Overfishing Sharks Damages Coral Reefs * Human Babies Learn from Lemurs * Mosquito Invisibility Cloak * Neanderthals Used Sophisticated Tools * Cat Parasite Brainwashes Mice * Were Ancient Sahara Rivers Migration Routes?

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Coral reefs around the world are under threat from warming waters, ocean acidification and pollution.  But on today's show, you'll hear about a threat to reefs you might not have guessed: shark hunting.  Also today, we'll find out how babies respond to the call of the wild;  we'll learn how to make yourself invisible to mosquitos; we'll learn how Neanderthals used sophisticated leatherworking tools; we'll discover how a tiny parasite might permanently brainwash mice; and we'll hear how rivers once flowed in the Sahara desert.

 

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Overfishing Sharks Damages Coral Reefs

A study comparing shark abundance on two reefs, off the north-east coast of Australia, has determined that overfishing is having a negative impact.  The shark is overfished on one reef, but not the other - mainly to supply body parts for shark fin soup.  A new study by Dr. Jonathan Ruppert, from the Biology Department at York University in Toronto, has determined that overfishing the shark may result in damage to the reef.  The reef that was not overfished remains pristine.  As the number of sharks decrease, species it preys on - including grouper and snapper - increase.  With the rise of those mid-level predators, herbivores such as parrot fish decrease for the same reason.  In turn, the herbivorous parrot fish play a key role in removing harmful algae from coral reefs.  It is hoped that understanding this process may help with conservation efforts elsewhere in the world, where shark decline is also impacting coral reef. 
Related Links

  • Paper in PLOS One
  • University of Toronto release
  • Australian Institute of Marine Science release
  • Blog from Australia's The Conversation

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Human Babies Learn from Lemurs

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Ring-tailed Lemur
At the age of 3 and 4 months, human babies are beginning to connect what they hear and what they see. Listening to human speech, especially the melodic vocalization of a mother, is key to the development of cognition.  But new research by Dr Sandra Waxman and colleagues from the Department of Psychology at Northwestern University in Evanston, Illinois, determined that the link between language and learning was much broader than previously thought. In an experiment, babies' responses to shapes were measured using a variety of sounds, including a human voice, a mechanical tone, backward human speech, and a non-human primate - the lemur.  Surprisingly, the babies' response to human speech and their response to the screech-like call of the lemur were an exact match.  The results suggest an evolutionary link, but one that is temporary, as the match was not recorded as the babies reach the age of 6 months.

Related Links


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Mosquito Invisibility Cloak

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Testing mosquito response is a hands-on job.  Greg Allen-USDA/ARS

Dr. Ulrich Bernier, from the Mosquito and Fly Research Unit of the US Department of Agriculture's Agriculture Research Service in Gainsville, Florida, has found a chemical that makes mosquitos effectively blind to the odours they use to find humans.  The substance is produced on human skin and was discovered when Dr. Bernier and his colleagues were studying which substances we produce that attract mosquitos.  The substance certainly shows promise for protecting us from mosquitos, but Dr. Bernier cautions that they don't yet understand how the chemical works, whether it is safe to use, and how it might best be used if safe.  


Related Links

  • 2013 American Chemical Society meeting release
  • National Geographic story
  • CBC News story
  • Smithsonian blog - Surprising Science

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Neanderthals Used Sophisticated Tools

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Neanderthal leather-burnisher, © Abri Peyrony & Pech-de-l'Azé I Projects
One of the differences that scientists thought existed between humans and Neanderthals was in their tool technology.  Humans were thought to be unique in their use of specialized bone tools that are different from stone tools.  But a new discovery by Dr. Shannon McPherron, an archaeologist with the Max Planck Institute for Evolutionary Anthropology in Leipzig Germany, and his colleagues, seems to undermine that notion.  At two Neanderthal sites in France, dating back roughly 50,000 years, they found bone leather-working tools, similar to tools still used today. That was a time before modern humans arrived in Europe, indicating that the Neanderthals did not get the idea from our ancestors.

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Cat Parasite Brainwashes Mice

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Cat and mouse - the most dangerous game - Ingram & A Greene 
Toxoplasma Gondii is a fascinating parasite that causes infected mice and rats to lose their fear of cats.  This serves the purposes of the parasite because it can only reproduce in cats, and a fearless mouse is an easy snack for a hungry feline.  While investigating just how the parasite manipulates the the brains of mice, Wendy Ingram, a PhD student in the Department of Molecular and Cell at the University of California, Berkeley, has discovered that the changes the parasite makes seem to be permanent.  She found that even when the parasite is removed from the mouse brain, the mouse's fearlessness persists.  She thinks this might provide interesting insights into why some infectious diseases leave residual impacts, even well after they are cured.

Related Links


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Were Ancient Sahara Rivers Migration Routes?


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A river ran through it, copyright Luca Galuzzi
Three river systems that once flowed over 100,000 years ago have been identified in the Sahara Desert of North Africa.  Satellite images from 30 years ago suggested they may be there, buried under the sands of Libya, Algeria and Tunisia. But new research by Dr. Michael Rogerson, a Senior Lecturer in Paleoclimatology at the University of Hull in England, has helped confirm their existence. Climate models from that era, together with the topography of the region, suggest that monsoons produced enough rainfall to form rivers that would have to have flowed south to north.  One of the rivers carried enough water to flow through Libya to the Mediterranean, possibly providing a green corridor for early human migration out of Africa.

Related Links

  • Paper in PLOS One
  • University of Hull release
  • Nature News story
  • Video showing three river systems that once crossed the Sahara.

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