January 30 COVER Desert locusts, Schistocerca gregaria, are normally solitary and avoid each other (green individual, lower right). Forced proximity between them leads to the release of the neurotransmitter serotonin, which changes their behavior to mutual attraction and initiates a cascade of events leading to swarm formation, including a change in appearance (black and yellow group). See page 627) Image: Tom Fayle, Swidbert Ott, and Stephen Rogers/University of Cambridge

February 6 COVER Charles Darwin’s abiding interest in the classification of barnacles, illustrated here, was one of the inspirations for his investigations into the origins and diversification of species. Science marks Darwin’s 200th birthday with a special section on speciation beginning on page 727) Image: Illustrations by George Sowerby, reproduced with permission from The Complete Work of Charles Darwin Online, John van Wyhe, Ed. (http://darwin-online.org.uk); background: iStockphoto.com

February 27 COVER Optical laser scan of early hominin footprints at Ileret, Kenya, color-rendered to illustrate depth; reds indicate areas of high elevation, blues lower elevation. The footprints are 1.5 million years old and were probably made by Homo ergaster/erectus. Two right footprints and a partial left are visible along with a range of animal prints. See page 1197).
Image processing in RapidformTM: Matthew Bennett/ Bournemouth University

March 13 COVER False-color scanning electron micrograph of oriented vaterite, a crystalline polymorph of calcium carbonate, formed through template-controlled nucleation. Formation starts with the aggregation of prenucleation clusters forming an amorphous phase from which the crystals develop at the template surface. This experimental process may be analogous to the natural formation of seashells and other marine skeletons. See page 1455. Image: W. J. E. M. Habraken and C. J. van den Hoogen/Eindhoven University of Technology

March 20 COVER Movement trajectories, each recorded during a 1-hour time period, for rats with brain lesions that reduce dopamine signaling. These animals serve as a model of Parkinson’s disease and display severe difficulty in initiating movements, as illustrated by the white trajectories (on black background) showing limited locomotion. Black trajectories (on white background) illustrate the recovery of locomotive activity induced by electrical stimulation of the dorsal columns of the spinal cord. See page 1578. Photo illustration: Yael Kats/Science; images: Per Petersson

March 27 COVER False-color, aberration-corrected transmission electron microscope image of a suspended single atomic layer of graphene. When an electron beam induces ejection of an atom from the edge of an intentionally made ~3-nm hole (black), the hole enlarges; the remaining edge carbon atoms rearrange from perfect hexagons into predicted metastable configurations. See page 1705. Image: Zettl Research Group and National Center for Electron Microscopy, Lawrence Berkeley National Laboratory; 3D visualization via WSxM software

April 3 COVER QuteMol-rendered image of human rhinovirus 3 (Protein Data Bank ID: 1rhi) illustrating virion topography. Red, blue, and yellow denote the three major surface capsid proteins; examples of RNA regional motifs are colored according to predicted base-pairing fidelity. Sequence diversity within the major surface proteins contributes to the wide range of immunogenic serotypes characteristic of the “common cold.” See page 55. Image: H. Adam Steinberg and Jean-Yves Sgro/University of Wisconsin-Madison

April 10 COVER The dynamic nature of the master calcium signaling protein, calmodulin, schematically illustrated by snapshots from an interpolation between its calcium-bound state (blue) and its structure bound to both calcium and a peptide derived from one of its downstream cellular targets, myosin light chain kinase (red), generated using the Yale Morph Server and PyMol software. See the special section beginning on page 197). Image: Robert Smock and Lila Gierasch

April 24 COVER Animal domestication has been key to the development of human societies. The sequence of the bovine genome reveals new insights into the history and biology of cattle. See pages 522 and 528, and related research on horse and sheep genetics and domestication on pages 485 and 532. Photo illustration: Yael Kats (images: Jupiterimages)

May 29 COVER A close-up of the tropical coral Favia speciosa. The position and age of related fossil corals have been used to constrain the timing of sea-level rise during the penultimate deglacial period. The timing of past sea-level change, relative to potential forcings, can help determine the mechanisms of climate change and the speed of ice sheet collapse. See page 1186 Photo: Getty Images

June 12 COVER The flight path of a maple seed visualized in a composite multiflash photograph. Autorotating seeds slow their descent by exploiting the low pressure generated by a vortex that forms at the leading edge of their spinning wing. A similar leading-edge vortex also elevates the lift of insect, bat, and hummingbird wings. See page 1438 Photo: David Lentink

June 26 COVER Colonies of human embryonic stem cells with differentiating cells at their edges, growing on mouse feeder cells. Cell nuclei are stained in blue, nuclear lamina in red, and cytoplasm in green (overlapping blue and red areas appear purple). The self-renewal capacity and pluripotency of human stem cells make them valuable for modeling human disease. These cells also display potential for transplantation medicine. See the special section beginning on page 1661 ). Image: Oded Kopper and Nissim Benvenisty, The Hebrew University of Jerusalem

July 10 COVER Skeletons of turtle, chicken, and mouse. The turtle body plan is unusual in that the ribs are transformed into a carapace, and the scapula, situated outside the ribs in other animals, is found inside the carapace. A report on page 193 )explains the evolutionary origin of this inside-out skeletal morphology. Drawings: Hiroshi Nagashima

July 17 COVER Average patterns of brain recruitment, as measured by functional magnetic resonance imaging, in children with typical reading development (left) or dyslexia (right) as they sound out printed words. Left-hemisphere brain regions engaged by typical readers, the parietal cortex (upper left) and fusiform gyrus (lower left), are less engaged by dyslexic readers. See page 280. Photo illustration: Yael Kats (brain scans, Susan Whitfield-Gabrieli and John Gabrieli; background, iStockphoto.com)

July 24 COVER A computer-generated map showing relationships between Internet blogs (colored spots), where lines represent links between individual blogs. In this map, blogs within the inner core cover technical topics and gadgetry, and blogs in the outer sphere involve nontechnical discussions and link back to the technical ones. See the special section on complex systems and networks beginning on page 405.

September 18 COVER Scheme of a photonic metamaterial composed of three-dimensional gold helices, each about 1.4 micrometers in diameter, fading to an oblique-view electron micrograph of the helices as fabricated (blue). The illuminated spiral symbolizes circularly polarized light impinging on the chiral metamaterial. The structure works as a circular polarizer for a frequency range exceeding one octave. See page 1513). Illustration: Michael S. Rill (structure fabrication by Justyna K. Gansel and Michael Thiel)

October 2 COVER Partial skeleton of Ardipithecus ramidus, a hominid species living about 4.4 million years ago in Ethiopia. This female stood about 1.2 meters high. Eleven papers from an international team of authors published in print and online in this special issue describe the anatomy of this species and its habitat and discuss the implications for understanding human evolution. One result is that extant great apes are poor models for our last common ancestor with chimpanzees. See page 60). Image: © T. White, 2008

October 9 COVER First described by David Hilbert in 1891, the Hilbert curve is a one-dimensional fractal trajectory that densely fills higher-dimensional space without crossing itself. A new method for reconstructing the three-dimensional architecture of the human genome, described on page 289, reveals a polymer analog of Hilbert’s curve at the megabase scale. Image: Leonid A. Mirny and Erez Lieberman-Aiden

October 16 COVER A frontal view of the fly brain (blue) showing two groups of dopamine-producing neurons pseudocolored green and magenta. The magenta neurons are engineered to express a light-sensitive protein. Optical signals (symbolized by a magenta beam of light) can selectively report and control the activity of these cells. Miesenböck (page 395) reviews the emerging field of optogenetics in a special section on advances in neuroscience methods starting on page 385. Confocal images: Adam Claridge-Chang; photomontage: Robert Roorda and Gero Miesenböck

October 23 COVER A three-color mosaic derived from the Moon Mineralogy Mapper (M3) near-infrared spectrometer. Orange and pink colors illustrate the distribution of iron-bearing minerals. Green represents the surface brightness at 2.4 micrometers. Blue indicates the presence of small amounts of surficial OH and H2O that are most prominent at these viewing geometries at cooler, higher latitudes. See page 568. Image: NASA/ISRO/Brown University/R. N. Clark, USGS

October 30 COVER Crystal structures of the 70S ribosome from the bacterium Thermus thermophilus in complex with translation elongation factors Tu (EF-Tu) and G (EF-G). During protein synthesis, EF-Tu (in periwinkle blue, center) delivers an aminoacyl transfer RNA (green) to the ribosome for each amino acid indicated by the messenger RNA. As the polypeptide chain grows, EF-G (in green at top right) helps move the mRNA and tRNAs through the ribosome. See pages 688 and 694. Image: Larissa Ulisko, Rebecca Voorhees, Martin Schmeing

December 18 COVER Ardipithecus ramidus, a possible human ancestor, inhabited then-wooded regions of Ethiopia 4.4 million years ago. This year, studies of the fossilized skeleton of a member of the species raised surprising questions about how key human traits evolved. See the Breakthrough of the Year special section beginning on page 1598) and at www.sciencemag.org/btoy2009/. Image: © 2009, Jay Matternes