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—