1200 New York Avenue, NW, Washington, DC 20005
Bateman House, 82-88 Hills Road, Cambridge, UK CB2 1LQ
Editor-in-Chief Marcia McNutt
Executive Editor Monica M. Bradford News Editor Tim Appenzeller
Managing Editor, Research Journals Katrina L. Kelner
Deputy Editors Barbara R. Jasny, Andrew M. Sugden(UK), Valda J. Vinson, Jake S. Yeston
Research and Insights
SR. EDI TORS Caroline Ash(UK), Gilbert J. Chin, Lisa D. Chong, Maria Cruz(UK), Julia Fahrenkamp-Uppenbrink(UK), Pamela J.
Hines, Stella M. Hurtley(UK), Paula A. Kiberstis, Marc S. Lavine(Canada), Kristen L. Mueller, Ian S. Osborne(UK), Beverly A.
Purnell, L. Bryan Ray, Guy Riddihough, H. Jesse Smith, Peter Stern(UK), Phillip D. Szuromi, Brad Wible, Nicholas S. Wigginton,
Laura M. Zahn ASSOCIATE EDITORS Brent Grocholski, Melissa R. McCartney, Margaret M. Moerchen, Jelena Stajic, Sacha Vignieri
BOOK REVIE W EDI TOR Sherman J. Suter ASSOCIATE LE TTERS EDI TOR Jennifer Sills EDI TORIAL MANAGER Cara Tate SR. COPY EDI TORS
Jeffrey E. Cook, Chris Filiatreau, Cynthia Howe, Harry Jach, Lauren Kmec, Barbara P. Ord way, Trista Wagoner SR. EDI TORIAL
COORDINATORS Carolyn Kyle, Beverly Shields EDI TORIAL COORDINATORS Ramatoulaye Diop, Joi S. Granger, Lisa Johnson, Anita
Wynn PUBLICATIONS ASSISTANTS Aneera Dobbins, Jeffrey Hearn, Dona Mathieu, Le-Toya Mayne Flood, Shannon McMahon, Scott
Miller, Jerry Richardson, Rachel Roberts(UK), Alice Whaley(UK), Brian White ADMINISTRATIVE SUPPORT Janet Clements(UK), Joan
Cuthbert(UK), Maryrose Madrid, John Wood(UK)
News
NE WS MANAGING EDITOR John Travis INTERNATIONAL EDI TOR Richard Stone DEPUTY NE WS EDITORS Daniel Clery(UK), Robert Coontz,
Elizabeth Culotta, David Grimm, David Malakoff, Leslie Roberts CONTRIBUING EDITORS Martin Enserink(Europe), Mara Hvistendahl
(Asia) SR. CORRESPONDENTS Jeffrey Mervis, Elizabeth Pennisi NEWS WRITERS Adrian Cho, Jon Cohen, Jennifer Couzin-Frankel,
Carolyn Gramling, Eric Hand, Jocelyn Kaiser, Kelly Servick, Robert F. Service, Erik Stokstad, Emily Underwood CON TRIBUTING
INTERNS Hassan DuRant, Xochitl Rojas-Rocha, Nadia Whitehead CORRESPONDENTS Pallava Bagla(South Asia), Michael
Balter(Paris), John Bohannon, Ann Gibbons, Sam Kean, Richard A. Kerr, Eli Kintisch, Kai Kupferschmidt(Berlin), Andrew Lawler,
Christina Larson(Beijing), Mitch Leslie, Charles C. Mann, Eliot Marshall, Virginia Morell, Dennis Normile(Tokyo), Heather
Pringle, Tania Rabesandratana(Brussels), Gretchen Vogel(Berlin), Lizzie Wade(Mexico City) CAREERS Jim Austin(Editor),
Donisha Adams COPY EDITORS Kara Estelle, Nora Kelly, Jennifer Levin ADMINISTRATIVE SUPPORT Scherraine Mack
Executive Publisher Alan I. Leshner
Publisher Beth Rosner Chief Digital Media Officer Rob Covey
BUSINESS OPERATIONS AND ADMINISTRATION DIRECTOR Deborah Rivera-Wienhold BUSINESS SYSTEMS AND FINANCIAL ANALYSIS DIRECTOR
Randy Yi MANAGER OF FULFILLMENT SYSTEMS Neal Hawkins SYSTEMS ANALYST Nicole Mehmedovich ASSISTANT DIRECTOR, BUSINESS
OPERATIONS Eric Knott MANAGER, BUSINESS OPERATIONS Jessica Tierney BUSINESS ANALYSTS Cory Lipman, Cooper Tilton, Celeste
Troxler FINANCIAL ANALYST Jeremy Clay RIGHTS AND PERMISSIONS: ASSISTAN T DIRECTOR Emilie David PERMISSIONS ASSOCIATE Elizabeth
Sandler RIGHTS, CON TRACTS, AND LICENSING ASSOCIATE Lili Kiser
MARKETING DIRECTOR Ian King MARKETING MANAGER Julianne Wielga MARKE TING ASSOCIATE Elizabeth Sattler SR. MARKETING EXECUTIVE
Jennifer Reeves SR. ART ASSOCIATE, PROJECT MANAGER Tzeitel Sorrosa ART ASSOCIATE Seil Lee ASSISTANT COMMERCIAL EDITOR Selby Frame
MARKETING PROJECT MANAGER Angelissa McArthur SR. WRI TER Bill Zimmer PROGRAM DIRECTOR, AAAS MEMBER CEN TRAL Peggy Mihelich
FULFILLMEN T SYSTEMS AND OPERATIONS
membership@aaas.org MANAGER, MEMBER SERVICES Pat Butler SPECIALISTS La Toya Casteel, Javia
Flemmings, Latasha Russell MANAGER, DATA ENTRY Mickie Napoleoni DATA ENTRY SPECIALISTS JJ Regan, Jaimee Wise, Fiona Giblin
DIRECTOR, SI TE LICENSING Tom Ryan DIRECTOR, CORPORATE RELATIONS Eileen Bernadette Moran SR. PUBLISHER RELATIONS SPECIALIS T Kiki
Forsythe PUBLISHER RELATIONS MANAGER Catherine Holland PUBLISHER RELATIONS, EASTERN REGION Keith Layson PUBLISHER RELATIONS,
WESTERN REGION Ryan Rexroth MANAGER, SI TE LICENSE OPERATIONS Iquo Edim FULFILLMENT ANALYST Lana Guz ASSOCIATE DIRECTOR,
MARKE TING Christina Schlecht MARKE TING ASSOCIATES Thomas Landreth, Minah Kim
DIRECTOR OF WEB TECHNOLOGIES Ahmed Khadr SR. DEVELOPER Chris Coleman DEVELOPER Dan Berger SR. PROJECT MANAGER Trista Smith
SYSTEMS ENGINEER Luke Johnson PRODUCT MANAGER Walter Jones
CREATIVE DIRECTOR, MULTIMEDIA Martyn Green DIRECTOR OF ANALYTICS Enrique Gonzales SR. WEB PRODUCER Sarah Crespi WEB PRODUCER
Alison Crawford VIDEO PRODUCER Nguyen Nguyen SOCIAL MEDIA PRODUCER Meghna Sachdev
DIRECTOR OF OPERATIONS PRINT AND ONLINE Lizabeth Harman PRINT PRODUCTION DIRECTOR Wendy K. Shank PREFLIGHT MANAGER
Marcus Spiegler ASSISTANT MANAGER ONLINE Lisa Stanford ASSISTANT MANAGER PRINT Rebecca Doshi SR SPECIALISTS Steve Forrester,
Amy Hardcastle, Jason Hillman, Antoinette Hodal, Tara Kelly, Anthony Rosen SPECIALISTS Jacob Hedrick, Nichele Johnston,
Yuse Lajiminmuhip, Lori Murphy, Kimberley Oster
DESIGN DIRECTOR Beth Rakouskas ASSOCIATE ART DIRECTOR Laura Creveling SR. ILLUSTRATORS Chris Bickel, Katharine Sutliff
ILLUSTRATOR Valerie Altounian SR. ART ASSOCIATES Holly Bishop, Preston Huey ART ASSOCIATES Kay Engman, Garvin Grullón,
Chrystal Smith SR. PHOTO EDI TOR William Douthitt PHOTO EDI TOR Leslie Blizard
DIRECTOR, GLOBAL COLLABORATION, CUSTOM PUBLICATIONS, ADVERTISING Bill Moran EDITOR, CUSTOM PUBLISHING Sean Sanders: 202-326-
6430 ASSISTANT EDI TOR, CUSTOM PUBLISHING Tianna Hicklin: 202-326-6463 ADVERTISING MARKE TING MANAGER Justin Sawyers: 202-326-7061
science_advertising@aaas.org ADVERTISING SUPPORT MANAGER Karen Foote: 202-326-6740 ADVERTISING PRODUCTION OPERATIONS MANAGER
Deborah Tompkins SR. TRAFFIC ASSOCIATE Christine Hall SALES COORDINATOR Shirley Young ASSOCIATE DIRECTOR, COLLABORATION,
CUSTOM PUBLICATIONS/CHINA/ TAI WAN/KOREA/SINGAPORE Ruolei Wu: +86-186 0822 9345, rwu@aaas.org EAS T COAST/E. CANADA Laurie
Faraday: 508-747-9395, FAX 617-507-8189 WEST COAST/W. CANADA Lynne Stickrod: 415-931-9782, FAX 415-520-6940 MIDWEST Jeffrey Dembksi:
847-498-4520 x3005, Steven Loerch: 847-498-4520 x3006 UK EUROPE/ASIA Roger Goncalves: TEL/FAX +41 43 243 1358 JAPAN Makiko Hara: +81
(0) 3 6802 4616, FAX +81 (0) 3 6802 4615, ads@sciencemag.jp CHINA/TAIWAN Ruolei Wu: +86-186 0822 9345
WORLDWIDE ASSOCIATE DIRECTOR OF SCIENCE CAREERS Tracy Holmes: +44 (0) 1223 326525, FAX +44 (0) 1223 326532 tholmes@science-int. co.uk
CLASSIFIED
advertise@sciencecareers.org U.S. SALES Tina Burks: 202-326-6577, Nancy Toema: 202-326-6578 SALES ADMINISTRATOR Marci Gallun
EUROPE/ROW SALES Axel Gesatzki, Sarah Lelarge SALES ASSISTANT Kelly Grace JAPAN Yuri Kobayashi: +81 (0)90-9110-1719,
careerads@sciencemag.jp
CHINA/ TAIWAN Ruolei Wu: +86-186 0822 9345
rwu@aaas.org MARKETING MANAGER Allison Pritchard MARKETING ASSOCIATE Aimee Aponte
AAAS BOARD OF DIRECTORS RE TIRING PRESIDENT, CHAIR Phillip A. Sharp PRESIDENT Gerald R. Fink PRESIDENT-ELECT Geraldine (Geri)
Richmond TREASURER David Evans Shaw CHIEF EXECU TIVE OFFICER Alan I. Leshner BOARD Bonnie L. Bassler, May R. Berenbaum,
Carlos J. Bustamante, Claire M. Fraser, Laura H. Greene, Elizabeth Loftus, Raymond Orbach, Inder M. Verma
SUBSCRIPTION SERVICES For change of address, missing issues, new orders and renewals, and payment questions: 866-434-AAAS (2227) or 202-326-
6417, FAX 202-842-1065. Mailing addresses: AAAS, P.O. Box 96178, Washington, DC 20090-6178 or AAAS Member Services, 1200 New York Avenue, NW,
Washington, DC 20005
INSTITUTIONAL SITE LICENSES 202-326-6755 REPRINTS: Author Inquiries 800-635-7181 COMMERCIAL INQUIRIES 803-359-4578 PERMISSIONS 202-326-6765,
permissions@aaas.org AAAS Member Services 202-326-6417 or http://membercentral.aaas.org/discounts
Science serves as a forum for discussion of important issues related to the advancement of science by publishing material on which a consensus has
been reached as well as including the presentation of minority of conflicting points of view. Accordingly, all articles published in Science—including
editorials, news and comment, and books reviews—are signed and reflect the individual views of the authors and not official points of view adopted by
AAAS or the institutions with which the authors are affiliated.
INFORMATION FOR AUTHORS See pages 680 and 681 of the 7 February 2014 issue or access www.sciencemag.org/about/authors
Adriano Aguzzi, U. Hospital Zürich
Takuzo Aida, U. of Tokyo
Leslie Aiello, Wenner-Gren Foundation
Judith Allen, U. of Edinburgh
Sonia Altizer, U. of Georgia
Virginia Armbrust, U. of Washington
Sebastian Amigorena, Institut Curie
Kathryn Anderson, Memorial
Sloan-Kettering Cancer Center
Peter Andolfatto, Princeton U.
Meinrat O. Andreae, Max-Planck Inst. Mainz
Paola Arlotta, Harvard U.
Johan Auwerx, EPFL
David Awschalom, U. of Chicago
Jordi Bascompte, Estación Biológica
de Doñana CSIC
Facundo Batista, London Research Inst.
Ray H. Baughman, U. of Texas, Dallas
David Baum, U. of Wisconsin
Mark Bear, Massachusetts Inst. of Technology
Kamran Behnia, ESPCI-ParisTech
Yasmine Belkaid, NIAID, NIH
Philip Benfey, Duke U.
Stephen J. Benkovic, Penn State U.
Gabriele Bergers, U. of California, San Francisco
Christophe Bernard, Aix-Marseille U.
Bradley Bernstein, Massachusettes
General Hospital
Gregory C. Beroza, Stanford U.
Peer Bork, EMBL
Bernard Bourdon, Ecole Normale
Supérieure de Lyon
Chris Bowler, École Normale Supérieure
Ian Boyd, U. of St. Andrews
Emily Brodsky, U. of California, Santa Cruz
Ron Brookmeyer, U. of California Los Angeles (S)
Christian Büchel, U. Hamburg-Eppendorf
Joseph A. Burns, Cornell U.
William P. Butz, Population Reference Bureau
Gyorgy Buzsaki, New York U. School of Medicine
Blanche Capel, Duke U.
Mats Carlsson, U. of Oslo
David Clapham, Children’s Hospital Boston
David Clary, U. of Oxford
Joel Cohen, Rockefeller U., Columbia U.
Jonathan D. Cohen, Princeton U.
James Collins, Boston U.
Robert Cook-Deegan, Duke U.
Alan Cowman, Walter & Eliza Hall Inst.
Robert H. Crabtree, Yale U.
Janet Currie, Princeton U.
Jeff L. Dangl, U. of North Carolina
Tom Daniel, U. of Washington
Frans de Waal, Emory U.
Stanislas Dehaene, Collège de France
Robert Desimone, MIT
Claude Desplan, New York U.
Ap Dijksterhuis, Radboud U. of Nijmegen
Dennis Discher, U. of Pennsylvania
Gerald W. Dorn II, Washington U. School of Medicine
Jennifer A. Doudna, U.of California, Berkeley
Bruce Dunn, U. of California, Los Angeles
Christopher Dye, WHO
Todd Ehlers, U. of Tuebingen
David Ehrhardt, Carnegie Inst. of Washington
Tim Elston, U. of North Carolina at Chapel Hill
Gerhard Ertl, Fritz-Haber-Institut, Berlin
Barry Everitt, U. of Cambridge
Ernst Fehr, U. of Zurich
Anne C. Ferguson-Smith, U. of Cambridge
Michael Feuer, The George Washington U.
Peter Fratzl, Max-Planck Inst.
Elaine Fuchs, Rockefeller U.
Daniel Geschwind, UCLA
Andrew Gewirth, U. of Illinois
Karl-Heinz Glassmeier, TU Braunschweig
Julia R. Greer, Caltech
Elizabeth Grove, U. of Chicago
Kip Guy, St. Jude’s Children’s Research Hospital
Taekjip Ha, U. of Illinois at Urbana-Champaign
Christian Haass, Ludwig Maximilians U.
Steven Hahn, Fred Hutchinson Cancer Research
Center
Michael Hasselmo, Boston U.
Martin Heimann, Max-Planck Inst. Jena
Yka Helariutta, U. of Finland
James A. Hendler, Rensselaer Polytechnic Inst.
Janet G. Hering, Swiss Fed. Inst. of Aquatic Science
& Technology
Michael E. Himmel, National Renewable Energy Lab.
Kai-Uwe Hinrichs, U. of Bremen
Kei Hirose, Tokyo Inst. of Technology
David Hodell, U. of Cambridge
David Holden, Imperial College
Lora Hooper, UT Southwestern Medical Ctr. at Dallas
Thomas Hudson, Ontario Inst. for Cancer Research
Raymond Huey, U. of Washington
Steven Jacobsen, U. of California, Los Angeles
Kai Johnsson, EPFL Lausanne
Peter Jonas, Inst. of Science & Technology
(IST) Austria
Matt Kaeberlein, U. of Washington
William Kaelin Jr., Dana-Farber Cancer Inst.
Daniel Kahne, Harvard U.
Daniel Kammen, U. of California, Berkeley
Masashi Ka wasaki, U. of Tokyo
Joel Kingsolver, U. of North Carolina at Chapel Hill
Robert Kingston, Harvard Medical School
Alexander Kolodkin, Johns Hopkins U.
Roberto Kolter, Harvard Medical School
Alberto R. Kornblihtt, U. of Buenos Aires
Leonid Kruglyak, UCLA
Thomas Langer, U. of Cologne
Mitchell A. Lazar, U. of Pennsylvania
David Lazer, Harvard U.
Thomas Lecuit, IBDM
Virginia Lee, U. of Pennsylvania
Stanley Lemon, U. of North Carolina at Chapel Hill
Ottoline Leyser, Cambridge U.
Marcia C. Linn, U. of California, Berkeley
Jianguo Liu, Michigan State U.
Luis Liz-Marzan, CIC biomaGUNE
Jonathan Losos, Harvard U.
Ke Lu, Chinese Acad. of Sciences
Christian Lüscher, U. of Geneva
Laura Machesky, CRUK Beatson Inst.
for Cancer Research
Anne Magurran, U. of St. Andrews
Oscar Marin, CSIC & U. Miguel Hernández
Charles Marshall, U. of California, Berkeley
C. Robertson McClung, Dartmouth College
Graham Medley, U. of Warwick
Yasushi Miyashita, U. of Tokyo
Richard Morris, U. of Edinburgh
Alison Motsinger-Reif, NC State U. (S)
Sean Munro, MRC Lab. of Molecular Biology
Thomas Murray, The Hastings Center
James Nelson, Stanford U. School of Med.
Karen Nelson, J. Craig Venter Institute
Daniel Neumark, U. of California, Berkeley
Timothy W. Nilsen, Case Western Reserve U.
Pär Nordlund, Karolinska Inst.
Helga Nowotny, European Research Advisory Board
Ben Olken, MIT
Luke O’Neill, Trinity College, Dublin
Joe Orenstein, U. of California
Berkeley & Lawrence Berkeley National Lab
Harry Orr, U. of Minnesota
Andrew Oswald, U. of Warwick
Steve Palumbi, Stanford U.
Jane Parker, Max-Planck Inst.
of Plant Breeding Research
Giovanni Parmigiani, Dana-Farber Cancer Inst. (S)
Donald R. Paul, U. of Texas, Austin
John H. J. Petrini, Memorial Sloan-Kettering
Cancer Center
Joshua Plotkin, U. of Pennsylvania
Philippe Poulin, CNRS
David Randall, Colorado State U.
Colin Renfrew, U. of Cambridge
Trevor Robbins, U. of Cambridge
Jim Roberts, Fred Hutchinson Cancer Research Ctr.
Barbara A. Romanowicz, U. of California,Berkeley
Jens Rostrup-Nielsen, Haldor Topsoe
Mike Ryan, U. of Texas, Austin
Mitinori Saitou, Kyoto U.
Shimon Sakaguchi, Kyoto U.
Miquel Salmeron, Lawrence Berkeley National Lab
Jürgen Sandkühler, Medical U. of Vienna
Alexander Schier, Harvard U.
Randy Seeley, U. of Cincinnati
Vladimir Shalaev, Purdue U.
Robert Siliciano, Johns Hopkins School of Medicine
Joseph Silk, Institut d’Astrophysique de Paris
Denis Simon, Arizona State U.
Alison Smith, John Innes Centre
Richard Smith, U. of North Carolina (S)
John Speakman, U. of Aberdeen
Allan C. Spradling, Carnegie Institution
of Washington
Jonathan Sprent, Garvan Inst. of Medical Research
Eric Steig, U. of Washington
Paula Stephan, Georgia State U. and National Bureau
of Economic Research
Molly Stevens, Imperial College London
V. S. Subrahmanian, U. of Maryland
Ira Tabas, Columbia U.
Sarah Teichmann, Cambridge U.
John Thomas, North Carolina State U.
Christopher Tyler-Smith, The Wellcome Trust
Sanger Inst.
Herbert Virgin, Washington U.
Bert Vogelstein, Johns Hopkins U.
Cynthia Volkert, U. of Göttingen
Douglas Wallace, Dalhousie U.
David Wallach, Weizmann Inst. of Science
Ian Walmsley, U. of Oxford
David A. Wardle, Swedish U. of Agric. Sciences
David Waxman, Fudan U.
Jonathan Weissman, U. of California,
San Francisco
Chris Wikle, U. of Missouri (S)
Ian A. Wilson, The Scripps Res. Inst. (S)
Timothy D. Wilson, U. of Virginia
Rosemary Wyse, Johns Hopkins U.
Jan Zaanen, Leiden U.
Kenneth Zaret, U. of Pennsylvania School of Medicine
Jonathan Zehr, U. of California, Santa Cruz
Len Zon, Children’s Hospital Boston
Maria Zuber, MIT
SENIOR EDITORIAL BOARD
A. Paul Alivisatos, Lawrence Berkeley Nat’l. Laboratory, Ernst Fehr, U. of Zürich
Susan M. Rosenberg, Baylor College of Medicine, Michael S. Turner, U. of Chicago
BOOK REVIEW BOARD
David Bloom, Harvard U., Samuel Bowring, MI T, Angela Creager, Princeton U.,
Richard Shweder, U. of Chicago, Ed Wasserman, DuPont
BOARD OF REVIEWING EDITORS (Statistics board members indicated with S)