xample—are caused by lone dysfunctional genes； but as a rule disruptivegenes are weeded out by natural selection long before they can bee permanentlytroublesome to a species or population。 for the most part our fate and fort—and even oureye color—are determined not by individual genes but by plexes of genes working inalliance。 that’s why it is so hard to work out how it all fits together and why we won’t beproducing designer babies anytime soon。
in fact； the more we have learned in recent years the more plicated matters have tendedto bee。 even thinking； it turns out； affects the ways genes work。 how fast a man’s beard grows； for instance； is partly a function of how much he thinks about sex （because thinkingabout sex produces a testosterone surge）。 in the early 1990s； scientists made an even moreprofound discovery when they found they could knock out supposedly vital genes fromembryonic mice； and the mice were not only often born healthy； but sometimes were actuallyfitter than their brothers and sisters who had not been tampered with。 when certain importantgenes were destroyed； it turned out； others were stepping in to fill the breach。 this wasexcellent news for us as organisms； but not so good for our understanding of how cells worksince it introduced an extra layer of plexity to something that we had barely begun tounderstand anyway。
it is largely because of these plicating factors that cracking the human genome becameseen almost at once as only a beginning。 the genome； as eric lander of mit has put it； is likea parts list for the human body： it tells us what we are made of； but says nothing about howwe work。 what’s needed now is the operating manual—instructions for how to make it go。
we are not close to that point yet。
so now the quest is to crack the human proteome—a concept so novel that the termproteome didn’t even exist a decade ago。 the proteome is the library of information thatcreates proteins。 “unfortunately；” observed scientific american in the spring of 2002； “theproteome is much more plicated than the genome。”
that’s putting it mildly。 proteins； you will remember； are the workhorses of all livingsystems； as many as a hundred million of them may be busy in any cell at any moment。 that’sa lot of activity to try to figure out。 worse； proteins’ behavior and functions are based notsimply on their chemistry； as with genes； but also on their shapes。 to function； a protein mustnot only have the necessary chemical ponents； properly assembled； but then must also befolded into an extremely specific shape。 “folding” is the term that’s used； but it’s amisleading one as it suggests a geometrical tidiness that doesn’t in fact apply。 proteins loopand coil and crinkle into shapes that are at once extravagant and plex。 they are more likefuriously mangled coat hangers than folded towels。
moreover； proteins are （if i may be permitted to use a handy archaism） the swingers of thebiological world。 depending on mood and metabolic circumstance； they will allowthemselves to be phosphorylated； glycosylated； acetylated； ubiquitinated； farneysylated；sulfated； and linked to glycophosphatidylinositol anchors； among rather a lot else。 often ittakes relatively little to get them going； it appears。 drink a glass of wine； as scientificamerican notes； and you materially alter the number and types of proteins at large in yoursystem。 this is a pleasant feature for drinkers； but not nearly so helpful for geneticists who aretrying to understand what is going on。
it can all begin to seem impossibly plicated； and in some ways itis impossiblyplicated。 but there is an underlying simplicity in all this； too； owing to an equallyelemental underlying unity in the way life works。 all the tiny； deft chemical processes thatanimate cells—the cooperative efforts of nucleotides； the transcription of dna into rna—evolved just once and have stayed pretty well fixed ever since across the whole of nature。 asthe late french geneticist jacques monod put it； only half in jest： “anything that is true of e。
coli must be true of elephants； except more so。”
every living thing is an elaboration on a single original plan。 as humans we are mereincrements—each of us a musty archive of adjustments； adaptations； modifications； andprovidential tinkerings stretching back 3。8 billion years。 remarkably； we are even quite closely related to fruit and vegetables。 about half the chemical functions that take place in abanana are fundamentally the same as the chemical functions that take place in you。
it cannot be said too often： all life is one。 that is； and i suspect will forever prove to be； themost profound true statement there is。
part vithe road to usdescended from the apes！ my dear；let us hope that it is not true； but if it is；let us pray that it will not beegenerally known。
…remark attributed to the wife ofthe bishop of worcester afterdarwin’s theory of evolution was explained to her
。d xs
27ICE TIME
…小……说。网
i had a dream； which was notall a dream。
the bright sun wasextinguish’d； and the starsdid wander 。 。 。
—byron； “darkness”
in 1815 on the island of sumbawa in indonesia； a handsome and long…quiescent mountainnamed tambora exploded spectacularly； killing a hundred thousand people with its blast andassociated tsunamis。 it was the biggest volcanic explosion in ten thousand years—150 timesthe size of mount st。 helens； equivalent to sixty thousand hiroshima…sized atom bombs。
news didn’t travel terribly fast in those days。 in london； the times ran a small story—actually a letter from a merchant—seven months after the event。 but by this time tambora’seffects were already being felt。 thirty…six cubic miles of smoky ash； dust； and grit haddiffused through the atmosphere； obscuring the sun’s rays and causing the earth to cool。
sunsets were unusually but blearily colorful； an effect memorably captured by the artist j。 m。
w。 turner； who could not have been happier； but mostly the world existed under anoppressive； dusky pall。 it was this deathly dimness that inspired the byron lines above。
spring never came and summer never warmed： 1816 became known as the year withoutsummer。 crops everywhere failed to grow。 in ireland a famine and associated typhoidepidemic killed sixty…five thousand people。 in new england； the year became popularlyknown as eighteen hundred and froze to death。 morning frosts continued until june andalmost no planted seed would grow。 short of fodder； livestock died or had to be prematurelyslaughtered。 in every way it was a dreadful year—almost certainly the worst for farmers inmodern times。 yet globally the temperature fell by only about 1。5 degrees fahrenheit。 earth’snatural thermostat； as scientists would learn； is an exceedingly delicate instrument。
the nineteenth century was already a chilly time。 for two hundred years europe and northamerica in particular had experienced a little ice age； as it has bee known； whichpermitted all kinds of wintry events—frost fairs on the thames； ice…skating races along dutchcanals—that are mostly impossible now。 it was a period； in other words； when frigidity wasmuch on people’s minds。 so we may perhaps excuse nineteenth…century geologists for beingslow to realize that the world they lived in was in fact balmy pared with former epochs；and that much of the land around them had been shaped by crushing glaciers and cold thatwould wreck even a frost fair。
they knew there was something odd about the past。 the european landscape was litteredwith inexplicable anomalies—the bones of arctic reindeer in the warm south of france； hugerocks stranded in improbable places—and they often came up with inventive but not terribly plausible explanations。 one french naturalist named de luc； trying to explain how graniteboulders had e to rest high up on the limestone flanks of the jura mountains； suggestedthat perhaps they had been shot there by pressed air in caverns； like corks out of apopgun。 the term for a displaced boulder is an erratic； but in the nineteenth century theexpression seemed to apply more often to the theories than to the rocks。
the great british geologist arthur hallam has suggested that if james hutton； the father ofgeology； had visited switzerland； he would have seen at once the significance of the carvedvalleys； the polished striations； the telltale strand lines where rocks had been dumped； and theother abundant clues that point to passing ice sheets。 unfortunately； hutton was not a traveler。
but even with nothing better at his disposal than secondhand accounts； hutton rejected out ofhand the idea that huge boulders had been carried three thousand feet up mountainsides byfloods—all the water in the world won’t make a boulder float； he pointed out—and becameone of the first to argue for widespread glaciation。 unfortunately his ideas escaped notice； andfor another half century most naturalists continued to insist that the gouges on rocks could beattributed to passing carts or even the scrape of hobnailed boots。
local peasants； uncontaminated by scientific orthodoxy； knew better； however。 thenaturalist jean de charpentier told the story of how in 1834 he was walking along a countrylane with a swiss woodcutter wh