This is Scientific American — 60-Second Science. I'm Christopher Intagliata.
In the frog world, romance is often accompanied by a song. "It's the norm. The vast majority of frogs have males calling to attract females."
Sandra Goutte is an evolutionary biologist and herpetologist at the University of Campinas, in Brazil. And she studies frogs called 'pumpkin toadlets' from the cloud forests of coastal Brazil. "They're extremely cool, they're teeny tiny." They're neon orange, and they wave their arms around when they feel threatened, "by either predator or herpetologist."
And, true to frog form, "they make this slow call that sounds like a cricket, like "che che."
But here's the weird part: it appears the pumpkin toadlets are not able to hear the sounds they make. Goutte and her colleagues playing recordings of the calls to the frogs to look for reactions. The researchers also traced electrical impulses from the frogs' ears to their brains, and even dissected the frog inner ear.
And it turns out, the frogs just don't have the equipment to hear their own voices. The study is in the journal Scientific Reports.
"Why would they call if they cannot hear their own calls, right?" Goutte does have a few theories. Perhaps, she says, the bulging throat movement associated with calling is a sexual signal, with the sound an inadvertent accompaniment—perhaps the frogs lost the ability to hear the calls at some point in their evolutionary history, when the displays did the job well enough on their own. After all, they're a highly visual species—out during the day, brightly colored, do the hand-waving thing.
Pumpkin toadlets are the only species unable to hear themselves. At least, as far as we know. "The thing is, it was really hard to convince even some of the co-authors to do the experiments, because they were like, 'Why would you test their hearing? If they're calling, they hear, they must hear, right?' So I think it's also the way we're doing science—we're not actually testing these obvious things. So maybe there are more examples out there but we don't know any yet." One can only hope that future research proposals will get a fair hearing.
Thanks for listening for Scientific American — 60-Second Science Science. I'm Christopher Intagliata.
在青蛙的世界，浪漫常与歌声相伴 。“这是一种常态 。在绝大多数蛙类中，雄性会通过叫声来吸引雌性 。”
桑德拉·古特是巴西坎皮纳斯大学的进化生物学家和爬虫学者 。她研究巴西沿海云雾林里的“短头蟾” 。“它们非常酷，而且体型非常小 。”它们呈霓虹色，当感受到威胁时会挥舞手臂，“无论威胁来自捕食者还是爬虫学家” 。
但是奇怪的是：短头蟾似乎无法听到自己发出的声音 。古特和同事给短头蟾播放它们自己叫声的录音来观察它们的反应 。研究人员还追踪了从短头蟾耳朵到大脑的电脉冲信号，甚至还分析了它们的内耳 。
研究结果表明，短头蟾没有能识别自己声音的器官 。这项研究结果发表在《科学报告》期刊上 。
“如果它们听不见自己的叫声，那为什么还要叫呢？”古特给出了一些理由 。她认为，可能与声音有联系的喉咙鼓胀活动是一种性信号，而声音是一种无意为之的附属物，也可能是短头蟾在进化过程中的某一时间点失去了听到自己叫声的能力，因为喉咙鼓胀在求偶方面足够奏效 。毕竟，它们是高度可视化物种，它们通常在白天外出，体色光鲜亮丽，还会挥舞肢体 。
短头蟾是唯一不能听到自己声音的物种 。至少就我们已知的情况来看，短头蟾是唯一的物种 。“问题是，说服一些合著者进行实验非常难，因为他们会说，‘为什么你要测试它们的听力？如果它们发出叫声，它们会听到，它们一定会听到，对吧？'因此，我认为这也是我们现在研究科学的方式——我们不去测试那些显而易见的事物 。也许那些事物中存在更多例证，可是我们目前还不知道 。”我们只能希望未来的研究计划能得到公平的对待 。
谢谢大家收听科学美国人——60秒科学 。我是克里斯托弗·因塔利亚塔 。
1. turn out 原来是；结果发现；
例句：Cosgrave's forecast turned out to be quite wrong.
2. after all 毕竟；终究；
例句：Perhaps I had misjudged him, and he was not so predictable after all.
3. unable to do sth. 不能…的；无法…的；
例句：I was so overpowered by my guilt and my shame that I was unable to speak.
4. as far as sb. know 据……所知；
例句：As far as I know he'll be away for three months.