Level 2 Reading 2B

Ch.4 Reading 2B

第4章 阅读2B

THE 1,000-YEAR BIRD SONG Every summer, the calls of thousands of swamp sparrows can be heard across North America's wetlands. These little brown birds know only a few songs, but they know them very well. In fact, their musical set list probably hasn't changed much for centuries. Like humans, baby swamp sparrows learn to communicate by copying adults. From a young age, they learn to copy, or mimic, songs sung by their elders. "Swamp sparrows very rarely make mistakes when they learn their songs," says biologist Robert Lachlan. In fact, their mimicry is so accurate that the music changes little between generations. Just like children, the sparrows don't remember every song they hear, Lachlan says. "They don't just learn songs at random; they pick up commoner songs rather than rarer songs." In other words, they learn songs they hear most often. It's an example of a strategy that scientists call conformist bias. Until recently, this learning ability was thought to be special only to humans. Between 2008 and 2009, Lachlan's research team recorded the calls of 615 male swamp sparrows across the northeastern United States. The researchers used computer software to break each song into a collection of notes, or syllables. They then measured the differences between the tunes. The research revealed that only 2 percent of male sparrows sung a different song from the standard tune. The combination of accurate mimicry and conformist bias allows the birds to create traditions that last for centuries. "With those two ingredients together, you end up with traditions that are really stable," says Lachlan. "The song-types that you hear in the marshes of North America today may well have been there 1,000 years ago." Lachlan's study is among the first to measure the longevity of song traditions within a bird species. Another aspect scientists are now exploring is the impact of habitat loss on songbirds. Man-made barriers—such as cities, roads, and plantations—can break up a bird population into a number of isolated groups. These barriers may prevent cultural interaction between songbird populations, such as the exchange of song types. The findings are really exciting, says scientist Andrew Farnsworth. He hopes that future research will evolve from these studies. For example, scientists may be able to identify how other animals are able to preserve their cultural traditions. "Seeing the potential for it in other organisms is super cool," says Farnsworth.

千年鸟鸣 每年夏天，北美湿地都能听到数千只沼泽麻雀的叫声。 这些棕色的小鸟只会唱几首歌，但它们非常熟悉。 事实上，他们的音乐曲目列表几个世纪以来可能没有太大变化。 像人类一样，沼泽麻雀宝宝通过模仿成年人来学习交流。 从很小的时候起，他们就学会了模仿长辈唱的歌。 生物学家罗伯特·拉克伦说：“沼泽麻雀在学习歌曲时很少出错。”。 事实上，他们的模仿是如此精确，以至于音乐在几代人之间几乎没有变化。 拉克伦说，就像孩子一样，麻雀不会记住它们听到的每一首歌。 “他们不只是随机学习歌曲；他们选择更普通的歌曲，而不是更稀有的歌曲。” 换句话说，他们学习他们最常听到的歌曲。 这是科学家们称之为顺从偏见的策略的一个例子。 直到最近，这种学习能力还被认为只有人类才有。 2008年至2009年间，拉克兰的研究小组记录了美国东北部615只雄性沼泽麻雀的叫声。 研究人员使用计算机软件将每首歌分成一组音符或音节。 然后，他们测量了曲调之间的差异。 研究表明，只有2%的雄性麻雀唱的歌与标准曲调不同。 准确的模仿和顺从的偏见相结合，使鸟类能够创造出持续几个世纪的传统。 拉克伦说：“将这两种成分结合在一起，你最终会得到真正稳定的传统。”。 “你今天在北美沼泽地听到的歌曲类型很可能在1000年前就存在了。” Lachlan的研究是首批测量鸟类歌唱传统寿命的研究之一。 科学家们现在正在探索的另一个方面是栖息地丧失对鸣禽的影响。 人造屏障，如城市、道路和种植园，可以将鸟类种群分成许多孤立的群体。 这些障碍可能会阻碍鸣禽种群之间的文化互动，例如歌曲类型的交流。 科学家安德鲁·法恩斯沃斯说，这些发现真的很令人兴奋。 他希望未来的研究能够从这些研究中发展出来。 例如，科学家们可能能够确定其他动物是如何保护其文化传统的。 法恩斯沃斯说：“看到它在其他生物体中的潜力真是太酷了。”。

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