|
Past Shows
January 16, 2010
Listen to the whole program:
or
 Download the whole program
Shaving a Fly with a Laser
Scientists have been puzzled for a while by the bizarre genitalia of the male fruit fly - genitalia that are covered in tiny claw-like spines. But they suspected that something so extreme must have evolved to ensure reproductive success. So they decided to see what effect it would have on the male fly's mating success, if the spines weren't there. And to do that, they had to shave them off - with a laser. Dr. Michal Polak, a Canadian evolutionary biologist at the University of Cincinnati, carefully removed the microscopic spines and then exposed those shaved male fruit flies to females. He found that they were far less successful at mating than the unshaved control group. He says the spines must help the males to hold onto the females while copulating - what he calls a Velcro effect.
Listen to this segment:
or right click to download
Related Links
Echoes of an Extinction
Scientists have been mystified for two decades by a huge spike in lung cancer rates among women in a remote region of China. Their suspicion was that it was somehow related to the coal that was being burned in unventilated stoves to heat and cook. This practice has been common in China, but why would cancer rates be so much higher - twenty times higher - only in this region? Well, in a nice piece of forensic geology, Dr. David Large, a geologist from Nottingham University, and his colleagues have determined that the local coal used in this region contains high levels of fine silica, which they think may be responsible for the cancer spike. This silica, they think, was deposited in the peat, which eventually formed this coal, as a result of the huge atmospheric disturbances of the Permian extinction, 250 million years ago.
Listen to this segment:
or right click to download
Related Links
Alligator Lungs
CT scans of American Alligator - courtesy C.G. Farmer & Kent Sanders
|
Birds and alligators may not appear to have much in common, but they share a common ancestor called archosaurs, which belong to the early Triassic period, nearly 250 million years ago. New research by Dr. C.G. Farmer, an Assistant Professor of Biology at the University of Utah, has found that alligators have inherited the same unidirectional lung function known to birds. Air flows in one direction as it loops through the lungs. This type of breathing is more efficient than mammalian lungs - when oxygen levels are low. It explains why some birds can fly so high, but it also helps explain why archosaurs became dominant after the Permian mass extinction of that time. The recovering ecosystem was warm and dry and oxygen levels were as low as 12% of the air, compared to 21% today. Unidirectional lungs are better at extracting oxygen, making early alligators more capable of vigorous activity essential to survival.
Listen to this segment:
or right click to download
Related Links
Venomous Dinosaurs
The first known venomous dinosaur has been identified by Dr. David Burnham, a paleontologist at the Biodiversity Institute of The University of Kansas. It is called Sinornithosaurus, and was found in northeastern China. It is a birdlike dinosaur that belongs to the same family as Velociraptor and lived 125 million years ago. Sinornithosaurus was about the size of a turkey, was covered in featherrs and was likely very fast. It subdued its prey with fangs, similar to those of rear-fanged venomous snakes or the Komodo dragon. The fangs had outer grooves that allowed venom to flow from a gland in the head, directly into the prey as it was being subdued. The venom induced a state of shock, which allowed Sinornithosaurus to take its prey away to eat later.
Listen to this segment:
or right click to download
Related Links
Permission for Planets
Artist's rendition of a Protoplanetary Disk, copyright ESO, cc-by-3.0
|
Until recently, astrophysicists' best models made it impossible for planets to form. As they simulated the early days of solar system evolution, the proto-planets that formed were all dragged into their star, due to gravitational interaction with the dust and gas in the planetary disk. Since we have lots of planets, it was clear that something important was missing from the understanding of what goes on in the early days of an evolving solar-system. Dr. Mordecai-Mark Mac Low, the chair of Astrophysics at the American Museum of Natural History, and his colleagues think they have figured out the problem. They've found that fluctuations in density and temperature of the gas in the disk, as the proto-planets passes through it, pushes the planets around and allows them to find orbital safe havens in which to exist.
Listen to this segment:
or right click to download
Related Links
Sleep Learning
It seems that humans may have the opportunity to strengthen their memories each time they take a nap. Phd student John Rudoy, at Northwestern University in Illinois, experimented by teaching 12 people to associate a unique image - each with its own sound - with a particular location on a computer screen. As the subjects slept, half of those sounds were replayed to them. Upon waking, the people were then asked to accurately place the images in their correct location on the computer screen again. The study found that the images that were cued during sleep were more accurately placed than the images that were not played during the nap time. It proved that we can strengthen memory as we sleep.
Listen to this segment:
or right click to download
Related Links
Theme music bed copyright Raphaël Gluckstein.
Creative Commons License by-nc-nd-2.0
Last week
|
