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This is Scientific American — 60-Second Science. I'm Karen Hopkin.

这里是科学美国人——60秒科学。我是凯伦·霍普金。

In the wild, monkeys need to keep their eyes peeled for all sorts of dangers, like leopards² and eagles and snakes. But the green monkeys studied by Julia Fischer of the German Primate³ Center have an additional challenge: they also have to scan the skies for drones.

在野外，猴子需要密切留意各种危险，比如豹子、老鹰和蛇。但德国灵长类动物研究中心的朱莉·费舍尔研究的绿猴还面临另一项挑战：它们还必须观察天空，注意无人机。

"Why did we fly a drone over green monkeys, one may ask."

“有人可能会问，为什么要让无人机在绿猴头顶上空飞？”

One may indeed. The answer is that Fischer and her colleagues are interested in how primates⁴ communicate.

可能的确有人问。答案是费舍尔和同事对灵长类动物的交流方式很感兴趣。

In a classic study back in the 1980s, scientists showed that East African vervet monkeys produce alarm calls that are specific for the predators⁵ they encounter. So for example, vervet monkeys hearing a leopard¹ alarm (clip) might scurry⁶ up a tree, whereas the eagle call (clip) sends them running for cover under the closest shrub⁷.

在上世纪80年代的一项经典研究中，科学家发现，东非长尾黑颚猴在遇到捕食者时会发出特定的警报叫声。例如，长尾黑颚猴听到豹子警报声（音频片段）时可能会迅速爬上树，而在听到老鹰警报声（音频片段）时会跑到最近的灌木丛中藏起来。

Now, the green monkeys that live in Senegal share a similar system to warn of leopards and snakes. But they aren't known to raise a ruckus in response to birds of prey⁸.

现在，生活在塞内加尔的绿猴会用类似的系统来警报遇到豹子和蛇的情况。但人们不知道它们对猛禽的反应会引起骚乱。

"And so therefore we decided⁹ to fly a drone over them."

“因此我们决定让无人机从它们的头顶上空飞过。”

The researchers treated 80 green monkeys to a show of drones. How did the animals react to this unfamiliar¹⁰ aerial intruder?

研究人员让80只绿猴观看无人机表演。它们对这个不熟悉的空中入侵者有何反应？

"The monkeys did respond. They responded with alarm calls (clip), and they responded by running away."

“猴子们确实做出了反应。它们发出了警报声（音频片段），而且逃走了。”

Here's where things get really interesting: the calls the green monkeys made after spotting the drones were different from the ones they use to signal leopards (clip) or snakes (clip). But even more intriguing¹¹:

有趣的是：绿猴发现无人机后发出的叫声，与它们用来警报遇到豹子（音频片段）或蛇（音频片段）时发出的声音不同。但更有趣的是：

"And when we did an acoustic¹² analysis, these alarm calls (clip) were almost eerily¹³ similar to the ones of the east African vervets. (clip)"

“我们进行声学分析后发现，这些警报叫声（音频片段）与东非长尾黑颚猴的警报声惊人地相似。（音频片段）”

The findings are described in the journal Nature Ecology & Evolution.

研究结果发表在《自然生态与进化》期刊上。

The fact that the two monkey species seem to speak the same language, if you will, even though they diverged¹⁴ from their last common ancestor some 3 million years ago, suggests that this vocal¹⁵ warning system is hardwired.

事实上，如果你允许我这么说的话，即使这两种猴子在300万年前就从它们最后一个共同祖先处分离出来，但它们似乎说着同样的语言，这表明这种声音警报系统是固有的。

So if you hear a monkey go (clip), watch out for a hungry bird. Or check to see if you got a package delivered.

因此，如果你听到猴子发出这样的叫声（音频片段），要小心饥饿的鸟。或者检查一下是不是包裹到了。

Thanks for listening for Scientific American — 60-Second Science. I'm Karen Hopkin.

谢谢大家收听科学美国人——60秒科学。我是凯伦·霍普金。