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Sometimes the biggest finds are the smallest finds.
有時候，重大發現源于很小的發現。
Researchers examining a segment of siltstone taken fromground along the Beard more glacier in Antarctica foundsomething unexpected. They found a fly.
研究人員在南極比爾德莫爾冰川采集回來的一塊粉砂巖中意外地發現了蒼蠅。
Well, not exactly a fly.
準確地說，不是蒼蠅，
They found a fly fossil–it's a segment ofthe exoskeleton, the protective shell, of a fly larva.
而是蒼蠅的化石。一塊保護幼蟲的外骨骼。
While the larvae are still growing, they areprotected by a thin shell.
在薄殼的保護下，幼蟲還在發育。
And where there's larval shell, there are flies.
幼蟲的蛹殼證明了蒼蠅的存在。
So what are flies doing in Antarctica?
那么，蒼蠅怎么會在南極呢？
It's much too cold there for flies.
南極冰冷的氣候不適宜蒼蠅生長啊！
And the closest fly-friendly location, South America,is thousands of miles away.
反而，最適宜蒼蠅生存的地方—南非，卻遠在幾千里之外。
Part of the answer is that the fly fossil is ancient–it was found with a number of other fossilized things that have been dated between three million and seventeen million years old.
正解可能是因為這塊蒼蠅的化石和一起發現的其它化石可以追溯到300萬到700萬年前了。
It'spossible that the fly lived during a period when sea levels were much lower there than they noware.
很可能，蒼蠅生長的那個時期，海水沒有現在那么高，
Lower sea levels means wider continents–think of standing on the edge of a beach andhaving the water pull back.
這意味著陸地面積更大。想象自己站在海邊，浪打回來。
And wider continents means it's more likely that living things mighttravel across the gap.
廣闊的陸地面積讓生物更有可能跨越于大陸間。
Or maybe not. Maybe flies are much older than anyone thought.
另種可能是蒼蠅在地球上生存的時間比我們想象的還要久遠。
We know that what we nowcall Antarctica was once connected to both South America and Australia.
要知道，現在的南極曾經和南美大陸及澳大利亞大陸是接壤的。
But that was aroundeighty million years ago, and flies aren't thought to be that old.
但這也是8000萬年前的事了，那時候，蒼蠅已經在地球上了？
Whatever the answer is, something in our understanding of the continents, the seas, or flyevolution has to be fixed.
不管答案究竟是什么，我們所認識的大陸、海洋、蒼蠅進化的常識之一要得以修正。
That's one of the best things about science–a really big change cancome from the discovery of something really small.
這就是科學的妙處，一個小小的發現或許能推翻重大定論。
