万物简史英文版_比尔·布莱森- 第87节

we鈥檙e　still　talking　millions　of　years。鈥�

incidentally；　reginald　sprigg　did　eventually　get　a　measure　of　overdue　credit。　one　of　themain　early　genera；　spriggina；　was　named　in　his　honor；　as　were　several　species；　and　the　wholebecame　known　as　the　ediacaran　fauna　after　the　hills　through　which　he　had　searched。　by　thistime；　however；　sprigg鈥檚　fossil…hunting　days　were　long　over。　after　leaving　geology　he　foundeda　successful　oil　pany　and　eventually　retired　to　an　estate　in　his　beloved　flinders　range；where　he　created　a　wildlife　reserve。　he　died　in　1994　a　rich　man。

锛凤挤锛贰�xi锛�os锛╱o锛达几锛础�



22　　　　GOOD…BYE　TO　ALL　THAT

脳灏徝楄�疵梩脳脳xt脳澶┟楀爞
when　you　consider　it　from　a　human　perspective；　and　clearly　it　would　be　difficult　forus　to　do　otherwise；　life　is　an　odd　thing。　it　couldn鈥檛　wait　to　get　going；　but　then；　having　gottengoing；　it　seemed　in　very　little　hurry　to　move　on。

consider　the　lichen。　lichens　are　just　about　the　hardiest　visible　organisms　on　earth；　butamong　the　least　ambitious。　they　will　grow　happily　enough　in　a　sunny　churchyard；　but　theyparticularly　thrive　in　environments　where　no　other　organism　would　go鈥攐n　blowymountaintops　and　arctic　wastes；　wherever　there　is　little　but　rock　and　rain　and　cold；　and　almostno　petition。　in　areas　of　antarctica　where　virtually　nothing　else　will　grow；　you　can　findvast　expanses　of　lichen鈥攆our　hundred　types　of　them鈥攁dhering　devotedly　to　every　wind…whipped　rock。

for　a　long　time；　people　couldn鈥檛　understand　how　they　did　it。　because　lichens　grew　on　barerock　without　evident　nourishment　or　the　production　of　seeds；　many　people鈥攅ducatedpeople鈥攂elieved　they　were　stones　caught　in　the　process　of　being　plants。　鈥渟pontaneously；inorganic　stone　bees　living　plant！鈥潯�rejoiced　one　observer；　a　dr。　homschuch；　in　1819。

closer　inspection　showed　that　lichens　were　more　interesting　than　magical。　they　are　in　facta　partnership　between　fungi　and　algae。　the　fungi　excrete　acids　that　dissolve　the　surface　of　therock；　freeing　minerals　that　the　algae　convert　into　food　sufficient　to　sustain　both。　it　is　not　avery　exciting　arrangement；　but　it　is　a　conspicuously　successful　one。　the　world　has　more　thantwenty　thousand　species　of　lichens。

like　most　things　that　thrive　in　harsh　environments；　lichens　are　slow…growing。　it　may　take　alichen　more　than　half　a　century　to　attain　the　dimensions　of　a　shirt　button。　those　the　size　ofdinner　plates；　writes　david　attenborough；　are　therefore　鈥渓ikely　to　be　hundreds　if　notthousands　of　years　old。鈥潯�it　would　be　hard　to　imagine　a　less　fulfilling　existence。　鈥渢hey　simplyexist；鈥潯�attenborough　adds；　鈥渢estifying　to　the　moving　fact　that　life　even　at　its　simplest　leveloccurs；　apparently；　just　for　its　own　sake。鈥�

it　is　easy　to　overlook　this　thought　that　life　just　is。　as　humans　we　are　inclined　to　feel　that　lifemust　have　a　point。　we　have　plans　and　aspirations　and　desires。　we　want　to　take　constantadvantage　of　all　the　intoxicating　existence　we鈥檝e　been　endowed　with。　but　what鈥檚　life　to　alichen？　yet　its　impulse　to　exist；　to　be；　is　every　bit　as　strong　as　ours鈥攁rguably　even　stronger。

if　i　were　told　that　i　had　to　spend　decades　being　a　furry　growth　on　a　rock　in　the　woods；　ibelieve　i　would　lose　the　will　to　go　on。　lichens　don鈥檛。　like　virtually　all　living　things；　they　willsuffer　any　hardship；　endure　any　insult；　for　a　moment鈥檚　additional　existence。　life；　in　short；　justwants　to　be。　but鈥攁nd　here鈥檚　an　interesting　point鈥攆or　the　most　part　it　doesn鈥檛　want　to　bemuch。

this　is　perhaps　a　little　odd　because　life　has　had　plenty　of　time　to　develop　ambitions。　if　youimagine　the　4；500…billion…odd　years　of　earth鈥檚　history　pressed　into　a　normal　earthly　day；then　life　begins　very　early；　about　4a。m。；　with　the　rise　of　the　first　simple；　single…celledorganisms；　but　then　advances　no　further　for　the　next　sixteen　hours。　not　until　almost　8：30　inthe　evening；　with　the　day　five…sixths　over；　has　earth　anything　to　show　the　universe　but　arestless　skin　of　microbes。　then；　finally；　the　first　sea　plants　appear；　followed　twenty　minuteslater　by　the　first　jellyfish　and　the　enigmatic　ediacaran　fauna　first　seen　by　reginald　sprigg　inaustralia。　at　9：04p。m。　trilobites　swim　onto　the　scene；　followed　more　or　less　immediately　bythe　shapely　creatures　of　the　burgess　shale。　just　before　10p。m。　plants　begin　to　pop　up　on　theland。　soon　after；　with　less　than　two　hours　left　in　the　day；　the　first　land　creatures　follow。

thanks　to　ten　minutes　or　so　of　balmy　weather；　by　10：24　the　earth　is　covered　in　the　greatcarboniferous　forests　whose　residues　give　us　all　our　coal；　and　the　first　winged　insects　areevident。　dinosaurs　plod　onto　the　scene　just　before　11p。m。　and　hold　sway　for　about　three…quarters　of　an　hour。　at　twenty…one　minutes　to　midnight　they　vanish　and　the　age　of　mammalsbegins。　humans　emerge　one　minute　and　seventeen　seconds　before　midnight。　the　whole　of　ourrecorded　history；　on　this　scale；　would　be　no　more　than　a　few　seconds；　a　single　human　lifetimebarely　an　instant。　throughout　this　greatly　speeded…up　day　continents　slide　about　and　bangtogether　at　a　clip　that　seems　positively　reckless。　mountains　rise　and　melt　away；　ocean　basinse　and　go；　ice　sheets　advance　and　withdraw。　and　throughout　the　whole；　about　three　timesevery　minute；　somewhere　on　the　planet　there　is　a　flashbulb　pop　of　light　marking　the　impact　ofa　manson…sized　meteor　or　one　even　larger。　it鈥檚　a　wonder　that　anything　at　all　can　survive　insuch　a　pummeled　and　unsettled　environment。　in　fact；　not　many　things　do　for　long。

perhaps　an　even　more　effective　way　of　grasping　our　extreme　recentness　as　a　part　of　this4。5…billion…year…old　picture　is　to　stretch　your　arms　to　their　fullest　extent　and　imagine　thatwidth　as　the　entire　history　of　the　earth。　on　this　scale；　according　to　john　mcphee　in　basin　andrange；　the　distance　from　the　fingertips　of　one　hand　to　the　wrist　of　the　other　is　precambrian。

all　of　plex　life　is　in　one　hand；　鈥渁nd　in　a　single　stroke　with　a　medium…grained　nail　file　youcould　eradicate　human　history。鈥�

fortunately；　that　moment　hasn鈥檛　happened；　but　the　chances　are　good　that　it　will。　i　don鈥檛wish　to　interject　a　note　of　gloom　just　at　this　point；　but　the　fact　is　that　there　is　one　otherextremely　pertinent　quality　about　life　on　earth：　it　goes　extinct。　quite　regularly。　for　all　thetrouble　they　take　to　assemble　and　preserve　themselves；　species　crumple　and　die　remarkablyroutinely。　and　the　more　plex　they　get；　the　more　quickly　they　appear　to　go　extinct。　whichis　perhaps　one　reason　why　so　much　of　life　isn鈥檛　terribly　ambitious。

so　anytime　life　does　something　bold　it　is　quite　an　event；　and　few　occasions　were　moreeventful　than　when　life　moved　on　to　the　next　stage　in　our　narrative　and　came　out　of　the　sea。

land　was　a　formidable　environment：　hot；　dry；　bathed　in　intense　ultraviolet　radiation；lacking　the　buoyancy　that　makes　movement　in　water　paratively　effortless。　to　live　onland；　creatures　had　to　undergo　wholesale　revisions　of　their　anatomies。　hold　a　fish　at　each　endand　it　sags　in　the　middle；　its　backbone　too　weak　to　support　it。　to　survive　out　of　water；　marinecreatures　needed　to　e　up　with　new　load…bearing　internal　architecture鈥攏ot　the　sort　ofadjustment　that　happens　overnight。　above　all　and　most　obviously；　any　land　creature　wouldhave　to　develop　a　way　to　take　its　oxygen　directly　from　the　air　rather　than　filter　it　from　water。

these　were　not　trivial　challenges　to　overe。　on　the　other　hand；　there　was　a　powerfulincentive　to　leave　the　water：　it　was　getting　dangerous　down　there。　the　slow　fusion　of　thecontinents　into　a　single　landmass；　pangaea；　meant　there　was　much；　much　less　coastline　thanformerly　and　thus　much　less　coastal　habitat。　so　petition　was　fierce。　there　was　also　anomnivorous　and　unsettling　new　type　of　predator　on　the　scene；　one　so　perfectly　designed　forattack　that　it　has　scarcely　changed　in　all　the　long　eons　since　its　emergence：　the　shark。　neverwould　there　be　a　more　propitious　time　to　find　an　alternative　environment　to　water。

plants　began　the　process　of　land　colonization　about　450　million　years　ago；　acpanied　ofnecessity　by　tiny　mites　and　other　organisms　that　they　needed　to　break　down　and　recycle　deadorganic　matter　on　their　behalf。　larger　animals　took　a　little　longer　to　emerge；　but　by　about　400million　years　ago　they　were　venturing　out　of　the　water；　t