Joshua Klein: The intelligence of crows

ジョシュア・クライン： カラスの知性

翻訳: Satoru Arao 校正: Takako Sato

How many of you have seen the Alfred Hitchcock film "The Birds"?

ヒッチコック監督の映画 「鳥」は見ましたか？

あまりの怖さに発狂した人は？

Any of you get really freaked out by that?

You might want to leave now.

席を外された方が...

(Laughter)

（笑）

So this is a vending machine for crows.

これはカラスのための自動販売機です

Over the past few days, many of you have been asking,

最近良く聞かれるんですよ

"How did you come to this? How did you get started doing this?"

”なんでこうなった？”ってね

It started, as with many great ideas,

素晴らしいアイデアとは いつも

or many ideas you can't get rid of, anyway,

まあそれほど素晴らしくなくとも

at a cocktail party.

カクテルパーティで生まれるものです

About 10 years ago, I was at a cocktail party with a friend of mine.

１０年ほど前 カクテルパーティで友達が

カラスが庭を荒らしまわると

We were sitting there, and he was complaining about the crows

カラスの文句を言い出しました

that were all over his yard and making a big mess.

And he was telling me we ought to eradicate these things,

絶滅させるべきだと言うんです

退治しなきゃ と言う彼に 僕は

kill them, because they're making a mess.

馬鹿げてる と言いました

I said that was stupid,

調教したら？と提案すると

maybe we should just train them to do something useful.

そんなの無理だろって言うんですね

And he said that was impossible.

And I'm sure I'm in good company in finding that tremendously annoying,

僕は誰かが「無理だ」と言うと

when someone tells you it's impossible.

妙にムカついちゃって

その後１０年間 空いた時間はカラスの勉強に費やしました

So I spent the next 10 years reading about crows in my spare time.

(Laughter)

（笑）

And after 10 years of this, my wife said,

１０年経って 妻が言いました

"You've got to do this thing you've been talking about,

「ずっと言い続けてた

自動販売機を作ってみたら？」ってね

and build the vending machine."

それで実行しました

So I did.

興味深いのは

But part of the reason I found this interesting is,

人間の居住地拡大に伴って

I started noticing that we're very aware of all the species

絶滅しそうな種の存在には

that are going extinct on the planet

敏感な私たちですが

as a result of human habitation expansion,

今現在「生き残っている」種に対しては

and no one seems to be paying attention to all the species

無関心だという点です

that are actually living; they're surviving.

特に 「共ヒト生」の種についてはそうです

And I'm talking specifically about synanthropic species,

人間の生活環境に適合してきた動物たちです

which have adapted specifically for human ecologies,

ネズミやゴキブリ カラスなどですね

species like rats and cockroaches and crows.

And as I started looking at them, I was finding that they had hyper-adapted.

彼らの適応力には目を見張ります

人類と共に生きられるよう進化したんです

They'd become extremely adept at living with us.

And in return, we just tried to kill them all the time.

それに引き替え 私たちは殺そうとするばかり

(Laughter)

And in doing so, we were breeding them for parasitism.

それが なおさら彼らを「寄生」させています

We were giving them all sorts of reasons to adapt new ways.

適合するしかない状況を作っているのです

So, for example, rats are incredibly responsive breeders.

ネズミは凄い速さで増えますし

And cockroaches, as anyone who's tried to get rid of them knows,

退治した経験のある方ならご存じのように

have become really immune to the poisons that we're using.

ゴキブリは殺虫剤に強くなりました

So I thought, let's build something that's mutually beneficial;

双方に有益な道はないのか考えたんです

お互いに利益を得られるものを考えてみようと

something that we can both benefit from,

新しい関係を模索しようと考えました

and find some way to make a new relationship with these species.

そしてこの機械なんですね

So I built the vending machine.

But the story of the vending machine is a little more interesting

その前に カラスについて少し

お話ししましょう

if you know more about crows.

It turns out, crows aren't just surviving with human beings;

彼らはかろうじて生き延びている訳ではなく

実際はとても繁栄しています

they're actually thriving.

They're found everywhere on the planet except for the Arctic

北極と南米大陸の最南端を除いた

あらゆる場所に生息していて

and the southern tip of South America.

そのほとんどが 人間の居住地から

And in all that area, they're only rarely found breeding

５キロ以内に住んでいます

more than five kilometers away from human beings.

私たちは気にしませんが

So we may not think about them, but they're always around.

彼らはいつも側にいるのです

And not surprisingly, given the human population growth,

人類の人口増加を考えれば－

more than half of the human population is living in cities now.

全人口の過半数は都市部に住んでいて

And out of those, nine-tenths of the human growth population

人口増加の９割が

都市部で起きているのですが－

is occurring in cities.

We're seeing a population boom with crows.

カラスも共に人口爆発しているのです

So bird counts are indicating

私たちは彼らの急激な増殖に

that we might be seeing up to exponential growth in their numbers.

立ち会っているのかも知れません

でもそれ以上に

So that's no great surprise.

But what was really interesting to me was to find out

本当に興味深いのは

that the birds were adapting in a pretty unusual way.

彼らの適応能力です

例をお見せしましょう

And I'll give you an example of that.

カレドニアガラスのベティです

This is Betty. She's a New Caledonian crow.

And these crows use sticks in the wild

この種のカラスは小枝を使って

to get insects and whatnot out of pieces of wood.

木からエサを捕る習性があります

Here, she's trying to get a piece of meat out of a tube.

今もエサを捕ろうとしていますが

研究員がミスをしました

But the researchers had a problem.

They messed up and left just a stick of wire in there.

ただの針金を与えてしまったのです

彼女はこんな経験は初めてです

And she hadn't had the opportunity to do this before.

うまくいかないようですね

You see, it wasn't working very well.

So she adapted.

でも彼女は適応するんです

これは完全に自発的な行動です　見た事もありません

Now, this is completely unprompted; she had never seen this done before.

No one taught her to bend this into a hook

曲げてフックにするなんて

or had shown her how it could happen.

誰も教えてないんです

でも自分で発見するんです

But she did it all on her own.

So keep in mind -- she's never seen this done.

見た事がないにも関わらずです

(Laughter)

Right.

そうそう

(Laughter)

（笑）

Yeah. All right.

はい 良くできました

(Applause)

（拍手）

So that's the part where the researchers freak out.

研究員が発狂した場面です

(Laughter)

（笑）

It turns out,

カラスは本当に賢いことが

we've been finding more and more that crows are really intelligent.

明らかになってきています

脳の大きさの比率は

Their brains are in the same proportion as chimpanzee brains are.

チンパンジーのそれと同等です

彼らの知恵の数だけ逸話もあります

There's all kinds of anecdotes

for the different kinds of intelligence they have.

スウェーデンでは

For example, in Sweden, crows will wait for fishermen

釣り人が氷の穴に糸を垂らすのを待ち

to drop lines through holes in the ice.

釣り人が場を離れると

And when the fishermen move off,

糸を引き上げ 魚や釣り餌を食べるのです

the crows fly down, reel up the lines, and eat the fish or the bait.

釣り人にとってはいい迷惑です

It's pretty annoying for the fishermen.

On an entirely different tack,

別の話になりますが

at University of Washington a few years ago,

数年前 ワシントン大学で

学生が研究のために カラスを捕まえていました

they were doing an experiment where they captured some crows on campus.

何人かの学生がカラスを捕獲して

Some students went out, netted some crows, brought them in,

体重を量ったりいろいろしてたんです

weighed and measured them, and let them back out again.

調査が終わると放します

And they were entertained to discover that for the rest of the week,

面白い事に

その週の間 カラスたちは

自分を捕まえた学生が現れる度に

whenever these particular students walked around campus,

彼らに向かってカーカー鳴いたり

these crows would caw at them and run around,

歩き回ったりして からかうんです

and make their life kind of miserable.

(Laughter)

こんな状態が翌月も 夏休みが明けても

They were significantly less entertained

when this went on for the next week.

まだ続いたので 笑ってもいられなくなりました

And the next month.

And after summer break.

Until they finally graduated and left campus,

結局 卒業するまで続きました

and -- glad to get away, I'm sure --

さぞ嬉しかったでしょうね

came back sometime later, and found the crows still remembered them.

でも卒業後もなお 彼らを覚えているんです

(Laughter)

カラスを怒らせると罰が当たりますよ

So, the moral being: don't piss off crows.

今では カラスについて

So now, students at the University of Washington

that are studying these crows, do so with a giant wig and a big mask.

研究する学生達は

カツラと覆面をかぶるんですよ

(Laughter)

（笑）

It's fairly interesting.

興味深いですね

(Laughter)

So we know these crows are really smart,

カラスは本当に賢いんです

but the more I dug into this, the more I found

でも 調べれば調べるほど

さらに高度な適応能力を発見しました

that they actually have an even more significant adaptation.

Video: Crows have become highly skilled at making a living

ビデオ： カラスは都会の環境の中で

巧みに生きるすべを見つけています

in these new urban environments.

In this Japanese city, they have devised a way of eating a food

この日本のカラスは 堅い木の実を

食べる方法を発見しました

that normally they can't manage:

drop it among the traffic.

車に轢いてもらうのです

The problem now is collecting the bits, without getting run over.

でも 自分が轢かれることなく拾うには

どうすれば良いでしょうか

Wait for the light to stop the traffic.

信号が変わるのを待ちましょう

Then, collect your cracked nut in safety.

そうすれば安全に拾えますね

(Laughter)

（笑）

(Applause)

（拍手）

Joshua Klein: Yeah, pretty interesting.

はい なかなか面白いですね

What's significant about this isn't that crows are using cars

ポイントは 車を使って木の実を割るところではありません

to crack nuts.

これはカラスには朝飯前なのです

In fact, that's old hat for crows.

１０年ほど前に

This happened about 10 years ago

in a place called Sendai City, at a driving school

仙台にある

in the suburbs of Tokyo.

自動車学校で起こりました

And since that time,

それからというもの

all the crows in the neighborhood are picking up this behavior.

近隣のカラスがマネをするようになりました

今ではこの辺りのカラスは お昼を食べようと

Now every crow within five kilometers is standing by a sidewalk,

みんな歩道で待ち構えています

waiting to collect its lunch.

So they're learning from each other. And research bears this out.

彼らは互いに学習することが実証されています

親は子供を教育しますし

Parents seem to be teaching their young.

仲間から学習し 敵からも学びます

They learn from their peers, they learn from their enemies.

If I have a little extra time,

時間があれば これを象徴するカラスの裏切りについて

I'll tell you about a case of crow infidelity

お話するんですけどね

that illustrates that nicely.

彼らは文化的適応を修得したんです

The point being, they've developed cultural adaptation.

昨日の講演で聞いたように

And as we heard yesterday,

that's the Pandora's box that's getting human beings in trouble,

これは人類を苦しめるパンドラの箱かも知れません

カラスにそれを見ているのです

and we're starting to see it with them.

彼らは環境や資源の変化に

They're able to very quickly and very flexibly adapt

to new challenges and new resources in their environment,

迅速に 柔軟に適応することが可能です

which is really useful if you live in a city.

都会に住むには好都合でしょう

さて カラスがどこにでも存在し

So we know that there's lots of crows.

頭が良く 互いに学習することが分かりました

We found out they're really smart and they can teach each other.

これらの事実が明確になったので

When all this became clear,

I realized the only obvious thing to do is build a vending machine.

自動販売機を作ろうと思い立ったんです

So that's what we did.

これがそうです

This is a vending machine for crows.

カラスのための自販機です

And it uses Skinnerian training to shape their behavior over four stages.

スキナー理論を使い ４つの段階に分けて学習させます

とても単純です

It's pretty simple.

Basically, what happens is that we put this out in a field

まず この機械を野原やどこかの

or someplace where there's lots of crows.

カラスがいる場所に設置します

We put coins and peanuts all around the base of the machine.

そしてコインとエサを周りにばらまきます

彼らはエサを食べに来るようになり

Crows eventually come by, eat the peanuts,

機械の存在にも慣れ

and get used to the machine being there.

やがて落ちているエサを食べ尽くします

Eventually, they eat all the peanuts.

機械のトレイにまだエサがあるのを見ると

Then they see peanuts here on the feeder tray,

and hop up and help themselves.

飛び乗って食べるようになります

Then they leave, the machine spits up more coins and peanuts,

彼らが去ったら 更にコインとエサをばらまきます

カラスにとっては夢のようです

and life is dandy if you're a crow --

ここに来れば食事にありつけるのです

you can come back anytime and get yourself a peanut.

So when they get really used to that, we move on to the crows coming back.

次の段階では 常連になったカラスに着目します

彼らは機械の騒音にも慣れ 何度も戻ってきては

Now they're used to the sound of the machine;

they keep coming back and digging out peanuts

コインの山からエサを探すのも苦にしません

from the pile of coins that's there.

彼らが幸せを享受しだしたら

When they get really happy about this, we stymie them.

苦難を授けます

We move to the third stage, where we only give them a coin.

３つ目の段階では コインしか与えません

Now, like most of us who have gotten used to a good thing,

楽な生活に慣れた人間と同様に

カラスも腹を立てます

this really pisses them off.

物を探すときに本能的にやるように

So they do what they do in nature when they're looking for something:

くちばしで辺りを掃き散らかします

sweep things out of the way with their beak.

そして偶然にもコインがスロットに入ると

They do that here, and that knocks the coins down the slot.

When that happens, they get a peanut.

エサが出てきます

This goes on for some time.

しばらくこれを続けます

やがて彼らはコインが出てくるのを待ち

The crows learn that all they have to do is show up,

スロットに入れればエサが出ることを学びます

wait for the coin to come out, put it in the slot,

then get their peanut.

この日常に慣れてきたら

When they're good and comfortable with that,

「何も起きない」 という最終ステージに進みます

we move to the final stage, where they show up and nothing happens.

This is where we see the difference between crows and other animals.

カラスが他の動物との違いを見せるところです

リスの場合 エサがなければ去っていきます

Squirrels, for example, would show up, look for the peanut, go away.

また探しに来ますが すぐ諦めます

Come back, look for the peanut, go away.

They do this maybe half a dozen times before they get bored,

これを数回繰り返して 飽きてしまいます

and then they go off and play in traffic.

そして道路に飛び出すんです

Crows, on the other hand, show up and they try and figure it out.

カラスの場合は 問題を解決しようとします

They know this machine has been messing with them

彼らは この機械が３つの段階を経て

through three different stages of behavior.

自分たちをもてあそんで来た事を知っています

(Laughter)

（笑）

They figure there must be more to it.

まだ何かあると考えるんですね

So they poke at it and peck at it.

なので 押したり突いたりするんです

And eventually some crow gets a bright idea:

やがて彼らはひらめきます

"Hey, there's lots of coins lying around from the first stage,

「ステージ１で使ったコインがたくさん落ちてるぞ」

地上のコインを拾い スロットに投入します

hops down, picks it up, drops it in the slot, and we're off to the races.

ここまで来たら話は早いです

That crow enjoys a temporary monopoly on peanuts,

そのカラスは一時的にエサを独占できますが

それも周りが気づくまでです

until his friends figure out how to do it, and then there we go.

So, what's significant about this to me

僕にとって重要なのは

isn't that we can train crows to pick up peanuts.

カラスで稼げるという事ではありません

Mind you, there's 216 million dollars' worth of change lost every year,

私たちは毎年２億ドルの小銭を紛失していますが

but I'm not sure I can depend on that ROI from crows.

カラスにそこまでの投資利益率は求められません

(Laughter)

Instead, I think we should look a little bit larger.

ですが より大きく考えてはどうでしょう

I think crows can be trained to do other things.

カラスは他の事にも訓練できると思うのです

For example, why not train them to pick up garbage after stadium events?

競技場でゴミを拾わせるとか

Or find expensive components from discarded electronics?

廃棄物から 高価なパーツを探させるとか

遭難者の探索などです

Or maybe do search and rescue?

この話のポイントは

The main point of all this for me is,

we can find mutually beneficial systems for these species.

共に有益な社会は構築可能だということです

彼らと共生していく方法－

We can find ways to interact with these other species

彼らを駆逐するのではなく

that doesn't involve exterminating them,

共に助け合う バランスの取れた関係はなし得るのです

but involves finding an equilibrium with them that's a useful balance.

Thanks very much.

ありがとうございました

(Applause)

（拍手）