September 23, 2013 | 1
“Some people think our research is crap.”
You might think that a phrase like that from the mouth of a scientist would be followed shortly by a tirade on other scientists who’ve done them wrong, or maybe people who don’t think their grant deserves funding. But no, this phrase was part of the opening statement of the winners of this year’s IgNobel Prize in Biology AND Astronomy.
Why is their research crap? Not at all! But when you work with dung beetles, well, sometimes the poop aspect gets a little over-emphasized.
Which is sad. It’s even more sad when you realize this study? Has dung beetles in little HATS! LITTLE HATS!!!
Dacke et al. “Dung Beetles Use the Milky Way for Orientation” Current Biology, 2013.
(Meet me under the stars, hot stuff. Source)
Dung beetles seem like very practical creatures. I mean, they spend their lives in…crap. Literally. With a life like that, where poop is a fine wedding present, you’d think that the dung beetle would live something of a joyless, prosaic existence.
But practicality can sometimes have the flavor of romance! Observe the humble dung beetle, as it gazes toward the stars. Sure, it’s using them for navigation, but it’s still kind of sweet, right?
The authors of this study were interested in dung beetle behavior. You see, dung beetles compete for their needs in life. You wouldn’t think that dung would be a super hot commodity, but when you’re a dung beetle, you can find yourself overwhelmed in a pile of s**t as there’s a sudden run on dung. You gotta grab your dung and get OUT.
But how? The authors hypothesized that the dung beetles were able to navigate using the stars. To test this, they set up an outdoor circular arena, full of sand, and put dung beetles in the middle with their ball of dung. They looked at the path they took to get to the edge of the arena. Half of the dung beetles were able to see the starry night (no moon), and the other half…had little HATS.
Note that the hats only covered the dorsal eyes, the ones on the top of their heads. The ventral eyes, which look down and ahead, were uncovered. But for all that the beetles could still see, the hats really didn’t help.
Above you can see two models of the area with paths that the dung beetles took. You can see that when the starry sky is visible (left), the dung beetles don’t need to travel far, they go in relatively straight lines and get to the edge (I won’t how much of the curving is due to ball rolling). When the full moon was visible, the beetles were by far the fastest, but just the stars presented no problem. But when they have little hats on and can’t see the starry sky (right), they’re wandering all over the place! And it wasn’t the hat that was the problem, it was that they couldn’t see the sky. When the authors fit the beetles with transparent plastic hats, they rolled as straight as ever.
But was it the stars? After all, the stars are very far away, and very dim. And beetles, to be honest, don’t see so good. Could they possibly be using something else?
To figure this out, they moved the whole big arena…to the inside of a planetarium. Dung beetles in a planetarium for science! When tested indoors, they found that the beetles could navigate with the stars, or just with the Milky Way, a diffuse band of light surrounding a density of stars.
How did they know it was the Milky Way? When the Milky Way was not visible (usually something that happens in October in South Africa), AND the moon is gone, previous studies showed that the poor little beetles wandered around like drunks, unable to move in a straight line.
So beetles can use something as dim as a bright band of stars to navigate! This might seem easy, but really it’s something that, so far, we thought only birds, seals, and humans could do. But now we know it’s much more widespread than we thought! And you can’t beat how they found out. Beetles. In little cardboard HATS.
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