Prehistoric human skulls found in Brazil share some traits with modern Africans, leading a Brazilian scientist to theorize that Africans rather than Asians first arrived in the Americas sometime before 11,000 years ago. (p. 212)

Scientists tinkering with a chemical now vital to life think they've recreated one of the central molecules that gave rise to the chemistry of life. (p. 212)

Researchers are discovering that some plants get their nutrients by robbing nitrogen from the flesh of soil-dwelling insects. (p. 213)

Far beyond the solar system's nine known planets, a body as massive as Mars may once have been part of our planetary system, and it might still be there. (p. 213)

A new optical tool allows physicians to scout for precancerous tissue by analyzing the fluorescent responses of cells when light is shone on them. (p. 214)

In mice, allergic reactions to food coincide with an accumulation of white blood cells called eosinophils in the small intestine. (p. 214)

A new analysis of tapeworm history suggests that people have been wrong about where we picked up pests: It was not domestication of cattle and pigs but increased meat eating in Africa. (p. 215)

New observations of the middle and upper atmosphere over Earth's polar regions may require scientists to revamp their mathematical models of temperature and other environmental conditions at high altitudes. (p. 215)

In a newly discovered trick for avoiding self-pollination, ginger flowers take turns at gender roles, switching from female to male or vice versa in unison around lunchtime. (p. 216)

People don't see ultraviolet light but birds do, so studies of egg mimickry may need to stop relying so much on human vision. (p. 216)

A highly active version of a gene for faster testosterone metabolism is also associated with early breast development—by the age of 9.5 years—in girls. (p. 216)

A synthetic enzyme that lowers blood pressure and causes blood vessels to constrict shows promise for treating skin and kidney cancers that have spread throughout the body. (p. 216)

A gene that is more active in prostate cancer tumors from African-American men than in tumors from white men may help explain why prostate cancer is both more common and more aggressive in African Americans. (p. 216)

Cosmologists are thinking dark thoughts about what kind of mystery force may be contorting the cosmos, pushing galaxies apart at a faster and faster rate. (p. 218)

Most people carry traces of toxic pollutiants, including metals, pesticides, and phthalates. (p. 221)

The new EPA administrator has delayed by 60 days the implementation of a final rule issued by the Clinton administration lowering the amount of arsenic allowed in drinking water. (p. 221)

By detecting vibrations of less than an atom's width of a tiny cantilever, physicists have made the most sensitive measurement of force ever by mechanical means. (p. 221)

Ultrafast laser pulses may have for the first time revealed the incredibly rapid, step-by-step progress of a complete chemical reaction on a surface, at the actual speed at which it took place. (p. 221)

Once believed to be a supporting cast, the brain cells called astrocytes appear to play important roles in many brain scenarios. (p. 222)