Science  01 Feb 2013:
Vol. 339, Issue 6119, pp. 496

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  1. With Genomes, Pecking Away at Pigeons' Plumage


    For centuries, bird breeders have cultivated pigeons with a startling variety of colors, feather arrangements, and behaviors, creating about 350 breeds that compete to be the fastest, longest-flying, or most beautiful. Now, Michael Shapiro, an evolutionary biologist at the University of Utah in Salt Lake City, and his colleagues have tracked down the mutation leading to one of the pigeon's more ostentatious traits: its head crest, which ranges from a simple peak to a hood of plumage. Using the pigeon genome newly sequenced by BGI in Shenzhen, China, Shapiro and colleagues found that the presence of a crest of any sort is determined by a gene called EphB2, they report online this week in Science. Now, researchers can look to see if this gene leads to head crests in wild birds. "The work now puts the spot on pigeons … [and] may attract other scientists to start using pigeons as models," says Hans Ellegren, an evolutionary biologist at Uppsala University in Sweden who was not involved with the work.

  2. Paradox Lost

    Last April, Masud Mansuripur, an electrical engineer at the University of Arizona in Tucson, claimed classical electrodynamics and relativity can lead to a paradox. Now, four physicists say in comments in press at Physical Review Letters that they have resolved the contradiction.

    Mansuripur's paradox posited an electric charge sitting near a magnet. In the "reference frame," where both are stationary, they don't interact. But, in the "moving frame," where they glide together, the magnet feels a twisting torque, according to both relativity and the standard formula for electric and magnetic forces. Yet the magnet can't spin in one frame and not in the other—so the force formula must be wrong, Mansuripur argues.

    But, others say, relativity demands that the magnet possess "hidden angular momentum," which, in the moving frame, constantly increases. So the torque in that frame feeds the hidden angular momentum instead of spinning the magnet. Problem solved.

    Mansuripur says hidden momentum is an ill-defined concept that papers over the problem. But Daniel Vanzella of the University of São Paulo in São Carlos, Brazil, says it's bedrock relativity, "not an ad hoc invention put in to reconcile things."

  3. Genes the Secret to Surviving a Siberian Winter


    Frigid Siberia has been home to humans for tens of thousands of years, including Homo sapiens and Neandertals. A study of today's Siberian peoples, presented last month at the Unravelling Human Origins meeting in Cambridge, U.K., finds that their genes may help them adapt to cold conditions.

    Alexia Cardona, a graduate student at the University of Cambridge, and her colleagues analyzed 200 DNA samples from 10 indigenous Siberian populations and looked for genes that might correlate with cold adaptation.

    Using techniques that detect natural selection in the human genome—that is, genetic variants favored by evolution because they helped humans survive and reproduce—Cardona found evidence for such variants in three genes in the Siberian populations. One gene, called UCP1, helps convert fat directly into heat to keep the body warm. A second, called ENPP7, is implicated in the metabolism of fats from meat and dairy products. And a third gene, PRKG1, is involved in smooth muscle contraction, key to shivering and the constriction of blood vessels to avoid heat loss.