Why do zebras have stripes?
Scientists have provided new evidence to help solve one of the world's oldest mysteries: why does a zebra have stripes? It appears that all those lines cause problems for insects and makes it very hard for them to land on the animal.
科學家提供了新的證據來幫助解決世界上最古老的謎團之一：為什麼斑馬身上有斑紋？似乎所有這些條紋給昆蟲帶來了問題，使它們很難降落到斑馬身上。
Researchers recently described experiments showing that horse flies have a difficult time landing on zebras while easily landing on horses of a single color.
最近，研究人員描述了實驗，馬蠅很難降落在斑馬身上，卻能輕易地降落在單一顏色的馬身上。
In one experiment, the researchers put blankets with stripes on horses and saw that fewer flies landed on them. They "fly past them or ...bump into them and bounce off," said Tim Caro of the University of California-Davis. He was the lead writer of a report on the study. The report was published in the journal PLOS ONE.
在一項實驗中，研究人員把帶有條紋的毯子放在馬的身上，發現落在上面的蒼蠅少了。蒼蠅「飛了過去，或撞到毯子又彈了回去」，加州大學戴維斯分校的Tim Caro表示。他是這項研究報告的主要撰寫者。該報告發表在PLOS ONE雜誌上。
Closely related to horses, the world's three zebra species are known for their black-and-white striped bodies.
世界上有三種斑馬與馬有親密的關係，它們因身上的黑白條紋而出名。
Zebras are native to Africa's savannas, or grasslands. The design and appearance of the stripes is different from one zebra to the next. No two zebras are alike.
斑馬原產於非洲大草原。每個斑馬的斑紋圖案和外觀都不相同。沒有任何兩個斑馬是一樣的。
There had been four main theories about the reasons zebras developed stripes. The first theory is to avoid attack by meat-eating animals. Another is so that zebras have an easier time recognizing other zebras. A third idea is thermoregulation. That is the ability of a creature to control its body temperature, even when the surrounding temperature is different. The fourth theory is to prevent attacks by biting flies.
關於為什麼斑馬身上有斑紋，有四個主要觀點。第一種解釋是為了避免食肉動物的攻擊。另一種解釋是以便斑馬更容易地認出別的斑馬。第三種觀點是體溫調節，這是生物控制自身體溫的能力，即使周圍的溫度不同。第四種解釋是防止蒼蠅叮咬。
"Only the last stands up..." Caro said. "Most biologists involved with research on mammal coloration accept that this is the reason that zebras have stripes."
「只有最後一種解釋站得住腳」，Caro表示。「大多數研究哺乳動物顏色的生物學家都同意，這就是斑馬身上有條紋的原因。」
African horse flies carry diseases, such as trypanosomiasis. The sickness can cause wasting and be deadly.
非洲馬蠅攜帶像錐蟲病這樣的疾病。這種疾病會引起體弱消瘦，甚至是致命的。
The researchers recorded videos of horse flies as they tried to bite zebras and horses at a farm in North Somerset, England. Stripes did not stop flies from a distance, as they circled horses and zebras at similar rates. But the flies were 25 percent less likely to land on zebras.
在英國薩默塞特郡北部的一個農場裡，研究人員記錄了馬蠅試圖咬斑馬和馬的視頻。斑紋並不能阻擋遠處的蒼蠅，因為它們是以相似的速度圍著馬和斑馬旋轉。但是，蒼蠅降落到斑馬身上的概率低了25%。
University of Bristol biologist Martin How worked with Caro on the study. He said stripes may confuse flies when they get too close to zebras.
布裡斯託大學的生物學家Martin How與Caro一起進行了這項研究。他表示，當馬蠅離斑馬太近時，斑紋會讓它們感到困惑。
"In addition to stripes that prevent controlled landings by horse flies, zebras are always moving their tail and may frighten off the horse flies if they do land successfully," How said. He added that zebras are also using behavioral means to prevent flies from biting them.
Martin How表示：「斑紋可以防止馬蠅降落，另外，斑馬還不停地擺動尾巴，即使馬蠅落到了身上，也會把馬蠅嚇跑的。」他補充道，斑馬在用行為手段來防止蒼蠅叮咬。
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