November 17, 2012 - Sticks & Stones * Fairy Wren Mother Knows Best * Mink Get Bored Too * Planets Go Rogue * Dawn of the Deed

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Certainly, we all owe a debt of gratitude to whomever invented sex.  Actually, that should probably be whatever, as the evolution and development of sexual reproduction has a long and stimulating history.  On today's show, we speak to a paleontologist who chronicles what we know about the history of sex, including how dinosaurs did the deed.  Plus, we'll hear how fairy wrens communicate with their unhatched chicks; we'll learn that even animals get bored, and we'll find out how a lonely planet found itself without a star. But first - hunting with sticks and stones.

 

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Sticks & Stones
spear_points.jpgReplicas of 500,000 year old spear points used in experiments.  Courtesy J Wilkins.

Among the many technological advances humans have made, developing the skills to attach a sharp rock to a long stick must have been one of the most important.  An effective spear would have allowed early humans to take down large animals, and made them a fearsome predator.  Now, a team including Jayne Wilkins, a PhD student in the Department of Anthropology at the University of Toronto, has found that early humans invented this technology half-a-million years ago - two-hundred-thousand years earlier than previous evidence had indicated.  They looked at the shape and wear patterns on stone points from an archeological site in South Africa, and made and tested their own stone-tipped spears to verify their conclusions.
          
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Fairy Wren Mother Knows Best

SuperbFairywren.jpgMale Superb Fairy-Wren listening for a password from the female.  Courtesy J. Robertson
The Superb Fairy-wren is a small songbird found throughout Western Australia.  It is best known because of the male's brilliant blue colour.  But Fairy-wren nests are parasitized by cuckoos.  The cuckoos lay their eggs in the fairy-wren nest in the hopes that the new host will raise all the young together.  But a new study, by Dr. Mark Hauber, a Professor of Animal Behaviour at Hunter College at the City University of New York, has found that the Fairy-wren has evolved a communication system to counter the cuckoo's strategy.  The mother fairy-wren emits a specific chirp repeatedly, for up to five days, to the unhatched embryo.  The chirp acts like a password that, when hatched, the young fairy-wren has learned, and repeats.  It emits the same chip when begging for food, and the mother then knows it is one of hers.  Usually, the young cuckoo hatches earlier and has not had the same amount of time to learn the password.  In this way, both fairy-wren parents and their young can tell who is who.

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Mink Get Bored, Too

bored_mink.jpgMink get bored without stimulation.  Credit: Rebecca Meagher
Like many pet owners, scientists wondered if animals kept in cages get bored.  It had always been assumed that they did, but had never been studied previously.  To find out, Dr. Georgia Mason and colleagues from the Animal and Poultry Science Department at the University of Guelph studied two groups of the common American mink, which is found throughout North America.  One group was kept in barren cages, the other in enriched cages.  Both groups were then exposed to a variety of stimuli, including items mink would normally be attracted to, items they would be threatened by; as well as neutral items.  The mink from barren cages, which had previously exhibited signs of boredom, including staring into space or pacing, reacted with equal excitement to all the new stimuli.  They also devoted as much as three times the amount of attention to the new stimuli as the mink from the already enriched cages.  The results of this study may have implications for other animals kept in cages or pens in zoos and on farms.    

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Planets Go Rogue

We've found planets around nearby stars in their hundreds in the past two decades, but astronomers think they're only a fraction of the planets out there in the galaxy.  "Rogue" or "free floating" planets that form independently, or have been stripped away from their stars, are thought to be drifting through interstellar space in the hundreds of millions.  We've seen very few, though, since they're small and dim.  But a team, including Jonathan Gagné, a PhD student in the Department of Physics at the Université de Montréal, has found what they think is a young rogue, between four and seven times the size of Jupiter, about 100 light years away.
 

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Dawn of The Deed

dawn_deed.jpg
The history of sex is as old as life itself.   Recently, a little more light was shed on that history with the discovery of a 380-million-year-old placoderm fish fossil in Australia.  It proved to contain the oldest vertebrate embryo fossil ever found; but more significantly, an indication of the earliest known evidence of internal fertilization. Put simply - vertebrate sex.  Dr. John A. Long, a Professor of Paleontology at Flinders University in South Australia, made that discovery and has documented it, along with a provocative history of prehistoric sex, in a new book called, "The Dawn of The Deed".  It includes the evolutionary history of copulation and insemination, descriptions of bizarre mating habits and unusual sexual organs, and as well as theories about how dinosaurs "did it."
   
 

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