Random Samples

Science  30 Jan 2009:
Vol. 323, Issue 5914, pp. 565


    Bees have good memories and can prioritize tasks. So biologist Jürgen Tautz of the University of Würzburg in Germany and colleagues decided to check out their ability to subitize—estimate small quantities at glance. They trained several groups of bees to fly through a Y-shaped maze. After being shown a sample picture with two dots, the bees had to choose whether to approach a two-dot pattern or one with three dots.

    With repetition and a sugary reward, bees achieved a success rate of about 80%. When patterns were made more complex, most bees were still able to learn the difference between two and three, and between three and four. Beyond that, they failed to make distinctions, the researchers reported 28 January in PLoS One.

    Tautz finds the division between “up to 4” and “a lot” intriguing, as it is mirrored in many human cultures. For biologist Lars Chittka of Queen Mary, University of London, the study shows that “even simple animals don't just associate visual signals with rewards but can extract [quantitative] features” from them.


    In a marriage of particle physics and meteorology, researchers say they've linked atmospheric temperature changes with high-energy particles measured deep underground.

    Cosmic rays collide with the atmosphere to produce mesons, which then decay into muons that penetrate deep into Earth. Mesons are destroyed if they interact, so an increase in temperature—and the resultant expansion of the atmosphere—gives them space to avoid collisions and become muons.

    Researchers at two U.K. organizations, the National Centre for Atmospheric Science, based at the University of Oxford, and the Science and Technology Facilities Council, noticed upticks in winter muon rates at a cosmic-ray detector located in an old northern Minnesota mine. They linked the increases—and the inferred temperature increases—to a Northern Hemisphere winter phenomenon called sudden stratospheric warming (SSW). That makes them the first to use cosmic-ray detection, rather than satellites and weather balloons, to identify abrupt weather events. SSWs can modify winter weather and help slow ozone-destroying reactions.

    Meteorologist Andrew Charlton-Perez of the University of Reading in the United Kingdom says the research, reported 21 January in Geophysical Research Letters, shows that particle physics can help understanding of specific climate events. “I think it's a very interesting look from left field,” he says. Physicist Karen Aplin of the Rutherford Appleton Laboratory in the U.K. adds that scientists may now be able to use historical cosmic-ray data to understand earlier atmospheric conditions.


    Diagnosed cases of autism in California rose by a whopping 600% between 1990 and 2003, according to a new study from the University of California, Davis, in this month's issue of Epidemiology. Epidemiologist Irva Hertz-Picciotto and colleagues reviewed records of 26,761 children to estimate how much of the increase is real and how much is owing to factors such as broadened definitions of the disorder and increased public awareness. They concluded that only about one-third of the increase could be attributed to such factors.


    Others say it's still not clear whether autism is on the rise. The Davis study “cannot demonstrate the increase is real,” says epidemiologist Eric Fombonne of McGill University in Canada, in part because it pays scant heed to “diagnostic substitution”—the fact that children formerly diagnosed as retarded or learning disabled are now being called autistic.


    In a piece of old-fashioned sleuthing, a U.K. archaeologist believes he has found evidence of the first known use of chemical warfare.

    In 256 C.E., the Roman garrison in the city of Dura-Europos, Syria, was under siege from the Sasanian Persian Empire. Excavations in the 1920s revealed a grisly scene: a Persian siege mine intercepted by a Roman countermine at the entrance to which lay the skeletons of 20 armored Romans.


    Mystery has always surrounded how the Romans died in a space too small to wield a sword and why they were all clumped together. Simon James of the University of Leicester in the United Kingdom thinks he has the answer: a jar of bitumen and sulfur crystals, believed to have been used to start a fire and collapse the Roman tunnel. These chemicals also produce clouds of choking gases. James thinks the Persians had prepared a “nasty surprise” for the Romans when they broke through, throwing chemicals on their fires and using bellows to suffocate their attackers. They then piled up the Romans to wall off the tunnel.

    “It's a dramatic story and derived totally through archaeology. There's no written record of these events,” says James, who reported his conclusion at the annual meeting of the Archaeological Institute of America this month.

    Dura-Europos ultimately fell to the Persians, was sacked, and lay forgotten until the last century.

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