不仅是人类：这些动物也懂得自我疗伤

Humans are not the only animals that treat each other’s injuries

人类并非唯一会治疗同类伤口的动物

Many ant species do so too

许多蚂蚁物种也会这样做

EYES TRAINED on the patient’s leg, the doctor proceeds with the operation. If the injured limb is not removed, infection and death will swiftly follow. The instrument of choice is a set of strong mandibles. The patient and surgeon are ants. Then comes post-operative care. The diminutive surgeon cleans the stump of potential pathogens with the help of its tongue.

医生的目光紧盯着病人的腿，继续进行手术。如果不切除受伤的肢体，感染和死亡很快就会接踵而至。选择的工具是一副强有力的颚。病人和外科医生都是蚂蚁。接下来是术后护理。这只小小的外科医生用舌头清理残肢上可能存在的病原体。

Erik Frank, a biologist at the University of Würzburg, has spent much of his career collecting such examples of ants tending to each other’s wounds. So far, his observations span more than two dozen species, from the amputation-performing Camponotus maculatus to Megaponera analis, which rescues injured comrades from the battlefield before covering their wounds with an antimicrobial goo.

维尔茨堡大学的生物学家埃里克·弗兰克在其职业生涯中，花费了大量时间收集蚂蚁互相照料伤口的这类例子。到目前为止，他的观察涵盖了二十多种蚂蚁，既有会实施“截肢”手术的黄斑弓背蚁，也有巨猛蚁——这种蚂蚁会把受伤的同伴从战场上救回来，然后用一种抗菌黏液覆盖它们的伤口。

These interventions seem effective. In Camponotus, a carpenter ant found mainly in Africa, amputations within an hour of upper-leg wounds boost survival rates from 30% to 80%. The ants employ a prophylactic approach, amputating regardless of whether the wound is infected or how recently it was inflicted. If ants waited until infection was apparent, the amputation would no longer be effective.

这些干预措施似乎是有效的。在主要分布于非洲的木工蚁——弓背蚁属中，腿部上端受伤后一小时内进行截肢，可将存活率从30%提高到80%。这些蚂蚁采用预防性策略，无论伤口是否感染以及受伤时间长短，都会进行截肢。如果蚂蚁等到感染明显时再截肢，那么这种截肢方式就不再有效了。

Anty septic

But ants do more than amputate. In earlier research on Megaponera, a predator equipped with a thick cuticle that probably precludes amputation, Dr Frank observed ants carrying nestmates injured in termite raids back to the nest and then cleaning their wounds. These ants keep checking on the wounded for another eight or nine hours. If the wound gets infected, they treat it with an antimicrobial glandular secretion, more than tripling the victim’s chance of survival. In another ant species, Dr Frank found that worker ants with infected wounds were expelled from the nest, while those with sterile leg injuries received continuous wound care.

但蚂蚁的行为不止于断肢。在早期对大齿猛蚁（一种拥有厚实表皮、可能无法进行断肢操作的捕食性蚂蚁）的研究中，弗兰克博士观察到，蚂蚁会将在白蚁袭击中受伤的同伴运回巢穴，然后为它们清理伤口。这些蚂蚁会在接下来的八九个小时里持续照看伤者。如果伤口出现感染，它们会用一种具有抗菌作用的腺体分泌物进行处理，这能使伤者的存活率提高两倍多。在另一种蚂蚁身上，弗兰克博士发现，伤口感染的工蚁会被逐出巢穴，而那些腿部只是受了无菌伤的工蚁则会得到持续的伤口护理。

Ants are an obvious group of animals in which to seek such behaviour. They lead injury-prone lives and their densely populated nests, in close proximity to bacteria-rich soil, make it easy for wounds to get infected. Moreover, as Dr Frank observes, it makes good sense for insects that live in large colonies to place a premium on the well-being of others.

蚂蚁显然是一类适合研究这种行为的动物。它们过着容易受伤的生活，而且它们居住的巢穴人口密集，紧挨着富含细菌的土壤，这使得伤口很容易感染。此外，正如弗兰克博士所观察到的，对于生活在大型群体中的昆虫来说，重视其他个体的福祉是很有道理的。

Such phenomena are examples of what is known as social immunocompetence—the ability of an organism to use social interactions and behaviours to enhance immunity and control infection. The full list of such behaviours spotted in ants includes the use of pharmaceuticals, grooming, social spacing, burying the dead, quarantine and exile.

这类现象是所谓“社会免疫能力”的例证——即生物体利用社会互动和行为来增强免疫力并控制感染的能力。在蚂蚁身上发现的这类行为的完整清单包括使用药物、梳理毛发、保持社交距离、掩埋死者、隔离和驱逐。

Susanne Foitzik of the University of Mainz is starting to look into the genes involved in rescue and wound-care behaviour. In Temnothorax longispinosus, a common North American species frequently injured when other ants raid their colonies to enslave them, she and colleagues recently identified genetic variants strongly associated with wound care. She plans further experiments to home in on what these genes are doing, which might relate to heightened sensitivity to pheromone signals from injured ants or the synthesis and secretion of antimicrobial substances. Dr Foitzik also found that Temnothorax ant colonies which live in warmer climates—where bacteria proliferate—lick wounds of their injured nestmates more frequently, pointing to the importance of climate as a selection pressure.

美因茨大学的苏珊娜·福伊齐克正开始研究与救援和伤口护理行为相关的基因。在北美常见的长刺切胸蚁（Temnothorax longispinosus）中，当其他蚂蚁突袭它们的巢穴以奴役它们时，这种蚂蚁经常会受伤。她和同事最近发现了与伤口护理密切相关的基因变异。她计划开展进一步实验，以深入探究这些基因的作用，这可能与对受伤蚂蚁释放的信息素信号的敏感性增强有关，也可能与抗菌物质的合成和分泌有关。福伊齐克博士还发现，生活在气候更温暖地区（那里细菌繁殖旺盛）的长刺切胸蚁群体，会更频繁地舔舐受伤同伴的伤口，这表明气候作为一种选择压力具有重要意义。

Humans might benefit from Dr Frank’s research. He has found a trove of 70 compounds, including 20 proteins, with antimicrobial and wound-healing properties. He notes that some might be useful against human pathogens that have developed resistance to antibiotics.

人类或许能从弗兰克博士的研究中获益。他发现了大量化合物，共70种，其中包括20种蛋白质，这些化合物具有抗菌和伤口愈合的特性。他指出，有些化合物可能对那些已对抗生素产生耐药性的人类病原体有效。

Ants are by no means the only animals to tend their sick and wounded. Crows, lions, macaque monkeys and chimpanzees do so as well. The mechanisms in these larger animals are, presumably, different. Insects, though capable of learning, have tiny brains, so in them this behaviour is surely genetically ingrained. The birds and mammals on the list, by contrast, are (except for lions, which have not, for obvious reasons, been studied experimentally in this way) species known to be capable of reasoning things out. But natural selection is about ends, not means. And in ants it seems to have arrived at complex medical systems that require neither empathy nor cognition. Just a strong pair of jaws.

蚂蚁绝不是唯一会照料生病和受伤同伴的动物。乌鸦、狮子、猕猴和黑猩猩也会这么做。想必这些体型更大的动物（所采用）的机制有所不同。昆虫虽然能够学习，但大脑极小，所以它们的这种行为肯定是基因决定的。相比之下，名单上的鸟类和哺乳动物（除了狮子，出于明显的原因，尚未通过这种方式对其进行实验研究）都是已知能够进行推理的物种。但自然选择关注的是结果，而非方式。在蚂蚁身上，自然选择似乎演化出了复杂的医疗系统，这种系统既不需要同理心，也不需要认知能力，只需要一对强有力的颚。