Random Samples

Science  27 Mar 2009:
Vol. 324, Issue 5923, pp. 19

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    Girl frog comes on to guy with red sac. CREDIT: MARY THERY AND DORIS GOMEZ

    Nocturnal tree frogs use their unique call to lure females through the night, but could the color of their sacs also help to drive the ladies mad?

    The sight of a pulsating vocal sac can excite a frog. To see if color could also be a turn-on, scientists at the Muséum National d'Histoire Naturelle in Paris exposed 70 female frogs to two computer screens displaying images of a male, adjusted to appear as he would at night. Speakers alternately played identical male calls; the only difference was that on one screen the male had a dark red vocal sac and on the other, a pale brown one. If a female lingered for 30 seconds in a “choice area” near either image, she was assumed to be signifying a desired mate.

    Females were overwhelmingly drawn to the image of a frog with a darker, more colorful sac. Some climbed onto the screen to solicit the virtual frog. So even when lights are low, sac coloration may signal a quality mate, says evolutionary biologist Marc Théry, co-author of a paper online 25 March in Biological Sciences.

    “This is a fascinating paper,” says ecology graduate student Victoria Arch of the University of California, Los Angeles. It shows “the importance of considering multimodal cues” in mating, even in nocturnal species.


    Mikhail Gromov of the Institut des Hautes Études Scientifiques (IHES) in Bures-sur-Yvette, France, has won this year's $950,000 Abel Prize in mathematics from the Norwegian Academy of Science and Letters.

    The Russian-born Gromov, 65, also a scholar at the Courant Institute of Mathematical Sciences in New York City, has made advances in the fields of symplectic and Riemannian geometry, which are closely tied to areas such as general relativity and string theory. He also founded the modern study of “geometric group theory,” which injects notions of distance and curvature into the study of finite algebraic structures.

    “Misha is often radical in his judgments,” says IHES Director Jean-Pierre Bourguignon. But that pays off in unconventional insights, including new connections between mathematics and biology. For example, Gromov, with a co-author, proved a “theorem” on the virtual certainty of unicellular life in pond water: Within a mathematical framework that stipulates what it takes for a random arrangement of chemicals to be considered living, they find, the “live” states vastly outnumber the “dead” ones.



    The famous 3300-year-old bust of Egypt's Queen Nefertiti is more than just a pretty face. Researchers at the Imaging Science Institute in Berlin, Germany, have used computed tomography scans to reveal that the limestone core under the millimeters-thick stucco skin is a slightly different sculpture. This inner face is probably closer to her true likeness, researchers report in the 31 March issue of Radiology.

    The alterations yield intriguing clues to the nobility's aesthetic ideals, the study's authors say. “Nefertiti's bust … is an intersection between realism and stylization,” says institute director Alexander Huppertz, the lead author. The inner sculpture has wrinkles at the corners of its mouth and a small bump on its nose; the sculptor eliminated those flaws by pasting them over with stucco for the final sculpture. Although most of the makeover was designed to flatter the queen, one element was not: The sculptor made the corners of Nefertiti's eyelids more pronounced in the final version. Huppertz says that could have been done to denote the queen's maturity and wisdom. “None of us really knows what the Egyptians' ideals were in those days,” says Nicholas Reeves, curator of Egyptian art at Eton College in Windsor, United Kingdom. “But I would say the sculptor only made improvements.”



    An orphaned chimpanzee awaits a buyer in Buta, in the northern Democratic Republic of the Congo. Cleveland Hicks, a graduate student at the Institute for Biodiversity and Ecosystem Dynamics at the University of Amsterdam, recently spent 13 months surveying the area. He reports that diamond and gold mining in the hitherto pristine Gangu forest is leading to destruction of habitat and an upsurge in the bushmeat trade (see http://www.wasmoethwildlife.org/).