Maybe it's their adorable faces, their puppy dog eyes, or maybe it's just because they've become a member of the family.

可能是牠們可愛的臉、小狗眼睛，或只是因為牠們已經成為家裡的一份子。

Those things are all true of course, but there's an actual scientific reason why we love dogs.

那些當然都是原因之一，但其實我們喜愛狗狗是有科學根據的。

Evolution has allowed our dogs to develop what is called the levator anguli oculi medialis.

演化讓狗狗們發展出所謂的顏面表情肌。

Yeah, that's a mouthful.

對，真的超長的。

So let's just call it by its simpler name, the inner eyebrow raise.

所以我們就把它簡稱為內挑眉。

You probably see it most often when your dog looks worried that he won't get a bite of your sandwich, or when he seems sad after his ball rolls under the furniture.

你可能最常看到它出現在你的狗狗看起來很擔心吃不到一口你的三明治，或是狗狗在球滾到家具底下時看起來很難過的時候。

You may be surprised, but actually researchers have been studying facial expressions in animals for quite some time.

你可能會很驚訝，但其實科學家研究動物的臉部表情已有好一段時間了。

An animal who has similar movements to dogs?

什麼動物和狗有相似的臉部運動？

Horses.

馬。

An animal who has little to no movement at all?

什麼動物少到幾乎沒有臉部運動？

Cats.

貓。

The team studied both dogs and wolves and found that despite facial muscles being almost exactly alike, wolves didn't possess the levator muscle.

研究狗和狼的小組發現，儘管牠們的臉部肌肉幾乎完全一樣，狼並沒有提顱骨肌。

Researchers believe dogs who have facial movements more closely resembling humans have been favored unconsciously by humans throughout evolution.

研究人員認為，擁有較接近人類臉部表情的狗在演化過程中受到人類不知不覺地偏愛。

So your puppy's been playing you this whole time.

所以你的狗狗一直以來都在玩弄你。

And we bet you're okay with that, because guess what?

而且我們敢說你一定覺得沒關係，知道為什麼嗎？

You know that amazing feeling you get when you fall in love?

你知道墜入愛河那種美妙的感覺嗎？

Dogs give you that exact same feeling.

狗狗會給你完全一樣的感覺。

Need proof? Just look into their eyes.

需要證據嗎？ 看著牠們的眼睛就會知道。

Not only are those puppy dog eyes cute, but scientists have also studied the connection between humans and canines when they make eye contact.

小狗眼睛不只可愛，科學家們還研究出人類和犬類在眼神接觸時會有所連結。

Studies have found that while gazing at your four-legged friend, Oxytocin spikes in both you and your dog.

研究顯示，當你注視你的四腳朋友時，催產素會在你和狗狗兩者體內增高。

Oxytocin, also known as the love hormone, is responsible for human behaviors associated with relationships and bonding.

催產素也被稱作愛的荷爾蒙，它負責和情感關係和親密關係形成有關的人類行為。

This means that we really do think of dogs as a part of our family.

這代表我們真的把狗狗視為家庭的一部份。

This hormone is the same one that bonds parents and children leading scientists to believe dogs do feel more like they're a kid in a family rather than an underdog in a pack.

這個荷爾蒙和連結雙親和孩童的是同一種，這讓科學家們相信狗狗感覺起來比較像家庭裡的小孩而非人類群體中的弱勢。

So the next time your best friend says you treat your dog like your child, just tell them, they practically are.

所以當下次你的好朋友說你養狗就像在小孩，就告訴他們，狗狗實際上簡直是自己的小孩。

This idea also mimics the behavior of dogs since they were domesticated.

這個概念和狗自被馴養以來的行為互相呼應。

Unlike wolves, but similar to children, when dogs are confused they look to their human for guidance.

狗狗不像狼反而與孩童相似，當牠們感到困惑時會向主人尋求指引。

So whatever it is, that adorable face or that special bond we share with them.

所以，無論是什麼原因，不管是可愛的臉還是我們之間特別的親密關係。

Evolution has shown the unique relationship we have with dogs is only getting stronger.

演化顯示出我們和狗狗之間獨特的關係只會越來越強大。

Now we just have to ask ourselves, how is it possible to love them any more?

現在我們只能問問自己，我們對狗狗的愛還能再更深嗎？