Random Samples

Science  30 Jun 2006:
Vol. 312, Issue 5782, pp. 1853

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    Over the course of 2 to 3 weeks last month, a volcanic lake in the Pacific island nation of Vanuatu suddenly changed color, from pale blue to a startling burgundy (above). It's “spectacular,” says Alain Bernard, a specialist on volcanic lakes at the Université Libre de Bruxelles, who knows of only one other example of the phenomenon, in the lakes of the Keli Mutu volcano in Indonesia.

    Philipson Bani, a volcanologist with the Institute of Research for Development in Noumea, New Caledonia, and two colleagues just returned from Voui. The lake has turned less acidic since readings were taken in February, with its pH rising from 2 to 3, he says. The lake bottom is “totally covered by orange-brown deposits”—iron oxides, Bani says, which are responsible for the magenta hue.

    The Ambae (Aoba) volcano cupping Lake Voui erupted last November, and a cone rising from the middle of the lake is growing. It's not clear, however, whether the lake's red shift reflects a worrisome change in the plumbing of Ambae, which Bani says is one of the biggest sources of sulfur dioxide in the world. Adding to the strange picture, Voui's water level is steadily dropping, having retreated 4 meters since November. Bani and his colleagues are keeping a close eye on the dazzling geophysical show.


    The world seems to get noisier all the time, but Americans' hearing is no worse today than it was 35 years ago, a government study reports. The study also adds to earlier evidence that blacks hear better than whites and women better than men.

    The study assessed the hearing of some 5000 subjects participating in the National Health and Nutrition Examination Survey from 1999–2004. Their threshold hearing level—the softest sound a person can hear—was tested at a variety of frequencies. In general, women did better than men, non-Hispanic blacks did the best, and non-Hispanic whites the worst, with Hispanics coming out in the middle, researchers from the National Institute for Occupational Safety and Health reported earlier this month at a meeting of the Acoustical Society of America.

    Study leader William Murphy says the pigment melanin may be a factor in the race difference. “Melanin has been demonstrated to have a protective effect with respect to hearing loss,” he says. Pigmentation in the inner ear appears to protect tiny hair cells from damage. The sex difference is thought to derive in large part from more male exposure to workplace noise.

    Audiologist Maurice Miller of New York University notes that the failure to find differences in hearing since the 1970s “may have been obscured by concentrating on mean data rather than subgroups.” He suspects, for example, that an “iPod effect” could be causing hearing loss at high frequencies.



    Italian copperplate engraving shows degradation between 1576 and 1604. An evolutionary biologist has devised a method for dating antique prints that's based on principles used to estimate when species diverged.

    Blair Hedges, a professor at Pennsylvania State University in State College who is a longtime collector of prints, reasoned that just as genes steadily accumulate mutations over time, the woodblocks and copperplates used in early printmaking deteriorate at a relatively constant rate. To test the idea, he digitized and examined 2674 Renaissance prints. Hedges found that whereas the initial editions of woodblock prints had clear lines, prints from the same block decades later had broken lines, probably from tiny cracks that developed in the aging wood. Copperplate prints became more faded over time at a constant rate that matches the corrosion of copper.

    Hedges then tested his strategy on woodblock prints in four editions of Isolario, a 16th century Italian atlas of islands. Calibrating the “print clock” from the three editions with known dates, Hedges estimated that the fourth was printed in early 1565 (give or take about a year). Scholars have long debated the date of this edition; now it appears to be the last, he reports in a paper published online 20 June in the Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences.

    The technique “has the potential to really revolutionize how we date old prints,” says David Gants, a bibliographer at the University of New Brunswick in Fredericton, Canada.



    Fargo dropped out of drug-sniffing school, but it hasn't hurt his career: He's become a key member of a team studying the world's dwindling population of North Atlantic right whales. Fargo, a Rottweiler, and his mutt colleague Bob can smell whale feces from up to 2 kilometers away, says veterinarian and whale researcher Rosalind Rolland of the New England Aquarium in Boston.

    Rolland and collaborators analyze whale waste for parasites, toxins, and hormone levels—potential clues as to why calving rates plummeted in the 1990s, leaving a population of only about 350 whales. Whale excrement stays afloat only briefly, and humans can't smell it from more than 50 meters away. Rolland says a colleague who uses dogs to track scat from bears and other landlubbing animals urged her to try canine help.

    Instead of using food to train the dogs, a game of ball, which they enjoy even more, is the reward for finding feces. Now, says Rolland, “they get extremely animated when they pick up the scent.” Since using the dogs' body language as a compass, the scientists have quadrupled the number of samples collected per outing, they report in an upcoming paper in the Journal of Cetacean Research and Management.