南极和北极有苍蝇吗?

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【英文原文】

Sometimes the biggest finds are the smallest finds. Researchers examining a segment of siltstone taken from ground along the Beardmore glacier¹ in Antarctica found something unexpected. They found a fly.

Well, not exactly a fly. They found a fly fossil–it’s a segment of the exoskeleton, the protective shell, of a fly larva. While the larvae² are still growing, they are protected by a thin shell. And where there’s larval shell, there are flies. So what are flies doing in Antarctica? It’s much too cold there for flies. And the closest fly-friendly location, South America, is thousands of miles away.

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. It’s possible that the fly lived during a period when sea levels were much lower there than they now are. Lower sea levels means wider continents –think of standing³ on the edge of a beach and having the water pull back. And wider continents means its more likely that living things might travel across the gap.

Or maybe not. Maybe flies are much older than anyone thought. We know that what we now call Antarctica was once connected to both South America and Australia. But that was around eighty million years ago, and flies aren’t thought to be that old.

Whatever the answer is, something in our understanding of the continents, the seas, or fly evolution has to be fixed⁴. That’s one of the best things about science–a really big change can come from the discovery of something really small.

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