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Why Does Freshly Cut Grass Smell So Nice?
为什么新割的草那么好闻
If you grew up in the suburbs, you recognize it immediately: the sweet, sharp smell of someone mowing a lawn or ballfield. As it wafts into your nostrils, it somehow manages to smell exactly like the color green. But what are we really smelling when we inhale that fresh-cut grass scent? And why do we like it so much?
如果你是在郊区长大的，你立刻就能闻出这个味道——刚修剪完草坪或棒球场后甜美、浓烈的气味。当它飘进你的鼻孔时，它的味道不知为何如绿色般清新。不过，当我们吸入新割的草的气味时，我们真正闻到的是什么呢？为什么我们这么喜欢这个味道？
Chemically speaking, that classic lawn smell is an airborne mix of carbon-based compounds called green leaf volatiles, or GLVs. Plants often release these molecules when damaged by insects, infections or mechanical forces — like a lawn mower.
从化学角度来讲，这种典型的草坪气味来源于空气中混合的碳基化合物，称为绿叶挥发物（简称GLVs）。植物在受到昆虫、传染病的入侵或机械外力如割草机的破坏时，会释放这些分子。
Plants manufacture slightly different forms of GLVs depending on what's happening to them, said Ian Baldwin, a plant ecologist and founding director of the Max Planck Institute for Chemical Ecology in Jena, Germany. In a 2010 study published in the journal Science, he and colleague Silke Allmann, of the University of Amsterdam, found that tobacco leaves punctured and rubbed with insect saliva released a different bouquet of volatile compounds than leaves that had been poked and brushed with water.
植物生态学家、德国耶拿马克斯普朗克化学生态学研究所创始所长Ian Baldwin说，植物制造的GLVs会根据它们所遭遇的不同入侵而略有不同。在2010年发表于《科学》杂志上的一项研究中，他和阿姆斯特丹大学同事Silke Allmann发现，被昆虫侵食和唾液摩擦的烟叶释放出的挥发物，与被水冲刷过后所释放的挥发物不同。
GLVs are small enough to take to the air and float into our nostrils. In some cases, they can be detected more than a mile from the plant where they originated. Other species, such as insects that eat plants and the predators that eat those insects, are extremely sensitive to different GLV aromas. For instance, Baldwin and Allmann discovered that predatory Geocoris bugs are attracted to the GLVs released by plants chewed on by a pest called the tobacco hornworm. In other words, the specific smell of the besieged plants indicates to the predators that a snack is nearby.
GLVs很小，它们混杂在空气中，飘进我们的鼻孔。某些时候，在离其原产植物一英里以外的地方就能闻到。像食草昆虫以及吃这些昆虫的捕食者等物种，它们对不同的GLV气味非常敏感。例如，Baldwin和Allmann发现，一种名为烟草天蛾的害虫啃食植物后，植物释放出的GLV会吸引有益的昆虫捕食者大眼虫，也就是说，被围困的植物释放的特殊气味向捕食者发出了附近有它们的食物的信号。
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