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GENETIC CODE: EVOLVED TO EVOLVE • CHOICE AND MISERY SPACESHIPS, INC. The Race to Build a Low-Cost Launch Industry APRIL 2004 WWW.SCIAM.COM
Neglected Cells Hold Keys to Thought and Learning
The First Nanochips Have Arrived
Dusty Clues to Hidden Planets
COPYRIGHT 2004 SCIENTIFIC AMERICAN, INC.
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april 2004 SCIENTIFIC AMERICAN Volume 290 Number 4
features
NEUROSCIENCE
54 The Other Half of the Brain BY R. DOUGLAS FIELDS
Glial cells, long viewed as mere support players in the brain, may be nearly as critical to thinking and learning as neurons. PLANETARY SCIENCE
62
The Hidden Members of Planetary Systems BY DAVID R. ARDILA
Planets sweep their orbits clean of the dust left in space by comets and colliding asteroids. Those telltale trails can help us spot planetary systems around other stars. PSYCHOLOGY
70
The Tyranny of Choice BY BARRY SCHWARTZ
Common sense suggests that having abundant options frees people to find the best route to their own happiness. But in fact, studies show that too much choice often makes for misery. INFORMATION TECHNOLOGY
76
The First Nanochips BY G. DAN HUTCHESON
As scientists and engineers continue to push back the limits of chipmaking technology, they have entered into the nanometer realm.
54 Glial cells regulate neurons in the brain
BIOTECHNOLOGY
84
Evolution Encoded BY STEPHEN J. FREELAND AND LAURENCE D. HURST
New discoveries about the genetic code’s robustness reveal nature’s sophisticated program for protecting life against catastrophic errors while accelerating evolution. SPACEFLIGHT
92
Blastoffs on a Budget BY JOAN C. HORVATH
Private ventures seeking to make access to space easy and affordable see a big potential in small vehicl