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科学美国人60秒:“健谈的海龟”颠覆了动物发声进化起源的剧本

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Pakinam Amer: This is Scientific American’s 60-Second Science. I’m Pakinam Amer.

这里是《科学美国人》的60秒科学。我是帕基纳姆·阿米尔。

Clicks, clucks, grunts and snorts—these are not sounds that we typically associate with turtles.

咔哒声、咯咯声、咕噜声和呼噜声——这些声音我们通常不会和乌龟联系在一起。

Amer: They’re actually thought to be very quiet or even silent. But it looks like we may have grossly underestimated how much sound they can make. Now a new study in Nature Communications has collected vocal recordings from 53 species of turtles and other animals that were otherwise considered to be mute.

实际上人们认为它们非常安静,甚至是无声的。但我们似乎严重低估了它们能发出的声音。现在,《自然通讯》杂志上的一项新研究收集了53种海龟和其他动物的发声记录,这些动物我们一直以为是哑巴。

Amer: Those clicks you’ve just heard were calls made by baby giant Amazon River turtles swimming together. A group of evolutionary biologists and other scientists in five different countries pored over these recordings and combined them with vocal repertoires of about 1,800 animal species from other studies.

你刚才听到的咔哒声是亚马逊河巨龟宝宝在一起游泳时发出的叫声。一组来自五个不同国家的进化生物学家和其他科学家仔细研究了这些录音,并将它们与来自其他研究的大约1800种动物的声音组合起来。

Amer: They were able to piece together evidence that the last common ancestor of all lungfish and tetrapods started vocalizing more than 400 million years ago. (And just in case you aren’t familiar, tetrapods are four-limbed vertebrates that include amphibians, mammals, birds and reptiles.) That’s at least 100 million years earlier than previous studies had suggested.

由此他们拼凑出了证据,证明所有肺鱼和四足动物的最后一个共同祖先,大约在4亿多年前开始发声。(以防你不熟悉,四足动物是四肢脊椎动物,包括两栖动物、哺乳动物、鸟类和爬行动物。)这比之前的研究认为的至少早了1亿年。

Amer: The new revelations amount to a rewriting of the acoustic history of animals with backbones.

新的发现相当于重写了脊椎动物的声学历史。

Gabriel Jorgewich-Cohen: I did fieldwork in the Brazilian Amazon with a researcher that published one of these first papers showing that turtles can communicate acoustically, and that inspired me. So I went back home, and I got a piece of equipment, and I started recording my own pets. And I discovered that they were producing sounds as well, and the species I had were not known to produce sounds. So I started thinking maybe they all do, and I went out there, and I recorded as many as I could [laughs].

我和一位研究人员在巴西亚马逊进行了实地调查,他发表了第一篇论文,表明海龟可以用声音交流,这启发了我。所以我回到家,拿了一件设备,开始录制我自己的宠物。我发现它们也会发出声音,而据我所知这个物种是不会发出声音的。所以我开始想,也许它们都是这样,我就去了亚马逊,尽可能多地录了下来(笑)。

Amer: That was Gabriel Jorgewich-Cohen, a researcher at the University of Zurich and study co-author. By the way, the pets he’s talking about are giant Amazon River turtles, more commonly known as red-eared slider turtles in the U.S.

加布里埃尔·约格维奇-科恩,苏黎世大学的研究员和研究的合著者。顺便说一下,他的宠物是巨型亚马逊河龟,在美国更常见的名字是红耳龟。

Jorgewich-Cohen: This is the only species known to have post-hatch parental care among all turtles, which is pretty amazing. And they discovered this by recording the sounds of the animal—not only this species but also sea turtles, for example. When they are in the nest, the hatchlings start vocalizing from within the egg to synchronize hatch. And also when they come out altogether, they individually have less chance of being eaten by another animal. And in the case of the Amazon River turtle, when they go to the water, the females are there, waiting for them, and they are also vocalizing. And they find each other, and then they migrate together up the river to the forest.

惊人的是,这是已知的唯一一种有孵化后亲代照料的海龟。他们通过记录动物的声音发现了这一点,不仅是这个物种,还有海龟。当它们在巢里时,孵化出来的小海龟开始在蛋里发声,以同步孵化。而且当它们一起破壳出来的时候,它们被其他动物吃掉的几率就更小了。以亚马逊河的海龟为例,当它们游到水里时,雌性海龟就在那里等着它们,它们也会发出声音。它们找到彼此后,一起向河上游的森林迁徙。

Amer: A previous study published in 2020 by researchers at the University of Arizona concluded that only two of 14 families of turtles vocalized. It also stated that acoustic communication evolved independently in most major tetrapod groups, with origins in the range of 100 million to 200 million years ago. But now we know that’s not the case.

亚利桑那大学的研究人员在2020年发表的一项研究认为,14个海龟家族中只有两个会发声。它还指出,声学通信在大多数主要的四足动物群体中独立进化,起源在1亿到2亿年前。但现在我们知道事实并非如此。

Jorgewich-Cohen: I was very surprised—happily surprised—when I found so many different types of sounds. And I kept recording more and more animals. And every animal I recorded made sounds; I had no negative results whatsoever. And that was surprising by itself.

当我发现有这么多不同类型的声音时,我非常惊讶——惊喜。我继续记录越来越多的动物。我记录的每一种动物都有声音;没有任何例外。这本身就很令人惊讶。

Amer: Jorgewich-Cohen recorded hundreds of hours’ worth of footage over two years—not just of turtles but also of lungfish, tuatara and other creatures. Animals typically produce sounds for many reasons: to define territory, to attract a mate or to communicate with their young ones. It’s a useful skill.

约格维奇-科恩在两年的时间里记录了数百小时的素材——不仅是海龟,还有肺鱼、鳄蜥和其他生物。动物发出声音的原因有很多:界定领地、吸引配偶或与幼崽交流。这是一项有用的技能。

Jorgewich-Cohen: I found that for many turtle species, there are sounds that are only made by males, there are some that are only made by females, and some only by juveniles, and some that males will only make when they are in front of the female.

我发现对于许多龟类物种来说,有些声音只由雄性发出,有些只由雌性发出,有些只由幼体发出,有些雄性只有在雌性面前才会发出。

Amer: If there’s one animal from this study that I would’ve sworn is 100 percent mute, it’s the caecilian. For those who’re not familiar, let me paint a little picture: Caecilians are slippery, slimy and slithery little things. They burrow, and they look like earthworms or even snakes. But they’re neither. They’re in fact amphibians. They have a backbone and a skull, jaws and all, but no limbs. And like many tetrapods, they emit sounds through their respiratory tract, just like their common ancestor. It’s actually not very easy to come across one.

如果在这项研究前,有一种动物我敢发誓是百分之百的哑巴,那就是蚓螈。很多人不熟悉,让我来描绘一下:蚓螈是一种又湿又黏又滑的小东西。它们会挖洞,看起来像蚯蚓,甚至像蛇。但都不是。它们实际上是两栖动物。它们有脊椎骨、头骨、下巴等等,但没有四肢。和许多四足动物一样,它们通过呼吸道发出声音,就像它们共同的祖先一样。实际上,要找到它们并不容易。

Jorgewich-Cohen: The caecilian was a special one because I definitely expected it not to make any sounds. And it’s not only that it does, but it makes very strange and very loud sounds.

蚓螈很特别,因为我完全不希望它发出任何声音。而它不仅会,还能发出非常奇怪和响亮的声音。

Amer: Not to be crass, but that sounds a bit like a fart.

不是我粗鲁,但这听起来有点像放屁。

Jorgewich-Cohen: When I heard it for the first time, I started laughing, and I sent it to my friends who did fieldwork with me. They also started laughing, and they said, “I cannot believe you. You made the sound with your mouth, and you’re sending me the file.” I was like, “No, I swear.”

当我第一次听到这个声音时,我开始大笑,我把它发给了和我一起做田野调查的朋友。他们也开始笑了,他们说:"我不信。是你用嘴发出了声音,把文件发给了我。" 我当时说:"不,我发誓。"

Amer: The study, “Common Evolutionary Origin of Acoustic Communication in Choanate Vertebrates,” is less focused on the function of these sounds and more on the evolution of acoustic signals. But in future studies, the researchers plan to dig deeper by analyzing the sounds further in an attempt to understand what they mean.

这项名为“内鼻孔类脊椎动物的发生交流拥有共同的演化起源”的研究较少关注这些声音的功能,而是更多地关注声源的进化。但在未来的研究中,研究人员计划通过进一步分析声音来深入挖掘,试图理解它们的含义。

Jorgewich-Cohen: We try to also make footage of the animals while we’re recording the sounds so we could try to correlate any type of behavior to the sound that they were making and try to understand how they use the sounds or what ideas they convey.

我们在录制声音的同时也尝试拍摄动物的片段,这样我们就可以尝试将行为与声音联系起来,并尝试了解它们是如何使用这些声音的,或者它们传达了什么想法。

Amer: Sometimes Jorgewich-Cohen and his colleagues would find more than 30 different sounds in a single species’ repertoire. It seems that the more socialized the animal is, the more vocally diverse it is, he says. But further studies are needed to confirm this.

有时约格维奇-科恩和他的同事会在一个物种的声库中发现30多种不同的声音。他说,似乎动物越社会化,声音就越多样化。但还需要进一步的研究来证实这一点。

Jorgewich-Cohen: Hopefully this is the beginning of a new field of study. So people are going to go out there and try to record more of these animals and get to new conclusions and new discoveries. But it will be really cool if we could, for example, do playback experiments and try to understand if they reply to the sounds we make. And then we can start understanding what these sounds mean and how they are used.

希望这是一个新的研究领域的开始。所以人们会尝试记录更多的这些动物,得到新的结论和新的发现。但如果我们可以,例如,做回放实验,试着了解它们是否对我们发出的声音做出反应,那就太酷了。然后我们就可以开始理解这些发音的意思以及它们的用法了。

Amer: Thank you for listening! For Scientific American’s 60-Second Science, I’m Pakinam Amer.

感谢收听《科学美国人》的60秒科学。帕基纳姆·阿米尔报道。

Pakinam Amer: This is Scientific American’s 60-Second Science. I’m Pakinam Amer.

Clicks, clucks, grunts and snorts—these are not sounds that we typically associate with turtles.

Amer: They’re actually thought to be very quiet or even silent. But it looks like we may have grossly underestimated how much sound they can make. Now a new study in Nature Communications has collected vocal recordings from 53 species of turtles and other animals that were otherwise considered to be mute.

Amer: Those clicks you’ve just heard were calls made by baby giant Amazon River turtles swimming together. A group of evolutionary biologists and other scientists in five different countries pored over these recordings and combined them with vocal repertoires of about 1,800 animal species from other studies.

Amer: They were able to piece together evidence that the last common ancestor of all lungfish and tetrapods started vocalizing more than 400 million years ago. (And just in case you aren’t familiar, tetrapods are four-limbed vertebrates that include amphibians, mammals, birds and reptiles.) That’s at least 100 million years earlier than previous studies had suggested.

Amer: The new revelations amount to a rewriting of the acoustic history of animals with backbones.

Gabriel Jorgewich-Cohen: I did fieldwork in the Brazilian Amazon with a researcher that published one of these first papers showing that turtles can communicate acoustically, and that inspired me. So I went back home, and I got a piece of equipment, and I started recording my own pets. And I discovered that they were producing sounds as well, and the species I had were not known to produce sounds. So I started thinking maybe they all do, and I went out there, and I recorded as many as I could [laughs].

Amer: That was Gabriel Jorgewich-Cohen, a researcher at the University of Zurich and study co-author. By the way, the pets he’s talking about are giant Amazon River turtles, more commonly known as red-eared slider turtles in the U.S.

Jorgewich-Cohen: This is the only species known to have post-hatch parental care among all turtles, which is pretty amazing. And they discovered this by recording the sounds of the animal—not only this species but also sea turtles, for example. When they are in the nest, the hatchlings start vocalizing from within the egg to synchronize hatch. And also when they come out altogether, they individually have less chance of being eaten by another animal. And in the case of the Amazon River turtle, when they go to the water, the females are there, waiting for them, and they are also vocalizing. And they find each other, and then they migrate together up the river to the forest.

Amer: A previous study published in 2020 by researchers at the University of Arizona concluded that only two of 14 families of turtles vocalized. It also stated that acoustic communication evolved independently in most major tetrapod groups, with origins in the range of 100 million to 200 million years ago. But now we know that’s not the case.

Jorgewich-Cohen: I was very surprised—happily surprised—when I found so many different types of sounds. And I kept recording more and more animals. And every animal I recorded made sounds; I had no negative results whatsoever. And that was surprising by itself.

Amer: Jorgewich-Cohen recorded hundreds of hours’ worth of footage over two years—not just of turtles but also of lungfish, tuatara and other creatures. Animals typically produce sounds for many reasons: to define territory, to attract a mate or to communicate with their young ones. It’s a useful skill.

Jorgewich-Cohen: I found that for many turtle species, there are sounds that are only made by males, there are some that are only made by females, and some only by juveniles, and some that males will only make when they are in front of the female.

Amer: If there’s one animal from this study that I would’ve sworn is 100 percent mute, it’s the caecilian. For those who’re not familiar, let me paint a little picture: Caecilians are slippery, slimy and slithery little things. They burrow, and they look like earthworms or even snakes. But they’re neither. They’re in fact amphibians. They have a backbone and a skull, jaws and all, but no limbs. And like many tetrapods, they emit sounds through their respiratory tract, just like their common ancestor. It’s actually not very easy to come across one.

Jorgewich-Cohen: The caecilian was a special one because I definitely expected it not to make any sounds. And it’s not only that it does, but it makes very strange and very loud sounds.

Amer: Not to be crass, but that sounds a bit like a fart.

Jorgewich-Cohen: When I heard it for the first time, I started laughing, and I sent it to my friends who did fieldwork with me. They also started laughing, and they said, “I cannot believe you. You made the sound with your mouth, and you’re sending me the file.” I was like, “No, I swear.”

Amer: The study, “Common Evolutionary Origin of Acoustic Communication in Choanate Vertebrates,” is less focused on the function of these sounds and more on the evolution of acoustic signals. But in future studies, the researchers plan to dig deeper by analyzing the sounds further in an attempt to understand what they mean.

Jorgewich-Cohen: We try to also make footage of the animals while we’re recording the sounds so we could try to correlate any type of behavior to the sound that they were making and try to understand how they use the sounds or what ideas they convey.

Amer: Sometimes Jorgewich-Cohen and his colleagues would find more than 30 different sounds in a single species’ repertoire. It seems that the more socialized the animal is, the more vocally diverse it is, he says. But further studies are needed to confirm this.

Jorgewich-Cohen: Hopefully this is the beginning of a new field of study. So people are going to go out there and try to record more of these animals and get to new conclusions and new discoveries. But it will be really cool if we could, for example, do playback experiments and try to understand if they reply to the sounds we make. And then we can start understanding what these sounds mean and how they are used.

Amer: Thank you for listening! For Scientific American’s 60-Second Science, I’m Pakinam Amer.


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