The Royal Society, the national academy of science ofthe UK and the Commonwealth, is at the cutting edgeof scientific progress. We support many top youngscientists, engineers and technologists, influencescience policy, debate scientific issues with the publicand much more. We are an independent, charitablebody and derive our authoritative status from over 1400Fellows and Foreign Members.

Our mission: to expand knowledge and further the roleof science and engineering in making the world a betterplace.

The Royal Society’s strategic priorities are to:

• invest in future scientific leaders and ininnovation,

• influence policymaking with the best scientificadvice,

• invigorate science and mathematics education,• increase access to the best science internationally,

and• inspire an interest in the joy, wonder and

excitement of scientific discovery.

For further information on the Society’s activities, pleasecontact the following departments on the extensionslisted by dialling +44 (0)20 7839 5561, or visit theSociety’s Web site (royalsociety.org).

Research Support (UK grants and fellowships)Research Appointments (Fellowships): 2542Research Grants: 2223International travel Grants: 2555Newton International Fellowships: 2559

Science Policy CentreGeneral enquiries: 2550

Science CommunicationGeneral enquiries: 2573

Library and Information ServicesLibrary/archive enquiries: 2606

Editor Professor Dame Linda Partridge

Publishing Editor Joanna Bolesworth

Publishing Editor: Joanna Bolesworth

(tel: +44 (0)20 7451 2602; fax: +44 (0)20 7976 1837;

philtransb@royalsociety.org)

Production Editor: Radha Dutia

6–9 Carlton House Terrace, London SW1Y 5AG, UK

rstb.royalsocietypublishing.org

AIMS AND SCOPE Each issue of Phil. Trans. R. Soc. B is devoted to a specific area of the biological sciences.This area will define a research frontier that is advancing rapidly, often bridgingtraditional disciplines. Phil. Trans. R. Soc. B is essential reading for scientists workingacross the biological sciences. In particular, the journal is focused on the following fourcluster areas: neuroscience and cognition; organismal and evolutionary biology;cell and developmental biology; and health and disease. As well as theme issues,the journal publishes papers from the Royal Society’s biological discussion meetings.For information on submitting a proposal for a theme issue, consult the journal‘swebsite at rstb.royalsocietypublishing.org.

Editorial Board

Neuroscience and cognition

Dr Brian BillupsProfessor Colin BlakemoreProfessor Graham CollingridgeDr Andrew GlennersterProfessor Bill HarrisProfessor Trevor Lamb Professor Tetsuro Matsuzawa Professor Andrew Whiten

Cell and developmental biology

Professor Makoto AsashimaDr Buzz BaumProfessor Martin BuckDr Louise CramerDr Anne DonaldsonProfessor Laurence HurstProfessor Fotis Kafatos Professor Elliot MeyerowitzProfessor Peter RigbyProfessor Dale SandersDr Stephen Tucker

Organismal, environmental and evolutionary biology

Professor Spencer BarrettProfessor Nick BartonDr Will CresswellProfessor Yadvinder MalhiProfessor Peter MumbyProfessor Karl SigmundProfessor Gabriele SorciProfessor Andrew Watkinson

Health and disease

Professor Mark EnrightDr Julius HafallaProfessor Mike MalimProfessor Angela McLeanDr Mario ReckerProfessor Nicholas WaldProfessor Joanne Webster

ISBN: 978-0-85403-878-7

Copyright © 2011 The Royal Society

Except as otherwise permitted under the Copyright, Designs and Patents Act, 1988, this publication may only be reproduced, stored ortransmitted, in any form or by any other means, with the prior permission in writing of the publisher, or in the case of reprographicreproduction, in accordance with the terms of a licence issued by the Copyright Licensing Agency. In particular, the Society permits themaking of a single photocopy of an article from this issue (under Sections 29 and 38 of this Act) for an individual for the purposes ofresearch or private study.

Selection criteriaThe criteria for selection are scientific excellence,

originality and interest across disciplines within biology.

The Editor is responsible for all editorial decisions and

she makes these decisions based on the reports received

from the referees and/or Editorial Board members. Many

more good proposals and articles are submitted to us

than we have space to print, we give preference to

those that are of broad interest and of high scientific

quality.

Publishing formatPhil. Trans. R. Soc. B articles are published regularly online

and in print issues twice a month. Along with all Royal

Society journals, we are committed to archiving and

providing perpetual access. The journal also offers the

facility for including Electronic Supplementary Material

(ESM) to papers. Contents of the ESM might include

details of methods, derivations of equations, large tables

of data, DNA sequences and computer programs.

However, the printed version must include enough detail

to satisfy most non-specialist readers. Supplementary

data up to 10Mb is placed on the Society's website free

of charge. Larger datasets must be deposited in

recognised public domain databases by the author.

Conditions of publicationArticles must not have been published previously, nor be

under consideration for publication elsewhere. The main

findings of the article should not have been reported in

the mass media. Like many journals, Phil. Trans. R. Soc. B

employs a strict embargo policy where the reporting of

a scientific article by the media is embargoed until a

specific time. The Editor has final authority in all matters

relating to publication.

Electronic Submission detailsFor full submission guidelines and access to all journal

content please visit the Phil. Trans. R. Soc. B website at

rstb.royalsocietypublishing.org.

Cover image: An androgynous composite average of male and female student faces shown as a mosaic. The small images

are made up of pairs of constituent individual images. Up close the individual faces can be seen but at a distance the

larger composite image becomes clearer. The mosaic was made using AndreaMosaic. Image courtesy of Anthony Little.

SUBSCRIPTIONSIn 2011 Phil. Trans. R. Soc. B (ISSN 0962-8436) will bepublished twice a month. Full details of subscriptions andsingle issue sales may be obtained either by contactingour journal fulfilment agent, Portland CustomerServices, Commerce Way, Colchester CO2 8HP; tel:+44 (0)1206 796351; fax: +44 (0)1206 799331; email:sales@portland-services.com or by visiting our websiteat http://royalsocietypublishing.org/info/subscriptions.The Royal Society is a Registered Charity No. 207043.

Subscription prices All other 2011 calendar year Europe USA & Canada countries

Electronic access only £2145/€2788 $4058 £2317/US$4153

Printed version plus £2574/€3345 $4869 £2780/US$4983electronic access

GUIDANCE FOR AUTHORS

Typeset in India by Techset Composition Limited, Salisbury, UK. Printed by Latimer Trend, Plymouth.This paper meets the requirements of ISO 9706:1994(E) and ANSI/NISO Z39.48-1992 (Permanence of Paper) effective with volume 335, issue 1273, 1992.Philosophical Transactions of the Royal Society B (ISSN: 0962-8436) is published twice a month for $4058 per year by the Royal Society, and is distributedin the USA by Agent named Air Business, C/O Worldnet Shipping USA Inc., 149-35 177th Street, Jamaica, New York, NY11434, USA. US Postmaster: Sendaddress changes to Philosophical Transactions of the Royal Society B, C/O Air Business Ltd, C/O Worldnet Shipping USA Inc, 149-35 177th Street Jamaica,New York, NY11414.

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