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  • We humans have always been very concerned about the health of our bodies,

    誰でも常に健康に関心がありますが

  • but we haven't always been that good at figuring out what's important.

    今まで必ずしも何が大切なのか 理解していたとは限りません

  • Take the ancient Egyptians, for example:

    例えば古代エジプトを見ると

  • very concerned about the body parts they thought they'd need in the afterlife,

    死後の世界に必要だと思われた 体の部分はとても大事に扱われ

  • but they left some parts out.

    その一方ある部分は除外されました

  • This part, for example.

    つまり

  • Although they very carefully preserved the stomach, the lungs,

    胃 肺 肝臓などは

  • the liver, and so forth,

    注意深く保存されましたが

  • they just mushed up the brain, drained it out through the nose,

    脳は潰され鼻から抽出され

  • and threw it away,

    捨てられていました

  • which makes sense, really,

    確かに

  • because what does a brain do for us anyway?

    脳は一体何の役に立つと言うのでしょう

  • But imagine if there were a kind of neglected organ in our bodies

    しかし脳程の重さで 我々自身ともいえる

  • that weighed just as much as the brain

    重要な臓器が我々の体に

  • and in some ways was just as important to who we are,

    他にあるでしょうか

  • but we knew so little about and treated with such disregard.

    なのに 知られている事も関心も 殆どありませんでした

  • And imagine if, through new scientific advances,

    しかし新しい科学の進歩で

  • we were just beginning to understand

    ヒトの理解に役立つ

  • its importance to how we think of ourselves.

    重要な事柄が 分かり始めて来たばかりだとしたら

  • Wouldn't you want to know more about it?

    もっと それについて 知りたいと思いませんか

  • Well, it turns out that we do have something just like that:

    実はその脳に似た物が 他にもあるのです

  • our gut,

    我々の腸です

  • or rather, its microbes.

    腸内の微生物と 言った方がいいでしょう

  • But it's not just the microbes in our gut that are important.

    でも大切なのは 腸内微生物だけではありません

  • Microbes all over our body

    体内外の微生物が

  • turn out to be really critical to a whole range of differences

    広範囲に渡り影響を及ぼし 大きく健康を左右していることが

  • that make different people who we are.

    分かってきました

  • So for example, have you ever noticed

    その例として

  • how some people get bitten by mosquitos way more often than others?

    蚊に刺され易い人がいる事に 気付かれた事がありますか

  • It turns out that everyone's anecdotal experience out camping is actually true.

    誰でも同じような経験がキャンプでありますね

  • For example, I seldom get bitten by mosquitos,

    私自身あまり蚊に刺される事はありませんが

  • but my partner Amanda attracts them in droves,

    私の妻アマンダには蚊の大群が寄ってきます

  • and the reason why is that we have different microbes on our skin

    その理由は人それぞれ 皮膚には異なる微生物が

  • that produce different chemicals that the mosquitos detect.

    固有の化学物質を 分泌しているからです

  • Now, microbes are also really important in the field of medicine.

    微生物は医療の分野でも とても重要です

  • So, for example, what microbes you have in your gut

    一例として腸内微生物は

  • determine whether particular painkillers are toxic to your liver.

    肝臓に対し毒性を持つ鎮痛剤や

  • They also determine whether or not other drugs will work for your heart condition.

    心臓病に効く薬を判断します

  • And, if you're a fruit fly, at least,

    そして あなたがミバエなら

  • your microbes determine who you want to have sex with.

    あなたのパートナーは あなたの微生物に決められます

  • We haven't demonstrated this in humans yet

    これはヒトでは検証されていませんが

  • but maybe it's just a matter of time before we find out. (Laughter)

    それが分かるのは時間の問題でしょう (笑)

  • So microbes are performing a huge range of functions.

    このように微生物は 広範囲に渡り活動しています

  • They help us digest our food.

    食物を消化したり

  • They help educate our immune system.

    免疫系に働きかけ

  • They help us resist disease,

    病気に対抗したりし

  • and they may even be affecting our behavior.

    また我々の行動にさえも影響を及ぼします

  • So what would a map of all these microbial communities look like?

    では微生物叢(そう)の分布図とは どんなものでしょうか

  • Well, it wouldn't look exactly like this,

    全くこれと同じではないでしょうが

  • but it's a helpful guide for understanding biodiversity.

    生物学的多様性を理解するには 助けとなる手段となります

  • Different parts of the world have different landscapes of organisms

    固有の様態をした有機体が

  • that are immediately characteristic of one place or another

    世界中その土地土地にいて それが直接その地の

  • or another.

    特性となります

  • With microbiology, it's kind of the same, although I've got to be honest with you:

    微生物学でも同じ様な事が言えますが

  • All the microbes essentially look the same under a microscope.

    正直言って 顕微鏡の下では 微生物は本質的に皆似ているので

  • So instead of trying to identify them visually,

    様相から識別するのでなく

  • what we do is we look at their DNA sequences,

    ヒト微生物のDNA配列を

  • and in a project called the Human Microbiome Project,

    ヒト微生物叢プロジェクト と呼ばれるプロジェクトで

  • NIH funded this $173 million project

    NIHから1億7300万ドルの 支援を受け研究しています

  • where hundreds of researchers came together

    何百人もの研究者が集まり

  • to map out all the A's, T's, G's, and C's,

    ヒト微生物全ての

  • and all of these microbes in the human body.

    ATGC配列を読み取り

  • So when we take them together, they look like this.

    集めて見てみるとこんな感じです

  • It's a bit more difficult to tell who lives where now, isn't it?

    どれがどれだか ちょっと見分けがつきませんね

  • What my lab does is develop computational techniques that allow us

    我々が開発した計算技法で

  • to take all these terabytes of sequence data

    テラバイトの配列データ全てを

  • and turn them into something that's a bit more useful as a map,

    マップとしてもっとよく使える様にし

  • and so when we do that with the human microbiome data

    250人の健康なボランティアから採った

  • from 250 healthy volunteers,

    ヒト微生物叢のデータを用い作ったものが

  • it looks like this.

    この様になります

  • Each point here represents all the complex microbes

    図の一点ずつが複雑な微生物の集合体

  • in an entire microbial community.

    微生物叢を表します

  • See, I told you they basically all look the same.

    言った通り どれも似ているでしょう

  • So what we're looking at is each point represents one microbial community

    1つの点が 健康な人体の1カ所から採取された

  • from one body site of one healthy volunteer.

    微生物叢を表しています

  • And so you can see that there's different parts of the map in different colors,

    様々な色がその箇所毎に個々の大陸を作って

  • almost like separate continents.

    地図を作っているかの様です

  • And what it turns out to be

    これで分かることは

  • is that those, as the different regions of the body,

    体の箇所により非常に

  • have very different microbes in them.

    微生物叢が異なるという事です

  • So what we have is we have the oral community up there in green.

    緑色は口腔の

  • Over on the other side, we have the skin community in blue,

    その反対側の青色は皮膚の

  • the vaginal community in purple,

    紫色は膣内の

  • and then right down at the bottom, we have the fecal community in brown.

    そして下の茶色の塊は 糞便の微生物叢を表しています

  • And we've just over the last few years

    そしてこの数年

  • found out that the microbes in different parts of the body

    体の部分により 微生物叢には信じられない程の

  • are amazingly different from one another.

    多様性がある事が分かりました

  • So if I look at just one person's microbes

    たった1人の口や腸内の

  • in the mouth and in the gut,

    微生物を見ただけでも

  • it turns out that the difference between those two microbial communities

    その2組の微生物叢の違いは

  • is enormous.

    とてつもなく

  • It's bigger than the difference between the microbes in this reef

    この珊瑚礁と草原の微生物叢の違いより

  • and the microbes in this prairie.

    著しいのです

  • So this is incredible when you think about it.

    そう考えると すごい事なんです

  • What it means is that a few feet of difference in the human body

    60センチ離れただけで人体の 微生物生態系は大きく変わり

  • makes more of a difference to your microbial ecology

    その相違は地球上何千キロ行っても

  • than hundreds of miles on Earth.

    あり得ない程の膨大さなのです

  • And this is not to say that two people look basically the same

    そして 同じヒトだからといって 我々の微生物の生態系は

  • in the same body habitat, either.

    皆同じだという訳ではありません

  • So you probably heard

    多分ご存知だと思いますが

  • that we're pretty much all the same in terms of our human DNA.

    遺伝子学的に言って 私たちは皆似ています

  • You're 99.99 percent identical in terms of your human DNA

    ヒトDNAから見ると私たちは99.9%

  • to the person sitting next to you.

    隣にいる人と同じですが

  • But that's not true of your gut microbes:

    微生物学的にはそうではなく

  • you might only share 10 percent similarity

    隣に座っている人とあなたは

  • with the person sitting next to you in terms of your gut microbes.

    同じ微生物を10%共有するかしないかです

  • So that's as different as the bacteria on this prairie

    それが この草原や森のバクテリアと

  • and the bacteria in this forest.

    ヒトのそれとの違いです

  • So these different microbes

    この違いが

  • have all these different kinds of functions that I told you about,

    今話した様な種々の機能—

  • everything from digesting food

    食物の消化から

  • to involvement in different kinds of diseases,

    あらゆる病気や薬物の代謝—

  • metabolizing drugs, and so forth.

    などに関与してきます

  • So how do they do all this stuff?

    どうして 微生物にこんな事が できるのでしょう?

  • Well, in part it's because

    その理由の一部は

  • although there's just three pounds of those microbes in our gut,

    私たちのお腹にいる 1.4キロ程の微生物の数が

  • they really outnumber us.

    人の数を凌いでいるからです

  • And so how much do they outnumber us?

    どれ程人を凌いでいるかと言うと

  • Well, it depends on what you think of as our bodies.

    比較するには地球上の人口では間に合いません

  • Is it our cells?

    細胞と比べてはどうでしょう

  • Well, each of us consists of about 10 trillion human cells,

    人体は約10兆程のヒト細胞で成っていますが

  • but we harbor as many as 100 trillion microbial cells.

    宿している微生物細胞の数は100兆で

  • So they outnumber us 10 to one.

    ヒト細胞数の10倍です

  • Now, you might think, well, we're human because of our DNA,

    「でもヒトはDNAで決まるのだから」 と思われるでしょうが

  • but it turns out that each of us has about 20,000 human genes,

    1人に約2万の遺伝子がある事が 分かっています—

  • depending on what you count exactly,

    正確に何を数えるかにも依りますが—

  • but as many as two million to 20 million microbial genes.

    しかし微生物遺伝子は2百万から2千万です

  • So whichever way we look at it, we're vastly outnumbered

    どちらを向いても共生微生物達の数には

  • by our microbial symbionts.

    とうてい敵いっこありません

  • And it turns out that in addition to traces of our human DNA,

    そして私たちが触るもの全てに ヒトDNAだけでなく

  • we also leave traces of our microbial DNA

    微生物のDNAまでをも我々は

  • on everything we touch.

    後に残すことが分かっています

  • We showed in a study a few years ago

    数年前の我々の研究で

  • that you can actually match the palm of someone's hand up

    コンピュータのマウスと それを使う人の手のひらの

  • to the computer mouse that they use routinely

    微生物が95%までの正確さで

  • with up to 95 percent accuracy.

    マッチしました

  • So this came out in a scientific journal a few years ago,

    これは数年前 科学誌に発表されましたが

  • but more importantly, it was featured on "CSI: Miami,"

    それより重要な『CSI: マイアミ』に 採用されたので

  • so you really know it's true.

    これで信じてもらえるでしょう

  • (Laughter)

    (笑)

  • So where do our microbes come from in the first place?

    そもそも我々の微生物は どこから来るのでしょう

  • Well if, as I do, you have dogs or kids,

    犬も子供もいる方は— 私には両方いますが—

  • you probably have some dark suspicions about that,

    多分 「もしかしたら」 と思っていらっしゃるでしょう

  • all of which are true, by the way.

    実は全くその通りでなのです

  • So just like we can match you to your computer equipment

    コンピュータとそれを使う人の微生物が

  • by the microbes you share,

    マッチするだけでなく

  • we can also match you up to your dog.

    犬と飼い主の微生物もマッチします

  • But it turns out that in adults,

    しかし成人の微生物は比較的

  • microbial communities are relatively stable,

    変動しない事が分かっているので

  • so even if you live together with someone,

    誰かと共同生活をしても

  • you'll maintain your separate microbial identity

    成人は固有の微生物を

  • over a period of weeks, months, even years.

    何週間も時には何年も持ち続けます

  • It turns out that our first microbial communities

    初期のヒトの微生物叢は 出産で大きく差が出る

  • depend a lot on how we're born.

    という事も分かっています

  • So babies that come out the regular way,

    普通分娩で産まれた赤ちゃんは

  • all of their microbes are basically like the vaginal community,

    基本的に母親の膣内微生物叢を持ち

  • whereas babies that are delivered by C-section,

    一方 帝王切開で産まれた赤ちゃんの

  • all of their microbes instead look like skin.

    微生物は全て皮膚常在菌となります

  • And this might be associated with some of the differences

    帝王切開で産まれた人は

  • in health associated with Cesarean birth,

    微生物との関わりがある

  • such as more asthma, more allergies, even more obesity,

    嘆息 アレルギーそして肥満さえも 普通分娩の人より罹り易く

  • all of which have been linked to microbes now,

    出産と健康との関係が 考えられています

  • and when you think about it, until recently, every surviving mammal

    思えば ごく最近まで ほ乳類は

  • had been delivered by the birth canal,

    全て自然分娩でした

  • and so the lack of those protective microbes

    我々と共進化して来た

  • that we've co-evolved with might be really important

    保護的微生物がないという事は

  • for a lot of these different conditions that we now know involve the microbiome.

    微生物が関わる健康問題には 本当に重大な事かもしれません

  • When my own daughter was born a couple of years ago

    数年前 私の娘が産まれた時

  • by emergency C-section,

    緊急の帝王切開でしたが

  • we took matters into our own hands

    私と妻は自分たちで

  • and made sure she was coated with those vaginal microbes

    普通分娩の様に娘が母体の膣内常在菌に

  • that she would have gotten naturally.

    覆われる様にしました

  • Now, it's really difficult to tell whether this has had an effect

    さあ これが娘の健康に どんな効果があったのか

  • on her health specifically, right?

    全く分かりませんが

  • With a sample size of just one child, no matter how much we love her,

    どれ程の愛情を持ってしても たった1人の子供からだけのサンプルサイズでは

  • you don't really have enough of a sample size

    一般的データを得るには

  • to figure out what happens on average,

    十分ではありません

  • but at two years old, she hasn't had an ear infection yet,

    この2年間 娘は耳感染症に 罹った事はありません

  • so we're keeping our fingers crossed on that one.

    これからも何もない事を祈っています

  • And what's more, we're starting to do clinical trials with more children

    さらに子供たちを使って 微生物に保護的な効果が

  • to figure out whether this has a protective effect generally.

    一様にあるものかどうか 臨床研究を始めました

  • So how we're born has a tremendous effect on what microbes we have initially,

    出産方法が大きく影響し 最初の微生物生態系が決まります

  • but where do we go after that?

    では この後どうなるのでしょう?

  • What I'm showing you again here is this map

    ヒト微生物プロジェクトのデータ分布図を

  • of the Human Microbiome Project Data,

    もう一度ご覧ください

  • so each point represents a sample from one body site

    点が一人の体の一部から採った微生物叢を表し

  • from one of 250 healthy adults.

    全部で250人からの物です

  • And you've seen children develop physically.

    子供の身体的成長や

  • You've seen them develop mentally.

    精神的成長は目にできたとしても

  • Now, for the first time, you're going to see

    これは初めてご覧になる物でしょう

  • one of my colleague's children develop microbially.

    ある同僚の子供の微生物学的成長です

  • So what we are going to look at

    今からご覧になるのは

  • is we're going to look at this one baby's stool,

    ある赤ちゃんの便からの物で

  • the fecal community, which represents the gut,

    腸内細菌叢を代表するものです

  • sampled every week for almost two and a half years.

    2年半近く 毎週試料を採取しました

  • And so we're starting on day one.

    1日目から始めました

  • What's going to happen is that the infant is going to start off as this yellow dot,

    嬰児はまず最初に黄色い粒

  • and you can see that he's starting off basically in the vaginal community,

    膣内微生物叢から始まります

  • as we would expect from his delivery mode.

    自然分娩から当然期待される事ですね

  • And what's going to happen over these two and a half years

    2年半の間で

  • is that he's going to travel all the way down

    この子の微生物叢は

  • to resemble the adult fecal community from healthy volunteers down at the bottom.

    健康な成人の糞便微生物叢に似通ってきます

  • So I'm just going to start this going and we'll see how that happens.

    始めますので どうなるか見て下さい

  • What you can see, and remember each step in this is just one week,

    見ているのは1週間に1ステップです

  • what you can see is that week to week,

    週毎に

  • the change in the microbial community of the feces of this one child,

    子供の糞便微生物叢の変化が見られ

  • the differences week to week are much greater

    その週毎の変化は ヒト微生物プロジェクトが行った

  • than the differences between individual healthy adults

    コホートの健康な成人と比べると

  • in the Human Microbiome Project cohort,

    ずっと大きいのです

  • which are those brown dots down at the bottom.

    その成人の微生物叢は 下の茶色の物です

  • And you can see he's starting to approach the adult fecal community.

    ご覧の様に成人の便のそれに 近くなっているのが見れますね

  • This is up to about two years.

    これが約2年程続き

  • But something amazing is about to happen here.

    ここでとても驚くことが起きます

  • So he's getting antibiotics for an ear infection.

    この子は耳感染症に対する抗体ができるのです

  • What you can see is this huge change in the community,

    ここで微生物叢に大きな変化が現れてきて

  • followed by a relatively rapid recovery.

    耳感染症からの回復が比較的速くなります

  • I'll just rewind that for you.

    巻き戻してみましょう

  • And what we can see is that just over these few weeks,

    ほんのこの数週間で

  • we have a much more radical change,

    劇的な変化が見られます

  • a setback of many months of normal development,

    何ヶ月も進展があまりなく

  • followed by a relatively rapid recovery,

    838日ぐらいして—

  • and by the time he reaches day 838,

    このビデオの最後の方ですが—

  • which is the end of this video,

    比較的回復が早くなるのです

  • you can see that he has essentially reached the healthy adult stool community,

    この頃には根本的に 成人の便と同じ微生物叢になります

  • despite that antibiotic intervention.

    途中 抗生物質の介入 有無に関わらずです

  • So this is really interesting because it raises fundamental questions

    実に興味深い事です なぜなら この事から

  • about what happens when we intervene at different ages in a child's life.

    年齢が変わると どうだろうか という基本的疑問が湧いてくるからです

  • So does what we do early on, where the microbiome is changing so rapidly,

    微生物叢の変化が大きい 生後数年間には我々の行動が

  • actually matter,

    影響するのでしょうか

  • or is it like throwing a stone into a stormy sea,

    それともその影響は あまりに微々たるもので

  • where the ripples will just be lost?

    何も影響しないのでしょうか

  • Well, fascinatingly, it turns out that if you give children antibiotics

    興味深い事に 生後6ヶ月間 嬰児に

  • in the first six months of life,

    抗生物質を投与すると

  • they're more likely to become obese later on

    抗生物質を与えなかった子供と比べ

  • than if they don't get antibiotics then or only get them later,

    後に肥満になる率が高い というデータがあり

  • and so what we do early on may have profound impacts

    生後6ヶ月間は十分注意しないと

  • on the gut microbial community and on later health

    初期の腸内細菌叢は後々 大きくその人の健康に影響する

  • that we're only beginning to understand.

    という事が分かってきました

  • So this is fascinating, because one day, in addition to the effects

    これで抗生物に対し耐性が出来る

  • that antibiotics have on antibiotic-resistant bacteria,

    薬物耐性菌の問題はもちろんの事—