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After visiting the zoo or watching an animal documentary, you may find yourself pondering this classic conundrum: Are zebras black with white stripes or white with black stripes? Though it may sound like a philosophical query, it is possible to answer this question with science. To do so, we need to take a look at the microbiology of the hairs that give zebras their dual-colored pattern.

從動物園回來后或在觀看一部動物紀錄片后，你也許會發現自己在思考一個非常經典的問題：斑馬到底是黑底白紋，還是白底黑紋？盡管這個問題聽起來有點哲學色彩，但是科學可以幫我們找到問題的答案。為了尋找這一答案，我們需要從微生物學的角度來觀察讓斑馬呈現兩種顏色的毛發。

Conundrum:令人迷惑的難題/a confusing problem or question that is very difficult to solve

Microbiology：微生物學

Zebras have black skin beneath their fur, but that doesn't mean that their stripes are necessarily white on black. The majority of a zebra's hairs are white—including the ones that grow on their bellies and inner legs, where their stripes appear to end. This suggests that the quadrupeds are white with black stripes, but according to Live Science, this is still the wrong way to look at the question.

斑馬毛的下面是黑色的皮膚，但這并不一定就表示斑馬為黑底白條紋。斑馬毛大部分是白色的-包括長在肚皮和腿內側的毛（條紋到肚皮和腿內側就消失了）。這表明四足動物的毛是白色并帶有黑條紋的。但是，根據“生活科學”（Live Science）的介紹，這并非是這一問題的正確答案。

Quadruped：四足動物

The true answer lies in a class of cells called melanocytes. Melanocytes are responsible for producing a pigment called melanin, which gives zebra hairs—and the hair and skin of all animals—their color.

真正的答案是一種細胞，這種細胞被稱為黑素細胞。黑素細胞會產生一種叫做黑色素的色素，這種色素會使斑馬毛-以及所有動物的毛皮呈現出自己的顏色。

Melanocytes：黑素細胞

When a zebra grows fur, melanocytes in their follicles dictate whether a strand will be light or dark depending on where it is on their body. In their normal state, these cells create the high-melanin black fur that makes up half of a zebra's signature coat. White zebra hairs contain no melanin, and they come from melanocytes that have been "turned off."

當一匹斑馬長大時，毛囊中的黑素細胞會根據毛在身體上的位置來決定它的顏色是深的還是淺的。在正常狀態下，這些細胞會形成黑色素含量高的黑毛，這樣的黑毛占斑馬標志性顏色的一半。斑馬身上白色的毛里沒有黑色素，這些毛來自于被“關掉”的黑素細胞。

Genetically speaking, zebras grow black hair by default, which makes the animals black with white stripes.

從基因角度來講，斑馬默認長黑毛，這使得它看上去是黑色并帶有白色條紋的。

While that solves one part of the zebra stripe mystery, scientists still don't know why they sport their striking stripes to begin with. One commonly held belief is that the busy pattern confuses predators trying to pick a single zebra out of the herd. Research from 2014 supports the theory that the stripes deter insects by disrupting the polarization of reflected light, which is known to attract biting horse flies. The stylish look is just a bonus.

盡管科學理論部分解決了斑馬的條紋之謎，但是科學家們仍舊不清楚為什么斑馬從一開始就呈現出醒目的條紋。一個普遍的觀點是，密集的圖案會讓捕食者很難從一群斑馬中選出一匹斑馬。2014年的研究證實了一個理論。這個理論是條紋可以通過破壞反射光的偏振來阻止蚊蟲。而反射光的偏振可以吸引牛虻叮咬。時髦的外觀只是一個額外的優點。

[h/t Live Science]   編輯&翻譯：Sarah，上海譯銳翻譯