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<jats:p> A monthly roundup of recent news and projects of <jats:italic>Science</jats:italic> 's publisher, the American Association for the Advancement of Science. </jats:p>

<jats:title>Kindergarten Scientists</jats:title> <jats:p> Becoming a scientist takes many years of training … or so it seems. It requires learning how to acquire data, to incorporate it into hypotheses, and then to test those hypotheses against newly acquired data; it requires learning how to think critically and to apply statistical analysis. <jats:bold>Gopnik</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1623" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1223416">1623</jats:related-article> ) reviews recent cognitive development findings that demonstrate how preschoolers act as young scientists in refining their intuitive representations of the world as they explore reality. </jats:p>

<jats:p>Digital information can be stored in DNA at densities higher than digital media such as flash memory or quantum holography.</jats:p>

<jats:title>Changing Rains</jats:title> <jats:p> The water cycle of the western United States has varied dramatically across the glacial cycles of the Pleistocene, possibly because of changes in the tracks of the storms that deliver moisture to the region. <jats:bold> Lyle <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1629" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1218390">1629</jats:related-article> ) present evidence from a collection of Great Basin lakes which show that water levels rose over the last 20,000 years because of moisture transported from the tropical Pacific, not from a southward diversion of the westerly storm track. Furthermore, the timing of the lake level highs in the Great Basin shows a progression from south to north that does not coincide with the northward progression of wet intervals. </jats:p>

<jats:title>Making the Change</jats:title> <jats:p> The Apocynaceae plant family produces toxic cardenolids. However, many insects have managed to escape the deleterious effects of these chemicals and even, in some cases, use them in their own defense. <jats:bold> Zhen <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1634" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1226630">1634</jats:related-article> ) investigated a broad range of taxa and found several examples of parallel changes, as well as duplications, in members of the ATPα family that likely explain the shift to allow insects to avoid the toxic effects of these plants. Thus, natural selection can harness a combination of gene duplication, protein evolution, and regulatory evolution to allow distantly related species to adapt to specific niches. </jats:p>

<jats:title>Our Constant Sun</jats:title> <jats:p> The exact shape of the Sun provides information on its internal structure. Based on data obtained by the Helioseismic and Magnetic Imager aboard NASA's Solar Dynamics Observatory, <jats:bold> Kuhn <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1638" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1223231">1638</jats:related-article> , published online 16 August; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6102" page="1611" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1226988">Gough</jats:related-article> </jats:bold> ) measured the solar shape during a 2-year period in which the Sun evolved from a minimum to a maximum of sunspot activity. Against expectations, the Sun's oblate shape was found to be constant and not to vary with the 11-year solar cycle. </jats:p>

<jats:title>Reversible Implants</jats:title> <jats:p> Silicon electronics are generally designed to be stable and robust—it would be counterproductive if the key parts of your computer or cell phone slowly dissolved away while you were using it. In order to develop transient electronics for use as medical implants, <jats:bold> Hwang <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1640" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1226325">1640</jats:related-article> , see the cover) produced a complete set of tools and materials that would be needed to make standard devices. Devices were designed to have a specific lifetime, after which the component materials, such as porous silicon and silk, would be resorbed by the body. </jats:p>

<jats:title>Gently Coupled</jats:title> <jats:p> Linked aryl rings are found in a broad range of commercial chemical products. Currently, the most versatile synthetic route to this motif involves cross-coupling of one ring with a halide substituent to another ring with a boron or metal-based substituent. Recent research has focused on eliminating the need for one or both of these activating substituents, but for the most part, the emerging methods have required high temperatures and high concentrations of one coupling partner. <jats:bold> Ball <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1644" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1225709">1644</jats:related-article> ) now present a gold catalyst that can couple silyl-activated arenes to unactivated arenes in comparable concentrations at room temperature. </jats:p>

<jats:title>Solid View of a Sigma Complex</jats:title> <jats:p> For decades, it has been clear from kinetic studies that saturated hydrocarbons can also act as weak ligands, often just prior to bond cleavage reactions. These short-lived intermediates—termed “σ complexes” because the donated electrons reside in single (sigma symmetry) C-H bonds—have been glimpsed spectroscopically but have largely eluded full structural characterization. <jats:bold> Pike <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1648" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1225028">1648</jats:related-article> , published online 23 August) now present the crystallographic characterization of an alkane bound to rhodium, which they captured by direct hydrogenation of a more stable crystalline precursor incorporating an alkene. </jats:p>

<jats:title>Beyond Youthful Aggression</jats:title> <jats:p> Two decades ago, the combination of a demographic bulge of young males in Enga Province of Papua New Guinea and more deadly armaments triggered a series of intertribal wars and a surge in war-related fatalities; more recently, both wars and deaths have dropped. Drawing upon 20 years of conflict data, as well as historical records of the local social institutions, <jats:bold>Wiessner and Pupu</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1651" related-article-type="in-this-issue" vol="337" xlink:href="10.1126/science.1221685">1651</jats:related-article> ) analyzed the impact of youth-driven violence upon the traditional hierarchies and the subsequent evolution of the indigenous institutions into political structures capable of controlling conflict and reducing bloodshed. </jats:p>