A statistical analysis of DNA from nearly 400 right whales around the world suggests there may be three species of Eubalena, not just two—a conclusion that may boost conservation efforts. (p. 343)

An experimental test for colon cancer may detect the disease at a treatable stage more accurately than current, noninvasive screening techniques. (p. 311)

A molecular connection between the timing of sleep—a part of circadian rhythms—and how long animals slumber each day is demonstrated for the first time. (p. 295)

Using a new technique to examine chromosomes of in vitro fertilization (IVF) embryos at the time they're implanted in the womb, researchers report abnormalities never seen later in development, possibly explaining why IVF has a low efficiency. (p. 276)

A newly discovered drug that prevents radiation from hastening egg cell death in mice might also prevent some human cancer patients from suffering sterility and premature menopause. (p. 228)

A new computer model based on particle interactions suggests ways to prevent a panicked crowd from stampeding. (p. 215)

Magnetic fields such as those found within a few feet of outdoor electric-power lines could make cells that are vulnerable to cancer behave like tumors. (p. 196)