3月15日下午，貴陽清鎮市一名休學在家的19歲大學男生，持刀殺害了一名兩歲女童。
經調查，就讀於廣東某高校的犯罪嫌疑人楊某某因病休學在家。案發當天，楊某某情緒波動較大，其父楊某發現後與其交流談心，楊某某反映其在校讀書期間，與寢室同學、老師、宿管關係較為緊張，學習生活不愉快。
在其父與校方電話溝通過程中，楊某某突然情緒失控，從自家廚房裡拿了一把菜刀衝出家門，竄至小區平合處將正在玩耍的被害人劉某某頭部砍傷。
Exploring the mind of a killer
探索殺人犯的大腦
I'm a neuroscientist, a professor at the University of California. And over the past 35 years, I've studied behavior on the basis of everything from genes through neurotransmitters, dopamine, things like that, all the way through circuit analysis. So that's what I normally do. But then, for some reason, I got into something else, just recently. And it all grew out of one of my colleagues asking me to analyze a bunch of brains of psychopathic killers.
我是一名神經學家，一名加州大學的教授。在過去的35年裡， 我都在研究人的行為。不過研究的基礎主要集中在基因，多巴胺之類的神經傳導素以及目標分析。這些都是我通常所做的。但出於某種原因，我最近開始迷上了另外的一樣東西。究其緣由，則是因為我的一個同事 叫我去研究一批心理變態的殺人犯的大腦。
And so this would be the typical talk I would give. And the question is, "How do you end up with a psychopathic killer?" What I mean by psychopathic killer are these people, these types of people. And so some of the brains that I've studied are people you know about. When I get the brains I don't know what I'm looking at. It's blind experiments. They also gave me normal people and everything.
所以你們這裡看到的就是我通常會給的演講。而我探索的問題就是，“一個人是怎樣變成心理變態的殺人兇手的呢？” 我對心理變態的殺手的定義主要是針對這些人，這些種類的人。所以我所研究的一些大腦實際上是屬於你們所聽說過的人的。當我剛拿到這些大腦的時候，我其實不知道我查看的究竟是何種大腦。算是一個單盲實驗，因為他們所給我的大腦中也混雜著正常人的大腦。
So I've looked at about 70 of these. And what came up was a number of pieces of data. So we look at these sorts of things theoretically, on the basis of genetics, and brain damage, and interaction with environment, and exactly how that machine works. So we're interested in exactly where in the brain, and what's the most important part of the brain. So we've been looking at this: the interaction of genes, what's called epigenetic effects, brain damage, and environment, and how these are tied together. And how you end up with a psychopath, and a killer, depends on exactly when the damage occurs. It's really a very precisely timed thing. You get different kinds of psychopaths.
我一共查看了大概70個大腦， 並從中獲取了一些數據。我們從理論化的角度出發， 將基因腦損傷、與環境的相互作用， 以及大腦的工作原理作為分析研究的基礎。我們所感興趣的是大腦中的具體位置 和大腦中最重要的部分。所以這就是我們長期以來的研究對象：基因之間的相互作用， 也就是所謂的後生效應， 大腦的損傷，環境因素， 以及他們之間的聯繫。而一個人變成心理變態狂，變成殺手的原因就決定於腦損傷發生的確切時間。時機的掌握真的需要恰到好處。心理變態狂是有各種各樣的。
So we're going along with this. And here's, just to give you the pattern. The pattern is that those people, every one of them I looked at, who was a murderer, and was a serial killer, had damage to their orbital cortex, which is right above the eyes, the orbits, and also the interior part of the temporal lobe. So there is the pattern that every one of them had, but they all were a little different too. They had other sorts of brain damage. A key thing is that the major violence genes, it's called the MAO-A gene.
這就是我們研究的主要方向。而我們所發現的規律就是這些人，我檢查過的每一個人， 每一個殺人兇手，每一個連環殺手， 都在大腦的額眶部皮質有所損傷， 就在眼睛、眼眶的正上方。再有就是太陽穴的內側。所以他們這些人之間是有規律可尋的。但彼此之間有稍微有點不同。他們也有其他類型的腦損傷。重點就在於 最主要的暴力基因 被稱作為MAO-A基因。
And there is a variant of this gene that is in the normal population. Some of you have this. And it's sex-linked. It's on the X chromosome. And so in this way you can only get it from your mother. And in fact this is probably why mostly men, boys, are psychopathic killers, or are very aggressive. Because a daughter can get one X from the father, one X from the mother, it's kind of diluted out. But for a son, he can only get the X chromosome from his mother.
正常人群中是有這個基因的變種。你們中的一些人就有這個變種。它是跟性別有關的。是在X染色體上。正因為如此， 你只能從你母親那裡遺傳這個基因。事實上，這也許就是為什麼男人、男孩更有可能成為心理變態的殺人兇手， 變得非常有暴力傾向。因為女兒還是可以從爸爸那裡得到一個X染色體， 從媽媽那裡得到另一個，所以總體上的效果就好像被抵消了一樣。但如果是個兒子的話， 他就只能從媽媽那裡得到一個X染色體。
So this is how it's passed from mother to son. And it has to do with too much brain serotonin during development, which is kind of interesting because serotonin is supposed to make you calm and relaxed. But if you have this gene, in utero your brain is bathed in this, so your whole brain becomes insensitive to serotonin, so it doesn't work later on in life.
這就是它如何從母親傳到兒子的。它也跟成長過程中分泌的血清素有關。這其實是挺有趣的現象， 因為血清素本該讓你平靜放鬆下來。但如果你擁有這個基因，在母體裡的時候你的大腦就是整個沉浸在血清素之中。所以你的整個大腦都對血清素麻木了。正因此，在你隨後的生命中，它就起不到它應有的作用。
And I'd given this one talk in Israel, just this past year. And it does have some consequences. Theoretically what this means is that in order to express this gene, in a violent way, very early on, before puberty, you have to be involved in something that is really traumatic — not a little stress, not being spanked or something, but really seeing violence, or being involved in it, in 3D. Right? That's how the mirror neuron system works.
我之前在以色列給過這個演講， 就在去年。而這項研究發現確實有著深遠的影響。因為從理論上來講， 若想讓這個基因發揮其作用， 引發暴力， 那麼在很早的時候，在青春期之前， 你就必須經歷一些非常慘痛的事情， 不只是一點小小的壓力，不只是被打屁股這麼簡單， 而是真正目睹暴力， 或者是置身其中。這就是鏡像神經元系統的工作原理，對吧？
And so, if you have that gene, and you see a lot of violence in a certain situation, this is the recipe for disaster, absolute disaster. And what I think might happen in these areas of the world, where we have constant violence, you end up having generations of kids that are seeing all this violence. And if I was a young girl, somewhere in a violent area, you know, a 14 year old, and I want to find a mate, I'd find some tough guy, right, to protect me. Well what the problem is this tends to concentrate these genes. And now the boys and the girls get them. So I think after several generations, and here is the idea, we really have a tinderbox.
這樣一來，如果你有那個基因， 而又在某個場合下目睹了大量的暴力， 那麼災難就會產生，絕對的災難。而我覺得在這些長期被暴力籠罩的區域， 很有可能發生的就是 一代又一代的孩子目睹著周邊的一切暴力。假如我是一個小女生，生活在某個暴力的地區， 14歲，想找個伴侶， 我當然是會找一個非常強壯的男生，來保護我。這樣一來，問題就產生了，因為這些基因被聚集到了一起。他們的兒子和女兒也因此會遺傳這些基因。所以我覺得幾代過後， 我們真的就有了個引發暴亂的根源。
So that was the idea. But then my mother said to me, "I hear you've been going around talking about psychopathic killers. And you're talking as if you come from a normal family." I said, "What the hell are you talking about?" She then told me about our own family tree. Now she blamed this on my father's side, of course. This was one of these cases, because she has no violence in her background, but my father did.
主要的概念就是這樣。但有一天我母親對我說道：“我聽說你到處進行演講， 討論心理變態的殺人狂， 聽起來你好像來自一個正常家庭一樣。” 我說道：“ 你到底在講什麼鬼？” 她隨後就告訴了我們自己的家庭史。當然了，她現在是把一切都歸咎在我爸爸那邊。這算得上是案例之一，因為她的家族史是沒有什麼暴力傾向的， 但我父親那邊卻有。
Well she said, "There is good news and bad news. One of your cousins is Ezra Cornell, founder of Cornell university. But the bad news is that your cousin is also Lizzie Borden.
她說：“我有一個好消息還有一個壞消息。埃茲拉-康奈爾，康奈爾大學的創辦者，是你的表兄。
Now I said, "Okay, so what? We have Lizzie."
但壞消息是利茲-伯頓是你的表姐。” 我回答到：“那又怎樣呢？利茲是我的親戚。”
She goes, "No it gets worse, read this book."
她說：“事情比這糟糕。讀讀這本書。”
And here is this "Killed Strangely," and it's this historical book. And the first murder of a mother by a son was my great-great-great-great-great-great-grandfather. Okay, so that's the first case of matricide. And that book is very interesting. Because it's about witch trials, and how people thought back then.
就是這本書，叫做《離奇謀殺》，是本記錄歷史的書。裡面記載的第一樁謀殺， 是一個兒子殺害母親的案件， 而犯案者就是我的曾曾曾曾曾祖父。那就是第一起殺母案。這本書其實非常有趣。它講述了巫女審判， 還有那時候人們的想法。
But it doesn't stop there. There were seven more men, on my father's side, starting then, Cornells, that were all murderers. Okay, now this gives one a little pause. (Laughter) Because my father himself, and my three uncles, in World War II, were all conscientious objectors, all pussycats. But every once in a while, like Lizzie Borden, like three times a century, and we're kind of due. (Laughter)
但它不單單僅此而已。在我父親那邊，還有七位男士， 都是康奈爾家族的人，都是殺人兇手。這就讓人不得不倒吸口冷氣了。 因為我老爸他自己， 還有我三個叔伯，在二戰的時候 都是反戰主義者，都是很溫和的。但我們家族隔三岔五，就會出現一個像利茲-伯頓這號人物，大概每100年出現三次， 現在差不多該輪到我們這一輩了。
So the moral of the story is: people in glass houses shouldn't throw stones. But more likely is this. (Laughter) And we had to take action. Now our kids found out about it. And they all seemed to be OK. But our grandkids are going to be kind of concerned here. So what we've done is I've started to do PET scans of everybody in the family. (Laughter) We started to do PET scans, EEGs and genetic analysis to see where the bad news is. Now the only person — it turns out one son and one daughter, siblings, didn't get along and their patterns are exactly the same. They have the same brain, and the same EEG. And now they are close as can be. But there's gonna be bad news somewhere. And we don't know where it's going to pop up. So that's my talk. (Laughter)
所以教訓就是：居住玻璃屋者不宜以石擲人。但真正的教訓是：我不管這個世界對我有多瞭解，只要我老媽不知道就好。我們家人不得不做點什麼。我們的孩子們也是得知了這些情況。他們看上去還不錯。但我們的孫子一輩則是需要格外注意的一輩。所以我開始為家裡面的每個人做大腦掃描。我們已經開始做腦掃描，腦電圖，基因分析， 來查明問題將會出現在哪裡。結果唯一有問題的 是一對兄妹，曾經合不來。他們的圖象是完全一樣。同樣的大腦，同樣的腦電圖。但他們現在卻是親密無間。可是我們知道肯定在某個地方有問題， 只不過我們不確定問題將會出現在哪裡。
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