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<jats:p>Electron microscopic and crystallographic studies shed light on key steps in the protein synthesis process in ribosomes.</jats:p>

<jats:p>The degree to which economic success is passed through generations and the ability of societies to generate wealth depend on their institutions and social arrangements.</jats:p>

<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:p>A laser that emits lines every 10 gigahertz can be used for frequency calibration in spectroscopy.</jats:p>

<jats:title>Origins of Egalitarianism</jats:title> <jats:p> Wealthy contemporary societies exhibit varying extents of economic inequality, with the Nordic countries being relatively egalitarian, whereas there is a much larger gap between top and bottom in the United States. <jats:bold> Borgerhoff Mulder <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="682" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1178336">682</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5953" page="678" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1181939">Acemoglu and Robinson</jats:related-article> </jats:bold> ) build a bare-bones model describing the intergenerational transmission of three different types of wealth—based on social networks, land and livestock, and physical and cognitive capacity—in four types of small-scale societies in which livelihoods depended primarily on hunting, herding, farming, or horticulture. Parameter estimates from a large-scale analysis of historical and ethnographic data were added to the model to reveal that the four types of societies display distinctive patterns of wealth transmission and that these patterns are associated with different extents of inequality. </jats:p>

<jats:title>Ribosomes Caught in Translation</jats:title> <jats:p> To synthesize proteins, the ribosome must select cognate transfer RNAs (tRNAs) based on base-pairing with the messenger RNA (mRNA) template (a process known as decoding), form a peptide bond, and then move the mRNA:tRNA assembly relative to the ribosome (a process known as translocation). Decoding and translocation require protein guanosine triphosphatases (GTPases), and, while high-resolution structures of the ribosome have greatly furthered our understanding of ribosome function, the detailed mechanism of these GTPases during the elongation cycle remains unclear. Two Research Articles now give a clearer view of these steps in bacterial protein synthesis (see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5953" page="677" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1181511" xlink:type="simple">Liljas</jats:related-article> </jats:bold> ). <jats:bold> Schmeing <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="688" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1179700" xlink:type="simple">688</jats:related-article> , published online 15 October) present the crystal structure of the ribosome bound to Elongation factor-Tu (EF-Tu) and amino-acyl tRNA that gives insight into how EF-Tu contributes to accurate decoding. <jats:bold> Gao <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="694" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1179709" xlink:type="simple">694</jats:related-article> , published online 15 October) describe the crystal structure of the ribosome bound to Elongation factor-G (EF-G) trapped in a posttranslocation state by the antibiotic fusidic acid that gives insight into how EF-G functions in translocation. </jats:p>

<jats:title>Ribosomes Caught in Translation</jats:title> <jats:p> To synthesize proteins, the ribosome must select cognate transfer RNAs (tRNAs) based on base-pairing with the messenger RNA (mRNA) template (a process known as decoding), form a peptide bond, and then move the mRNA:tRNA assembly relative to the ribosome (a process known as translocation). Decoding and translocation require protein guanosine triphosphatases (GTPases), and, while high-resolution structures of the ribosome have greatly furthered our understanding of ribosome function, the detailed mechanism of these GTPases during the elongation cycle remains unclear. Two Research Articles now give a clearer view of these steps in bacterial protein synthesis (see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5953" page="677" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1181511">Liljas</jats:related-article> </jats:bold> ). <jats:bold> Schmeing <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="688" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1179700">688</jats:related-article> , published online 15 October) present the crystal structure of the ribosome bound to Elongation factor-Tu (EF-Tu) and amino-acyl tRNA that gives insight into how EF-Tu contributes to accurate decoding. <jats:bold> Gao <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="694" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1179709">694</jats:related-article> , published online 15 October) describe the crystal structure of the ribosome bound to Elongation factor-G (EF-G) trapped in a posttranslocation state by the antibiotic fusidic acid that gives insight into how EF-G functions in translocation. </jats:p>

<jats:title>Superconductivity Sliced Thin</jats:title> <jats:p> Since the initial characterization of high-temperature cuprate superconductors, an intriguing challenge has been determining the minimum number of copper oxide planes needed to support the superconducting state. The observation of superconductivity at interfaces of metallic oxides and insulators provides a route to addressing this question. <jats:bold> Logvenov <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="699" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1178863">699</jats:related-article> ) describe a method for layer-by-layer synthesis of alternating oxides of metal and insulators based on La and Cu. Layers three unit cells thick supported superconductivity with a transition temperature of 32 kelvin. When selected layers were then doped with Zn atoms to suppress superconductivity, the interface superconductivity was shown to arise from a single copper-oxide plane. </jats:p>

<jats:title>Electron Comings and Goings</jats:title> <jats:p> Advances in computational chemistry have enabled remarkably detailed calculations of electrons' spatial arrangements in complex molecules. Experimental confirmation of these orbital geometries remains challenging, however, particularly for molecules bound in thin layers to underlying surfaces—a morphology of increasing interest in organic semiconductor development. <jats:bold> Puschnig <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="702" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1176105">702</jats:related-article> , published online 10 September) mapped the trajectories of photoelectrons emitted from polycyclic aromatic molecules deposited on copper and extracted spatial profiles of the orbitals from which these electrons emerged. The method of analysis takes advantage of the straightforward Fourier relation between position and momentum and complements orbital imaging techniques based on scanning tunneling microscopy. </jats:p>

<jats:title>Zinc-Based Bases</jats:title> <jats:p> Conventional methods of stripping a proton from a hydrocarbon yield an alkali metal-coordinated carbanion as the preliminary product. In certain cases, however, this preliminary product falls apart before it can be used for further constructive synthetic purposes. <jats:bold> Kennedy <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="706" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1178165">706</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5953" page="673" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1181863">Marek</jats:related-article> </jats:bold> ) show that in such cases, zinc ions can act as potent stabilizers. Specifically, a bimetallic base incorporating both sodium and zinc ions was used to deprotonate the common cyclic ethers tetrahydrofuran and tetrahydropyran. Zinc coordination to the carbanion inhibited an otherwise rapid ring-opening decomposition pathway. Similarly, a zinc-potassium combination facilitated deprotonation of ethylene to a stabilized product. </jats:p>