In Brief

By Lisa McLaughlin

WHICH WAY OUT? Here's a scientific explanation for all those arguments with your spouse over directions. Researchers at the University of Ulm in Germany scanned the brains of men and women as they tried to escape a 3-D virtual-reality maze and found that the sexes use different parts of the brain to process directions. Men relied on their left hippocampus and used geometry to find their way. Women used their right frontal cortex, trusting memory to keep landmarks in mind.

TAP VS. BOTTLED Many parents assume that drinking bottled water is healthier for their families, but recent research shows that may not be true. Tap water is actually more closely monitored by the EPA for bacteria and pollutants. About 20% of bottled water contains higher levels of bacteria than does the tap water in most cities. Another concern is fluoridation: only 5% of bottled water contains recommended levels of fluoride. If your children are drinking primarily bottled water, check with your dentist to see if fluoride supplements are needed.

BOY OR GIRL? Mothers who conceive in warmer countries are more likely to have boys, according to a recent study published in the Journal of Epidemiology and Community Health. Victor Grech, a pediatrician in Malta, surveyed 17 countries' birth statistics. After separating them into three climatic bands, he determined that the coldest group had the lowest rate of male births and the hottest group had a consistently high proportion of baby boys. Researchers are still examining the results to figure out why heat affects gender.

--By Lisa McLaughlin