53Chinapeople huntbats, they eat bats.
Theytakebats out ofnetswiththeir
hands,they getbitten...Some gointo
caves with sticks andspikethem.
People getbatfaecesoutof cavesand
spreadit onthevegetablegardens.
Wehaveevenheardof eyedropsthat
usebat faeces inthem.”Thisisnow
themainstreamhypothesis.Sometime
inautumnsomeoneate,breathed,or
eveneye-droppedabitof corona-
virus-infectedbat intotheirbody.It
changed hosts,and itwasonlya
matter of timebeforethese mysterious
pneumoniacases appeared.
Howcan weprove it,though?How
canweinterview thefirst caseswhen
theorigins ofthe virushave ceasedto
be amere scientificquestion, andwherethetruthhassometimes
had seriousconsequences?Canwe eversampleenoughbats and
sequenceenoughviruses tolocatethe onethatmadethe leap?
Manycluesthatcould helpus retracethe stepsofthevirusfrom
before last NewYear’sEvehave beenlost.Butone clue cannever
be lost –thatcontainedin thegenomeitself.
Eachtimethevirus copies itself, there isachanceof amutation.
Mutationscanbe bad–if, for instance,they letabat virus pass
intohumans.Most ofthetime,though,theydo nothingforthe
virus.Butforscientists,they are atimesignature–theybecome
aclockthatagesthevirus.Takeallof the manystrainsnowin
existence,countback throughthe mutations,and youfindthe
pointwhere they branched,theircommonancestor:avirus that
replicateditselfinlate 2019 ,inChina.“Wecanbe pretty
confident thatitwasasimplejump. Ithappenedjust once;thereis
no diversity,”saysProfessorBalloux. “Therearegood reasons to
presumethiswas the originalhostjump–thepointwhereit came
fromanimals.”
Caseclosed?Notquite.There
isanannoyingwrinklein the
Covidtimeline.InSeptember
2019 ,alungcancerscreening
trialtookplacein Italy.Blood
samples fromthe 959 patientswerefrozen and stored.Inlate
2020 ,scientists wentback andanalysedthe blood.Init,six
monthsbefore coronavirus wouldoverwhelmItaly’shealth
service,fourmonthsbeforeitwasmeant tobeinEurope,they
foundantibodiesspecifictothevirus.Mostscientistshave
dismissed this asanoutlier –afreakresult best ignoredon the
basisthatextraordinaryclaimsrequireextraordinary evidence.
Theysaythefindingsmustbe falsepositives. ButnotProfessor
Wang,fromDuke-NUS Medical School, Singapore.
Imagine,he says, ifwhen thecoronavirus explored itsfirst human
host,itwas not so welladapted,and notsodeadly. Thereare
many coronaviruses in the world,inmany animals.Thereare four
that have beenhumanity’s constantseasonalcompanionslong
beforethis crisis. Youcould conceive of this versionofthe virus
going unnoticed. What’s anotherbad case of flu here andthere?
Thenoneday,perhaps years later,close toaChinese seafood
market, this coronavirusmutatedinto thescarier version we
seetoday, thesingle ancestor seenby ProfessorBalloux.“The
questionis: is Covid-19abrandnew virus withnorelatives, that
just jumped intohumansinWuhan in December,”asks Professor
Wang.“Or is itactuallyavariantofone ormore close cousins,
which are notas transmissible, but towhichhumans have been
exposedin unspecifiedlocations,including Italy?”
Thisis morethanmerely an alternative hypothesis, more than an
explanationfor the Italianfindings. In fact, havinghad the virus
circulatingunknownwould answer anothermysterypuzzling
scientists–why coronavirus is so good atwhat it does. When, last
autumn,thevirusjumpedintomink
inDenmark,itdid whatvirusesdo
when they jump,evolved,improving
itsabilityto existinmink. Forthe
firstsixmonthsthecoronaviruswas
spottedinhumans,it didn’tdo that:
not untiltheautumn diditgain
mutationsthatgaveitanadvantage.
It wasasifitdroppedfromthesky,
alreadytunedto infectus.“Onescenarioisthatitwasjust
apparentlyverylucky,”saysAlina
Chan,fromtheBroadInstitute.
“Somehowthevirusthatrecently
spilledoverfromanimalswasreally
super-goodat infectinghumans.”
Relyingonsheer chancefeels
unsatisfactory.“Alot ofexperts
don’tlikethathypothesis.”Along withher colleagueShing
Zhan,fromtheUniversityofBritishColumbia,she was oneofthe
first to research thisoddity.She was also oneof the first –publicly
at least–to propose anotherexplanationthatcut rightthrough
thegeopoliticsand science.Yes,itcould bethattheviruswas
lucky.Yes,itcouldbethat ithadspreadunnoticed. Orit could
be thatwe did theadaptation ourselves,thatitescaped from
alaboratory.In the centreofWuhan,betweenthescenicEastLake and the
Yangtze River,you willfindtheWuhanInstituteofVirology.
Here,they studyan dstorebat coronaviruses.We nowknow
thatoneof the bat coronavirusestheyhave,called RaTG13,is
theclosest knownrelative tothe pandemicstrain.Fromthestart
ofthe pandemic,oftenin seedierparts oftheinternet,people have
questionedwhetherthisiscoincidence. They havebeendismissed
as conspiracytheorists.It’s notthatDrChanthinksthevirus
definitely came fromthelaboratory.It’s just,she says,thatshe
doesn’tunderstandwhyothers
are sosureit didn’t.Mistakes
happen.Sodocover-ups.“No
countrywants toadmitthey
havecovert human pathogen
research,ongoing,that iscausing
mass deatharound the world,”
shesays. “It’seasierto tell the publicthat thishappenedbecause
we traffickedtoomanypangolinsor thatit cameon frozenfood
importedfrom another country.”Publicly,manyextremelyseniorscientists haveopposed this idea.
“Westand togetherto stronglycondemn conspiracytheories
suggestingthatCovid-19does nothaveanaturalorigin,” wrote
onegroup intheLancetlast February.Privately,some toldThe
Times itwasnot so absurd. Releaseddocuments showthat figures
advisingthe US government seriously entertained theideain
February. Professor Balloux said there was no evidenceinthe
virus’s genome to support theideait hadbeenengineered. “There
is nothingnotabletodistinguishthisfromothernaturalcorona-
virusescirculating inhumans,” he said. But,“Icannotdismissit.
Icannotdisprove itis the workofsomenefarious boffin.”Sometimes, when we wanttoexplain howsmall eventshave
momentousconsequences,we sayabutterfly flappingitswings
couldcauseastorm ontheother side of theAtlantic.This
pandemic wasstarted by something so smallthat abutterfly’s flap
woulditself beastorm. Anditsconsequences werefargreater
than themostferocious hurricane. The answers the scientistsseek,
if they exist, comein thissmallest of events,asingle virus particle
finding itswayintoasingle human.Willweeveridentify it?“The
tricky thing about thistopic is thatwedancearounduncertainty,”
saysDrZhan. “AndIsee no end of uncertainty.”Alonger versionofthisarticleappearedintheTheTimes.
©TheTimes/News LicensingThelastword6February2 021 THE WEEKBats: the one uncontested piece of the puzzle“In rural China people hunt bats, they eat bats.
They take bats out of nets with their hands, they
get bitten. Some go into caves and spike them”