IF YOUR tO parents  bonded just o t be s  bonded in a preciselytimely manner, you  be s  done likes before tely, you  be here.

    Pusime and tral debts begin to add up. Go back just eigions to about time t Cimely couplings your existence depends.

    Continue furto time of Sors earnestly excic material in a  ually and miraculously, result in you.

    At ty generations ago, ting on your beo1,048,576. Five generations before t, and ted couplings your existence depends. By ty generations ago, yourtotal number of forebears—remember, t cousins and aunts and otalrelatives, but only parents and parents of parents in a line leading ineluctably to you—is overone billion (1,073,741,824, to be precise). If you go back sixty-four generations, to time oftive efforts your eventual existencedepends o approximately 1,000,000,000,000,000,000, otal number of people who have ever lived.

    Clearly somet may interest you tolearn, is t your line is not pure. You couldn’t be  a little incest—actually quitea lot of incest—albeit at a genetically discreet remove. itors inyour background, tive from your moted ant cousin from your fat, if you are in a partnersry, t t you are at some level related. Indeed, if you look around you on abus or in a park or café or any cro of tives. s to you t  once: “Me, too!” In t literal andfundamental sense we are all family.

    e are also uncannily alike. Compare your genes  99.9 percent t is inydifferences in t remaining 0.1 percent—“rougide base in every thousand,”

    to quote tisicist and recent Nobel laureate Joon—are y. Muc years of t, t. Otical. It is tions of ourgenomes—eacical, but not quite—t make us h as individualsand as a species.

    But ly is t, come to t, are genes?

    ell, start y-six little bundles of complexity, of y-ty-tions, every cell in yourbody—99.999 percent of t of cions are red blood cells, some immune system cells, and egg and sperm cells,  carry tic package.) Citutete set of instructions necessary to make and maintain you and are made of longstrands of ttle raordinary molecule on Eart has been called.

    DNA exists for just one reason—to create more DNA—and you  of it inside you:

    about six feet of it squeezed into almost every cell. Eacters of coding, enougo provide 103,480,000,000possible combinations, “guaranteed tobe unique against all conceivable odds,” in tian de Duve. t’s a lot ofpossibility—a one follo ake more t to print t figure,” notes de Duve. Look at yourself in t upon t t you are been trillion cells, and talmost every one of ted DNA, and you begin toappreciate just uff you carry around o a single fine strand, t to stretco t once or t again and again. Altogeto onecalculation, you may y million kilometers of DNA bundled up insideyou.

    Your body, in s, loves to make DNA and  it you couldn’t live. Yet DNA is notitself alive. No molecule is, but DNA is, as it  is “among tnonreactive, c molecules in ticistRicin. t is cigations and coaxed from t Neandertals. It also explainsook scientists so long to  ance so mystifyingly lo t of life itself.

    As a knoity, DNA  t   tyof tübingen in Germany. ance  recognize and called it nuclein (because itresided in t time, Miesctle more te its existence, butnuclein clearly remained on y-ter in a letter to y t sucs bey. traordinary insig one so far in advance of tific requirements t itattracted no attention at all.

    For most of t ury tion  terial—no a subsidiary role in matters of y. Itoo simple. It  four basic components, called nucleotides,  four letters. e tory of life ary alp? (t you do it in muc you create complexmessages s and dasdo anyt all, as far as anyone could tell. It just sat ty on command or fulfilling someotrivial task t no one  t of. ty, it ,o exist in proteins in the nucleus.

    t, t:

    teemed it in some important op of t kept turning up, like t in a murder mystery, in experiments. In tudies in particular, one involving terium and anoteriop infect bacteria), DNA betrayed an importance t could only beexplained if its role ral t alloed t DNA al to life,yet it  proteins side t ing their assembly.

    No one could understand ting messages to teins. ts as an interpreter bet is a notable oddity of biology t DNA and proteins don’t speak t four billion years t double act, andyet to mutually incompatible codes, as if one spoke Spanisher hindi.

    to communicate tor in translates information from a cell’s DNA into terms proteinscan understand and act upon.

    ory, ill a very long anding t, or indeed almost anyto do y.

    Clearly tation, and itude to undertake it.  Morgan, and in 1904, just four years after timely rediscovery of Mendel’sexperiments s and still almost a decade before gene ed th chromosomes.

    Co see under turn of tietury it rongly suspected t traits,but no one knew his.

    Morgan c of study a tiny, delicate fly formally called Drosoper, but more commonly kno fly (or vinegar fly, banana fly, orgarbage fly). Drosopo most of us as t frail, colorless insect t seems too droory specimens fruit flies ainvery attractive advantages: t almost noto tles,  from egg to productive parenten days or less, and  four c tly simple.

    orking out of a small lab ( Columbia University in Neiculous breeding and crossbreeding involving millions of flies (onebiograp is probably an exaggeration), eaco becaptured iny variations ininance. For six years tried to produce mutations by any means tion and X-rays, rearing t ligly in ovens, spinning trifuges—but notable mutation—a fly te eyes ratants o generate useful deformities, alloo track a trait tions. By suc tions beticular ceristics and individual cually proving to more or lesseveryone’s satisfaction t c t of inance.

    t level of biological intricacy: tic genesand t composed trickier to isolate and understand. Aslate as 1933,  convinced t genes even existed. As Morgan noted at time, to itious.” It may seemsurprising t scientists could struggle to accept ty of sometal to cellular activity, but as allace, King, and Sanders point out in Biology: t rarest text), oday al processes suc and memory. e kno  kno  time you could pluck one from your body and take it audy o many of Morgan’s peers as t scientists today migure a strayt and examine it under a microscope.

    ainly true  someted ingcell replication. Finally, in 1944, after fifteen years of effort, a team at titute in Mantan, led by a brilliant but diffident Canadian named Osricky experiment in eria ly infectious by crossing it  DNA  certainly ive agent in y. trian-born bioc Ered quite seriously t Avery’s discovery wo Nobel Prizes.

    Unfortunately, Avery itute, a strong-ein ent named Alfred Mirsky,  Avery’s  ies at titute in Stock to give Avery a Nobel Prize. Avery by time y-six years old and tired. Unable to deal ress and controversy, ion and never  near a lab again. But ots elseructure of DNA.

    ting person in t certainly ec, to crack tructure of DNA.

    Pauling ermining tecture of molecules and allograpec o peering into t of DNA. In an exceedingly distinguis  tructureriple  a double one, and never quite got on t track. Instead, victory fellto an unlikely quartet of scientists in England eam, often  onspeaking terms, and  part novices in the field.

    Of t to a conventional boffin omic bomb. tis—Crick of type t bloype t produce coal.

    t unconventional of tson, an American prodigy  least part of tion for some of tered ty of C fifteen. y-ttaco tory in Cambridge. In1951, y-trikingly lively  appearsin pograpo be straining to attacself to some po just out of frame.

    Crick, till  a doctorate, son’s account ed as blustery, nosy, cative, impatient o sion, and constantly in danger ofbeing asked to go elsewrained in biocry.

    tion  if you could determine to see—correctly, as it turned out— did  did. to ac tle  tely necessary. As atson coucobiograp  be solved my learning any cry.” t actually assigned to one point o stop it. atson ensibly mastering t of crystallograpo be completing a tion of large molecules.

    Altson enjoy nearly all t in popular accounts for solving tery of DNA, t on experimental itors, ts of uitously,” in tactful orian Lisa Jardine. Far a least at tKing’s College in London, ilkins and Franklin.

    tiring figure, almost to t of invisibility. A1998 PBS documentary on tructure of DNA—a feat for o overlook irely.

    t enigmatic cer of all tering portrait,atson in ted Franklin as a o irritate  tractive and mige stunning aken even a mild interest in clot in ted all expectations. Seven use lipstick, ed in s.”

    1 images in existence of tructure of DNA,acallograpeced by Linus Pauling.

    Crystallograpo map atoms in crystals (allograp DNA molecules o get good results from t to ilkins’s perennial exasperationso share her findings.

    If Franklin   be altoget King’s in treated dazzles modern sensibilities (actually any sensibilities).  alloo t instead o take tilitarian c even atson conceded opof tantly pressed—at times actively o ss rio of men o get a peek at tcies, like respect. “I’m afraid o adopt—let’s say a patronizing attitudetoing institution and t s s s locked away.

    t ilkins and Franklin did not get along  t atson and Crick seem to ed to t. Altson respassing raterritory, it   altogeto act in a decidedly queer ss DNA definitely o all t it . toilkins’s presumed dismay and embarrassment, in ted a mocknotice around tment t said: “It is  regret t  is  Dr. M.h.F.

    ilkins e helix.”

    tcome of all t in January 1953, ilkins sson Franklin’simages, “apparently  .” It atement to callit a significant er atson conceded t it “ . . . it mobilizedus.” Armed antelements of its dimensions, atson and Crick redoubled ts. Everyto go t one point Pauling e to a conference in England at o correct tions t   tained at Idle in Need,on t oo liberal of temperament to be alloo travel abroad. Crickand atson also  good fortune t Pauling’s son tly kept t of any nes and setbacks athome.

    Still facing ty of being trumped at any moment, atson and Crick appliedto t  DNA y Press canceled publication of ter Crick and ilkinscomplained about its cerizations, uitouslyful.quot; tions quoted above are after atson softened s.

    components—called adenine, guanine, cytosine, and t ticular  into tsonand Crick o   toget famous in modern science—consisting of metal plates boltedtogeted ilkins, Franklin, and t of to have a look.

    Any informed person could see at once t t question a brilliant piece of detective  t of Franklin’s picture.

    tion of Nature carried a 900-icle by atson and Crick titled“A Structure for Deoxyribose Nucleic Acid.” Accompanying it e articles byilkins and Franklin. It ful time in t about toclamber to top of Everest o be cro of life ly overlooked. It received a smallmention in the News Chronicle and was ignored elsewhere.

    Rosalind Franklin did not s t ty-seven in 1958, four years before ted. Nobel Prizes are nota certainly arose as a result of co X-rays t ed t Franklin rarely en steppedcarelessly in front of a beam. Oserity, t least isfaction of living just longenougo see ed. he died in 1955.

    atson and Crick’s discovery  actually confirmed until t took over ty-five years for our model of DNA to go from being onlyrato being very plausible . . . and from to being virtually certainlycorrect.”

    Even so, ructure of DNA understood progress in genetics , and by 1968ticle titled “t as t as,”

    suggesting—it  it is so—t tics  anend.

    In fact, of course, it  beginning. Even no deal about DNA tand, not least  actually seem to do anything.

    Ninety-seven percent of your DNA consists of not long stretcs prefer to put it. Only rand do you find sections t control and organize vital functions. thecurious and long-elusive genes.

    Genes are notructions to make proteins. tain dull fidelity. In te and notrifle monotonous. But combine te ce variety.

    Put all togeto continue tap sympence knohe human genome.

    An alternative and more common o regard tructionmanual for ters and tructions for making proteins. tructions are ten are called codons, and tters are knoters of tic alp—consist of tides mentioned a page or two back:

    adenine, tosine. Despite tance of ances are not made of anytic. Guanine, for instance, is tuff tabounds in, and gives its name to, guano.

    taircase orted rope ladder: ts of tructure are made of a typeof sugar called deoxyribose, and teps) are formed by tosine and tters appear as youmove up or doitutes t .

    Noicular brilliance of DNA lies in its manner of replication.  is time toproduce a nerands part do, and eaco form a nenerside along astrand pairs up ide, eacrand serves as a template for tion of a necrand. If you possessed just one strand of your o tc tnerships:

    if topmost rung on one strand  topmost rung on tcrand must be cytosine. ork your ide pairings, and eventually you   t nature does it really quickly—inonly a matter of seconds, .

    Most of time our DNA replicates iful accuracy, but just occasionally—aboutone time in a million—a letter gets into tidepolymorpo biocs as a “Snip.” Generally tretcectable consequence for the body.

    But occasionally t leave you predisposed to some disease,but equally t confer some sligage—more protective pigmentation, forinstance, or increased production of red blood cells for someone living at altitude. Over time,t modifications accumulate in botions, contributing totinctiveness of both.

    tion is a fine one. too many errors andt function, but too fe sacrifices adaptability. A similar balance mustexist betability in an organism and innovation. An increase in red blood cells can  ions to move and breat additional red cells also too many,and “it’s like pumping oil,” in temple University ant Cz.

    t’s . to live at itude get increased breat pay for it s. By sucuralselection look after us. It also o explain  let you become too different—not  becoming a new species anyway.

    t difference beted for by our Snips.

    Nocorrespondence, but t part, be in different places. Add morepeople to t yet more Snips in yet more places. For every one ofyour 3.2 billion bases, some coding in t position. So not only is it o refer to “t in a sense  even  t equally, in t David Cox, “you could sayall  , too.”

    But o explain  DNA  startsto get a little unnerving, but it does really seem t to perpetuate DNA.

    t of our DNA commonly called junk is largely made up of clumps of letterst, in Ridley’s  for t t gettingted.”

    2Most of your DNA, in ot devoted to you but toitself: you are a mac, not it for you. Life, you  s tobe, and DNA is  so.

    Even ions for making genes—ists put it—it is not necessarily ioning of the organism in mind.

    One of t genes ranscriptase, does do is make itpossible for retroviruses, suco slip unnoticed into tem.

    In ote considerable energies to producing a protein t doesnot is beneficial and sometimes clobbers us. Our bodies  to do sobecause t. e are vessels for toget  proportion yet found in any organism—don’t do anyt all, as far asell, except reproduce themselves.

    All organisms are in some sense slaves to t’s ures more or less beyond counting are prepared to die in ting. to breed, to disperse one’s genes, is t poure.

    As S it: “Empires fall, ids explode, great sympten,and be is a single instinct t demands satisfaction.” From an evolutionary pointof vie a reo pass on our genetic material.

    Scientists  most of our DNA doesn’t doanyted findings began to turn up. First in Germany and tzerland researcs t produced curiouslyunbizarre outcomes. In one took t controlled t of a mouse’seye and inserted it into t fly. t  it migerestingly grotesque. In fact, t only made a viable eye int fly, it made a fly’s eye. ures t  sor for 500 million years, yet could sic material as if ters.

    tory  to certain cells of flies, and t it as if it heir own.

    2Junk DNA does  is tion employed in DNA fingerprinting. Its practicality for tally by Alec Jeffreys, a scientist at ty of Leicester in England. In 1986Jeffreys udying DNA sequences for genetic markers associated able diseases  to to ly for solving criminal cases-and so it proved. A young baker cenced to terms in prison for the murders.

    Over 60 percent of  turns out, are fundamentally t flies. At least 90 percent correlate at some level to tail, if only tcer field,researc ode udying essentially t appeared,  of blueprints.

    Furtence of a clutcer control genes, eacingt of a section of tic (from a Greek icalDNA, knoo do—t tretc of ting is t instruct t for all organisms in muche same way.

    Interestingly, t of genetic material and  is organized doesn’t necessarily, oreven generally, reflect tication of ture t contains it. e y-six c some ferns  evolved of all complex animals, y times as muc is more genetically splendorous tor of five.

    Clearly it is not t aken a big  lately. Until recently it t  least 100,000 genes, possibly a good many more, but tnumber ically reduced by t results of t,  t came as botment.

    It  tention t genes ed in anynumber of ies. Exultant scientists  various times declared toy, scy, criminality,violence, alcoing and erminism udy publisending tically inferior at matics. In fact,  notyou is so accommodatingly simple.

    ty in one important sense, for if you  determined or propensity to diabetes or to baldness or any otinguisrait, t ively easy anyo isolate and tinker unately, ty-five tioning independently is not nearly enougo produce ty t makes a satisfactory cooperate. A feon’s disease, andcystic fibrosis, for example—are caused by lone dysfunctional genes, but as a rule disruptivegenes are  by natural selection long before tlytroublesome to a species or population. For t part our fate and comfort—and even oureye color—are determined not by individual genes but by complexes of genes ’s   all fits toget beproducing designer babies anytime soon.

    In fact, t years ted matters endedto become. Even t turns out, affects t a man’s beardgroance, is partly a function of  sex (because t sex produces a testosterone surge). In tists made an even moreprofound discovery al genes fromembryonic mice, and t only often born  sometimes uallyfitter ters ampered ain importantgenes royed, it turned out, otepping in to fill t ne not so good for our understanding of  introduced an extra layer of complexity to somet and anyway.

    It is largely because of ting factors t cracking t at once as only a beginning. t  it, is likea parts list for t tells us  says not ’s needed noing manual—instructions for o make it go.

    e are not close to t point yet.

    So no is to crack teome—a concept so novel t termproteome didn’t even exist a decade ago. teome is tion tcreates proteins. “Unfortunately,” observed Scientific American in teome is muced the genome.”

    t’s putting it mildly. Proteins, you ems; as many as a  any moment. t’sa lot of activity to try to figure out. orse, proteins’ beions are based notsimply on try, as  also on to function, a protein mustnot only s, properly assembled, but t also befolded into an extremely specific serm t’s used, but it’s amisleading one as it suggests a geometrical tidiness t doesn’t in fact apply. Proteins loopand coil and crinkle into s are at once extravagant and complex. t owels.

    Moreover, proteins are (if I may be permitted to use a abolic circumstance, to be ped, glycosylated, acetylated, ubiquitinated, farneysylated,sulfated, and linked to glycopidylinositol anc else. Often ittakes relatively little to get t appears. Drink a glass of ificAmerican notes, and you materially alter types of proteins at large in yoursystem. t feature for drinkers, but not nearly so icists o understand w is going on.

    It can all begin to seem impossibly complicated, and in some is impossiblycomplicated. But ty in all too, oo an equallyelemental underlying unity in tiny, deft canimate cells—tive efforts of nucleotides, transcription of DNA into RNA—evolved just once and ayed pretty ure. Aste Frencicist Jacques Monod put it, only : “Anyt is true of E.

    coli must be true of eleps, except more so.”

    Every living tion on a single original plan. As s—eacy arcments, adaptations, modifications, andprovidential tinkerings stretceclosely related to fruit and vegetables. About ions t take place in abanana are fundamentally tions t take place in you.

    It cannot be said too often: all life is one. t is, and I suspect o be, t profound true statement there is.

    PARt  VItO USDescended from t us  it is not true, but if it is,let us pray t it  becomegenerally known.

    -Remark attributed to ter afterDarion o her