Jaap de Roode: How butterflies self-medicate

譯者: Coco Shen 審譯者: Bill Hsiung

So infectious diseases, right?

傳染病，

Infectious diseases are still the main cause

傳染病仍然是全球人類

of human suffering and death around the world.

生病和死亡的主因。

Every year, millions of people die of diseases such as T.B., malaria, HIV,

每一年，全球有百萬人口

死於肺結核、瘧疾、愛滋，

around the world and even in the United States.

Every year, thousands of Americans die of seasonal flu.

甚至在美國， 每年都有成千上萬的人因流感致命。

Now of course, humans, we are creative. Right?

人類不是很有創意嗎？

We have come up with ways to protect ourselves against these diseases.

我們想出不少辦法保護自己，

We have drugs and vaccines.

用藥物和疫苗抵抗傳染病。

And we're conscious -- we learn from our experiences

我們從經驗中學習，

and come up with creative solutions.

不斷想出新的解決方案。

We used to think we're alone in this, but now we know we're not.

我們以為我們為此孤軍奮戰，

We're not the only medical doctors.

我們不是唯一會醫治自己的動物，

Now we know that there's a lot of animals out there that can do it too.

許多動物也有自己的方法，

Most famous, perhaps, chimpanzees.

最有名的例子是黒猩猩，

Not so much different from us,

就像人類，

they can use plants to treat their intestinal parasites.

牠們懂得用藥草驅逐腸胃裡的寄生蟲。

But the last few decades have shown us that other animals can do it too:

過去幾十年間我們發現其它動物也能，

elephants, porcupines, sheep, goats, you name it.

大象、刺蝟、山羊、綿羊，等等。

And even more interesting than that is that recent discoveries are telling us

有趣的是我們最近發現，

that insects and other little animals with smaller brains can use medication too.

昆蟲與其它腦子較小的動物也會用藥。

The problem with infectious diseases, as we all know,

我們都知道，傳染病的問題

is that pathogens continue to evolve,

是病原體不斷演化，

and a lot of the drugs that we have developed

以致我們開發出的藥物

are losing their efficacy.

隨之失效。

And therefore, there is this great need to find new ways to discover drugs

我們迫切需要新方法

that we can use against our diseases.

開發新藥物來治療傳染病。

Now, I think that we should look at these animals,

我認為我們應該研究這些動物，

and we can learn from them how to treat our own diseases.

從牠們身上學習，來治療我們自己。

做為生物學家， 過去十年我致力研究帝王斑蝶，

As a biologist, I have been studying monarch butterflies for the last 10 years.

Now, monarchs are extremely famous for their spectacular migrations

帝王斑蝶以牠們的遷徙習性而出名

from the U.S. and Canada down to Mexico every year,

從加拿大、美國南遷到墨西哥

where millions of them come together,

數量以百萬計，

but it's not why I started studying them.

但這不是我研究牠們的原因。

I study monarchs because they get sick.

而是因為牠們和我們一樣

They get sick like you. They get sick like me.

會罹患傳染病，所以我研究牠們。

And I think what they do can tell us a lot about drugs

我想研究牠們可以學習到

that we can develop for humans.

為人類開發藥物的方法。

Now, the parasites that monarchs get infected with

斑蝶染上的寄生蟲有個很長的名字，

are called ophryocystis elektroscirrha -- a mouthful.

叫 ophryocystis elektroscirrha。

What they do is they produce spores,

它們在蝴蝶表面

millions of spores on the outside of the butterfly

生產數以百萬的孢子，

that are shown as little specks in between the scales of the butterfly.

可以從翅膀上鱗與鱗之間的斑點見到。

And this is really detrimental to the monarch.

帝王斑蝶為此受到很大傷害

It shortens their lifespan,

不但縮短了牠們的壽命，

it reduces their ability to fly,

也降低了牠們的飛行能力。

it can even kill them before they're even adults.

甚至能在牠們成熟前就殺死牠們。

Very detrimental parasite.

一種極為可怕的寄生蟲。

As part of my job, I spend a lot of time in the greenhouse growing plants,

我的工作內容包括長時間在溫室養植物

and the reason for this is that monarchs are extremely picky eaters.

因為帝王斑蝶很挑食。

They only eat milkweed as larvae.

帝王斑蝶的幼蟲只吃乳草。

Luckily, there are several species of milkweed that they can use,

好險有幾種不同的乳草可供其食用，

and all these milkweeds have cardenolides in them.

所有的乳草中都有 強心甾 (cardenolides)

These are chemicals that are toxic.

一種對許多動物都有影響的致命毒素。

They're toxic to most animals, but not to monarchs.

但帝王斑蝶例外。

In fact, monarchs can take up the chemicals,

帝王斑蝶甚至能吸收這些化學成份，

put it in their own bodies, and it makes them toxic

以體內毒素抵抗牠們的天敵，

against their predators, such as birds.

例如鳥類。

And what they do, then, is advertise this toxicity

牠們用身上鮮豔的黃黒白斑紋

through their beautiful warning colorations

來廣告自己的毒性，

with this orange, black and white.

一種自然警告標識。

So what I did during my job is grow plants in the greenhouse,

當我在溫室工作善盡己責

different ones, different milkweeds.

種植不同乳草時，

Some were toxic, including the tropical milkweed,

某些毒性很高，像是熱帶乳草，

with very high concentrations of these cardenolides.

有大量的強心甾 (cardenolides)，

And some were not toxic.

某些卻沒有毒素。

And then I fed them to monarchs.

在我餵食帝王斑蝶時，

Some of the monarchs were healthy. They had no disease.

某些斑蝶沒有染病，很健康。

But some of the monarchs were sick,

某些斑蝶則生著病，

and what I found is that some of these milkweeds are medicinal,

我發現某些乳草有藥效，

meaning they reduce the disease symptoms in the monarch butterflies,

有效減低帝王斑蝶的症狀，

meaning these monarchs can live longer when they are infected

只要牠們食用這些藥草，

when feeding on these medicinal plants.

就可以延長自己的性命。

And when I found this, I had this idea,

當我發現的時候，

我有了一個很多人覺得很瘋狂的想法。

and a lot of people said it was a crazy idea,

but I thought, what if monarchs can use this?

我想，如果帝王斑蝶可以應用呢？

What if they can use these plants as their own form of medicine?

如果牠們可以把這些乳草當做藥物呢？

What if they can act as medical doctors?

如果牠們可以為自己開藥方呢？

So my team and I started doing experiments.

我的團隊和我開始實驗。

In the first types of experiments,

在第一類實驗裡，

we had caterpillars, and gave them a choice:

我們給幼蟲兩種選擇：

medicinal milkweed versus non-medicinal milkweed.

有藥性的乳草和沒有藥性的乳草。

And then we measured how much they ate of each species over their lifetime.

然後測量牠們一生各自吃了多少。

And the result, as so often in science, was boring:

就像大部分的科學研究結果一樣， 答案很無聊：

Fifty percent of their food was medicinal. Fifty percent was not.

有藥性和沒有藥性的各半。

These caterpillars didn't do anything for their own welfare.

這些幼蟲沒有為自己做出有利的選擇。

So then we moved on to adult butterflies,

於是我們轉為研究成蝶，

and we started asking the question

我們想

whether it's the mothers that can medicate their offspring.

母蝶會對自己的幼蟲用藥嗎？

Can the mothers lay their eggs on medicinal milkweed

牠們會把卵產在有藥效的乳草上，

that will make their future offspring less sick?

減輕幼蟲的症狀？

We have done these experiments now over several years,

我們複製這個實驗多年，

and always get the same results.

得到一樣的結果。

What we do is we put a monarch in a big cage,

我們把帝王斑蝶放進大籠子裡

a medicinal plant on one side, a non-medicinal plant on the other side,

一邊是的乳草是有藥性的，一邊沒有，

and then we measure the number of eggs that the monarchs lay on each plant.

然後測量牠們在兩種乳草上的產卵數，

And what we find when we do that is always the same.

獲得的結果是一致的。

What we find is that the monarchs strongly prefer the medicinal milkweed.

我們發現帝王斑蝶偏好藥性乳草。

In other words, what these females are doing

換句話說，

is they're laying 68 percent of their eggs in the medicinal milkweed.

雌蝶把 68％ 的卵產在藥性乳草上。

Intriguingly, what they do is they actually transmit the parasites

事實上，在牠們產卵的時候，

when they're laying the eggs.

也不可避免的

They cannot prevent this.

傳播了寄生蟲。

They can also not medicate themselves.

牠們不能治療自己。

But what these experiments tell us

但這個實驗告訴我們

is that these monarchs, these mothers, can lay their eggs on medicinal milkweed

帝王斑蝶把卵產在有藥性的乳草上，

that will make their future offspring less sick.

減輕幼蟲的病況。

Now, this is a really important discovery, I think,

我覺得這個發現很重要。

not just because it tells us something cool about nature,

不只是因為它顯示了大自然的奧妙

but also because it may tell us something more about how we should find drugs.

更提醒我們應該如何開發藥物。

Now, these are animals that are very small

這些動物都很小，

and we tend to think of them as very simple.

我們曾經覺得牠們構造單純，

They have tiny little brains,

牠們的大腦很小，

yet they can do this very sophisticated medication.

但牠們卻懂得利用自然草藥。

Now, we know that even today, most of our drugs

直到今日，

derive from natural products, including plants,

我們從自然中提取藥物，包括植物，

and in indigenous cultures,

在一些原始文化中，

traditional healers often look at animals to find new drugs.

傳統療法時常借鏡動物來找新藥。

In this way, elephants have told us how to treat stomach upset,

大象教我們如何治療腸胃不適，

and porcupines have told people how to treat bloody diarrhea.

刺蝟教我們如何處理腹瀉。

What I think is important, though, is to move beyond

我想，最重要的是，

these large-brained mammals and give these guys more credit,

除了那些大腦發達的哺乳類動物外，

我們也應該更加注重

these simple animals, these insects that we tend to think of

那些構造簡單的動物、昆蟲。

as very, very simple with tiny little brains.

The discovery that these animals can also use medication

發現這些動物懂得用藥，

opens up completely new avenues,

讓我們進入全新領域。

and I think that maybe one day, we will be treating human diseases

也許有一天，

我們會用蝴蝶找到的藥物來治療人類，

with drugs that were first discovered by butterflies,

and I think that is an amazing opportunity worth pursuing.

我想這個機會是值得把握的。

Thank you so much.

謝謝各位。

(Applause)

（掌聲）