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ntific requirements that itattracted no attention at all。
for most of the next half century the mon assumption was that the material鈥攏owcalled deoxyribonucleic acid； or dna鈥攈ad at most a subsidiary role in matters of heredity。 itwas too simple。 it had just four basic ponents； called nucleotides； which was like having an alphabet of just four letters。 how could you possibly write the story of life with such arudimentary alphabet？ （the answer is that you do it in much the way that you create plexmessages with the simple dots and dashes of morse code鈥攂y bining them。） dna didn鈥檛do anything at all； as far as anyone could tell。 it just sat there in the nucleus； possibly bindingthe chromosome in some way or adding a splash of acidity on mand or fulfilling someother trivial task that no one had yet thought of。 the necessary plexity； it was thought；had to exist in proteins in the nucleus。
there were； however； two problems with dismissing dna。 first； there was so much of it：
two yards in nearly every nucleus； so clearly the cells esteemed it in some important way。 ontop of this； it kept turning up； like the suspect in a murder mystery； in experiments。 in twostudies in particular； one involving the pneumonococcus bacterium and another involvingbacteriophages （viruses that infect bacteria）； dna betrayed an importance that could only beexplained if its role were more central than prevailing thought allowed。 the evidencesuggested that dna was somehow involved in the making of proteins； a process vital to life；yet it was also clear that proteins were being made outside the nucleus； well away from thedna that was supposedly directing their assembly。
no one could understand how dna could possibly be getting messages to the proteins。 theanswer； we now know； was rna； or ribonucleic acid； which acts as an interpreter betweenthe two。 it is a notable oddity of biology that dna and proteins don鈥檛 speak the samelanguage。 for almost four billion years they have been the living world鈥檚 great double act； andyet they answer to mutually inpatible codes； as if one spoke spanish and the other hindi。
to municate they need a mediator in the form of rna。 working with a kind of chemicalclerk called a ribosome； rna translates information from a cell鈥檚 dna into terms proteinscan understand and act upon。
however； by the early 1900s； where we resume our story； we were still a very long wayfrom understanding that； or indeed almost anything else to do with the confused business ofheredity。
clearly there was a need for some inspired and clever experimentation； and happily the ageproduced a young person with the diligence and aptitude to undertake it。 his name wasthomas hunt morgan； and in 1904； just four years after the timely rediscovery of mendel鈥檚experiments with pea plants and still almost a decade before gene would even bee a word；he began to do remarkably dedicated things with chromosomes。
chromosomes had been discovered by chance in 1888 and were so called because theyreadily absorbed dye and thus were easy to see under the microscope。 by the turn of thetwentieth century it was strongly suspected that they were involved in the passing on of traits；but no one knew how； or even really whether； they did this。
morgan chose as his subject of study a tiny； delicate fly formally called drosophilamelanogaster； but more monly known as the fruit fly （or vinegar fly； banana fly； orgarbage fly）。 drosophila is familiar to most of us as that frail； colorless insect that seems tohave a pulsive urge to drown in our drinks。 as laboratory specimens fruit flies had certainvery attractive advantages： they cost almost nothing to house and feed； could be bred by themillions in milk bottles； went from egg to productive parenthood in ten days or less； and hadjust four chromosomes； which kept things conveniently simple。
working out of a small lab （which became known inevitably as the fly room） inschermerhorn hall at columbia university in new york； morgan and his team embarked ona program of meticulous breeding and crossbreeding involving millions of flies （onebiographer says billions； though that is probably an exaggeration）； each of which had to becaptured with tweezers and examined under a jeweler鈥檚 glass for any tiny variations ininheritance。 for six years they tried to produce mutations by any means they could think of鈥攝apping the flies with radiation and x…rays； rearing them in bright light and darkness； bakingthem gently in ovens； spinning them crazily in centrifuges鈥攂ut nothing worked。 morgan wason the brink of giving up when there occurred a sudden and repeatable mutation鈥攁 fly thathad white eyes rather than the usual red ones。 with this breakthrough； morgan and hisassistants were able to generate useful deformities； allowing them to track a trait throughsuccessive generations。 by such means they could work out the correlations betweenparticular characteristics and individual chromosomes； eventually proving to more or lesseveryone鈥檚 satisfaction that chromosomes were at the heart of inheritance。
the problem； however； remained the next level of biological intricacy： the enigmatic genesand the dna that posed them。 these were much trickier to isolate and understand。 aslate as 1933； when morgan was awarded a nobel prize for his work； many researchers stillweren鈥檛 convinced that genes even existed。 as morgan noted at the time； there was noconsensus 鈥渁s to what the genes are鈥攚hether they are real or purely fictitious。鈥潯t may seemsurprising that scientists could struggle to accept the physical reality of something sofundamental to cellular activity； but as wallace； king； and sanders point out in biology： thescience of life （that rarest thing： a readable college text）； we are in much the same positiontoday with mental processes such as thought and memory。 we know that we have them； ofcourse； but we don鈥檛 know what； if any； physical form they take。 so it was for the longest timewith genes。 the idea that you could pluck one from your body and take it away for study wasas absurd to many of morgan鈥檚 peers as the idea that scientists today might capture a straythought and examine it under a microscope。
what was certainly true was that something associated with chromosomes was directingcell replication。 finally； in 1944； after fifteen years of effort； a team at the rockefellerinstitute in manhattan； led by a brilliant but diffident canadian named oswald avery；succeeded with an exceedingly tricky experiment in which an innocuous strain of bacteria wasmade permanently infectious by crossing it with alien dna； proving that dna was far morethan a passive molecule and almost certainly was the active agent in heredity。 the austrian…born biochemist erwin chargaff later suggested quite seriously that avery鈥檚 discovery wasworth two nobel prizes。
unfortunately； avery was opposed by one of his own colleagues at the institute； a strong…willed and disagreeable protein enthusiast named alfred mirsky； who did everything in hispower to discredit avery鈥檚 work鈥攊ncluding； it has been said； lobbying the authorities at thekarolinska institute in stockholm not to give avery a nobel prize。 avery by this time wassixty…six years old and tired。 unable to deal with the stress and controversy； he resigned hisposition and never went near a lab again。 but other experiments elsewhere overwhelminglysupported his conclusions； and soon the race was on to find the structure of dna。
had you been a betting person in the early 1950s； your money would almost certainly havebeen on linus pauling of caltech； america鈥檚 leading chemist； to crack the structure of dna。
pauling was unrivaled in determining the architecture of molecules and had been a pioneer inthe field of x…ray crystallography； a technique that would prove crucial to peering into theheart of dna。 in an exceedingly distinguished career； he would win two nobel prizes （for chemistry in 1954 and peace in 1962）； but with dna he became convinced that the structurewas a triple helix； not a double one； and never quite got on the right track。 instead； victory fellto an unlikely quartet of scientists in england who didn鈥檛 work as a team； often weren鈥檛 onspeaking terms； and were for the most part novices in the field。
of the four； the nearest to a conventional boffin was maurice wilkins； who had spent muchof the second world war helping to design the atomic bomb。 two of the others； rosalindfranklin and francis crick； had passed their war years working on mines for the britishgovernment鈥攃rick of the type that blow up； franklin of the type that produce coal。
the most unconventional of the foursome was james watson； an american prodigy whohad distinguished himself as a boy as a member of a highly popular radio program called thequiz kids （and thus could claim to be at least part of the inspiration for some of the membersof the glass family in franny and zooey and other works by j。 d。 salinger） and who hadentered the university of chicago aged just fifteen。 he had earned his ph。d。 by the age oftwenty…two and was now attached to the famous cavendish laboratory in cambridge。 in1951； he was a gawky twenty…three…year…old with a strikingly lively head of hair that appearsin photographs to be strain