Question: How has our difficulty in understanding and reading about science contributed to our lack of scientific understanding, and how can we begin to fix this problem?Assignment: Use Carl Sagan’s

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T it le :

D ata b ase:

A nyb ody O ut T here ? B y: S acks, O liv e r, N atu ra l H is to ry , 0 02807 12, N ov2 0 02, V ol. 1 11 , Is su e 9

E nvir o nm ent C om ple te

A nyb ody O ut T here ?

Sectio n:

R EFLE C TIO NS

O r is lif e , in ste ad , " a g lo rio us a ccid en t" ?

O ne o f th e fir s t b ooks I r e ad a s a b oy w as H . G . W ells 's 1 901 fa ble , T he F ir s t M en in th e M oon. T he tw o m en, C avo r a nd

B edfo rd , la nd in a c ra te r, a ppare ntly b arr e n a nd lif e le ss, ju st b efo re th e lu nar d aw n; th en, a s th e S un r is e s, th ey r e aliz e th ere is

a n a tm osp here . T hey s p ot s m all p ools a n d e ddie s o f w ate r, a nd th en lit tle r o und o bje cts s ca tte re d o n th e g ro und. O ne o f th em ,

as it is w arm ed b y th e S un, b urs ts o pen a nd r e ve a ls a s liv e r o f g re en. ( " 'A s e e d,' s a id C avo r . . . . A nd th en . . .v e ry s o ftly ,

'L if e !'" ) T hey lig ht a p ie ce o f p aper a nd th ro w it o nto th e s u rfa ce o f th e M oo n. It g lo w s a nd s e nds u p a th re ad o f s m oke ,

in dic a tin g th at th e a tm osp here , th ough th in , is r ic h in o xyg en a nd w ill s u p port lif e a s th ey k n ow it .

H ere , th en, w as h ow W ells c o nce iv e d th e p re re quis it e s o f lif e : w ate r, s u n lig ht ( a s o urc e o f e nerg y), a nd o xyg en. " A L unar

M orn in g" th e e ig hth c h apte r in h is b ook, w as m y fir s t in tr o ductio n to a str o bio lo gy.

It w as a ppare nt, e ve n in W ells 's d ay, th a t m ost o f th e p la nets in o ur s o la r s yste m w ere n ot p ossib le h om es fo r lif e . T he o nly

r e aso nable s u rro gate fo r th e E arth w as M ars , w hic h w as k n ow n to b e a s o lid p la n et o f r e aso nable s iz e , in s ta ble o rb it , n ot to o

dis ta nt fr o m th e s u n, a nd s o , it w as th ou ght, h avin g a r a nge o f s u rfa ce te m pe ra tu re s c o m patib le w it h th e p re se nce o f liq uid

w ate r.

B ut fr e e o xyg en g as--h ow c o uld th at o ccu r in a p la n et 's a tm osp here ? W hat w ould k e ep it fr o m b ein g m op ped u p b y fe rro us ir o n

and o th er o xyg en-h ungry c h em ic a ls o n th e s u rfa ce , u nle ss, s o m eh ow , it w as c o n tin uously p um ped o ut in h uge q uantit ie s,

e nough to o xid iz e a ll th e s u rfa ce m in era ls a nd k e e p th e a tm osp h ere c h a rg ed a s w ell?

I t w as th e b lu e-g re en a lg ae, o r c ya noba cte ria , th at in fu se d th e E arth 's a tm osp h ere w it h o xyg en, a p ro ce ss th at to ok b etw een a

b illio n a nd tw o b illio n y e ars . T he fo ssil r e co rd s h o w s th at c ya nobacte ria g o b ack th re e a nd a h alf b illio n y e ars . Y et, a m azin gly ,

s o m e o f th em s till th riv e to day, in o dd c o rn ers o f th e w orld , fo rm in g s tr a nge, c u sh io n-s h aped c o lo nie s c a lle d s tr o m ato lit e s [s e e

photo gra ph o n o pposit e p age]. It is a n e xtr a ord in ary e xp e rie nce to g o to S hark B ay in w este rn A ustr a lia , w here s tr o m ato lit e s

flo uris h in th e h yp er-s a lin e w ate rs , to w atc h th em s lo w ly b ubblin g o xyg en, a nd to r e fle ct th at, th re e b illio n y e ars a go, th is w as

how th e E arth w as tr a nsfo rm ed. T he c ya n obacte ria in ve n te d p hoto syn th esis : b y c a ptu rin g th e e nerg y o f th e s u n, th ey w ere a ble

t o c o m bin e c a rb on d io xid e ( m assiv e ly p re se n t in th e E arth 's e arly a tm osp h ere ) w it h w ate r to c re ate c o m ple x m ole cu le s--s u gars ,

ca rb ohyd ra te s--w hic h th e b acte ria c o uld th en s to re a nd ta p fo r e nerg y a s n eeded. T his p ro ce ss g enera te d fr e e o xyg en a s a b y-

p ro duct- -a w aste p ro duct th at w as to d e te rm in e th e fu tu re c o u rs e o f e vo lu tio n.

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A lt h ough fr e e o xyg en in a p la n et 's a tm osp here w ould b e a n in fa llib le m ark e r o f lif e , a nd o ne th at, if p re se n t, s h o uld b e r e adily

d ete cte d in th e s p ectr a o f e xtr a so la r p la n ets , it is n ot a p re re quis it e fo r lif e . P la nets , a fte r a ll, g et s ta rte d w it h out fr e e o xyg en,

and m ay r e m ain w it h out it a ll th eir liv e s. A naero bic o rg anis m s s w arm ed b efo re o xyg en w as a va ila ble , p erfe ctly a t h om e in th e

atm osp here o f th e e arly E arth , c o nve rtin g n it r o gen to a m monia , s u lf u r to h yd ro gen s u lf id e, c a rb on d io xid e to fo rm ald ehyd e, a nd

so fo rth . ( F ro m fo rm ald ehyd e a nd a m monia th e b acte ria c o u ld m ake e ve ry o rg anic c o m pound th ey n eeded.)

T here m ay b e p la nets in o ur s o la r s yste m a nd e ls e w here th at la ck a n a tm osp h ere o f o xyg en b ut a re n oneth ele ss te em in g w it h

a naero bes. A nd s u ch a naero bes n eed n ot liv e o n th e s u rfa ce o f th e p la n et ; th ey c o uld o ccu r w ell b elo w th e s u rfa ce , in b oilin g

ve nts a nd s u lf u ro us h ot p ots , a s th ey d o o n E arth to day, to s a y n oth in g o f s u b te rra nean o ce ans a nd la ke s. ( T here is th ought to

b e s u ch a s u bsu rfa ce o ce an o n J u pit e r's m oo n E uro pa, lo cke d b eneath a s h e ll o f ic e s e ve ra l m ile s th ic k, a nd it s e xp lo ra tio n is

o ne o f th e a str o bio lo gic a l p rio rit ie s o f th is c e n tu ry . C urio usly , W ells , in T he F ir s t M en in th e M oon, im agin es lif e o rig in atin g in a

c e ntr a l s e a in th e m id dle o f th e M oon a nd th en s p re adin g o utw ard to it s in hosp it a ble p erip hery .)

I t is n ot c le ar w heth er lif e h as to " a dva nce "-- w heth er e vo lu tio n m ust ta ke p la ce --if th ere is a s a tis fa cto ry s ta tu s q uo.

B ra ch io pods-la m psh ells --fo r in sta nce , h a ve r e m ain ed v ir tu ally u nch a nged s in ce th ey fir s t a ppeare d in th e C am bria n P erio d,

m ore th an 5 00 m illio n y e ars a go. B ut th ere d oes s e e m to b e a d riv e fo r o rg anis m s to b eco m e m ore h ig hly o rg aniz e d a nd m ore

e ff ic ie nt in r e ta in in g e nerg y, a t le ast w hen e nvir o nm en ta l c o n dit io ns a re c h a ngin g r a pid ly , a s th ey w ere b efo re th e C am bria n.

T he e vid ence in dic a te s th at th e fir s t p rim it iv e a naero bes o n E arth w ere p ro ka ry o te s: s m all, s im ple c e lls --ju st c yto pla sm , u su ally

b ounded b y a c e ll w all, b ut w it h lit tle if a n y in te rn al s tr u ctu re .

B y d egre es, h ow eve r--a nd th e p ro ce ss t o ok p la ce w it h g la cia l s lo w ness--p ro ka ry o te s b eca m e m ore c o m ple x, a cq uir in g in te rn al

str u ctu re , n ucle i, m it o ch ondria , a nd s o o n. T he m ic ro bio lo gis t L yn n M arg ulis o f th e U niv e rs it y o f M assa ch use tts , A m hers t, h as

co nvin cin gly s u ggeste d th at th ese c o m ple x s o -c a lle d e uka ry o te s a ro se w hen p ro ka ry o te s b egan in co rp ora tin g o th er

pro ka ry o te s w it h in th eir o w n c e lls . T he in co rp ora te d o rg anis m s a t fir s t b eca m e s ym bio tic a nd la te r c a m e to fu nctio n a s e sse ntia l

org anelle s o f th eir h osts , e nablin g th e r e su lt a nt o rg anis m s to u tiliz e w hat w as o rig in ally a n oxio us p ois o n: o xyg en.

P rim it iv e a s th ey a re , p ro ka ry o te s a re s till h ig hly s o p his tic a te d o rg anis m s, w it h fo rm id able g enetic a nd m eta bolic m ach in ery .

E ve n th e s im ple st o nes m anufa ctu re m ore th an 5 00 p ro te in s, a nd th eir D NA in clu des a t le ast h alf a m illio n b ase p air s . H ence it

i s c e rta in th at s till m ore p rim it iv e lif e fo rm s m ust h ave p re ce d ed th e p ro ka ry o te s.

P erh aps, a s th e p hysic is t F re em an D yso n o f th e In stit u te fo r A dva n ce d S tu dy in P rin ce to n h as s u ggeste d, th ere w ere " p ro -

genote s" c a pable o f m eta boliz in g, g ro w in g, a nd d iv id in g b ut la ckin g a ny g enetic m ech anis m fo r p re cis e r e plic a tio n. A nd b efo re

th em th ere m ust h ave b een m illio ns o f y e ars o f p ure ly c h e m ic a l, p re bio tic e vo lu tio n--th e s yn th esis , o ve r e ons, o f fo rm ald ehyd e

and c ya nid e, o f a m in o a cid s a nd p eptid es, o f p ro te in s a nd s e lf - re plic a tin g m ole cu le s. P erh aps th at c h em is tr y to ok p la ce in th e

m in ute v e sic le s, o r g lo bule s, th at d eve lo p w hen flu id s a t v e ry d if f e re nt te m pe ra tu re s m eet, a s m ay w ell h ave h appened a ro und

th e b oilin g m id oce an v e nts o f th e A rc h aea n s e a .

Lif e a s w e k n ow it is n ot im agin able w it h o ut p ro te in s, a nd p ro te in s a re b uilt fr o m p eptid es, a nd u lt im ate ly fr o m a m in o a cid s. It is

e asy to im agin e th at a m in o a cid s w ere a b undant in th e e arly E arth , e it h er fo rm ed a s a r e su lt o f lig htn in g d is ch arg es o r b ro ught

to th e p la n et b y c o m ets a nd m ete ors .

T he r e al p ro ble m is to g et fr o m a m in o a cid s a nd o th er s im ple c o m po unds to p eptid es, n ucle otid es, p ro te in s, a nd s o o n. It is

u nlik e ly th at s u ch d elic a te c h em ic a l s yn th ese s w ould o ccu r in " s o m e w arm lit tle p ond," a s D arw in im agin ed, o r o n th e s u rfa ce o f

a p rim ord ia l s e a. In ste ad, th ey w ould p ro ba bly r e quir e u nusu a l c o n dit io ns o f h eat a nd c o nce ntr a tio n, a s w ell a s th e p re se nce o f

sp ecia l c a ta ly sts a nd e nerg y-ric h c o m po unds to m ake th em p ro ce e d. T he b io ch e m is t C hris tia n d e D uve o f R ocke fe lle r

U niv e rs it y s u ggests th at c o m ple x o rg anic s u lf u r c o m po unds p la ye d a c ru cia l r o le in p ro vid in g c h em ic a l e nerg y, a nd th at th ese

co m pounds m ay h ave fo rm ed s p onta neou sly e arly in E arth 's h is to ry , p erh aps in th e h ot, a cid ic , s u lf u ro us d epth s o f th e s e aflo or

ve nts ( w here , it is in cre asin gly b elie ve d, lif e p ro bably o rig in ate d). D e D uve im ag in es th is p ure ly c h em ic a l w orld a s th e p re cu rs o r 11/30/2018 Anybody Out There?: EBSCOhost

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o f a n " R NA w orld ," b elie ve d b y m any to r e pre se n t th e fir s t fo rm o f s e lf - re plic a tin g lif e . H e th in ks th at th e m ove m ent fr o m o ne to

t h e o th er w as b oth in evit a ble a nd fa st.

T he tw o p re em in ent e vo lu tio nary c h anges in th e e arly h is to ry o f lif e o n E arth --fr o m p ro ka ry o te to e uka ry o te , fr o m a naero be to

a ero be--to ok th e b ette r p art o f tw o b illio n y e a rs . A nd th ere th en h ad to p ass a noth er 1 ,2 00 o r 1 ,3 00 m illio n y e ars b efo re lif e r o se

a bove th e m ic ro sco pic fo rm s, a nd th e fir s t " h ig her" m ult ic e llu la r o rg anis m s a ppeare d. S o if th e E arth 's h is to ry is a nyth in g to g o

by, o ne s h ould n ot e xp ect to fin d a ny h ig h er lif e o n a p la n et th at is s till y o ung. E ve n if e xtr a te rre str ia l lif e h as a ppeare d, a nd a ll

g oes w ell, it c o uld ta ke b illio ns o f y e ars fo r e vo lu tio nary p ro ce sse s to m ove it a lo ng to th e m ult ic e llu la r s ta ge.

M ore ove r, a ll th ose " s ta ges" o f e vo lu tio n, in clu din g th e e vo lu tio n o f in te llig ent, c o n scio us b ein gs fr o m th e fir s t m ult ic e llu la r

fo rm s--m ay h ave h appened a gain st d aun tin g o dds. S te phen J a y G ould s p o ke o f lif e a s " a g lo rio us a ccid ent" ; R ic h ard D aw kin s

of O xfo rd U niv e rs it y lik e ns e vo lu tio n to " c lim bin g M ou nt Im pro bable ." A nd lif e , o nce s ta rte d, is s u bje ct to v ic is sit u des o f a ll k in ds:

fr o m m ete ors a nd v o lc a nic e ru ptio ns to g lo bal o ve rh eatin g a nd c o o lin g; fr o m d ead e nds in e vo lu tio n to m yste rio us m ass

e xtin ctio ns; a nd fin ally ( if th in gs g et th at fa r) fr o m th e fa te fu l p ro cliv it ie s o f a s p e cie s lik e o urs e lv e s.

W e k n ow th ere a re m ic ro fo ssils in s o m e o f th e E arth 's m ost a ncie nt r o cks, r o cks m ore th an th re e a nd a h alf b illio n y e ars o ld . S o

lif e m ust h ave a ppeare d w it h in o ne o r tw o h undre d m illio n y e a rs a fte r th e E arth h ad c o ole d o ff s u ff ic ie ntly fo r w ate r to b eco m e

liq uid . T hat a sto nis h in gly r a pid tr a nsfo rm atio n m ake s o ne th in k th at lif e m ay d eve lo p r e adily , p erh aps in evit a bly , a s s o on a s th e

rig ht p hysic a l a nd c h em ic a l c o ndit io ns a p pear.

B ut c a n o ne a rg ue fr o m a s in gle e xa m ple ? C an o ne s p e ak c o n fid ently o f " e a rth lik e " p la nets , o r is th e E arth p hysic a lly ,

c h em ic a lly , a nd g eolo gic a lly u niq ue? A nd e ve n if th ere a re o th er " h a bit a ble " p la nets , w hat a re th e c h ance s th at lif e , w it h it s

t h ousa nds o f p hysic a l a nd c h em ic a l c o in cid ence s a nd c o n tin gencie s, w ill e m erg e? L if e m ay b e a o ne-o ff e ve nt.

O pin io n h ere v a rie s a s w id ely a s it c a n. T he F re nch b io ch e m is t J a cq u es M on od r e gard ed lif e a s a fa nta stic a lly im pro bable

a ccid ent, u nlik e ly to h ave a ris e n a nyw here e ls e in th e u niv e rs e . In h is b ook C hance a nd N ece ssit y , h e w rit e s, " T he u niv e rs e

w as n ot p re gnant w it h lif e ." D e D uve ta ke s is su e w it h th is , a nd s e e s th e o rig in o f lif e a s d ete rm in ed b y a la rg e n um ber o f s te ps,

m ost o f w hic h m ust h ave h ad a " h ig h lik e lih ood o f ta kin g p la ce u nder th e p re va ilin g c o ndit io ns." In deed, d e D uve b elie ve s th at

th ere is n ot m ere ly u nic e llu la r lif e th ro ugh out th e u niv e rs e , b ut c o m ple x, in te llig ent lif e , to o, o n tr illio ns o f p la nets . H ow a re w e to

a lig n o urs e lv e s b etw een th ese u tte rly o ppo sit e , b ut th eore tic a lly d efe nsib le p osit io ns?

W hat w e n eed, w hat w e m ust h ave , is h ard e vid ence o f lif e o n a noth er p la n et o r h eave nly b ody. M ars is th e o bvio us c a ndid ate :

it w as w et a nd w arm th ere o nce , w it h la ke s a nd h yd ro th erm al v e n ts a nd p erh aps d eposit s o f c la y a nd ir o n o re . It is e sp ecia lly in

s u ch p la ce s th at w e s h ould lo ok, s u ggests M alc o lm W alt e r, a n e xp e rt o n fo ssil b acte ria th at d ate fr o m th e E arth 's e arlie st

e poch s. If th e e vid ence s h ow s th at lif e o n ce e xis te d o n M ars , w e w ill th en n eed to k n ow , c ru cia lly , w heth er it o rig in ate d th ere , o r

w as tr a nsp orte d ( a s w ould h ave b een r e ad ily p ossib le ) fr o m th e y o u ng, te em in g, v o lc a nic E arth . If w e c a n d ete rm in e th at lif e

o rig in ate d in dependently o n M ars ( if M ars , fo r in sta nce , o nce h arb ore d D NA n ucle o tid es d if f e re nt fr o m o ur o w n), w e w ill h ave

m ade a n in cre dib le d is co ve ry --o ne th at w ill a lt e r o ur v ie w o f th e u niv e rs e , a nd e nable u s to p erc e iv e it , in th e w ord s o f th e

physic is t P aul D avie s, a s a " b io -fr ie ndly " o ne. It w ould h elp u s to g auge th e p ro babilit y o f fin din g lif e e ls e w here in ste ad o f

bom bin atin g in a v a cu um o f d ata , c a ugh t b etw een th e p ole s o f in evit a bilit y a nd u niq ueness.

In ju st th e p ast tw enty y e ars lif e h as b een d is co ve re d in p re vio usly u nexp e cte d p la ce s o n o ur o w n p la n et , s u ch a s th e lif e -ric h

b la ck s m oke rs o f th e o ce an d epth s, w here o rg anis m s th riv e in c o n dit io ns b io lo gis ts w ould o nce h ave d is m is se d a s u tte rly

d eadly . L if e is m uch to ugher, m uch m ore r e silie nt, th an w e o nce th ought. It n ow s e em s to m e q uit e p ossib le th at

m ic ro org anis m s o r th eir r e m ain s w ill b e f o und o n M ars , a nd p erh aps o n s o m e o f th e s a te llit e s o f J u p it e r a nd S atu rn .

It s e em s fa r le ss lik e ly , m any o rd ers o f m agnit u de le ss lik e ly , th at w e w ill fin d a ny e vid ence o f h ig her-o rd er, in te llig ent lif e fo rm s,

a t le ast in o ur o w n s o la r s yste m . B ut w ho k n o w s? G iv e n th e v a stn ess a nd a ge o f th e u niv e rs e a t la rg e, th e in num era ble s ta rs

a nd p la nets it m ust c o nta in , a nd o ur r a dic a l u nce rta in tie s a bout lif e 's o rig in a nd e vo lu tio n, th e p ossib ilit y c a nnot b e r u le d o ut. 11/30/2018 Anybody Out There?: EBSCOhost

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A nd th ough th e r a te o f e vo lu tio nary a nd g eoch e m ic a l p ro ce sse s is in cre dib ly s lo w , th at o f te ch nolo gic a l p ro gre ss is in cre dib ly

f a st. W ho is to s a y ( if h um anit y s u rv iv e s) w hat w e m ay n ot b e c a p able o f, o r d is co ve r, in th e n ext th ousa nd y e ars ?

F or m yse lf , s in ce I c a nnot w ait , I tu rn to s cie nce fic tio n o n o cca sio n--a nd, n ot le ast, b ack to m y fa vo rit e W ells . A lt h ough it w as

w rit te n a h undre d y e ars a go, " A L unar M orn in g" h as th e fr e sh n ess o f a n ew d aw n, a nd it r e m ain s fo r m e, a s w hen I fir s t r e ad it ,

t h e m ost p oetic e vo ca tio n o f h ow it m ay b e w hen, fin ally , w e e nco u nte r a lie n lif e .

D ougla s P rin ce , S ig ns o f L if e : O ak L eave s o ve r M ars , S ch ia pare lli H em is p here , 1 997

P H O TO ( C O LO R): S tr o m ato lit e s a re c o lo nie s o f c ya nobacte ria . T hey b egan c h a rg in g th e E arth 's a tm osp here w it h o xyg en

so m e 3 .5 b illio n y e ars a go.

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B y O liv e r S acks

O liv e r S acks is a n euro lo gis t a nd th e a uth or o f n in e b ooks, in clu din g, m ost r e ce n tly , U ncle T ungste n: M em orie s o f a C hem ic a l

B oyh ood a nd O axa ca Jo urn al. H e liv e s in N ew Y ork C it y .

C opyrig ht o f N atu ra l H is to ry is th e p ro perty o f N atu ra l H is to ry M ag azin e, In c. a nd it s c o nte nt m ay n ot b e c o pie d o r e m aile d to

m ult ip le s it e s o r p oste d to a lis ts e rv w it h out th e c o p yrig ht h old er's e xp re ss w rit te n p erm is sio n. H ow eve r, u se rs m ay p rin t,

d ow nlo ad, o r e m ail a rtic le s fo r in div id ual u se .

M obile S it e iP hone a nd A ndro id a pps E BSC O S upport S it e P riv a cy P olic y Te rm s o f U se C opyrig ht