Scientific American Magazine Vol 266 Issue 4

Scientific American Magazine

Volume 266, Issue 4

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Features

Where did Modern Humans Originate?

The Recent African Genesis of Humans

Genetic studies reveal that an African woman of 200,000 years ago was our common ancestor

Allan C. Wilson, Rebecca L. Cann

The Multiregional Evolution of Humans

Both fossil and genetic evidence argues that various human groups arose where they are found today

Alan G. Thorne, Milford H. Wolpoff

Mountain Belts and the Supercontinent Cycle

Every 500 million years the continents assemble into a single landmass. The tectonic interactions associated with the formation and breakup of such supercontinents provide a new way to view the origin of mountain belts

J. Brendan Murphy, R. Damian Nance

Superantigens in Human Disease

These proteins cause food poisoning and toxic shock. They may also contribute to arthritis and AIDS. Investigators are learning how superantigens overstimulate the immune system and induce disease

Howard M. Johnson, Jeffry K. Russell, Carol H. Pontzer

The International Thermonuclear Experimental Reactor

This tokamak fusion reactor, sponsored by four industrial powers, will be the most powerful ever built. By fusing deuterium and tritium, ITER should generate more energy than it consumes

Robert W. Conn, Valery A. Chuyanov, Nobuyuki Inoue, Donald R. Sweetman

Solid Acid Catalysts

Great progress has been made in the design of these important industrial materials. Some novel solid acid catalysts can reduce the emission of environmentally harmful products

Sir John Meurig Thomas

Phantom Limbs

People who have lost an arm or a leg often perceive the limb as though it is still there. They can also feel excruciating pain in specific parts of the phantom limb

Ronald Melzack

Hacking the Genome

The masses of information written in human DNA are being translated into the precise ones and zeros of computer code. The choices made now will determine whether the genome project is a font for future discovery or a binary junkyard of data.

Deborah Erickson

Departments

Errata

Letters to the Editors, April 1992

50 and 100 Years Ago: April 1992

Brain Drain

The Plankton Stalkers

First-Class Culprit

A Census of Stranglers

Vexing Vortices

D2 or not D2

A Second Glance

Fire in Water

Charlotte's Patent

Desktop Artisans

Avoiding the Potholes on Optical Highways

Waste Not...

Ballpark Physics

Helping the Little Guy Buy a Computer

Compensation Beyond the Call of Duty

All Paths Lead Away from Rome

Book Reviews, April 1992

Essay: A Case of Dèjà Vu