Animals Can Sniff Cancers Out动物嗅癌

Next time you’re irritated that ants have gotten into your kitchen， you might take a moment to consider their extraordinary powers of perception.

当你下次再为厨房里进入蚂蚁而苦恼时，不妨静下来想一想它们那超强的感知能力。

These tiny animals can detect markers of illness， such as cancer. In fact， ants are just one of many creatures whose senses can register signs of human disease： dogs， rats， bees， and even tiny worms can as well.

这些微小的动物能够察觉到癌症等疾病信号。实际上，许多动物都能感知人类疾病的信号，蚂蚁只是其中之一，其他诸如狗、老鼠、蜜蜂，甚至小型蠕虫等也具备这种能力。

Here’s what we know about these animals and their incredible abilities.

下面让我们一起走近这些动物，了解它们的神奇能力。

Working ants

工蚁

The silky ant， Formica fusca， a common species found throughout Europe， can be taught to identify the scent of breast cancer in urine.

丝光褐林蚁广泛分布于整个欧洲。经过训练，它们能够识别出尿液中乳腺癌的气味。

Research from the University Sorbonne Paris Nord1 in France published this year in Proceedings of the Royal Society B shows ants can learn to distinguish between the scent of urine derived from mice carrying human breast cancer tumors from that of healthy mice.

2023年，法国索邦巴黎北大学的研究人员在《英国皇家学会学报B》上发表了一项研究。该研究表明，蚂蚁能够学会辨别携带人类乳腺癌细胞的老鼠和健康老鼠之间尿液气味的差异。

Ants and other animals pick up signs of disease by perceiving various volatile organic compounds， or VOCs. These chemicals are produced in a variety of ways and can be found in exhaled breath， and in sweat， urine， and blood. Diseases can change the VOCs we emit， resulting in giving off a different odor. By placing a sugar reward near the cancer sample the ants learned to seek out that scent， a process called operant conditioning2.

蚂蚁等动物主要是通过感知各种挥发性有机化合物来识别疾病信号。此类化合物的产生途径有很多，我们呼出的气体以及汗液、尿液和血液中都可以发现其踪迹。有些疾病会改变人体所释放的挥发性有机化合物，使其散发出异样的气味。研究人员利用操作性条件反射原理，在癌细胞样本附近放置糖作为奖励，结果蚂蚁很快就学会了识别癌细胞的气味。

“We were surprised by the rapidity of ants. In just ten minutes one ant can be trained，” says lead author Baptiste Piqueret， now a post doctoral researcher at the Max Planck Institute for Chemical Ecology in Germany.

“蚂蚁的学习效率令人惊叹，训练一只蚂蚁仅需10分钟。”该研究的主要作者巴蒂斯特·皮克雷如是说。他目前是德国马克斯·普朗克化学生态研究所的博士后研究员。

After scientists trained the ants they put the insects in a petri dish with urine samples from the mice with tumors and healthy mice. They spent 20 percent more time with the cancerous samples.

训练完成后，研究人员将蚂蚁放入装有两份不同尿液样本的培养皿中，一份来自生有肿瘤的老鼠，一份来自健康的老鼠。结果，它们在含癌样本前多停留了20%的时间。

Ants smell the chemicals that make up odors with olfactory receptors on their antennae. Scent is their main form of communication， says study co-author Patrizia d’Ettorre， an ethologist at the Université Sorbonne Paris Nord.

蚂蚁的触角上分布着嗅觉感受器，它们通过这些感受器来识别化合物的气味。该研究报告的合著者、索邦巴黎北大学动物行为学家帕特里齐娅·德埃托雷指出，气味是蚂蚁进行信息交流的主要方式。

“They recognize group members by detecting their body odor，” and use pheromones—often in tiny concentrations—to communicate an astonishing array of complex signals.

“它们通过感知体味来识别群体成员”，并使用信息素（浓度通常很低）来传递一系列复杂无比的信号。

These ants also don’t sting and are “inexpensive to get and maintain. Honey and dead insects， and ants are happy，” Piqueret says. This makes them excellent candidates for such work.

皮克雷提到，这些蚂蚁不会咬人，且“获取和饲养成本都很低。只要蜂蜜和昆虫尸体即可满足它们。”这使得它们能够胜任癌症检测。

What exact chemicals the ants are smelling is unknown， says d’Ettorre， which is often the case with the other cancer-detecting animals.

德埃托雷表示，蚂蚁嗅探的究竟是什么化学物质，目前还不得而知。对于其他能够探测癌症的动物而言，情况也是如此。

A human’s best friend

人类最好的朋友

Dogs can be trained to smell several types of cancers， including melanoma， breast and gastrointestinal cancers and some infectious diseases in humans， including malaria. In the U.S， dogs have worked in the field screening people for COVID-19， including at some schools in California， in several locations in Massachusetts， and at Miami Heat basketball games.

狗在经过训练后也能嗅出人类身上的多种癌症，包括黑色素瘤、乳腺癌和胃肠道癌，以及一些传染性疾病，比如疟疾。在美国，狗已经正式上岗，参与了新冠疫情的检测工作，例如在加利福尼亚州的部分学校、马萨诸塞州的多个地区以及迈阿密热火队的篮球比赛中都能见到它们的身影。

They can also smell infectious disease in other animals， including chronic wasting disease， which affects the brains of deer and can be fatal.

此外，狗还可以闻出其他动物身上的传染性疾病，比如慢性消耗性疾病。这种疾病会影响鹿的大脑，甚至会致命。

“It’s devastating to the deer and the only way to detect it is by autopsy，” says Cynthia Otto， with the University of Pennsylvania School of Veterinary Medicine.

宾夕法尼亚大学兽医学院的辛西娅·奥托说：“这种疾病对鹿的危害极大，而尸检是检测这种疾病的唯一方式。”

Dogs， however， can be trained to detect the disease in deer feces， according to a study published in the journal Prion， on which Otto was a co-author. Researchers think the dogs may possibly do so by smelling the infectious agent itself， Otto says， in this case and others.

然而，一份发表于期刊《朊病毒》的研究报告表明，经过训练，狗可以闻出鹿粪中慢性消耗性疾病的气味。奥托是该报告的合著者之一。她说，研究人员认为，无论是在此项研究还是其他研究中，狗可能都是通过嗅闻传染性病原体本身来感知疾病。

“We’ve done some pilot studies， looking at bacterial infections and if we train the dogs on the bacteria itself， the dogs can respond to samples from infected subjects，” she says. Medical Detection Dogs， a British charity， has trained dogs to detect a record 28 diseases， including specific bacteria.

她还说：“我们已经做了初步研究，看看在细菌感染的情况下，狗的表现如何。结果显示，如果我们训练狗嗅闻细菌本身，它们也能够对感染对象的样本做出反应。”一家名为“医疗检测犬”的英国慈善机构曾训练狗检测出28种疾病，创下纪录，其中包括特定的细菌。