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A Scientist’s Attention Is Fixed on Fruit Flies
科學家鑽研果蠅的奧秘
By James Gorman
SEATTLE – To hear Michael Dickinson tell it, there is nothing quite as wonderful as a fruit fly.
聽狄金森說起來，沒有什麼東西比果蠅更奇妙了。
And it’s not because the fly is one of the most important laboratory animals in the history of biology, often used as a simple model for human genetics or neuroscience.
這並非因為果蠅是生物學領域最重要的實驗室生物之一。牠們經常充當人類遺傳學或神經科學的簡單模型。
“I don’t think they’re a simple model of anything,” he said. “These animals, you know, they’re not like us.
他說：「我不認為牠們是任何東西的簡單模型。要知道，牠和我們可大不相同。」
“They can taste with their wings,” he went on. “No one knows any reason why they have taste cells on their wing. Their bodies are just covered with sensors. This is one of the most studied organisms in the history of science, and we’re still fundamentally ignorant about many features of its basic biology. It’s like having an alien in your lab.
狄金森接著說：「牠們可以用翅膀去嘗味道。沒有人知道牠們的翅膀為什麼會有味覺細胞。牠們的身體佈滿感應器。這是科學史上研究得最多的生物之一。基本上，我們對牠的許多基本生物學特徵還是相當無知。這有如一個外星人闖進你的實驗室。」
“And,” he said, pausing, “they can fly!”
他說：「還有…」，然後停了一下，接著說「牠們會飛！」
Dr. Dickinson, 50, studies the basis of behavior in the brain at the University of Washington, in Seattle. In practice he is a polymath of sorts who has targeted the fruit fly, Drosophila melanogaster, and its flying behavior for studies that involve physics, mathematics, neurobiology, computer vision, muscle physiology and other disciplines.
50歲的狄金森在西雅圖的華盛頓大學研究大腦的行為基礎。實際上他是個博學之士，他的研究鎖定黑腹果蠅及其飛行行為，內容涉及物理學、數學、神經生物學、電腦視覺、肌肉生理與一些其他學科。
Early on Dr. Dickinson and a mentor solved a longstanding physics problem of insect flight, and he has continued to investigate. His influence on new research extends from basic neuroscience to robotics. Researchers at Harvard who built a fly-sized flying robot earlier this year, for example, based it partly on his work.
狄金森早年曾與指導他的學者聯手破解昆蟲飛行物理學一個待解已久的謎團。事後，他繼續深入研究。他對新研究的影響從基本神經科學延伸至機器人學。哈佛大學研究人員今年稍早造出一個蒼蠅大小的機器人，就是以他的研究成果為部分基礎。
His research for his dissertation at the University of Washington was on fly development and neurobiology, but, he said, “I was almost instantly much more interested in the function of the whole fly than the more mechanistic but probably more well-posed problems of how the little axons grow to the brain.”
他的華盛頓大學博士論文研究鎖定蒼蠅的發育與神經生物學。不過他說：「我幾乎立刻對整個蒼蠅的功能產生了濃厚的興趣，程度遠大於更偏向機械學的大腦如何長出小小神經細胞軸索的問題。」
After he left one postdoctoral position, he began working with Karl Georg Gotz at the University of Tübingen on insect flight. “We built this very, very simple model of a wing flapping back and forth in 200 liters of sugar water,” Dr. Dickinson said. What they found was that when the wings flap, “they generate this flow structure called a leading-edge vortex.”
離開一個博士後職位後，他開始與德國圖賓根大學的戈茨共同研究昆蟲的飛行。狄金森說：「我們在200公升的糖水中建造這個非常非常簡單的翅膀來回拍動模型。」他們發現，翅膀拍動時，「會產生名為前沿渦流的氣流結構」。
At the time, the nature of insect flight was still a puzzle, the basis of the myth that engineers had proved that bumblebees could not fly. “We were able to measure the forces,” he said, and to” make simple calculations that, you know, actually insects can fly.”
當時，昆蟲為何能飛本質上還是個謎，科學界有工程師已（依空氣動力學原理）證明熊蜂應該無法飛行的偽科學謎思。他說：「我們當時可以計算各種力，經簡單運算後得到的結論是，昆蟲果然可以飛。」
He was hooked. “Fly flight is just a great phenomenon to study,” he said. “It has everything –from the most sophisticated sensory biology; really, really interesting physics; really interesting muscle physiology; really interesting neural computations. Just the entire process that keeps a fly hovering in space or flying through the air – it links to ecology, it links to energetics.”
他從此著了迷。他說：「蒼蠅的飛行是值得深究的重要現象。它包含一切，從最精密複雜的感應生物學；的的確確引入入勝的物理學；很有趣的肌肉生理學，以及很有趣的神經運算。它們使蒼蠅可以在空中盤旋或飛來飛去。它涉及生態學與動力學。」
When Dr. Dickinson moved to a faculty position, at the University of Chicago, he said, “I tried from that day on to set up a lab that worked in this very integrative way.”
狄金森轉往芝加哥大學擔任教職時說：「我從那一天開始試著建立一個以如此極整合方式運作的實驗室。」
His graduate students and postdoctoral researchers have come from backgrounds including engineering, physics and biology.
他團隊裡的研究所學生與博士後研究人員，背景涵蓋工程學、物理學與生物學。
Gwyneth Card, who was a researcher in Dr. Dickinson’s lab at the California Institute of Technology, said it was a rich environment for a graduate student.
狄金森加州理工學院實驗室的研究員葛妮絲‧卡德說，對研究所的學生來說，這是個豐富的環境。
“He’ll set you a great problem,” she said. “For me he kind of picked out takeoff in flies.” She set up a system for taking infrared video at 7,000 frames per second of flies taking off spontaneously and also when they were frightened by an image of an apparent predator.
她說：「他會向你提出一個好問題。對我而言，他挑的大概是蒼蠅起飛的環節。」她設計了一套紅外線系統，以每秒7000格錄下蒼蠅自然起飛的畫面，以及被掠食者接近的影像驚嚇時的反應。
What she found, and reported in Current Biology in 2008, was that when a predator loomed, the takeoff was not just a reflex action. The flies made preliminary leg movements to prepare for takeoff away from the predator, so somewhere in the fly’s brain the best response to a threat was being computed and a decision being made.
她2008年在「當代生物學」期刊發表報告指出，掠食者逼近時，起飛不只是反射動作。蒼蠅的腳會採取初步動作以準備起飛並遠離掠食者。蒼蠅大腦某個部位會計算對威脅的最佳反應，再下決定。
In Dr. Dickinson’s lab at the University of Washington, there are micro-treadmills for the flies and macro tanks of viscous fluid for robotic wings. His lab has worked with flies that are tethered and engaged in a kind of virtual reality theater, where the flies react to video of stimuli, which they use as targets during flight. Sometimes the flies can control the display, as in a video game.
狄金森的華盛頓大學實驗室配備一些針對蒼蠅設計的微型踏車，以及針對機器翅膀設計的大型黏液槽。實驗室的蒼蠅活動範圍受到限制，同時處於真實劇場。在這裡，它們對刺激的影像產生反應。飛行時，它們把這些影像當成目標。有時候，蒼蠅可以控制顯示的影像，原理類似電視遊戲。
Neuron for neuron, Dr. Dickinson said, the fly brain has a wider range of behavior than more complex mammalian brains. One reason seems to be that the presence of different chemicals called neuromodulators in the fly brain can change how a given group of neurons acts at different times.
狄金森表示，以神經元而言，蒼蠅的大腦具備比更複雜的哺乳類還要廣泛的行為功能。原因之一似乎是，蒼蠅大腦內有稱為神經調質的化學物質，可改變一組神經元在不同時候的反應。
“One of our more recent observations is that drosophila can read the sky compass,” he continued, “so they have the same capability that monarch butterflies have of being able to basically look at the sky” and figure out direction based on the polarization of light.
他說：「我們最近一項觀察結果是，果蠅會從天空判讀方位。換言之，牠具備與帝王蝶相同的天空觀察能力，而且會根據光的偏極辨別方向。」
With this ability, there’s no need to see the whole sky or star patterns. “It works even when you have only a tiny patch of blue sky,” he said. “It’s a solution vertebrates didn’t come upon, humans didn’t come upon, but insects did.”
這種能力使牠們不必觀察整個天空或星辰的形態。他說：「即使只能看到一小塊藍天，它還是管用。脊椎動物並未獲得這種解決能力，人類也沒有。昆蟲卻有。」
原文參照：
http://www.nytimes.com/2013/10/08/science/focusing-on-fruit-flies-curiosity-takes-flight.html
Video： The Flight of the Fly: Michael Dickinson has spent his career studying how flies fly and researchers in his lab have invented new devices to investigate the complex feat of insect flight.
http://nyti.ms/1aglThI
2013-10-22聯合報/G5版/UNITEDDAILYNEWS 陳世欽譯 原文參見紐時週報十版上
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