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    Re: Dung beetle navigates with the help of the stars
    From: Frank Reed
    Date: 2014 Feb 4, 16:19 -0800

    Just over a year ago, this story was making the rounds. As expected, this research was awarded an "Ig Nobel" back in September for its unique oddity: http://www.improbable.com/ig/winners/#ig2013

    This is not "celestial navigation" even in the most limited sense of the phrase. The stars and/or the glow of the Milky Way are low-level light sources. Any reasonably motionless light source would almost certainly suffice. Here are some thoughts I had on the topic last year:

    These beetles are doing something very simple --naturally... tiny bug brains and all that. They're obviously not doing any position finding --no teeny, tiny insect sextants in their claws. They're also not using the Milky Way as an astro-compass to provide a true orientation, which would be very difficult even for a human navigator if all you have is the glow of the Milky Way. Assuming the theory is correct (and I am skeptical since there's little incentive for anyone to double-check this sort of claim), all the beetles are really doing is using the Milky Way to maintain a course, whatever direction that may be, for some relatively short period of time. The Milky Way is a stripe of light across the sky, and whatever orientation it has over the beetle's head when it starts, it presumably keeps that relative orientation as it's rolling along. Very simple bug brain software could accomplish this. And if the model is correct, any comparably bright stripe of light across the sky would work just as well. I can think of some observational tests. Do the beetles perform more poorly on nights with a featureless overcast? On such nights, if we shine a spotlight beam over their little bug heads, do they use that instead of the Milky Way for orientation?

    For marine navigation (humans now), this sort of aid wouldn't work as well because the orientation given by the Milky Way changes as the Earth turns. Like the bugs, you could steer a course by it for a short period of time but your course will change by the usual rate of 15 degrees per hour. You can't steer by the stars unless you're careful in your selection. The Milky Way is, at least, visible nearly all night long, almost everywhere on the globe. And since the star clouds of the Milky Way lie about the galactic equator, it's a band along a great circle, which means it always looks like a "straight line" across the sky wherever you are. One of these days, I'll have to visit some spot along latitude 27.1 (N or S) at the right time of night to see a dark sky full of stars but with NO Milky Way (or really, with the star clouds of the Milky Way running right along the horizon and therefore made invisible by extinction).

    It is interesting to note that this research on beetle orientation was conducted partly in Johannesburg, South Africa, close to 27.1S, which just happens to be one of those places where the Milky Way can be aligned right along the horizon for a portion of each night, rendering it completely invisible. Do the dung beetles panic when that happens??

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