National Geographic : 2001 May
GEOGRAPHICA Virginia (left). The beetles are nearly impervious to pesticide assaults. Forest managers have little recourse but to haul away infested trees. Some researchers ENVIRONMENT __ MATTAYRES.DARTMOUTHCOLLEGE(ABOVE:JAMESL. STANIIEL Assassin of the Pine Forests think drought makes pines vul nerable, but others disagree. Do predatorsaffect pine beetles' vicious cycles? "There appears to be no rela tionship," says John D. Reeve of T he most destructive insect their eggs within winding tun- Southern Illinois University. plaguing pine forests in nels (above right). They emit a He points instead to a natural the southern U.S., the pheromone that attracts not only enemy, clerid beetles, which feed southern pine beetle caused an males but also more females, re- voraciously on southern pine estimated 900 million dollars suiting in a mass infestation. The beetles. Clerids' cycles fluctuate, in damage from 1960 to 1990. beetles quickly spread, killing the and when they are scarce, pine Females bore into trees and lay forest, as on Assateague Island in beetle populations may explode. CHEMISTRY Disappearing Prints At crime scenes, dust for children's finger prints immediately. That's the message chemists at the Oak Ridge National Laboratory in Tennessee have for police inves tigators. They found that children's fin gerprints contain more evaporative substances than adults' oilier prints and can disappear entirely within 24 hours, especially in high temperatures. NATIONAL GEOGRAPHIC * MAY 2001 ANNIEGRIFFITHSBELT(ABOVE;)ARTBY DOUGSTERN THE HUMAN BODY Speaking of Laughter hy is it that babies can laugh long before they can talk? The laughing mechanism, says researcher Robert R. Pro vine of the University of Maryland, Baltimore County, might actually be a remnant of the earliest primate communication and not related to speech at all. "Laughter is a tool to study vocal evo lution," he says, pointing out that chimpanzees laugh too-though in a manner much different from the universal human "ha." Chimps' mostly four-legged locomotion, he says, prevents the breath control that is necessary for human-sounding laughter and for vocal speech.