Syntheticbiologistshavebeenredesigninglifefor
decadesnow,butsofarthey’vemostlybeenmessing
aboutwithsinglecells– a kindof souped-upversion
of geneticmodification.In2010,CraigVenterandhis
teamcreatedthefirstsyntheticcell,basedona bug
thatinfectsgoats.Fouryearslater,oneof thefirst
productsof thesyntheticbiologyerahitthemarket,
whenthedrugcompanySanofistartedselling
malariadrugsmadebyre-engineeredyeastcells.
Today,though,biologistsarestartingto findways to
organisesinglecellsintocollectivescapableof
performingsimpletasks.They’retinymachines,oras
biologistJoshBongardat theUniversityof Vermont
refersto them,‘xenobots’.Theideais to ‘piggyback’on
thehardworkof nature,whichhas been building tiny
machinesforbillionsof years.
Currently,Bongard’steammakesitsxenobotswith
ordinaryskinandheartcellsfromfrogembryos,
producingmachinesbasedondesignsetchedoutona
super-computer.Justbycombiningthesetwotypesof
cellsit designedmachinescapableof crawlingacross
thebottomof a petridish,pushinga smallpellet
aroundandevencooperating.“Ifyoubuilda bunch of
thesexenobotsandsprinklethepetridishwith
pellets,insomecasestheyactlikelittlesheepdogs
and push these pellets into neat piles,” Bongard says.Theircomputerrunsa simpleevolutionary
algorithmthatinitiallygeneratesrandomdesignsand
rejectsover99%of them– selectingonlythosedesigns
capableof performingtherequiredtaskina virtual
versionof a petridish.AsBongardexplains,the
scientistsstillhaveto turnthefinisheddesignsinto
reality,layeringandsculptingthecellsbyhand.This
partof theprocesscouldeventuallybeautomated,
using3Dprintingortechniques to manipulate cells
usingelectricalfields.
Youcouldn’tyetcallthesexenobotsliving
organisms,though,astheydon’t,forexample,eator
reproduce.Sincetheycan’tutilisefood,theyalso‘die’,
orat leastdecompose,andquickly,meaningthere’s no
obvioushazardto theenvironmentorpeople.
However,combiningthisapproachwithmore
traditionalsyntheticbiologytechniquescouldleadto
thecreationof newmulticellularorganismscapable
of performingcomplextasks.Forexample,theycould
actasbiodegradabledrugdeliverymachines,and if
madefromhumancells,theywouldalsobe
biocompatible,avoidingtriggeringadverseimmune
reactions.Butthat’snotall.“Infuturework,”says
Bongard,“we’relookingat addingadditionalcell
types,maybelikenervoustissue, so these xenobots
would be able to think.”THERISEOFLIVINGMACHINES
Biological robots could start solving our problems3
AIautomaticallydesignscandidate
lifeformsinsimulation(toprow),then
a cell-basedconstructiontoolkitis
used to create the living systems