Elephants Call EachOther by Name Across the Savanna
Humans have a long history of inventing names for elephants. There is Disney's Dumbo, of course, and Jumbo, a 19th-century circus attraction, and Ruby, a famed painting elephant from the Phoenix Zoo in Arizona. But new research suggests wild African elephants may pick their own names, too—and use them to call and greet one another on the savanna.
人类给大象起名的历史由来已久。比如有迪士尼的小飞象、19世纪马戏团的明星大象Jumbo，以及亚利桑那州凤凰城动物园的著名绘画大象Ruby。但是新的研究表明，野生非洲象也能选择自己的名字——并用这些名字在大草原上互相呼唤和问候。
Most animals are born with a fixed set of sounds for communication. A few, such as songbirds, can imitate other sounds they hear around them. Certain species of dolphins and parrots may learn to mimic human words for objects in their environment (like the proverbial Polly who wants a cracker). Much rarer, however, is an ability to assign vocal labels—something akin to names—to fellow members of the flock or pod.
大多数动物生来就拥有一套固定的交流声音。少数动物，如鸣禽，可以模仿它们周围听到的其他声音。某些种类的海豚和鹦鹉可能会模仿人类词汇来指代环境中的物体（就像那个常说的故事里的想要饼干的波莉）。然而，更罕见的是能够给群体中的其他成员分配声音标签——类似于名字的东西。
Bottlenose dolphins and orange-fronted parakeets are thought to address peers with specific calls, to which a unique receiver tends to react. But in these cases, the calls consist of one animal simply imitating the features of another's habitual or trademark sound. (It's as if someone went around constantly repeating their own name, like "Mark," and you mimicked it back at them.) A dolphin may copy another dolphin's “signature whistle” to attract its attention, and the second animal will respond by repeating that very same whistle.
宽吻海豚和橙额长尾小鹦鹉被认为会用特定的叫声来称呼同伴，而且独特的接收者往往会对此做出反应。在这些情况下，叫声其实是一种动物对另一种动物习惯性或标志性声音的简单模仿。（这就像有人不停地重复自己的名字，比如“马克”，而你也跟着模仿他。）一只海豚可能会模仿另一只海豚的“标志性哨声”来吸引它的注意力，第二只动物则会重复同样的哨声来回应。
Now a study in Nature Ecology and Evolution reveals that African elephants engage in a type of communication previously unknown in nonhuman animals. Researchers used machine learning to analyze 469 contact, greeting and caregiving rumbles made by wild savanna elephants in Kenya and discovered that the animals use specific vocal labels to identify one another. Instead of imitating an individual's signature call to signal a particular elephant's identity, they come up with an original sound.
最新发表在《自然·生态与进化》上的一项研究表明，非洲象展现了一种非人类动物中前所未有的交流方式。研究人员利用机器学习技术，分析了肯尼亚野生稀树草原大象发出的469种接触、问候和看护时的隆隆叫声，发现这些动物使用特定的声音标签来识别彼此。它们不是模仿某只大象的标志性叫声来表明身份，而是发出一种独特的原创声音。
“It might seem obvious to me and other elephant researchers that these calls are very specific because you see that a certain individual will respond, but no one has [previously] shown it,” says Caitlin O’Connell-Rodwell, an elephant behavioural ecologist at Harvard Medical School, who was not part of the new study.
“对我和其他大象研究人员而言，这些叫声具有高度的特异性，因为我们会观察到特定的个体会对其作出反应，但此前尚未有人对此进行证实，”哈佛医学院的大象行为生态学家凯特琳·奥康奈尔-罗德维尔表示，她并未参与这项新研究。
Most people associate elephants with loud trumpeting, but the most common elephant sound is actually a low-frequency rumble. Some rumbles are so deep that humans cannot detect them—we hear only down to about 20 hertz, and these sounds reach as low as 5 Hz. Elephants, however, possess unique ear anatomy designed to pick up rumbles from as far away as 1.5 miles. This range is important because female savanna elephants live in an elaborate “fission-fusion” society: their extended family units split up and rejoin on a regular basis as they follow food resources and avoid predators.
大多数人一想到大象，就会联想到它们响亮的号叫声，但实际上，大象最常发出的声音是低频的隆隆声。有些隆隆声频率极低，低至5赫兹，超出了人类的听觉范围（我们的听觉下限约为20赫兹）。而大象的耳朵结构独特，能够捕捉到1.5英里外的隆隆声。这种远距离的听觉能力对雌性稀树草原象来说至关重要，因为它们生活在一个复杂的“裂变-融合”社会中，家族群体会根据食物资源和捕食者的情况定期分裂和重组。
Study co-author Joyce Poole, a co-founder of the charity ElephantVoices, has been studying elephants for almost five decades. She has long suspected that these cognitively advanced animals, which show empathy, mourn their dead and may imitate human speech, address one another from afar with something resembling names. She says she has often observed an elephant calling out and only one responding; the others “would just keep on feeding as if they hadn't even heard her,” Poole says.“I did wonder, are they being just rude by not answering, or is it because she’s actually addressing somebody specific?”
这项研究的合著者乔伊斯·普尔，作为慈善机构ElephantVoices的联合创始人，已经研究大象近50年了。她一直怀疑，这些认知高度发达的动物（它们能表现出同理心，会为同伴的死亡哀悼，甚至可能模仿人类语言）在远处呼唤彼此时，使用的是类似名字的东西。她说，她经常观察到一头大象发出呼唤，而只有另一头特定的大象作出回应；其他大象“则继续进食，仿佛根本没听到呼唤一样”，普尔说道。“我确实好奇，它们不回应是出于无礼，还是因为她实际上是在呼唤某个特定的个体？”
Machine learning helped Poole and her colleagues locate vocal labels among the hundreds of previously recorded female elephant calls. To discern which specific elephants were addressing each other, Poole went back to her old field notes, looking for interactions such as “so-and-so was separate from so-and-so and was calling so-and-so.”In the end, the researchers identified 101 callers and 117 receivers. Next, they measured the acoustic features of the calls to assess whether they contained individual vocal labels.
机器学习助力普尔和她的同事，在数百段先前录制的母象叫声中识别出了声音标签。为了确定哪些特定的大象在相互呼唤，普尔翻阅了她以往的野外观察笔记，寻找类似“某某与某某分开后，正在呼唤某某”这样的互动记录。最终，研究人员确定了101头呼唤者大象和117头被呼唤者大象。随后，他们分析了这些呼唤的声学特征，以评估其中是否包含独特的声音标签。
The model was able to predict the specific receiver of a call with a success rate far better than chance. The vocalizations weren't simply dolphinlike imitation, either; the scientists found no statistical evidence of the animals copying one another. The researchers then verified their findings in the field. They approached 17 wild elephants and played calls addressed to each of them through a speaker. Although the elephants rarely reacted to the “names” of other animals, they quickly responded to their own. “It's a very sharp response,” Poole says. “The head jerks up, the ears spread out, the mouth opens wide.”
该模型预测呼叫具体接收者的成功率远高于随机猜测。而且，这些叫声并非简单的海豚式模仿；科学家们并未发现这些动物之间存在相互模仿的统计证据。随后，研究人员在野外对他们的发现进行了验证。他们靠近17头野生大象，并通过扬声器播放针对每头大象的特定叫声。虽然大象很少对其他动物的“名字”做出反应，但它们对自己的“名字”却迅速作出了回应。“这是一个非常敏锐的反应，”普尔说，“它们会猛地抬起头，耳朵展开，嘴巴张得大大的。”
Study lead author Michael Pardo, a behavioural ecologist now at Cornell University, notes that the researchers couldn't pinpoint which part of a call was labelling an individual and that the data were inconclusive on whether multiple elephants use the same name for an individual. It's possible that the recordings simply lack sufficient examples or that different elephants use slightly different versions of the same name. To parse out the calls, the researchers may need to collect many more samples of elephant rumbles—a challenging task that would entail spending many hours in close proximity to the studied group. “Collecting this type of data is really intense,” says study senior author and Colorado State University biologist George Wittemyer.
该研究的主要作者迈克尔·帕尔多，现任康奈尔大学行为生态学家，指出研究人员无法确定叫声中哪一部分是在标记个体，同时，对于多头大象是否对同一个体使用相同的名字，数据也未能给出明确结论。有可能是因为录音样本不足，或者不同大象对同一个名字使用了略有差异的版本。为了深入解析这些叫声，研究人员可能需要收集更多大象发出的隆隆声样本——这是一项艰巨的任务，因为这意味着需要长时间近距离跟随研究群体。“收集这类数据真的非常耗时费力，”资深作者、科罗拉多州立大学生物学家乔治·维特迈尔说道。
Although humans are still just scratching the surface of elephant communication, Wittemyer suggests the existence of individual vocal labels in these calls indicates a capacity for abstract thinking. What's more, he says, such labels' emergence could add to our understanding of how human language might have evolved. In complex societies where members often lose sight of one another—such as those of elephants or our hominin ancestors—the need to identify and attract others' attention might have driven cognitive abilities and language development.
尽管人类对大象交流方式的理解还只是冰山一角，但维特迈尔认为，这些叫声中存在的个体声音标签表明了大象具备抽象思维的能力。更重要的是，他指出，这种标签的出现可能有助于我们深入理解人类语言的进化过程。在像大象社会或我们的人类祖先所处的那样复杂的社会中，成员间经常会看不到彼此，这时识别和吸引他人注意力的需求可能促进了认知能力和语言的发展。
“If you can name things without relying on imitation, then, at least in theory, it is possible for you to talk about a wider range of subjects because you could potentially come up with names for objects and ideas that don't make any imitable sound,” Pardo says. As O’Connell-Rodwell puts it, “Modifying a vocalization tailored to a specific individual does get you into a conversation. And that's what I would say is a first step.”
帕尔多表示：“如果你能在不依赖模仿的情况下为事物命名，那么至少在理论上，你能够谈论更广泛的主题，因为你有可能为那些无法发出可模仿声音的物体和概念创造出名称。”奥康奈尔-罗德维尔则指出：“为特定个体量身定制的发声方式，确实能开启一段对话。而我认为，这就是第一步。”
重点词汇
savanna n. 热带稀树草原
songbird n. 鸣禽（指能唱歌的鸟类）
mimicked v. 模仿，模拟
rumble n. 隆隆声，低沉的轰鸣声
acoustic adj. 声音的，声学的
proximity n. 接近，邻近
往期回顾
文章来源｜Scientific American:Elephants Call Individuals’ Names across the Savanna
图片来源｜小红书
译者｜龙梦洋
译审｜王春渝
复审｜李小辉
执行编辑｜龙梦洋
审核编辑｜王春渝
