and that also applies to other pets like cats, rats, and mice.

其實對其他寵物也是如此，例如：貓或老鼠

but that just doesn't seem fair.

但這聽起來似乎不太合理

Why do we get to go to town on a giant bar of dark chocolate

為什麼我們可以狂嗑一大條黑巧克力棒

but Fido shouldn't even have one bite?

但狗狗卻連一口都不能吃呢？

It all has to do with a molecule called theobromine

原因出在一種名叫可可鹼的分子上

which is made up of carbon, hydrogen, nitrogen and oxygen atoms.

可可鹼是由碳、氫、氮以及氧原子所組成

And along with its partner caffeine, is one of the many reasons

除了它的好夥伴咖啡因以外，可可鹼是其中一個

humans have loved chocolate for thousands of years.

讓人類著迷於巧克力數千年的原因之一

Both molecules are dangerous for dogs but chocolate contains

咖啡因以及可可鹼對於狗來說都相當危險，但巧克力中含有的

a lot more theobromine than it does caffeine

可可鹼成分相比咖啡因還要來得多

so it's the molecule to watch out for. Like caffeine,

所以要注意的是這兩種成分，和咖啡因一樣

theobromine is a type of alkaloid, which is a huge class of molecules

可可鹼屬於生物鹼的一種，生物鹼是相當大的一類分子

that generally contain rings with at least one nitrogen atom in them

一般來說它的環中會包含至少一個氮原子

and alkaloids often have physiological effects on humans and other animals.

生物鹼通常會使人類及其他動物產生生理作用

Also like caffeine, theobromine makes our heart pump faster,

就像咖啡因，可可鹼也會促使我們心跳加快

our blood vessels dilate, and some of our muscles

血管擴張，以及讓部分肌肉

get more energy, which sounds great!

得到更多能量。這聽起來很棒

But, too much of it can make our hearts pump too quickly

但是，太多的可可鹼卻會造成我們的心跳過快

and our muscles contract uncontrollably,

以及肌肉不受控制地收縮

eventually leading to nausea, convulsions, heart attack, and even death.

進而導致噁心、痙攣、心肌梗塞甚至是死亡

Luckily for our taste buds, we humans process theobromine pretty quickly,

但好消息是，人體代謝可可鹼的速度非常的快

so that's not something you have to worry about.

所以你其實不需要擔心太多

It rarely sticks around long enough to cause any harm.

可可鹼待在身體裡的時間幾乎不會長到對人體造成危害

But, our pets aren't so lucky. They process theobromine a lot more slowly,

可是我們的寵物就沒那麼好運了。他們代謝可可鹼的速度很慢

so it can easily build up and cause those dangerous effects.

所以可可鹼很容易在體內累積並造成危害

It's hard to know exactly why we evolved to be better at digesting theobromine,

我們很難確切瞭解為什麼我們的身體會進化成能較容易消化可可鹼

but it might be because alkaloids mostly come from plants,

有可能是因為生物鹼大部分都來自植物

and our ancestors ate a lot more plants than early cats or dogs did.

而我們的祖先吃的植物比以前的貓和狗所吃的植物多很多

Whatever the reason, the same amount of theobromine

無論原因如何，等量的可可鹼

stays in pets' bodies much longer,

會停留在寵物的身體裡更久的時間

giving it more time to pile up and cause harm.

使得可可鹼更容易累積並造成傷害

On top of that, most pets are a lot lighter than humans,

除此之外，大部分的寵物都比人類還要輕

so it really doesn't take much chocolate to make them sick.

所以其實不需要太多的巧克力就能讓他們感到不舒服

Cats don't often get poisoned from chocolate

貓不太會因為食用巧克力而中毒

because they can't taste sweet things,

因為他們對甜食無感

so they're generally not too interested in it,

所以他們對巧克力其實不太感興趣

But, dogs sure are.

但狗就不一樣了

Your average adult human would need to eat about 8 kilograms of dark chocolate

一般成年人需要吃掉大約8公斤的黑巧克力

to get a lethal dose of theobromine.

才會攝入份量足以致死的可可鹼

But, a medium-sized dog would only need to eat about one kilogram, and

但是，一隻中型犬只需要吃下大約一公斤的巧克力就足以致死

a house cat would only need a tenth of a kilogram.

而一隻家貓則是只需要吃下100克的巧克力

Sweeter chocolates have less theobromine, so the lethal dose is higher;

較甜的巧克力所含的可可鹼較少，所以足以致死的份量相對會較高

about 5 kilograms of milk chocolate for dogs and about a third of a kilogram for cats,

吃下約 5 公斤的牛奶巧克力會導致狗狗死亡，貓則是要吃下約 300 多公克

but they'd be sick long before eating that much.

不過他們在吃下那麼多分量之前就會先感到噁心了

Meanwhile, you and I will have to eat about half of our body weight in milk chocolate for a lethal dose,

而我們人類需要吃下約我們體重一半的牛奶巧克力才會致死

which might sound wonderful, but I don't want to see any of you writing "challenge accepted" in the comments,

雖然聽起來是好事，但我可不希望有人在下面留言「我接受挑戰」

because you'd be very sick way before finishing that much chocolate.

因為在吃到那麼多之前你就會大喊吃不消了

Among other things, I'm trying very hard not to picture what that would do to your digestive system

而且我幾乎不敢想像吃那麼多的巧克力會對你的消化系統造成什麼影響

But the next time you decide to indulge in a chocolate bar,

下次你決定來根巧克力棒...

or three,

或三根時

just keep it to yourself, no matter how long your dog gives you those adorable puppy eyes.

記得只要自己享受就好了，就算你的狗再怎麼施展眼神攻勢也不能給他

Thanks for asking, and a special thanks to our patrons on Patreon who keep these answers coming.

謝謝提問，也謝謝Patreon的贊助者們持續幫助我們尋找答案

If you'd like to submit questions to be answered,

如果你想提問的話

you can go to patreon.com/scishow,

請到 patreon.com/scishow

and don't forget to go to youtube.com/scishow and subscribe.

也別忘了到 youtube.com/scishow 並訂閱！