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Saturday November 5, 2011

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* Dueling with a Duet * Teeth Tell Trip Tale * Scared to Death by Stress * The God Species * Listener Feedback - The 7 Billion * Science Fact or Science Fiction - Hummingbirds *



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Dueling with a Duet

Plain-tailedwren.jpgPlain-tailed wren, copyright Browerk
The male and female Plain-tailed Wren, a South American songbird, sing a remarkable duet.  The song sounds like a single bird, but involves the male and female alternating back and forth with remarkable speed and precision.  The song is used by females testing the skills of potential mates, and also by breeding pairs defending their territory against others.  Dr. Eric Fortune, of the Department of Psychological and Brain Sciences at Johns Hopkins University in Baltimore, has been studying the duet, and has uncovered part of the brain mechanism that the birds use to coordinate their song.
     

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Teeth Tell Trip Tale
Camarasaurs.jpg Camarasaurus reconstruction, copyright Dmitry Bogdanov
Fossils of dinosaurs often allow us to build reconstructions of what they looked like, but only rarely do we get insight into what they did - their behaviour.  For example, while many paleontologists have assumed that some dinosaurs migrated, the evidence for this has been scanty.  Now, Dr. Henry Fricke, a geochemist from Colorado College in Colorado Springs, and his colleagues, have found evidence in fossil teeth that 150 million years ago, giant sauropods called Camarasaurs migrated seasonally. They traveled a distance of 300km from lowlands to highlands, probably to ensure a good supply of food to fuel their giant bodies.
      

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Scared to Death by Stress
dragonfly.jpg Juvenile Dot-tailed whiteface dragonfly, courtesy Shannon McCauley
Most of us experience some form of stress in our daily lives from a variety of sources.  But there is stress in the life of an insect as well.  In the case of the dot-tailed whiteface dragonfly, the main source of stress is the fear of being eaten.  New research by Dr. Marie-Josée Fortin, a Professor in the Department of Ecology and Evolutionary Biology at the University of Toronto, and her colleagues, has found that stress can result in an elevated mortality rate.  In a recent experiment, dragonfly larvae were able to see and smell predator fish but were protected by glass from being eaten by them.   The mere presence of the predator was found to increase the death rate of the larvae four times over that of a control group.  Scientists also believe that this source of stress, when compounded with other stressful events, such as metamorphosis, or human factors like pollution and loss of habitat, can have even more negative effects.   

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The God Species

Lynas-God-Species1.jpg 
There's a sign you sometimes see in stores: "If you break it, you bought it."  Well, environmentalist and science writer Mark Lynas thinks that now applies to the Earth and the human race.   We're breaking the planet, and we have to take responsibility for it.  In fact, it's worse than that.  Our impact on the planet has been so great that we have to take control of the Earth and actively manage the planet.  In his new book, The God Species: How the Planet Can Survive the Age of Humans,  Mr. Lynas outlines his controversial argument that our impact is so large that we can't just leave the Earth to fend for itself, even if we scale back our activity.  We need to actively manage the planet, a little like a garden or park, to preserve biodiversity, prevent nitrogen overload, limit climate change, and avoid passing a number of "planetary boundaries," which we dare not exceed if we're to keep the planet healthy.  Among the solutions he suggests, which are not part of the environmental mainstream, are the wider adoption of nuclear power and genetically modified crops.

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Listener Feedback - The  7 Billion

Last week on the program we had a panel discussion about the world's population reaching the symbolic number of 7 billion. Our 2 guests looked at the political, social, and environmental impact of the population explosion. And that created an explosion of feedback from you.

So this week, we're reading a few samples from the audience mailbag.

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Science Fact or Science Fiction - Hummingbirds

This is another episode of our occasional feature, Science Fact or Science Fiction. From time to time, we present a commonly held idea or popular saying - and ask a Canadian scientist to set us straight on whether we should believe it or not. 

Today's popular belief comes to us from listener John McKay in Montreal, who writes  - "Hummingbirds can beat their wings 200 times per second".  To settle the matter, we contacted Dr. Douglas Altshuler, Assistant Professor in the Department of Zoology at the University of British Columbia.  He says it is science fiction.

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Theme music bed copyright Raphaël Gluckstein, Creative Commons License by-nc-nd-2.0


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