"Morning, Kelly. The tulips looks great."

「おはよう、ケリー。チューリップがきれいだね」

Have you ever wondered how your dog experiences the world?

犬はどうやって世界を感じ取っているのか、不思議に思ったことはありますか？

Here's what she sees.

これが、犬が見ているものです。

Not terribly interesting.

ものすごく面白いというわけではありませんね。

But what she smells, that's a totally different story.

でも、感じ取るにおいについては、まったく別問題です。

And it begins at her wonderfully developed nose.

素晴らしく発達した鼻から、すべては始まります。

As your dog catches the first hints of fresh air, her nose's moist, spongy outside helps capture any scents the breeze carries.

犬が、新鮮な空気にかすかに触れると

The ability to smell separately with each nostril, smelling in stereo, helps to determine the direction of the smell's source,

湿った、スポンジのような鼻の外部で、そよ風が運んでいるどんな香りをもかぎ取ることができます。

so that within the first few moments of sniffing, the dog starts to become aware of not just what kinds of things are out there but also where they're located.

2つの鼻の穴で別々ににおいをかぐことができます。

As air enters the nose, a small fold of tissue divides it into two separate folds, one for breathing and one just for smelling.

つまりステレオ型の嗅覚なんですね。

This second airflow enters a region filled with highly specialized olfactory receptor cells, several hundred millions of them, compared to our five million.

これによって、においの発生源の方向を特定することができ

And unlike our clumsy way of breathing in and out through the same passage, dogs exhale through slits at the side of their nose,

クンクンとし始めてすぐに

creating swirls of air that help draw in new odor molecules and allow odor concentration to build up over mulitple sniffs.

どんなものがあるのかだけでなく

But all that impressive nasal architecture wouldn't be much help without something to process the loads of information the nose scoops up.

それがどこにあるのかも、認識し始めるのです。

And it turns out that the olfactory system dedicated to processing smells takes up many times more relative brain area in dogs than in humans.

空気が鼻の中に入ると

All of this allows dogs to distinguish and remember a staggering variety of specific scents at concentrations up to 100 million times less than what our noses can detect.

小さなひだ状の組織が、その空気を2つのひだに分けます。

If you can smell a spritz of perfume in a small room, a dog would have no trouble smelling it in an enclosed stadium and distinguishing its ingredients to boot.

1つは呼吸のため、もう1つはにおいをかぐためです。

And everything in the street, every passing person or car, any contents of the neighbor's trash, each type of tree,

この2つ目の空気の流れは

and all the birds and insects in it has a distinct odor profile telling your dog what it is, where it is, and which direction it's moving in.

高度に特化した嗅覚受容細胞で満たされた部分へと入ります。

Besides being much more powerful than ours, a dog's sense of smell can pick up things that can't even be seen at all.

この細胞は、人間では500万ですが、犬には何億もあります。

A whole separate olfactory system, called the vomeronasal organ, above the roof of the mouth, detects the hormones all animals, including humans, naturally release.

そして、人間はぎこちなく、同じ鼻孔を通して呼吸をしますが

It lets dogs identify potential mates, or distinguish between friendly and hostile animals.

犬は鼻の横側にある切り込みから息を吐きだし

It alerts them to our various emotional states, and it can even tell them when someone is pregnant or sick.

空気の渦を作り出して、新しいにおいの分子を取り入れて

Because olfaction is more primal than other senses, bypassing the thalamus to connect directly to the brain structures involving emotion and instinct,

何度かかぐことにより、においの濃度を高められるようにしているのです。

we might even say a dog's perception is more immediate and visceral than ours.

でも、こんなにすごい鼻の構造を持っていても

But the most amazing thing about your dog's nose is that it can traverse time.

その鼻がかぎ取った大量の情報を処理するものがなければ、あまり意味がありませんね。

The past appears in tracks left by passersby, and by the warmth of a recently parked car or the residue of where you've been and what you've done recently.

犬の脳では、においを処理するのに特化した嗅覚系が

Landmarks like fire hydrants and trees are aromatic bulletin boards carrying messages of who's been by, what they've been eating, and how they're feeling.

関係する部分を、人間の何倍も多く占めていることが分かっています。

And the future is in the breeze, alerting them to something or someone approaching long before you see them.

この全てにより、犬は

Where we see and hear something at a single moment, a dog smells an entire story from start to finish.

圧倒的な種類のにおいを区別、記憶することができるのですね。

In some of the best examples of canine-human collaboration, dogs help us by sharing and reacting to those stories.

しかも、人間の鼻が探知できるものの、最高1億倍薄い濃度で大丈夫なのです。

They can respond with kindness to people in distress, or with aggression to threats because stress and anger manifest as a cloud of hormones recognizable to the dog's nose.

あなたが小さな部屋で、かすかに香水の香りをかぐことができるなら

With the proper training, they can even alert us to invisible threats ranging from bombs to cancer.

犬は問題なく、その香りを屋根付きのスタジアムでかぎ取り

As it turns out, humanity's best friend is not one who experiences the same things we do, but one whose incredible nose reveals a whole other world beyond our eyes.

おまけにその成分まで判別することができるでしょう。