少年的大脑亮起来的区域比小孩或成年人更多，但当奖赏很小时
teen brains hardly fired at all.
他们的大脑几乎没有反应。
So basically, give an adolescent a pat on the back, and you'll get a shrug.
所以基本上，在一个青少年背后轻拍一下，他只会耸耸肩。
Give them a hot date or a wining goal, and their brains light up like Vegas.
给他们一个火辣的约会或一个令人振奋的目标，他们的大脑会闪亮得像拉斯维加斯。
This of course, does not always result in great judgment.
基于这样的反应，你不能指望他们能做出多伟大的决定。
A jacked up thrill-seeking impulse, combined with exquisite pang of peer pressure,
一股上涌的寻找刺激的冲动加上同伴的压力带来的痛苦
plus a new driver's license, new sex parts, and access to substances can lead to some not good results.
和一个新的驾照、新的性伴侣再加上毒品，这些足够导致一些不好的结果。
But still, this long and some times tedious remodeling process that our bodies go through in the teenage years, isn't all bad.
但是话说回来，我们青春期的身体经历的这个长长的、有时候有些乏味的重塑过程并不全是坏事。
Many scientists have pointed out that our delayed adolescence lets our brains keep their flexibility longer,
许多科学家指出，较长的青春期使得我们的大脑保持灵活更长的时间
which Yeah, may make teens a little slow, but also more adaptable, as they prepare for the adult world.
也许会使青少年长得有点慢，但更能适应随后到来的成人世界。
In this way, you can see teen impulsiveness as boldness; or independent thinking, and moodiness,
从这个意义上说，你可以将青春期的冲动当成大胆或独立思考，
as a source of new found empathy; and excitability, as passion.
将感性当作共鸣，兴奋过度当作热情。
Which means, there's a lot of awesome energy floating around out there ready to decrease all kinds of world suck
就是说，这些精力旺盛的青春期的人们在准备改变这个世界的旧有成见。
Thanks for watching the SciShow, and thanks specially to all of our subscribers on Subbable, who make this channel possible!
感谢观看SciShow。特别要谢谢我们在Subbale上的所有贡献者。有他们才有这个频道！
You can be an honorary associate producer of SciShow, or even pick the topic of a future episode!
你也可以成为SciShow的一名荣誉制作者，甚至决定未来某一系列的主题！
To find out how, go to "subbable.com/scishow". And you can always find us on Facebook and Twitter, and in the comments below,
具体方式，请至subbale.com/scishow。你也可以在Facebook和Twitter及其下的评论部分找到我们。
and if you wanna keep gettin' smarter with us here at SciShow, you can go to "youtube.com/scishow" and subscribe.
如果你想和我们一起变得更聪明，欢迎至youtube.com/scishow订阅我们的节目。
