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Did Animal Calls Start in the Dark?

The animal kingdom is a noisy place. There's bird song,  choruses of frogs , and lots of lesser¹ known sounds… like the ray-gun-like sounds of baby alligators³ hatching and calling for mom.  (There's lots of videos of them doing this on YouTube if you are curious.)

动物王国是一个嘈杂的地方。有鸟鸣，青蛙的合唱声，还有很多不为人知的声音，比如短吻鳄幼崽孵化和呼唤妈妈时发出的类似雷鸣枪的声音。(如果你好奇的话，YouTube上有很多他们这样的视频。)

"When I was a kid growing up, I had a pet alligator². It vocalized a lot." John Wiens, an evolutionary⁴ ecologist at the University of Arizona. "So I had this baby alligator when I was a teenager, sometimes I could hear "urh urh urh urh," and when they grow up they make bellows⁵ and slaps and all sorts of sounds."

“我小时候养过一只鳄鱼当宠物。它发出很多声音。”约翰·维恩斯是亚利桑那大学的进化生态学家。“我十几岁的时候养了一只小鳄鱼，有时我能听到‘啊，啊，啊，啊’，等它们长大了，就会发出吼声、拍打声和各种声音。”

Wiens and his collaborator⁶ Zhuo Chen wondered: why did animals start vocalizing in the first place? One hypothesis was that the ability originated in nocturnal animals. Cause, you know, sound works a lot better than colors or horns or other visual cues when you can’t see.

Wiens和他的合作者Zhuo Chen想知道:为什么动物一开始就会发声?一种假设是这种能力起源于夜行动物。因为，你知道，当看不见的时候，声音比颜色、喇叭或其他视觉提示更有效。

Wiens and Chen built an evolutionary tree of nearly 1800 vertebrate species, and mapped onto it information on whether each lived by day or night, and whether they made sound.  

维恩斯和陈建立了一个包含近1800种脊椎动物物种的进化树，并在上面绘制了它们生活在白天还是夜晚，以及它们是否发声的信息。

"So one of the things we did then was to do a statistical⁷ correlation⁸ between the evolution of acoustic⁹ communication, and whether they were active by day or by night. And we found a very strong relationship. Those that are active at night, tend to evolve acoustic communication." Suggesting that the nocturnal notion was more than just a shot in the dark.

“因此，我们当时做的一件事是做一个统计相关性之间的演变声通信，以及他们是否在白天或晚上活跃。我们发现了一种非常牢固的关系。那些在晚上活动的，倾向于进化成声音交流。”表明夜间活动的概念不仅仅是在黑暗中拍摄的。

The findings are in the journal Nature Communications.

这项研究结果发表在《自然通讯》杂志上。

This ability to vocalize likely arose independently, multiple times, hundreds of millions of years ago—in frogs, mammals, geckos, and birds and crocodilians. And though vocalization might have originated with nocturnal animals, some night-dwellers seem to have lost the ability—like pangolins. While others, which evolved to be active by day, retained it. Like, of course, you and me.

这种发声能力可能是在数亿年前独立地、多次地出现在青蛙、哺乳动物、壁虎、鸟类和鳄鱼中。尽管发声能力可能起源于夜行动物，但一些夜行动物似乎已经丧失了像穿山甲一样的能力。而另一些进化为白天活动的动物则保留了这种能力。当然，其中也包括你和我。