As animals grow, the sounds they make change. But some sounds continue to change, even after an animal matures.

随着动物的成长，它们的声音也在发生着变化。有过，即使有些动物长大了，声音仍在继续发生变化。

That's true for humans, and now it turns out to be true for North Atlantic right whales, too.

对于人类来说是这样的，对北大西洋露脊鲸来说也是如此。

A member of the baleen¹ family of whales, the endangered North Atlantic right whales spend most of their time along the eastern coast of North America from Canada's Bay of Fundy south to Florida.

北大西洋露脊鲸是须鲸家族的成员，也是濒临灭绝的一种动物。它们大部分时间都在沿着北美大陆东部海岸活动，范围是加拿大的芬迪湾到佛罗里达。

Syracuse University biologist Holly² Root-Gutteridge analyzed³ recordings⁴ of whale calls to see if researchers could use those sounds to identify individual whales. In an audio program on a computer screen, a call has a particular shape.

锡拉丘兹大学生物学家霍利·罗特·特里奇分析了鲸鱼呼叫的录音，以便判断研究人员是否可以使用这些声音来识别鲸鱼。在电脑屏幕上的一个音频程序里，鲸鱼的每一次叫声都会产生一条形状独特的线条。

"Staring at these calls all day, I started to notice they were changing. And then we looked a little bit harder at the data, and realized that they weren't just changing from being a little tiny baby to being a fair sized adult…but that they kept changing over time."

“整天盯着这些声音线条，我开始注意到，它们一直在变化。然后我们把更多注意力放在数据变化上，才发现原来它们的声音不仅从鲸鱼宝宝到成年时期有变化，而且在成年后还在一直改变。”

Root-Gutteridge and her colleagues rounded up seventeen years' worth of whale recordings. In all, they gathered nearly a thousand calls from 49 individual whales between the ages of one month and 37 years.

罗特·特里奇和她的同事收集了这种鲸鱼十七年的录音。总的来说，他们手上有来自一个月至37岁之间的49头鲸鱼的近千条叫声。

Like many other animals, mature whales produced calls that were clearer, longer, and more structurally⁵ complex.

与其他动物一样，成年鲸鱼发出的声音比幼年时期的更加清晰、绵长，结构上也更加复杂。

But the researchers also found that the calls continued to develop long after the whales reached sexual and physical maturity⁶.

但研究人员同时也发现，这些叫声在鲸鱼的性和生理成熟之后很久仍然在继续变化。

"Instead of just changing from the age of 0 to 15 when they're pretty much full-grown, they kept changing after the age of 15 and just kept going throughout their whole lives. Compared to say, a bird, where usually they get to their full-grown state and then they don't change these calls."

“它们不仅从0岁到15岁时的快速生长期声音在改变着，15岁后也在不断变化，并持续一生。相比之下，鸟类在完全成熟后，其鸣叫声往往不会再改变。”

"Well, it means that instead of having a completely instinctive⁷ reaction where they always make the same call in response to the same stimuli⁸ -- a reflex, basically -- that the whales are capable of changing what they're calling and how they're communicating. Which means that they may be thinking about what they call."

“这意味着，北大西洋露脊鲸发声并不是一个完全出自本能的行为，比如面对某种特定的刺激会发出特定的叫声，而是鲸鱼拥有改变叫声和交流方式的能力。这意味着它们在发声时或许是经过思考了的。”

In other words, understanding the calls of North Atlantic right whales might shed some light on the minds of North Atlantic right whales.

换句话说，对北大西洋露脊鲸叫声的理解，可能会对分析它们的头脑带来一些启发。

In the meantime, scientists announced recently that they did not observe any newly born North Atlantic right whales this year -- bad news for an already imperiled species. With luck, the work of biologists like Root-Gutteridge might offer insights that help us we try to help them survive.

另一方面，科学家们最近宣布，他们今年还没有发现新出生的北大西洋露脊鲸--这对于这个本就濒危的物种来说是个坏消息。但愿，像罗特·特里奇这样的生物学家的工作，能对我们挽救这个物种的生存提供更多启示。