TED日本語 - ヘレン・フィッシャー: 恋する脳

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TED日本語 - ヘレン・フィッシャー: 恋する脳

TED Talks

恋する脳
The brain in love
ヘレン・フィッシャー
Helen Fisher

内容

時には命をも掛けて、なぜ人間はこうも恋を切望するのでしょうか。非常にリアルで、人間の身体的欲求である恋愛。その謎を解き明かすべく、ヘレン・フィッシャー(Hele-n Fisher) および調査チームは恋愛中の人、失恋したばかりの人を集め、MRIスキャナ(磁気共鳴-画像装置)で脳を検査しました。

Script

I and my colleagues Art Aron and Lucy Brown and others, have put 37 people who are madly in love into a functional MRI brain scanner. 17 who were happily in love,15 who had just been dumped, and we're just starting our third experiment: studying people who report that they're still in love after 10 to 25 years of marriage. So, this is the short story of that research.

In the jungles of Guatemala, in Tikal, stands a temple. It was built by the grandest Sun King, of the grandest city-state, of the grandest civilization of the Americas, the Mayas. His name was Jasaw Chan K'awiil. He stood over six feet tall. He lived into his 80s, and he was buried beneath this monument in 720 AD. And Mayan inscriptions proclaim that he was deeply in love with his wife. So, he built a temple in her honor, facing his. And every spring and autumn, exactly at the equinox, the sun rises behind his temple, and perfectly bathes her temple with his shadow. And as the sun sets behind her temple in the afternoon, it perfectly bathes his temple with her shadow. After 1,300 years, these two lovers still touch and kiss from their tomb.

Around the world, people love. They sing for love, they dance for love, they compose poems and stories about love. They tell myths and legends about love. They pine for love, they live for love, they kill for love, and they die for love. As Walt Whitman once said, he said, "Oh, I would stake all for you." Anthropologists have found evidence of romantic love in 170 societies. They've never found a society that did not have it.

But love isn't always a happy experience. In one study of college students, they asked a lot of questions about love, but the two that stood out to me the most were, "Have you ever been rejected by somebody who you really loved?" And the second question was, "Have you ever dumped somebody who really loved you?" And almost 95 percent of both men and women said yes to both. Almost nobody gets out of love alive.

So, before I start telling you about the brain, I want to read for you what I think is the most powerful love poem on Earth. There's other love poems that are, of course, just as good, but I don't think this one can be surpassed. It was told by an anonymous Kwakiutl Indian of southern Alaska to a missionary in 1896, and here it is. I've never had the opportunity to say it before. "Fire runs through my body with the pain of loving you. Pain runs through my body with the fires of my love for you. Pain like a boil about to burst with my love for you, consumed by fire with my love for you. I remember what you said to me. I am thinking of your love for me. I am torn by your love for me. Pain and more pain -- where are you going with my love? I am told you will go from here. I am told you will leave me here. My body is numb with grief. Remember what I said, my love. Goodbye, my love, goodbye." Emily Dickinson once wrote, "Parting is all we need to know of hell." How many people have suffered in all the millions of years of human evolution? How many people around the world are dancing with elation at this very minute? Romantic love is one of the most powerful sensations on Earth.

So, several years ago, I decided to look into the brain and study this madness. Our first study of people who were happily in love has been widely publicized, so I'm only going to say a very little about it. We found activity in a tiny, little factory near the base of the brain called the ventral tegmental area. We found activity in some cells called the A10 cells, cells that actually make dopamine, a natural stimulant, and spray it to many brain regions. Indeed, this part, the VTA, is part of the brain's reward system. It's way below your cognitive thinking process. It's below your emotions. It's part of what we call the reptilian core of the brain, associated with wanting, with motivation, with focus and with craving. In fact, the same brain region where we found activity becomes active also when you feel the rush of cocaine.

But romantic love is much more than a cocaine high -- at least you come down from cocaine. Romantic love is an obsession. It possesses you. You lose your sense of self. You can't stop thinking about another human being. Somebody is camping in your head. As an eighth-century Japanese poet said, "My longing had no time when it ceases." Wild is love. And the obsession can get worse when you've been rejected.

So, right now, Lucy Brown and I, the neuroscientist on our project, are looking at the data of the people who were put into the machine after they had just been dumped. It was very difficult actually, putting these people in the machine, because they were in such bad shape. (Laughter) So anyway, we found activity in three brain regions. We found activity in the brain region, in exactly the same brain region associated with intense romantic love. What a bad deal. You know, when you've been dumped, the one thing you love to do is just forget about this human being, and then go on with your life -- but no, you just love them harder. As the poet Terence, the Roman poet once said, he said, "The less my hope, the hotter my love." And indeed, we now know why. Two thousand years later, we can explain this in the brain. That brain system -- the reward system for wanting, for motivation, for craving, for focus -- becomes more active when you can't get what you want. In this case, life's greatest prize: an appropriate mating partner.

We found activity in other brain regions also -- in a brain region associated with calculating gains and losses. You know, you're lying there, you're looking at the picture, and you're in this machine, and you're calculating, you know, what went wrong. How, you know, what have I lost? As a matter of fact, Lucy and I have a little joke about this. It comes from a David Mamet play, and there's two con artists in the play, and the woman is conning the man, and the man looks at the woman and says, "Oh, you're a bad pony, I'm not going to bet on you." And indeed, it's this part of the brain, the core of the nucleus accumbens, actually, that is becoming active as you're measuring your gains and losses. It's also the brain region that becomes active when you're willing to take enormous risks for huge gains and huge losses.

Last but not least, we found activity in a brain region associated with deep attachment to another individual. No wonder people suffer around the world, and we have so many crimes of passion. When you've been rejected in love, not only are you engulfed with feelings of romantic love, but you're feeling deep attachment to this individual. Moreover, this brain circuit for reward is working, and you're feeling intense energy, intense focus, intense motivation and the willingness to risk it all to win life's greatest prize.

So, what have I learned from this experiment that I would like to tell the world? Foremost, I have come to think that romantic love is a drive, a basic mating drive. Not the sex drive -- the sex drive gets you out there, looking for a whole range of partners. Romantic love enables you to focus your mating energy on just one at a time, conserve your mating energy, and start the mating process with this single individual. I think of all the poetry that I've read about romantic love, what sums it up best is something that is said by Plato, over 2,000 years ago. He said, "The god of love lives in a state of need. It is a need. It is an urge. It is a homeostatic imbalance. Like hunger and thirst, it's almost impossible to stamp out." I've also come to believe that romantic love is an addiction: a perfectly wonderful addiction when it's going well, and a perfectly horrible addiction when it's going poorly.

And indeed, it has all of the characteristics of addiction. You focus on the person, you obsessively think about them, you crave them, you distort reality, your willingness to take enormous risks to win this person. And it's got the three main characteristics of addiction: tolerance, you need to see them more, and more, and more; withdrawals; and last, relapse. I've got a girlfriend who's just getting over a terrible love affair. It's been about eight months, she's beginning to feel better. And she was driving along in her car the other day, and suddenly she heard a song on the car radio that reminded her of this man. And she -- not only did the instant craving come back, but she had to pull over from the side of the road and cry. So,one thing I would like the medical community, and the legal community, and even the college community, to see if they can understand, that indeed, romantic love is one of the most addictive substances on Earth.

I would also like to tell the world that animals love. There's not an animal on this planet that will copulate with anything that comes along. Too old, too young, too scruffy, too stupid, and they won't do it. Unless you're stuck in a laboratory cage -- and you know, if you spend your entire life in a little box, you're not going to be as picky about who you have sex with -- but I've looked in a hundred species, and everywhere in the wild, animals have favorites. As a matter of fact ethologists know this. There are over eight words for what they call "animal favoritism:" selective proceptivity, mate choice, female choice, sexual choice. And indeed, there are now three academic articles in which they've looked at this attraction, which may only last for a second, but it's a definite attraction, and either this same brain region, this reward system, or the chemicals of that reward system are involved. In fact, I think animal attraction can be instant -- you can see an elephant instantly go for another elephant. And I think that this is really the origin of what you and I call "love at first sight."

People have often asked me whether what I know about love has spoiled it for me. And I just simply say, "Hardly." You can know every single ingredient in a piece of chocolate cake, and then when you sit down and eat that cake, you can still feel that joy. And certainly, I make all the same mistakes that everybody else does too, but it's really deepened my understanding and compassion, really, for all human life. As a matter of fact, in New York, I often catch myself looking in baby carriages and feeling a little sorry for the tot. And in fact, sometimes I feel a little sorry for the chicken on my dinner plate, when I think of how intense this brain system is. Our newest experiment has been hatched by my colleague, Art Aron -- putting people who are reporting that they are still in love, in a long-term relationship, into the functional MRI. We've put five people in so far, and indeed, we found exactly the same thing. They're not lying. The brain areas associated with intense romantic love still become active,25 years later.

There are still many questions to be answered and asked about romantic love. The question that I'm working on right this minute -- and I'm only going to say it for a second, and then end -- is, why do you fall in love with one person, rather than another? I never would have even thought to think of this, but Match.com, the Internet-dating site, came to me three years ago and asked me that question. And I said, I don't know. I know what happens in the brain, when you do become in love, but I don't know why you fall in love with one person rather than another. And so, I've spent the last three years on this. And there are many reasons that you fall in love with one person rather than another, that psychologists can tell you. And we tend to fall in love with somebody from the same socioeconomic background, the same general level of intelligence, the same general level of good looks, the same religious values. Your childhood certainly plays a role, but nobody knows how. And that's about it, that's all they know. No, they've never found the way two personalities fit together to make a good relationship.

So, it began to occur to me that maybe your biology pulls you towards some people rather than another. And I have concocted a questionnaire to see to what degree you express dopamine, serotonin, estrogen and testosterone. I think we've evolved four very broad personality types associated with the ratios of these four chemicals in the brain. And on this dating site that I have created, called Chemistry.com, I ask you first a series of questions to see to what degree you express these chemicals, and I'm watching who chooses who to love. And 3.7 million people have taken the questionnaire in America. About 600,000 people have taken it in 33 other countries. I'm putting the data together now, and at some point -- there will always be magic to love, but I think I will come closer to understanding why it is you can walk into a room and everybody is from your background, your same general level of intelligence, your same general level of good looks, and you don't feel pulled towards all of them. I think there's biology to that. I think we're going to end up, in the next few years, to understand all kinds of brain mechanisms that pull us to one person rather than another.

So, I will close with this. These are my older people. Faulkner once said, "The past is not dead, it's not even the past." Indeed, we carry a lot of luggage from our yesteryear in the human brain. And so, there's one thing that makes me pursue my understanding of human nature, and this reminds me of it. These are two women. Women tend to get intimacy differently than men do. Women get intimacy from face-to-face talking. We swivel towards each other, we do what we call the "anchoring gaze" and we talk. This is intimacy to women. I think it comes from millions of years of holding that baby in front of your face, cajoling it, reprimanding it, educating it with words. Men tend to get intimacy from side-by-side doing. (Laughter) As soon as one guy looks up, the other guy will look away. (Laughter) I think it comes from millions of years of standing behind that -- sitting behind the bush, looking straight ahead, trying to hit that buffalo on the head with a rock. (Laughter) I think, for millions of years, men faced their enemies, they sat side by side with friends. So my final statement is: love is in us. It's deeply embedded in the brain. Our challenge is to understand each other. Thank you. (Applause)

同僚のアート アロンとルーシー ブラウンと共に MRIスキャナで 熱愛中の37人を検査しました 17人はラブラブ 15人は振られたばかり また 3度目の実験を始めたばかりですが 結婚生活を10年から25年経て 今も恋をしている人の研究も行っています 今日は そのリサーチの話をします

グァテマラのジャングル ティカルに寺院があります 建設したのは 偉大な太陽の王 壮大な国家都市 北南米で最も偉大な文明 マヤの王 王の名はハサウ チャン カウィール 180センチ以上の長身で 80代まで生き― 紀元720年 この遺跡に葬られました マヤ碑文によると 王は妻にベタ惚れで 彼の神殿に面して 妻の神殿を建設 毎年 ちょうど春分と秋分の日 王の神殿側に日が昇ると 彼の影が 妻の神殿を優しく撫で 妻の神殿側に日が沈むと 妻の影が 王の神殿を優しく撫でる 1300年の時を越えた今も 2人は石碑越しに 抱擁し くちづけを交わしています

世界中で 人々は恋をし 恋に歌い 恋に踊ります 愛の詩や物語を書き 恋の神話や伝説を語る 恋に恋焦がれ 恋の為に生きます 人を殺め 死まで選びます ウォルト・ホイットマンの言葉 “君のためなら全てを賭けてもいい” 人類学者は 170ヶ国にて 恋愛の存在を確認 どの社会にも 例外なく存在します

でも 恋は常に幸せなものではありません ある大学生が 研究で 恋に関する質問を沢山しました その中で印象に残った2つが “愛する人に振られた事がありますか” もう1つが “自分を愛する人を振った事がありますか” ほぼ95%の男女が両方に Yesと答えています つまり 恋はほぼ実らないものだと....

脳について話す前に 少し朗読します 地球上で最もパワフルな愛の詩です 優れた詩は沢山ありますが 勝る詩はないと思います 南アラスカの クワキウトル族インディアンが 1896年 伝道者に聞かせました 公の場で初めて読みます “炎のような愛の痛み 愛の炎が痛みとなって体中を駆け巡る 貴方への愛で 心は張り裂け 貴方への愛で 火傷する 貴方の言葉を覚えてる 貴方の愛を思う 貴方の愛が心を裂く 私の愛を連れて 貴方はどこへ さらなる痛み 貴方が 旅立つと聞いた 私を置いていくと 悲しみで感覚を失う 私の言葉を忘れないで さよなら 愛しい人 さようなら ” エミリー・ディキンソンの言葉 “別れさえ経験すれば 地獄が分かる” 人類が進化してきた中で どれだけの人が苦しんだでしょう? どれだけの人々が この地球で たった今 歓喜に踊っているでしょう? 恋愛は 最もパワフルな感覚のひとつ

そこで数年前 研究を始めました 脳と恋の狂気についてです 幸せな恋愛の研究は公表済みなので 詳細は省いてお話します 脳底付近にある 腹側被蓋野と呼ばれる領域で A10細胞群が 活発になっていることを発見しました 天然興奮剤 ドーパミンを作る細胞で ドーパミンを脳に放出します 腹側被蓋野は脳の報酬系の一部で 認知思考処理のずっと深部 感情よりも下部にあります 爬虫類脳と呼ばれる一部で 欲望 やる気 集中力 切望に― 関係する領域です コカインでハイになると 同じ領域が活発になります

恋愛はコカインのハイ状態を勝ります コカインだと恍惚感は一時的ですからね 恋愛は執着で 人を支配します 自分を失い 相手の事を考えずにいられない 頭の中に誰かが居座ってます 8世紀 日本の歌人が言いました ”我が恋やまめ命死なずは” 恋は狂気 振られると執着心は悪化します

現在 神経科学者の ルーシー ブラウンと共に 振られて間もない人の 検査結果を 研究しています この人達を スキャンにかけるのは 大変でした みなさんボロボロですから(笑) とにかく 脳の3領域に 活動が見られました 激しい恋愛と関連のある― 脳の領域です ひどい仕打ちです 失恋したときは 相手のことを忘れて 暮らしていきたいもの なのに いっそう愛してしまう ローマの詩人 テレンスの言葉 “望みが低いほど燃える” その理由は解明されました 2千年経った今 説明がつきます 欲望 やる気 切望 集中力などの 脳の報酬系は 手に入らないと さらに活動的になるのです この場合 人生最大のプライズとは― 最適な交配相手です

他の領域でも活動を発見 損得計算に関連する脳領域です 脳スキャナの中で 絵を眺めながら 何が悪かったのか 何を失ったのかと あれこれ計算する ルーシーと笑い話をすることがあります デビット・マメットの演劇の中で 2人のえせ芸術家がおり 女性が一人をたぶらかします 男は女性に言う ”お前は悪い子馬だ お前には賭けないね” 損得勘定をするとき 脳の坐核側と呼ばれる部分が 活動し始めます 大きな損得を賭けて 危険を冒すときも 同じ脳領域が活動します

他人への深い愛着と関連する― 脳の領域にも活動を確認しました 世界中で人が苦しむのも 不思議でありません 情熱からくる犯罪も多いわけです 失恋すると 恋愛感情に苛まれるだけでなく 深い愛着心を感じます 脳回路は報酬のために活動し 強い活力 集中力 動機 危険を冒す気力まで込み上げてきます 人生最大のプライズを得るためです

この実験から学んだこと 世界に伝えたいことはですね まず思いました 恋愛は欲動であり 交配欲望だと 性欲ではない 性交相手の標的は広いが 恋愛だと 標的は一度に一人 交配精力を他者に浪費せず 一人の相手と交配行為を始めます 今まで読んだ愛の詩で 最もうまく要約してるのが2千年前の プラトンの言葉だと思います “愛の神は必要性があり存在する 要求であり 本能的 恒久性なアンバランスであり 空腹と口渇のように 根絶は不可能に近い” また 恋愛は中毒性を伴うと思います 順調なときは素敵な中毒 悪くなると 悪夢のような中毒

事実 中毒のあらゆる症状が確認できます 一人に神経を集中し 執拗にその人を思います 切望し 現実を歪め 獲得には危険をも負う 中毒の主症状が3つ見られます 忍耐- もっと会いたい 会わずにはいられない 離脱 そして 再発 失恋から立ち直ろうとしてる女友達がいます かれこれ8ヶ月になります 先日 彼女は車を運転中 ある歌をラジオで 聴いて 突然 彼のことを思い出しました 彼への切望が戻ってきただけでなく 車を路肩に止め 泣き崩れずにはいれませんでした ですから 医学界や 法曹界や 大学の教育界に 恋愛が極めて中毒的な物質だと― 理解してほしい

また 動物にだって愛情はあるのです 地球上の動物で 見境なく交配を行う種はいません 相手に魅力を感じなければ 交尾はしません 実験室に隔離されるなら話は別です 仮に 窮屈な檻の中で一生過ごせば それほど性交相手を選り好みしないでしょう 百種以上の生物を観察しましたが どの動物にも好みがあります 動物行動学者は知っています “動物の偏愛”には 8項目以上の趣向があり 求愛相手趣向や交尾相手選択 雌選択や性選択 事実 この引力に注目した― 3つの学術論があります 引力は数秒で消えますが 確実に 恋の引力です 恐らく 報酬系脳領域に関係するか― 報酬系物質に関わるのでしょう 動物の引力は瞬間的だと思います 象が一瞬で別の象に求愛する例もある これが まさに “一目惚れ”の原型だと思うのです

恋愛の研究をしていて 私生活でマイナスがあったかと よく聞かれます ないと答えます チョコレートケーキの材料は全部分かります それでも 座って食べてみると ケーキはやっぱり美味しいものです それに 私も他の人と 同じように失敗をします ただ 人に対する理解と 思いやりが深まりました 脳システムの奮闘を考えると ベビーカーの中の幼児を眺め ときどき 同情を感じます 夕食のチキンが 不憫に思えたりもします 同僚のアート・アーロンのアイデアで始まった― 新しい実験も進行中です 長い付き合いで 今も恋心があると言う人を MRIスキャナで検査する実験です すでに 5名検査しましたが 結果は同じ 彼らの恋心は偽りではありません 激しい恋愛と関連する― 脳の領域に 25年経った今も 活動がありました

恋愛に関しては まだまだ 明かされていない答えや問いはあります 進行中の研究は 簡単に述べるに留めますが なぜ 多数の中から "その人"に恋するか です 考えたことがなかったのですが 3年前 ある出会いサイトが 私に この質問をしてきました 分からないと答えました 恋に落ちたときの脳の活動は分かりますが なぜ "その人" なのか― 理由は分かりません この3年間それについて研究してきました 1人に恋する理由は無数です 心理学者も同意 傾向としては 同じ社会経済的背景 同レベルの知性 同レベルの外見や 宗教的価値などの一致が挙げられます 子供時代も何らかの形で影響します でも分かるのは その程度 相性が合う性格パターンなどの 確定には辿り着いていません

そこで思い始めました 恐らく 生物学的に ある種の人に惹かれるのではないかと そこでアンケートを作り 物質の発生度を観察 ドーパミン セロトニン エストロゲン テストステロンです 脳内の4物質の比率と関連する 4種のおおまかな性格を考案しました 私の作った出会いサイト Chemistry.comで まずアンケートを取り この4物質の発生度合いや 恋愛相手の選択傾向を観察してます 米国で370万人がアンケートに回答 33カ国で60万人に回答いただきました 現在 データ集計中 恋には常に魔法があるでしょうが 確信に近づいてきています ある会場を訪れるとします 誰もが 同じ社会背景を持ち 同じ知性レベル 外見レベル なのに全員に魅了されるわけではない 生物学的なものがあるでしょう なぜ特定の人に魅了されるのか― あと数年で あらゆる脳の仕組みが 理解できると思います

そろそろ締めくくります この写真は年配の協力者 フォークナーの言葉 “過去は死んでない 過去ですらない” 事実 人間は脳内に長年の 荷物を背負って生きています 人間の本質を 理解したいと 私を突き動かす理由は この写真が表しています 2人の女性 女性の親密さは男性とは異なり 対面での会話 向かい合わせで親近感を感じます 目を離さず注視して話します それが 女性にとっての親近感 何百万年も前から 顔の傍で幼児をあやし なだめ 叱り 言葉で教育してきたせいでしょう 男性は 横並びで親近感を感じます (笑) 1人がそっちを向くと もう1人は別方向を見る (笑) 何百万年も前から 木の茂みで立ったり座ったり まっすぐ前を向き 石を片手に 水牛を追ってきたからでしょう (笑) 古代から 男性は敵と直面し 友人とは横並びで座ってきた 最後に 愛は人の中に息づいてます 脳内に深く組み込まれてます 私たちの課題は お互いを理解することです ありがとう (拍手)

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