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Past Shows
November 22, 2008
 Download an MP3 of the entire program (22MB).
It's Alive!
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Early Earth (NASA artist's impression)
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About four billion years ago, on a hostile and violent early Earth, rocks, gases and water somehow combined to form the first chemical life. Just how this happened all those millennia ago is a puzzle that scientists are increasingly confident they're going to solve the next decade or two. In fact, we may now understand some of the earliest steps.
For example, how the first simple organic molecules formed used to be considered a major challenge. But now, according to Dr. Robert Hazen, of the Geophysical Laboratory at the Carnegie Institution of Washington, we now realize that these molecules form under all sorts of different conditions, including in the depths of space. Combining these simple molecules into more and more complex molecules is a process we are also understanding better.
The last significant step, according to Dr. Jeffrey Bada, of the Scripps Institution of Oceanography at the University of California at San Diego, is understanding how these complex molecules can begin making copies of themselves. At that point, you have something like a simple, chemical living system.
Another challenge scientists are working on is generating scenarios for where and when these chemical reactions might have taken place on the early Earth. Dr. Michael Russell, who works in the Astrobiology program at NASA's Jet Propulsion Laboratory in Pasadena, California, thinks one likely scenario is that the first chemical life appeared in mineral-rich, warm springs under the sea. But many other scenarios seem possible as well, including sheltered pools on the surface, or even briny pockets in the ice pack. What seems increasingly likely, especially to those who study the origins of life, is that life may have the potential to arise under many different circumstances, which increases the chance that our kind of life is not the only kind in the universe.
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Bisexual Beetles
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Male flour beetles - courtesy Sara Lewis
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Homosexuality is quite common in the animal kingdom, from insects to mammals. But it's also kind of puzzling. After all, if the purpose of sex is to pass one's genes on to the next generation, how is it that homosexuality has persisted throughout evolution? Dr. Sara Lewis, a professor of evolutionary and behavioural ecology at Tufts University, has been studying the common flour beetle to try to answer this question. Dr. Lewis has found that, in some cases, males are able to indirectly sire offspring via another male they have copulated with, when their sperm is passed on to a female.
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Mammoth Redux
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There's no going back to the days when the Earth was covered in glaciers and wooly mammoths roamed the continents. However, Dr. Stephan Schuster and his colleagues have done the next best thing, by bringing back a woolly mammoth from the great beyond -- well, kind of. Dr. Schuster, an associate professor of biochemistry and molecular biology at Penn State University, has recently sequenced the woolly mammoth's genome. Dr. Schuster says this is the first step to being able to reverse-engineer a living mammoth, but that's not something he's intending to do. It is also an unwieldy technical challenge.
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Inefficient Ants
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A rock ant marked with model paint, courtesy Anna Dornhaus
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We tend to think of ants as the very definition of hard-working efficiency. Scientists who study ants have long been intrigued by the fact that worker ants have specialized positions: some ants forage for food, some defend the colony and others do construction work. This specialization is one of the reasons ants have earned themselves such a large evolutionary niche. Or so scientists thought. Dr. Anna Dornhaus, a professor of Ecology and Evolutionary Biology at the University of Arizona, has been studying specialization in ants and she's stumbled on a surprising discovery: specialist ants aren't particularly efficient. In fact, Dr. Dornhaus says they can be far less efficient than ants that do a little bit of everything, leaving her with the question: if specialist ants aren't any more efficient than other ants, then why did they evolve such behaviour in the first place?
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Theme music bed copyright Raphaël Gluckstein. Creative Commons License by-nc-nd-2.0
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