Study Reveals Keep the Eyes Moist
睫毛可讓眼睛保持濕潤
By James Gorman

Long and luxurious eyelashes have been in fashion at least since Cleopatra. But scientists now suggest that their real function is to help protect eyes from drying out.
至少從埃及豔后克莉奧佩特拉開始，長而濃密的睫毛就始終很時麾。而現在，科學家還認為，睫毛的真正功能是協助保護眼睛，避免乾燥。

David Hu at the Georgia Institute of Technology first decided to investigate eyelashes after seeing his newborn daughter bat hers three years ago. He enlisted graduate students in his biomechanics lab and colleagues to join the investigation. They measured the lashes of different mammals, most of which have them. They made an artificial eye with lashes, put it in a wind tunnel and blew air at it. And they created mathematical models of airflow over lashes.
任教於喬治亞理工學院的胡立德最初決定研究睫毛，是3年前看見他剛出生的女兒睫毛搧呀搧的。於是他從他的生物力學實驗室找來研究生，又找了同事一起加入研究。他們測量不同哺乳動物的睫毛，多數哺乳動物都有睫毛。他們還製作了一個有睫毛的人工眼睛，置於風洞，朝它吹氣。接著他們以通過睫毛的氣流，建立了一些數學模型。

They found that across a wide variety of mammals, eyelashes are always about one-third as long as the eye is wide, which, it turns out, is the ideal length for diverting airflow around the eye and reducing evaporation.
他們發現，許多種哺乳動物睫毛的長度，大概總是眼睛寬度的三分之一，結果證明，這是可讓眼睛周遭氣流轉向，減少蒸發的理想長度。

Dr. Hu, Guillermo J. Amador and several other researchers, all from Georgia Tech, published their findings in the Journal of the Royal Society Interface.
胡博士、吉勒莫．J．艾馬鐸，和數名全來自喬治亞理工學院的其他研究員，將研究結果發表於「皇家學會界面雜誌」。

Steven Vogel, a professor emeritus at Duke University in North Carolina, who studies similar problems in biomechanics, said the research was “terrific.” Now, he said, that now “we know why eyelashes are the length they are.”
北卡羅來納州杜克大學榮譽教授史蒂芬．沃格在生物力學領域中研究類似問題，他說，這項研究結果「棒透了」。他說，現在，「我們知道為什麼睫毛會是這種長度」。

Frank Fish, a biologist at West Chester University who studies the movement of animals in water, also complimented the work. “What I like is that they have a number of approaches to help validate the ideas,” he said.
西徹斯特大學生物學家法蘭克．費雪研究動物在水中的運動，他也對這項研究結果讚美有加。他說：「我喜歡他們的研究，因為他們以許多方法驗證他們的想法。」

In the past, scientists have offered different explanations for the existence of eyelashes, including protecting the eye by catching dust as it settled from above, and acting as sensors to trigger blinking, which helps protect eyes and keep them lubricated.
以往，科學家對睫毛的存在提供諸多解釋，包括擋住從上頭落下的灰塵以保護眼睛，或是充當感應器，觸發眨眼，藉以保護眼睛並讓眼睛保持濕潤。

And of course, in humans, lashes were also thought to have a role in sex and seduction, or, in biological terms, mating. All of these functions may be true, Dr. Hu said, but changing airflow around the eye is so important that, from elephants to rabbits, the proportion of lash length to eye width does not change.
當然，人類的睫毛被認為在性和誘惑，或者套句生物用語，在交配上也扮演一角。胡博士說，這些功能可能都是真的，但改變眼部周遭氣流非常重要，因此從大象到兔子，睫毛長度與眼睛寬度的比例從未改變。

The research began with measurements of eyelashes of 22 species of animals preserved at the American Museum of Natural History. Those measurements showed the constant relation to eye size.
這項研究從測量保存在美國自然歷史博物館的22種動物的睫毛開始。結果顯示，睫毛長度和眼睛大小的關係始終一致。

Mathematical models of airflow showed that this length, one-third the width of the eye, should be the most efficient for diverting airflow. Wind tunnel experiments reinforced the conclusion.
氣流的數學模型顯示，眼睛寬度三分之一的長度，在使氣流轉向上最具功效。風洞實驗強化了這項結論。

The researchers used a dish of water the size of an eye, with a circle of mesh around it to mimic eyelashes. They first determined that the mesh functioned the same as false eyelashes made with human hair.
研究人員以網格充當睫毛，將它圈在眼睛大小的一碟水的四周。他們研判，這個網格和以人髮製成的假睫毛功能相同。

The actual length of mammalian eyelashes worked best to prevent evaporation of the water and to prevent the very small particles that air currents carry from landing on the water. If eyelashes are too long, Dr. Hu said, they channel air to the eye.
哺乳動物睫毛的實際長度，最能防止水分蒸發，且可防止氣流攜帶的極小顆粒落在水上。若是睫毛太長，胡博士說，它會引導空氣進入眼中。

Apart from satisfying his curiosity, and providing a potential worry for wearers of long false eyelashes, Dr. Hu said the research might have some application to things like solar panels, which suffer from reduced efficiency when particles are deposited on them.
除了滿足好奇心，以及為配戴長假睫毛者提供一個可能值得關切的觀點，胡博士說，研究結果還可能應用於太陽能板之類東西。太陽能板會因顆粒堆積其上而效率降低。

And it is, Dr. Vogel said, an example of what Dr. Hu does best. In the past, he and his students have studied the time it takes for mammals to empty their bladders, the physics of fire ants and the frequency at which wet dogs shake.
沃格說，這是讓胡博士的這項研究特別傑出的一例。過去，他和學生研究過哺乳動物清空膀胱所需的時間，火蟻的物理學，以及全身濕透狗兒搖動身體的頻率。

He has a talent, Dr. Vogel said, for “looking at what everybody has looked at, and seeing what nobody has seen.”
沃格說，他天賦異稟，他會「研究所有人都看見的事物，卻有獨特的發現。」

原文參照：
http://www.nytimes.com/2015/02/25/science/length-of-lashes-keeps-eyes-from-drying-study-finds.html

2015-03-24聯合報/G5版/UNITED DAILY NEWS 王麗娟譯 原文參見紐時週報十版右