Everyone's familiar with cancer, but we don't normally think of cancer as being a contagious disease. The Tasmanian devil has shown us that, not only can cancer be a contagious disease, but it can also threaten an entire species with extinction.
每個人都熟悉癌症, 但是一般我們並不認為癌症 是一種傳染性疾病。 然而塔司馬尼亞惡魔告訴我們 癌症不僅是一種傳染性疾病 而且它會威脅到 整個物種的存亡。
So first of all, what is a Tasmanian devil? Many of you might be familiar with Taz, the cartoon character, the one that spins around and around and around. But not many people know that there actually is a real animal called the Tasmanian devil, and it's the world's largest carnivorous marsupial. A marsupial is a mammal with a pouch like a kangaroo. The Tasmanian devil got its name from the terrifying nocturnal scream that it makes.
所以,首先,什麼是塔司馬尼亞惡魔呢? 許多人或許很熟悉塔司, 那個總是不斷旋轉的卡通動物。 但是,並不是很多人知道 實際上真的有一種動物叫做塔司馬尼亞惡魔, 而且牠是世界上最大的肉食性有袋類動物。 有袋類動物是一種有一個口袋的哺乳類動物 比如袋鼠。 塔司馬尼亞惡魔得名于 牠在夜間發出的可怕尖叫聲。
(Screaming)
(尖叫)
(Laughter)
(笑)
The Tasmanian devil is predominantly a scavenger, and it uses its powerful jaws and its sharp teeth to chomp on the bones of rotting dead animals. [The] Tasmanian devil is found only on the island of Tasmania, which is that small island just to the south of the mainland of Australia. And despite their ferocious appearance, Tasmanian devils are actually quite adorable little animals. In fact, growing up in Tasmania, it always was incredibly exciting when we got a chance to see a Tasmanian devil in the wild.
塔司馬尼亞惡魔主要以食腐為生。 牠用有力的下顎 和尖銳的牙齒 啃食腐爛的動物屍體。 唯有塔司馬尼亞島上才有這種動物。 這個小島 就在澳洲大陸南方 盡管長相兇惡, 塔司馬尼亞惡魔實際上 是一種很可愛的動物。 實際上,牠在塔司馬尼亞成長, 當我們有機會 在野外親眼看見塔司馬尼亞惡魔時 總是會感到非常興奮。
But the Tasmanian devil population has been undergoing a really extremely fast decline. And in fact, there's concern that the species could go extinct in the wild within 20 to 30 years. And the reason for that is the emergence of a new disease, a contagious cancer.
但是塔司馬尼亞惡魔的數量 卻在急速減少中。 實際上,有人擔心 這種動物可能會在20至30年間 滅絕 原因是 一種新疾病的出現, 一種具傳染性的癌症。
The story begins in 1996 when a wildlife photographer took this photograph here of a Tasmanian devil with a large tumor on its face. At the time, this was thought to be a one-off. Animals, just like humans, sometimes get strange tumors. However, we now believe that this is the first sighting of a new disease, which is now an epidemic spreading through Tasmania. The disease was first sighted in the northeast of Tasmania in 1996 and has spread across Tasmania like a huge wave. Now there's only a small part of the population, which remains unaffected.
事情起自於1996年 一個野生攝影師拍下這張 塔司馬尼亞惡魔的照片。 牠的臉上有一個巨大的腫瘤。 當時,人們認為這是偶發狀況。 因為動物,就像人一樣, 有時也會長奇怪的腫瘤。 然而,我們現在相信, 這是某種目前正在塔司馬尼亞蔓延 的傳染性疾病,最早被目擊的案例。 這種疾病最早 是在1996年塔司馬尼亞州的東北部被發現的, 其後就如大浪般席捲了整個塔司馬尼亞。 現在僅有一小部分 未受傳染。
This disease appears first as tumors, usually on the face or inside the mouth of affected Tasmanian devils. These tumors inevitably grow into larger tumors, such as these ones here. And the next image I'm going to show is quite gruesome. But inevitably, these tumors progress towards being enormous, ulcerating tumors like this one here.
通常,在臉上或嘴裡 長出腫瘤 是塔司馬尼亞惡魔被感染後的第一病徴。 之後腫瘤就越長越大,勢不可擋, 就像這些一樣。 我要讓各位看的下一張圖片 十分可怕。 但是,無可奈何是,這些腫瘤會 越長越大,就像這個巨大的潰瘍性腫瘤。
This one in particular sticks in my mind, because this is the first case of this disease that I saw myself. And I remember the horror of seeing this little female devil with this huge ulcerating, foul-smelling tumor inside her mouth that had actually cracked off her entire lower jaw. She hadn't eaten for days. Her guts were swimming with parasitic worms. Her body was riddled with secondary tumors. And yet, she was feeding three little baby Tasmanian devils in her pouch. Of course, they died along with the mother. They were too young to survive without their mother. In fact, in the area where she comes from, more than 90 percent of the Tasmanian devil population has already died of this disease.
這一個我特別難忘, 因為這是在此種疾病中 我所見到的第一個案例。 我還記得我見到這隻母塔司時的恐懼感覺。 她的嘴裏長着一個非常大的潰瘍性腫瘤 散發出難聞的氣味。 腫瘤使她的整個下顎崩塌, 她好幾天沒吃東西。 她的肚子裏有許多寄生蟲, 她的身上長滿了繼發性腫瘤, 但是,她還在餵她口袋裏的 三個小寶貝。 當然,在母親去世後,牠們也跟着去了。 因為牠們還太小,無法離開母親。 實際上在她生活的地區 已有百分之九十以上的塔司馬尼亞惡魔死於 這種疾病。
Scientists around the world were intrigued by this cancer, this infectious cancer, that was spreading through the Tasmanian devil population. And our minds immediately turned to cervical cancer in women, which is spread by a virus, and to the AIDS epidemic, which is associated with a number of different types of cancer. All the evidence suggested that this devil cancer was spread by a virus. However, we now know -- and I'll tell you right now -- that we know that this cancer is not spread by a virus. In fact, the infectious agent of disease in this cancer is something altogether more sinister, and something that we hadn't really thought of before. But in order for me to explain what that is, I need to spend just a couple of minutes talking more about cancer itself.
全世界的科學傢 都對這種癌症很感興趣, 這種傳染性的癌症 在塔司馬尼亞惡魔中傳播, 讓我們不由立即想起子宮頸癌 也是由病毒傳播的, 還有愛滋病的傳播 和好幾種不同類型的癌症有關。 所有的證據都表明塔司馬尼亞惡魔所得的癌症 是由病毒傳染的。 但是,我們現在知道-我現在就告訴各位: 這種癌症並非由病毒傳染。 實際上,這種癌症的傳染性病原體 非常兇險, 而且是我們以前甚至不曾想到的。 但是為了向各位解釋它究竟是什么, 我需要花一兩分鐘的時間, 談談癌症本身。
Cancer is a disease that affects millions of people around the world every year. One in three people in this room will develop cancer at some stage in their lives. I myself had a tumor removed from my large intestine when I was only 14. Cancer occurs when a single cell in your body acquires a set of random mutations in important genes that cause that cell to start to produce more and more and more copies of itself. Paradoxically, once established, natural selection actually favors the continued growth of cancer. Natural selection is survival of the fittest. And when you have a population of fast-dividing cancer cells, if one of them acquires new mutations, which allow them to grow more quickly, acquire nutrients more successfully, invade the body, they'll be selected for by evolution.
癌症這種疾病 每年感染全球數百萬人 在座的三分之一 將會在今後人生的不同階段患上癌症 我自己就曾動過大腸腫瘤切除手術, 當時我年僅14歲。 癌症的發生 是由於體內某個細胞中 的重要基因發生了一系列突變, 導致該細胞開始 不斷自我複製。 矛盾的是,一旦出現這種情況, ‘自然選擇’實際上更傾向於 不斷增長的癌症。 因為‘自然選擇’就是適者生存。 當你有相當數目的快速分裂的癌細胞時, 如果其中之一發生新的突變 而增長更為迅速 更成功的獲得營養 侵入身體, 它就會成為演變的選擇。
That's why cancer is such a difficult disease to treat. It evolves. Throw a drug at it, and resistant cells will grow back. An amazing fact is that, given the right environment and the right nutrients, a cancer cell has the potential to go on growing forever. However cancer is constrained by living inside our bodies, and its continued growth, its spreading through our bodies and eating away at our tissues, leads to the death of the cancer patient and also to the death of the cancer itself.
這就是癌症如此難以治療的原因。 因為它會進化。 對它用藥, 抗性細胞會重新生長。 驚人的事實是, 如果有合適的環境和營養, 一個癌細胞就有可能 永遠生長下去。 可是癌症 受到生活在我們體內的限制, 如果它繼續生長, 就會遍佈我們的身體 啃噬我們的組織, 導致癌症病人死亡 最後自己也被消滅。
So cancer could be thought of as a strange, short-lived, self-destructive life form -- an evolutionary dead end. But that is where the Tasmanian devil cancer has acquired an absolutely amazing evolutionary adaptation. And the answer came from studying the Tasmanian devil cancer's DNA. This was work from many people, but I'm going to explain it through a confirmatory experiment that I did a few years ago.
所以癌症是一種 奇怪的,短命的,自我毀滅的生命形式-- 一種演化的死亡終結。 但是塔司馬尼亞惡魔所得的癌症 卻獲得了一種絕對神奇的 進化適應。 這個結論是來自 對塔司馬尼亞惡魔的癌症DNA研究。 這項研究工作有許多人參與, 但是我想通過一個驗證實驗來向大家解釋。 這個試驗是在好幾年前做的。
The next slide is going to be gruesome. This is Jonas. He's a Tasmanian devil that we found with a large tumor on his face. And being a geneticist, I'm always interested to look at DNA and mutations. So I took this opportunity to collect some samples from Jonas' tumor and also some samples from other parts of his body. I took these back to the lab. I extracted DNA from them. And when I looked at the sequence of the DNA, and compared the sequence of Jonas' tumor to that of the rest of his body, I discovered that they had a completely different genetic profile. In fact, Jonas and his tumor were as different from each other as you and the person sitting next to you. What this told us was that Jonas' tumor did not arise from cells of his own body. In fact, more genetic profiling told us that this tumor in Jonas actually probably first arose from the cells of a female Tasmanian devil -- and Jonas was clearly a male.
下一張幻燈片會很可怕。 這是喬納斯。 我們發現這隻塔司馬尼亞惡魔 的臉上長着巨大的腫瘤。 我是基因學家, 對于DNA 和突變總是很感興趣。 所以我抓住這個機會, 從喬納斯的腫瘤當中取樣, 同時也從它身體的其它部分取樣。 我把這些樣本帶回實驗室 從中提取DNA。 我研究喬納斯的DNA序列, 把它的腫瘤DNA的序列 和它身體其它部分作比較。 我發現它們的基因圖譜完全不同。 實際上,喬納斯和它身上的腫瘤的基因 就好像妳和妳的鄰座的一樣 完全不同。 這說明喬納斯的腫瘤 不是來自於它自身的細胞 實際上,更多的基因圖譜 告訴我們喬納斯的這個腫瘤 最早可能是來自於 一隻母惡魔的細胞, 而喬納斯是公的。
So how come a tumor that arose from the cells of another individual is growing on Jonas' face? Well the next breakthrough came from studying hundreds of Tasmanian devil cancers from all around Tasmania. We found that all of these cancers shared the same DNA. Think about that for a minute. That means that all of these cancers actually are the same cancer that arose once from one individual devil, that have broken free of that first devil's body and spread through the entire Tasmanian devil population.
那麼,為什么 一個來自別人細胞的腫瘤 會長在喬納斯的臉上呢? 下一個突破 來自于對于整個塔司馬尼亞地區數百隻 塔司馬尼亞惡魔的研究。 我們發現所有的癌症 有同樣的DNA。 想一想吧。 這說明這些癌症 實際上是來源於 一隻塔司馬尼亞惡魔, 癌細胞突破了這隻惡魔的身體 傳染到整個種群。
But how can a cancer spread in a population? Well the final piece of the puzzle came when we remember how devils behave when they meet each other in the wild. They tend to bite each other, often quite ferociously and usually on the face. We think that cancer cells actually come off the tumor, get into the saliva. When the devil bites another devil, it actually physically implants living cancer cells into the next devil, so the tumor continues to grow. So this Tasmanian devil cancer is perhaps the ultimate cancer. It's not constrained by living within the body that gave rise to it. It spreads through the population, has mutations that allow it to evade the immune system, and it's the only cancer that we know of that's threatening an entire species with extinction.
可是癌症是怎樣在整個族群裡傳播的呢? 最後一個謎團終於解開。 我們想起它們在野外見面時的表現。 它們喜歡啃咬對方 常常很兇猛,而且通常是咬對方的臉。 我們認為癌細胞 是從腫瘤脫落,進入唾液的。 當一隻惡魔咬了另一隻的時候, 實際上它把活的癌細胞移植到另一隻的體內, 由此腫瘤就繼續生長。 所以這隻塔司馬尼亞惡魔感染的 可能就是已發展的癌症。 從而使得這種癌症不受限於在體內生長, 而可以在整個族群中傳播。 它的突變體使其得以避開免疫系統。 它是我們所知道的唯一一種 威脅到整個種群生存的癌症。
But if this can happen in Tasmanian devils, why hasn't it happened in other animals or even humans? Well the answer is, it has. This is Kimbo. He's a dog that belongs to a family in Mombasa in Kenya. Last year, his owner noticed some blood trickling from his genital region. She took him to the vet and the vet discovered something quite disgusting. And if you're squeamish, please look away now. He discovered this, a huge bleeding tumor at the base of Kimbo's penis. The vet diagnosed this as transmissible venereal tumor, a sexually transmitted cancer that affects dogs. And just as the Tasmanian devil cancer is contagious through the spread of living cancer cells, so is this dog cancer.
但是,既然塔司馬尼亞惡魔會患上這種癌症, 為什麼其他動物, 或者說人類就不會感染呢? 實際上已經有了。 這是金波, 是一個住在肯亞盟巴撒島的家庭所養的一隻小狗。 去年,牠的主人發現 牠的生殖器部位淌血。 她帶牠去看獸醫。 而獸醫發現情況頗為糟糕。 如果你覺得噁心,請不要看下面的畫面。 他發現了這個, 巨大的出血性腫瘤 長在金波的隂莖底部。 根據獸醫的診斷,這是傳染性花柳腫瘤 是一種犬類會經過性行為感染的 傳染性癌症。 正如塔司馬尼亞惡魔所患的癌症, 是通過感染癌症活細胞而傳播的, 這隻狗也是同樣情況。
But this dog cancer is quite remarkable, because it spread all around the world. And in fact, these same cells that are affecting Kimbo here are also found affecting dogs in New York City, in mountain villages in the Himalayas and in Outback Australia. We also believe this cancer might be very old. In fact, genetic profiling tells that it may be tens of thousands of years old, which means that this cancer may have first arisen from the cells of a wolf that lived alongside the Neanderthals. This cancer is remarkable. It's the oldest mammalian-derived life form that we know of. It's a living relic of the distant past.
但是牠的癌症更驚人 因為這種癌症傳播到全世界。 實際上,同樣的細胞 在此感染到金波, 也一樣感染到 紐約市、 喜馬拉雅山村、 和澳洲內地的狗。 我們還認為這種癌症的來歷可能非常久遠。 事實上,根據基因圖譜, 這種癌症可能已有超過萬年以上的歷史。 這意味著這種癌症 最早可能是 來自那些住在 尼安德塔人聚落附近的狼群。 這個癌症很驚人, 因為這是我們迄今所知最古老的哺乳類生命, 是遠古時代的 活化石。
So we've seen that this can happen in animals. Could cancers be contagious between people? Well this is a question which fascinated Chester Southam, a cancer doctor in the 1950s. Ad he decided to put this to the test by actually deliberately inoculating people with cancer from somebody else. And this is a photograph of Dr. Southam in 1957 injecting cancer into a volunteer, who in this case was an inmate in Ohio State Penitentiary. Most of the people that Dr. Southam injected did not go on to develop cancer from the injected cells. But a small number of them did, and they were mostly people who were otherwise ill -- whose immune systems were probably compromised.
我們已經看到這在動物身上發生, 那麼癌症是否也會在人們之間傳染呢? 這個問題 吸引了50年代的 一位癌症專傢--切斯特.索思姆。 他決定做一個試驗, 將癌症病人的細胞 注射到其他人體內。 這張照片是1957年索思姆醫生 將癌細胞注射到在監獄服刑 的志願囚犯身體的照片。 這是在俄亥俄州監獄。 大部分接受索思姆醫生注射的志願者 沒有因注射 而產生癌症。 但是有一小部分人則罹患了癌症。 他們多數已患有其它疾病 免疫系統可能早已遭到破壞。
What this tells us, ethical issues aside, is that ... (Laughter) it's probably extremely rare for cancers to be transferred between people. However, under some circumstances, it can happen. And I think that this is something that oncologists and epidemiologists should be aware of in the future.
這告訴我們 且不討論倫理道德 就是說... (笑) 癌症在人類之間傳染的 機率或許微乎其微。 但是,在某些情況下, 確實會發生。 我覺得這是 腫瘤學家和流行病學家 在今後應該關注的。
So just finally, cancer is an inevitable outcome of the ability of our cells to divide and to adapt to their environments. But that does not mean that we should give up hope in the fight against cancer. In fact, I believe, given more knowledge of the complex evolutionary processes that drive cancer's growth, we can defeat cancer. My personal aim is to defeat the Tasmanian devil cancer. Let's prevent the Tasmanian devil from being the first animal to go extinct from cancer.
最後, 癌症是 細胞分裂 以及適應其自身環境的 必然結果。 但是我們不應放棄 擊敗癌症的信心。 實際上,我相信,如果我們掌握 更多引起癌症生長的複雜進化過程相關知識 我們一定能打敗癌症。 我個人的目標 就是打敗塔司馬尼亞惡魔所患的癌症。 我們不能讓塔司馬尼亞惡魔 變成第一種 因癌症而滅絕的動物。
Thank you.
謝謝。
(Applause)
(掌聲)