Stranded in Humanity's Past

Cover: Scientists who use DNA to probe the evolutionary roots of modern humans have run into a vexing problem: Genetic data support either of two competing perspectives. One traces Homo sapiens to a single African source just 200,000 years ago, the other to multiple groups in Africa and elsewhere at least a million years ago. (Illustration: Tim Teebken) <Full story>

AIDS Virus Jumped From Chimps
Genetic studies confirm that the roots of the AIDS virus can be traced to viruses infecting chimpanzees living in west-central Africa.

South Pacific has a severe case of anemia
Iron limitations hinder plant growth in large regions of the South Pacific Ocean.

Long live the ovary: Mutant mice keep eggs
A genetic mutation endows mice with ovaries that don't age.

New element leaves lightweights behind
The unconfirmed discovery of the new element 114 suggests that a hypothesized "island of stability" inhabited by long-lived superheavy elements has been found.

Half-asleep birds choose which half dozes
Birds that sleep with one eye open, and with one hemisphere of the brain asleep, control which side of the brain stays awake.

Does tetracycline limit heart attacks?
Heart attack patients are less likely than other patients to have taken the common antibiotic tetracycline within the past 3 years, implicating infection as a potential cause of cardiovascular disease.

Budget boosts information technology
President Clinton submitted a $78.2 billion research and development budget to Congress that emphasizes funds for computer and information technology.

AAAS

Few authors report financial interests
Even in journals that have formal financial-disclosure policies, authors rarely state potential conflicts of interest.

Cost estimates rocket for uninvited guests
Introduced species-including weeds, rats, and disease microbes-cost the United States some $122 billion a year-more than 75 times the previous assessment.

What will ease the pain? Ask a frog
Frogs may leap to the forefront of pain research as the preferred guinea pig for testing new analgesics.

Good parents still make the difference
When children get sent to day care, they don't lose the language-development benefits of interacting with attentive parents at home.

Biomedicine

Breast cancer allayed by mastectomy
A 33-year study shows that preventive mastectomies protect against breast cancer in many women who have a high inherited risk of getting the disease.

AZT shows no ill effects on babies
Exposure to the anti-HIV drug AZT shows few long-term effects in babies not infected with HIV.

Mathematics

The scarcity of cluster primes
Recent computations suggest that so-called cluster primes are less numerous than twin primes, which consist of pairs of consecutive prime numbers that differ by 2.

Cracking a prime cryptosystem
Breaking the widely used RSA cryptosystem may be easier than factoring large numbers into their prime-number components.

DNA's Evolutionary Dilemma
Genetic studies collide with the mystery of human evolution
DNA studies of humanity's origins have hit an impasse over how to choose between competing explanations of genetic findings.

Whole-Sky Catalog
A modest but universal map of the nearby cosmos proves its power
With little fanfare, astronomers have developed a detailed map of the local universe that includes galaxies from virtually every part of the sky.

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