Friday, January 4, 2013

A tragically ironic way of proving birds share humanlike traits


White-throated Sparrow detail

In late November 2012, two researchers in the psychology department at Emory University in Atlanta published a study in Frontiers in Evolutionary Neuroscience. They wanted to learn whether birdsong and the music we humans produce serve similar purposes or have the same evolutionary underpinnings. Other scientists have explored tonal and rhythmic similarities and differences between our music and various bird songs, and whether birds are creative in song production. This study focused on whether birds listening to their songs get similar sensations of pleasure as humans listening to music.

Many behavioral studies have shown that both birds and humans approach sources of their species’ music and will learn simple tasks in order to hear a song. But is there a similarity in the physiological response to music? Brain imaging studies in humans show that hearing music induces neural responses in at least 20 different brain regions. When experimental participants describe music as pleasurable, the brain response is most particularly found in the mesolimbic reward pathway. Does something comparable happen when female White-throated Sparrows hear the songs of males?

The scientists predicted that females in breeding readiness would find the song more pleasurable than would females not hormonally ready for courting, and that breeding males would find the song less pleasant or even stressful. The scientists manipulated the experimental birds’ hormonal levels so half of each sex was put into breeding readiness, and half of each of those groups was exposed to a normal White-throated Sparrow song; the other half was exposed to a random series of tones on the same frequencies as a proper song. Sadly, the scientists couldn’t use the same brain imaging techniques that are used in human experiments because the comparable brain centers in songbirds are so very tiny. Instead, 60-90 minutes after playing the series of songs or random tones to each bird, they anesthetized and decapitated it to retrieve its brain to analyze protein products of the genes that would be associated with pleasure. As one would predict, females treated with breeding hormones were extremely receptive to the male song over the control tone, and every region of the mesolimbic reward pathway that responds to music in humans was found to respond to song in the sparrows. The response in males treated with testosterone was comparable physiologically to that of humans listening to unpleasant or fearful music.

My ill-fated Ph.D. project in the 1990s was studying nighthawk digestion, but I worked out with my professor from the start a plan for conducting my research without killing a single bird, or even causing it distress. I can’t imagine having a research question so pressing that the answer would be worth decapitating even one White-throated Sparrow, much less the 46 used in this experiment. I don’t know if I find it more satisfying or sadder that the results were so predictable. 

We start with the premise that other species are not just different but of so little consequence and with such little individual value that a decapitation experiment is reasonable and ethical, even as the experiment itself proves that birds share so many traits with us. I find it amusingly mystifying that anyone could possibly think that if there is life “out there” in the universe we’d somehow be able to communicate with extraterrestrials when we have so abysmally failed to communicate with or understand or value the intelligent life right here on earth.

8 comments:

  1. Oh boy, I certainly agree with your views! Shame on them. It continues to be sad that so many still do not have compassion for all beings even as we learn so much from them. Thank you for your post. One of my favorite quotes about Loren Eiseley by Kenneth Heurer in The Lost Notebooks of Loren Eiseley:

    “The love that transcends the boundaries of species is the highest spiritual expression.”

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  2. Hi, Laura, from Becky in Detroit (remember meeting on the Ohio turnpike in our Priuses?) I saw something the other day that your headline reminds me of and I wonder about. Husband and I were on hike in state park, saw in the distance a small bird dragging something across the ice, and when we got there saw a tufted titmouse pulling a carcass of some kind into the bushes. It was there when we returned, hour and a half later. Closeups of pictures show what appears to be the wings and some of the back and belly of another tufted titmouse. It pulled the remains onto a branch and I supposed, before I looked at the pictures, it was going to eat the little shreds of meat left hanging from the feathers. Now I wonder if it would have eaten one of its own kind, or if it pulled that other bird to shelter for a different reason.

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  3. Becky! Long time no see or hear from!!!

    Tufted Titmice tend to stick with their mate and offspring through winter, so I suspect this bird was panicking about what happened, but impossible to be sure without following its behavior for hours. How sad, though, no matter what it was doing.

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  4. Yeah, it does seem like we happened upon a small, sad event. I notice the titmice in the yard sticking together during the winter. I'm hoping that bird wouldn't have waited around too awfully long?

    I know, it's been too long. Nice to "hear" your voice! I'm eager to check out your Conservation Big Year. I just finished the book The Big Year this very morning, didn't enjoy it that much, and ended up glad it was over. How's THAT for a positive review? :D

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  5. Laura, I wrote about the titmouse on the Sierra Club Great Lakes Program blog and was pleased to be able to include your perspective about titmice and their habits. Photos of the bird holding the carcass it had dragged across the ice are included. Thanks again for your help! Make we'll cross paths in person again soon.

    Becky H.

    http://sierraclubgreatlakes.blogspot.com/2013/01/the-profound-nature-of-what-we-work-to.html

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  6. Well that's exciting! Thanks so much for the plug.

    If we happen to pass on I-80 again, I'm still in a Prius with license plate BOO JAY!

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  7. Just found your site and will be busy catching up on past posts. Interesting study - are we sure we're the planets most advanced species?
    I look forward to following your blog.

    ---Wally (Florida)

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  8. Brilliant observations, Laura. I enjoy the way you combine intellect and feeling to get a clearer view of things. Thanks for you blog, radio show, books, and all you do for birds.

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