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Hair helps keep you warm, right? But hair can also keep you cooler than bare skin, as long as the hair is not too thick. So says a study in the journal PLoS ONE.
毛發(fā)能幫助身體保暖，對(duì)嗎？然而只要毛發(fā)不是太厚，其散熱效果甚至比裸露的皮膚更強(qiáng)。一項(xiàng)發(fā)表在《公共科學(xué)圖書館·綜合》雜志上的研究如是說道。
Researchers studied elephants, which have very thin coats of hair. It's easy for the beasts to overheat: they may face temperatures of up to 120 degrees Fahrenheit, and they don't have much skin surface area to radiate the heat relative to their big body volume.
研究人員以毛發(fā)稀疏的大象作為研究對(duì)象。野生動(dòng)物總是很容易就身體過熱：它們的體溫可能超過120華氏攝氏度，而且能夠輻射熱量的皮膚表面積也不多。
That's where the hair comes in. The researchers wrote equations modeling the elephants' hairy skin. As they expected, thick hair traps air and keeps the body warm. But below a certain density, hair stops insulating and wicks heat off the body instead—helping the elephants get rid of an extra 20 percent of their body heat, especially on windless days.
這時(shí)毛發(fā)就派上用場了。研究人員編寫了程序，建立了大象的體表毛發(fā)模型。正如他們所預(yù)期的，厚毛發(fā)隔絕空氣，使身體保持溫暖。但當(dāng)毛發(fā)密度低于一定程度時(shí)就不再隔熱，而是散發(fā)身體的熱量——大象可通過這種方式散發(fā)20%的身體熱量，尤其是在無風(fēng)的日子里。
Heat sinks inside computers work in a similar way, with pins sticking up to help dissipate the interior heat.
電腦內(nèi)部的散熱器就是以類似的方式，利用突出的插腳幫助內(nèi)核散熱。
The researchers speculate that hair may have actually evolved to help animals stay cool, because it first sprouted in mammals over a hundred million years ago in a hot climate. Hair-raising times, indeed.
研究而人員推測，進(jìn)化出毛發(fā)是為了保持身體涼爽，因?yàn)槊l(fā)是在一億年前炎熱的季節(jié)首次在哺乳動(dòng)物身上生長的。真是“毛骨悚然”的時(shí)代。
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