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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。 cro