MELISSA BLOCK, HOST:
From NPR News, this is ALL THINGS CONSIDERED. I'm Melissa Block.
AUDIE CORNISH, HOST:
And I'm Audie Cornish. And we have a story now about celestial navigation - that is, looking to the sky for guidance.
BLOCK: But before we get too lofty, this story also happens to be about dung beetles. And so we start with this lowly central unpleasant fact about dung beetles.
ERIC WARRANT: Dung beetles and their grubs eat dung and everything about dung beetles has to do with dung in some form.
BLOCK: That's professor Eric Warrant. He's an Australian professor of zoology teaching at the University of Lund in Sweden.
CORNISH: Five years ago, he and a group of other scientists began studying the remarkable navigational skills of dung beetles. These insects harvest material from a fresh pile of feces in the desert. They shape their bounty into a sphere and roll it away.
WARRANT: They have to get away from the pile of dung as fast as they can and as efficiently as they can because the dung pile is a very, very competitive place with lots and lots of beetles all competing for the same dung. And there's very many lazy beetles that are just waiting around to steal the balls of other industrious beetles and often there are big fights in the dung piles.
BLOCK: That's right - lazy dung beetles. Now, the dung beetles need to plot a direct course or they might accidentally circle back and thus lose a precious dung ball to another beetle.
WARRANT: It's a little bit like kicking the ball back into your own goal posts.
BLOCK: Which means no food to feed the next generation. As you can see, there's a lot riding on the beetles making a beeline to the place they hope to roll their ball.
CORNISH: Beeline it, wrong bug, I think.
BLOCK: Yeah, maybe a beetle line. Anyway, professor Eric Warrant and his colleague have just published conclusion about how the dung beetles keep to a straight path.
WARRANT: What we discovered was that dung beetles can roll their balls of dung in straight lines by using the Milky Way as a compass queue.
BLOCK: The Milky Way, billions of stars that form a white streak across the sky, serve as a guide for these little harvesters of waste. It was understood earlier that both the sun and the moon serve as guides, but no one knew how dung beetles could follow a straight path when the moon isn't out. So at the edge of the Kalahari, professor Warrant and the team built a small arena.
WARRANT: We tested them with and without a little cardboard hat, which we put on top of their head with a piece of tape. And this little cardboard hat effectively blocked out the view of the starry sky. And when we did this, they rolled around and around and around in circles. They couldn't keep a straight path.
BLOCK: The Swedish scientists also tested dung beetles at a planetarium. They altered the star pattern on the ceiling and watched what the beetles did. Without the Milky Way, the beetles could not walk the straight and narrow.
CORNISH: Professor Warrant suspects other creatures also navigate using the Milky Way, but currently only dung beetles are known to do so.
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