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Past Shows
February 23, 2008
 Download an MP3 of the entire program (22MB).
Your Inner Fish
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As a species, humans owe fish a lot more respect than we give them. After all, just about every characteristic we consider as human really was invented by the fish. Take a look at your hand, for instance. It's really just a modified fin, right down to the bone structure. The jaw we use to talk? That's a slightly changed set of gills. Even the fact we have two arms and two legs is thanks to our fishy origins.
In his new book, Your Inner Fish, Dr. Neil Shubin, the Robert R. Bensley Professor of Organismal Biology and Anatomy at the University of Chicago, explores this relationship between modern humans and ancient fish. As he points out, when you look at anatomy in the context of evolution, some of the seemingly crazy human physical characteristics make a lot more sense. Even some disorders, including hernias and hiccups, are really just legacies of our watery past.
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Mars' Salty Past
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Martian Landscape courtesy NASA/JPL-Caltech/Cornell University |
The Mars Rovers, Spirit and Opportunity, have now spent more than four years on the surface of the Red Planet. Over that time, they've been able to examine many rocks in detail, and have a good picture of what Mars looked like almost four billion years ago. And what they've found doesn't bode well for the existence of life. Dr. Andrew Knoll, the Fisher Professor of Natural History at Harvard University, says there was water on Mars 3.5 billion years ago, but it would have had very high salt and acid levels. The environment would have been so severe, he doubts any micro-organisms could have survived there at that time. That doesn't mean there never was life on Mars, but that if there was, it would have died out by about 4 billion years ago
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Gecko Tape
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A gecko clings to glass |
It's hard to outdo a gecko when it comes to scrambling up vertical surfaces and hanging out on the ceiling. The surface of their feet are covered with millions of fine hair-like structures that allow them to cling to just about any surface without fail. Researchers have long admired the gecko's grip. Now, Dr. Jeffery Karp, Director of the Laboratory for Advanced Biomaterials and Stem Cell-Based Therapeutics with the Harvard-MIT Division of Health Sciences and Technology, has come up with a surgical adhesive that's based on some of the same principles that give geckos their grip.
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Mimic No More
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Toxic colorful butterfly, its mimic, and the mimic stripped of its disguise. Courtesy Dr. K. Prudic |
Some butterflies have evolved to fool predators by imitating the bright colours of other poisonous butterflies. Predators like birds won't take the risk of a nasty mouthful, even if there's a chance that the insect they find might be a nice tasting mimic. Dr Katy Prudic, a postdoctoral researcher in the department of Biology at Yale University, wanted to know what happens when the poisonous butterfly disappears from the environment. The mimic's bright colours are now no longer a protection, but an advertisement to hungry hunters. Dr Prudic found one case in which the mimic species quickly regained its previous camouflage, essentially taking off its disguise
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Feathered Fashions
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A male lark bunting, photo: Alexis S. Chaine |
A snazzy beak, a bushy tail, or a flashy patch of colour on the wings -- we're all familiar with the various forms of physical ornamentation that male birds employ, in order to attract a mate. And while these traits differ from species to species, scientists have assumed there is one constant: from one breeding season to the next, females find the same physical trait attractive. It would be odd, after all, to find a peahen that prefered a peacock's beak to his flashy tail. However, Dr. Bruce Lyon, an ecologist at the University of California, in Santa Cruz, has found that female lark buntings prefer different physical traits from year to year. It's the avian equivalent of a new fall fashion line.
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Theme music copyright Raphaël Gluckstein. Creative Commons License by-nc-nd-2.0
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