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.
每个人都熟悉癌症 但我们通常认为 癌症不是传染病 袋獾(又称塔斯马尼亚恶魔)已经向我们证实 癌症不但可能是传染病 也可能 导致整个一个物种灭绝
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.
首先,袋獾是什么? 很多人可能熟悉塔斯这个卡通形象(华纳兄弟-Looney Tunes) 一直不停转圈的那个 但很多人并不知道 确实有一种动物叫塔斯马尼亚恶魔(袋獾) 这是世界上最大的肉食性有袋动物 有袋动物是一种身前有口袋的哺乳动物 比如袋鼠 袋獾被称作塔斯马尼亚恶魔 是因为它们在夜间发出吓人的尖叫声
(Screaming)
(尖叫)
(Laughter)
(笑声)
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.
袋獾主要食腐肉 它们用有利的下颌骨 和尖利的牙齿 啃食腐烂动物尸体的骨头 袋獾只分布在塔斯马尼亚岛 这是一个 在澳洲大陆南边的小岛 虽然袋獾的面孔有点吓人 但它们其实 是很可爱的小动物 我本人在塔斯马尼亚岛长大 能在野外看到 袋獾 一直是件令人兴奋的事情
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.
但袋獾数量 呈急速下降的趋势 很多人担心 这个物种可能将在二三十年内 消失殆尽 原因就是 一种新疾病的出现 一种传染性癌症
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.
事情始于1996年 一位野外摄影师拍下了这张 袋獾的照片 它的脸部有个巨大的肿瘤 当时这被认为是个个例 动物,和人一样 有时会长出奇形怪状的肿瘤 但是,如今我们发现 那是这种新型疾病的初露端倪 现在已经肆虐整个塔斯马尼亚岛 这种新型疾病首先 于1996年在塔斯马尼亚岛北部发现 然后大规模波及到整个岛 如今只剩下群体的小部分 还未被感染
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.
这种病首先表现为肿瘤 通常出现在袋獾的 脸部或口腔内 这些肿瘤最终长成大块的肿瘤 比如这样的 下一张图片 比较恶心 最终,这些肿瘤 不断繁殖,溃烂的肿瘤就像这样
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.
这个病例我一直记忆犹新 因为这是我接触的 第一个病例 我仍然记得当时看到这个嘴里长着 溃烂并发出恶臭的大肿瘤的袋獾时 受到的惊吓 实际上它的整个下巴因为这个肿瘤已经脱开 几天没有进食 腹中大量寄生虫繁殖 整个身体因为次发性肿瘤已经千疮百孔 然而它还得喂养袋里三个嗷嗷待哺的 小袋獾 毫无疑问,小袋獾和妈妈一起死掉了 他们太幼小无法独立生存 事实上,在这只袋獾的生活区域 那里百分之九十以上的袋獾 都已经死于这种病
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.
世界上的科学家 开始研究这种癌症 这种在整个袋獾群体中 传播的传染性癌症 我们首先立刻想到了子宫颈癌 这是通过病毒传播 还有艾滋病 感染者可能患上几种不同的癌症 所有证据都表明这种癌症 是通过病毒传播 然而现在我们知道-我正要告诉你们的- 是这种癌症并不是通过病毒传播 事实上,该癌症的传播病原体 是更险恶的东西 一种完全出乎意料的东西 为了更好地解释此内容 先让我花上几分钟 谈谈癌症本身
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.
每年全世界有 上百万人患上癌症 这个屋子里的人有三分之一 会在未来患上不同程度的癌症 我14岁的时候就从大肠摘除了 一个肿瘤 当你体内的 一个细胞上的重要基因 发生一系列的偶发突变 这个细胞开始不断自我增殖 癌症就产生了 然后,一旦上述情况发生 自然选择的规律 却使癌症不断长大 自然选择是适者生存 在一群快速分裂的癌细胞中 如果一个细胞获得新的突变 从而更快的繁殖 更好的吸收营养 侵入机体 他们则被自然保留
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.
所以癌症是非常难以治疗的疾病 它会进化 进行药物治疗 抗药性的细胞会卷土重来 令人不可思议的是 如果给以适当的环境和营养 一个癌细胞 可以无限繁殖 然而癌症也受制于 它寄生的身体 癌细胞不断生长 遍布整个身体 吞噬掉组织 最后导致癌细胞的寄主死亡的同时 也是癌细胞自己的末日
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.
所以癌症可以被看作 一个奇怪的,短命的,自我毁灭性的生命形式 进化的死胡同 但是袋獾的癌细胞 具备一种令人无比惊奇的 进化适应能力 通过研究袋獾癌症的DNA 我们找到了答案 这是很多人工作的结果 但是将通过几年前我做的一个验证试验 来向各位解释
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.
下张幻灯片会比较恶心 这是乔纳斯 我们发现它的脸上 有一个大肿瘤 作为遗传学家 我一直对DNA及其突变感兴趣 所以我借此机会 收集了一样乔纳斯肿瘤的样本 和他身体其他部位的样本 带回实验室 我从样本上提取了DNA 当我完成DNA测序 并将肿瘤的测序结果和 身体其他部分的测序结果对比时 我发现两者的基因图谱完全不同 实际上,乔纳斯和它的肿瘤 就像你和你旁边的人一样 完全不同 这就告诉我们乔纳斯的肿瘤 并不是来自它的身体 更多的基因图谱 告诉我们乔纳斯的肿瘤 可能最先来自于 一个雌袋獾 而乔纳斯是雄性
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.
所以 一个来自另一个体的细胞是如何 长到乔纳斯脸上去的? 下一个研究突破来自于 塔斯马尼亚岛上 成千只袋獾的癌细胞研究 我们发现所有的癌细胞 具有一样的DNA 这意味着什么? 意味着所有的癌细胞 实际上是同一个癌细胞 从第一个袋獾个体上产生的癌症 突破了单个个体的限制 传播到了整个袋獾群体
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.
那一个癌症是怎么在群体中扩散的? 揭开谜题最后答案的是 袋獾在野外相遇时的行为方式 它们会咬对方 通常会很激烈,并且常常是咬脸部 我们认为癌细胞 从肿瘤进入唾液 当袋獾相互撕咬时 癌细胞就被植入另一个袋獾体内 从而肿瘤得以继续生存 所以袋獾癌症 可能是终极版癌症 它不受产生个体的限制 可以在群体中传播 并通过突变侵入免疫系统 这是唯一一个我们目前知道的 能导致一个物种整体灭绝的癌症
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.
但是如果这种癌症见于袋獾 为什么没有发生在其他动物身上 甚至是人类? 答案是,确实有过。 这是金波 它的主人住在肯尼亚的蒙巴萨 去年,它的主人发现 它的生殖器官区域开始滴血 她带着金波去看兽医 兽医发现些很恶心的东西 如果你比较敏感,请转头看别处 兽医发现了这个 一个很大的滴血的肿瘤 长在金波的阴茎上 兽医诊断为一种传染性生殖道肿瘤 一种犬类间传染的 性病 正如同袋獾的癌症 通过癌细胞活体传播 这只狗的癌症也是
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.
但这只狗的更厉害 因为它已经传播到全世界 事实上,金波感染的 这种癌细胞 也出现于 纽约的狗身上 喜马拉雅山区村子里狗的身上 还有澳大利亚的内陆 我们认为这种癌症很久历史了 基因图谱告诉我们 它有几万年之久 这意味着它可能 最初来自 一个生活在 尼安德特人年代的狼身上 这个癌症十分厉害 这是我们目前所之的最古老的哺乳动物源性生命体 这是从遥远上古 活下来的遗迹
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.
我们了解到动物感染的情况 那在人类间传播的癌症呢? 这个问题 引起切斯特・索伦医生的极大兴趣 他是50年代的一个癌症医生 他决定通过对人体 进行实际注射癌细胞 来进行试验 这是索伦医生于1957的照片 他正给一个志愿者注射癌细胞 这个志愿者是俄亥俄州管教所的 一个犯人 索伦医生注射过的大部分人 并没有因为注射的癌细胞 患上癌症 但是一小部分得了 患癌这些人大部分也会生病 因为他们的免疫系统估计早败下阵来
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.
这告诉我们 不追究道德问题的话 就是 (笑声) 是人之间传播的癌症 是非常罕见的 但是,在某些情况下 仍然可能发生 我认为这是 肿瘤学家和流行病学家 将来要关注的问题
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.
最后 癌症是 细胞分化 并适应环境的 必然结果 但是这不意味着我们在与癌症的斗争中 毫无希望 我相信,在掌握更多的 关于癌细胞生长的复杂进化过程的知识后 我们可以打败癌症 我的个人目标是 打败袋獾癌症 让我们共同努力 不让袋獾成为第一个 因癌症灭绝的物种
Thank you.
谢谢
(Applause)
(掌声)