Origins of life

112 Pages·2004·0.92 MB·English

by  Freeman Dyson

PP11::SSDDLL//FFAAXX PP22::SSPPEE
CCBB221188//DDyyssoonn CCBB221188--FFMM JJuullyy55,,11999999 99::3333
This page intentionally left blank
iiii
P1:SDL/FAX P2:SPE
CB218/Dyson CB218-FM July5,1999 9:33
Origins of Life
HowdidlifeonEarthoriginate?Didreplicationormetabolismcome
firstinthehistoryoflife?Inthisextensivelyrewrittensecondedi-
tion, Freeman Dyson examines these questions and discusses the
twomaintheoriesthattrytoexplainhownaturallyoccurringchem-
icalscouldorganizethemselvesintolivingcreatures.
The majority view is that life began with replicating molecules,
theprecursorsofmoderngenes. Theminoritybeliefisthatrandom
populations of molecules evolved metabolic activities before exact
replicationexistedandthatnaturalselectiondrovetheevolutionof
cellstowardgreatercomplexityforalongtimewithoutthebenefit
of genes. Dyson analyzes both of these theories with reference to
recentimportantdiscoveriesbygeologistsandbiologists,aimingto
stimulatenewexperimentsthatcouldhelpdecidewhichtheoryis
correct.
Since the first edition of this book was published in 1985, rev-
olutionary discoveries have been made in biology, genetics, and
geology, casting new light on the questions of the origins of life.
Molecularbiologistsdiscoveredribozymes,enzymesmadeofRNA.
Geneticistsdiscoveredthatmanyofthemostancientcreaturesare
thermophilic,livinginhotenvironments. Geologistsdiscoveredev-
idenceoflifeinthemostancientofallterrestrialrocksinGreenland.
Thissecondeditioncoverstheenormousadvancesthathavebeen
madeinbiologyandgeologyinthepastdecadeandahalfandthe
impacttheyhavehadonourideasabouthowlifebegan. Freeman
Dyson’sclearlywritten,fascinatingbookwillappealtoanyonein-
terestedintheoriginsoflife.
Freeman Dyson, currently Emeritus Professor at the Institute for
AdvancedStudyinPrinceton,isadistinguishedscientistandagifted
writer. HeisafellowoftheRoyalSocietyofLondonandamember
of the U.S. National Academy of Sciences, as well as the holder of
eighteenhonorarydegrees. HismostrecentbooksincludeImagined
Worlds(1997)andFromErostoGaia(1992).
i

P1:SDL/FAX P2:SPE
CB218/Dyson CB218-FM July5,1999 9:33
Origins of Life
Revised Edition
FREEMAN DYSON
InstituteforAdvanced
Study,Princeton
iii
         
The Pitt Building, Trumpington Street, Cambridge, United Kingdom
  
The Edinburgh Building, Cambridge CB2 2RU, UK
40 West 20th Street, New York, NY 10011-4211, USA
477 Williamstown Road, Port Melbourne, VIC 3207, Australia
Ruiz de Alarcón 13, 28014 Madrid, Spain
Dock House, The Waterfront, Cape Town 8001, South Africa
http://www.cambridge.org
©Cambridge University Press 2004
First published in printed format 1999
ISBN 0-511-03559-4 eBook (Adobe Reader)
ISBN 0-521-62668-4 paperback
P1:SDL/FAX P2:SPE
CB218/Dyson CB218-FM July5,1999 9:33
Contents
Preface pagevii
CHAPTER ONE
IllustriousPredecessors 1
CHAPTER TWO
ExperimentsandTheories 22
CHAPTER THREE
AToyModel 48
CHAPTER FOUR
OpenQuestions 72
Bibliography 93
Index 97
v
P1:SDL/FAX P2:SPE
CB218/Dyson CB218-FM July5,1999 9:33
vi
P1:SDL/FAX P2:SPE
CB218/Dyson CB218-FM July5,1999 9:33
Preface
ThedeliveryofmyTarnerLecturesinCambridgehappenedtocoin-
cideexactlywiththetwo-hundredthanniversaryofthefirstman-
nedflightacrosstheEnglishChannelbyBlanchardandJeffriesin
January1785. Liketheintrepidballoonists,apubliclecturermust
carrysuppliesofhotairandofballasttoregulatehisflight–hotair
tobeinsertedwhenthetextofthelectureistooshortandballastto
bedroppedwhenthetextistoolong. Inpreparingthelecturesfor
publication I was able to retrieve some of the dropped ballast and
to vent some of the inserted air. I am grateful to my hosts at Trin-
ityCollegefortheirhospitalityandtomyaudiencesfortheirsharp
questionsandcriticisms. Inrevisingthebookforthissecondedition
in1998, Ihavehadthebenefitofmanyadditionalcriticismsfrom
readersofthefirstedition.Iamgratefultoeveryonewhocorrected
mymistakesandtoldmeaboutrecentdevelopmentsinevolution-
ary biology. I am especially grateful to Professor Cairns-Smith for
readingandcriticizingthenewedition.Thefirsteditionwasalightly
editedtranscriptofthelectures.Thesecondeditionissubstantially
enlargedandisnolongeratranscript. Muchhashappenedinthe
lastthirteenyearstodeepenourunderstandingofearlyevolution.
I have changed my story to take account of new discoveries. But
thebasicmysteryoflife’soriginremainsunsolved,andthecentral
themeofthebookremainsunchanged.
TheTarnerLectureswereestablishedwiththerequirementthat
the lecturer speak “on the philosophy of the sciences and the re-
lations or want of relations between the different departments of
knowledge.” IintendedtoignorethisrequirementwhenIplanned
the lectures. I preferred to deal with concrete scientific problems
rather than with philosophical generalities. I chose the origins of
vii
P1:SDL/FAX P2:SPE
CB218/Dyson CB218-FM July5,1999 9:33
viii Preface
lifeasmythemebecauseIjudgedthetimetoberipeforanewex-
perimental attack on the problem of origins. The main purpose of
thelectureswastostimulateexperiments.Nevertheless,ithappens
that the study of the origins of life touches many scientific disci-
plines and raises many philosophical questions. I therefore found
myself,inspiteofmypragmaticandunphilosophicalintentions,for-
tuitouslyfollowingMr.Tarner’swishes.Itwasimpossibletospeak
forfourhoursabouttheoriginsoflifewithoutencounteringsome
ideasthatconnectwidelyseparatedbranchesofscienceandother
ideasthatstrayovertheborderfromsciencetophilosophy.
Thelectureswereaddressedtoageneraluniversityaudience. The
readers of this book are likewise expected to be educated but not
expert. Thesamethingcanbesaidoftheauthor. Idonotpretendto
beanexpertinbiology. Ihavenotreadsystematicallythroughthe
technicalliterature. Inmysurveyofexperimentsandideas,Imade
noattempttobecompleteoreventobefair. Iapologizeinadvance
to all the people, living and dead, whose contributions to knowl-
edgeIhaveignored,especiallytoJ.B.S.Haldane,DesmondBernal,
SidneyFox,HymanHartman,PierLuisi,JulianHiscox,LeeSmolin,
and Stuart Kauffman. I apologize also to Paul Davies, whose ex-
cellent book (Davies, 1998) was published just as mine was going
to press. I missed the chance to engage in a friendly debate with
Davies,explainingwhereweagreeandwherewedisagree.
IamgratefultoMartinReesandSydneyBrennerforinvitingme
toameetingwiththetitle“FromMattertoLife,”whichwasheldat
King’sCollege,Cambridge,inSeptember1981.Biologists,chemists,
physicists,andmathematicianscametogethertotalkabouttheori-
gins of life, and in three days I acquired the greater part of my
educationasanevolutionarybiologist. Thatmeetingledmetothe
pointofviewIamexpressinginthisbook.Iwishalsotothankthe
MasterandFellowsofTrinityCollegeforinvitingmetoCambridge
asTarnerLecturerin1985.
Thefirsttwochaptersofthebookarehistorical. Chapter1intro-
ducesthesixcharacterswhocontributedthemosttomythinking
about the origins of life. Chapter 2 describes in greater detail the
leadingtheoriesandtheexperimentalbackgroundfromwhichthey
arose. Chapter3isthemosttechnicalchapter. Itdescribesmyown
contributiontothesubject,amathematicalmodelthatisintended
torepresentinabstractformthetransitionfromchaostoorganized
metabolicactivityinapopulationofmolecules. Chapter4discusses