by the Mycenaeans, the mainland Greeks
who prospered as the fortunes of Crete declined.
A leader of the Palaikastro team,
Belgian archaeologist Jan Driessen, contends that the wave of destruction was
the tail end of a spiral of instability that the Thera catastrophe set in
motion. A steep drop-off in the number of Minoan sites suggests that there had
been a famine or an epidemic, one perhaps touched off by the environmental
effects of the eruption combined with the later tsunami.
There may have been a spiritual crisis
as well. At Palaikastro, archaeologists found that a shrine had been violently
destroyed and a cult statuette deliberately smashed and burned. Driessen
suggests there may have been a reaction against the religious cult represented
by the statuette, perhaps as part of a populist uprising against the elite in
their villas and temple-palaces. The loss of life and livelihood after the
eruption may have aggravated problems of class difference and widened the gap
between the elite and the commoners, which Driessen says “existed already in
Minoan society.”
The terrifying scale of the Thera
eruption, followed by the devastating force of the giant tsunami it created,
may have led to a gradual unraveling of the values and beliefs that had
sustained this brilliant civilization for so long. In his poem “The Hollow
Men,” T. S. Eliot writes these famous lines: “This is the way the world ends /
This is the way the world ends / This is the way the world ends / Not with a
bang but a whimper.”
For the Minoans, it appears their
world ended with both.
In 2007, excavators of a remote site
in southeastern Iran reported finding evidence of a writing system that dates
back more than 4,000 years. Featuring odd geometric symbols, three baked mud
tablets unearthed near the Iranian city of –Jiroft could reveal much about a sophisticated and independent
urban culture that flourished between the Mesopotamian and Indus Valley
civilizations. However, many scholars are skeptical about the authenticity of
the finds, which they –suspect
may have been planted by locals.
Archaeologists first began digging at
large mounds near Jiroft in 2001 after flash floods uncovered ancient graves
nearby. The team has since found evidence of a large city dating to 2500 B.C.
Then, in 2005, a worker brought Yousef
Madjidzadeh, the archaeologist in charge of the excavation, a tablet covered
with strange symbols on the front and back, saying he dug it up in his village
a few hundred yards away. Last winter, Madjidzadeh ordered his team to dig at
the spot, where they uncovered two more tablets. The three appear to show a
progression: The first has 8 simple geometric signs; the second includes 15
slightly more complex signs, while the third has a total of 59 signs. The
variants might be precursors to Elamite, the writing system used on the Iranian
plateau in the late third millennium B.C. They could also be unrelated or, as
some have said, fakes. Madjidzadeh vows to return in 2008 to uncover more
tablets and silence his critics.
The temples of Angkor are
architectural marvels and international tourist attractions. But in an August
paper in the Proceedings of the National Academy of Sciences, archaeologists
from Australia, Cambodia, and France reported using a combination of ground
surveys and aerial scans to create a broader, more comprehensive map of the
ancient Cambodian ruin, confirming that it was once the center of an incredibly
vast city with an elaborate water network.
Lead researcher Damian Evans, an
archaeologist at the University of Sydney, says the true extent of the city is
apparent only from above. Between A.D. 800 and 1500, Angkor’s complex canals,
roads, irrigated fields, and dense settlements sprawled across more than 1,160
square miles, almost the size of Rhode Island—and far beyond the area protected
within the UNESCO World Heritage Site’s zone today. The city was the
preindustrial world’s largest urban complex, made possible by some of the most
complicated hydraulic works the world had ever seen.
American technology played a critical
role in the analysis. NASA’s Jet Propulsion Laboratory flew a 747 specially
equipped with ground-scanning radar over the site, teasing out subtle
differences in elevation and soil content. Added to conventional aerial
photography and confirmed through ground surveys, the radar images showed that
Angkor was unsustainable. Stripping off the area’s natural forest cover exposed
the complex irrigation systems to unexpected erosion and flooding. “They very
intensively reengineered the landscape wherever they went,” Evans says. “When
you start creating these incredibly elaborate engineering works, it’s
inevitable that you create problems. Angkor engineered itself out of
existence.”
In September, a team of surgeons and
immunologists at Duke University proposed a reason for the appendix, declaring
it a “safe house” for beneficial bacteria. Attached like a little wiggly worm
at the beginning of the large intestine, the 2- to 4-inch-long blind-ended tube
seems to have no effect on digestion, so biologists have long been stumped
about its purpose. That is, until biochemist and immunologist William Parker
became interested in biofilms, closely bound communities of bacteria. In the
gut, biofilms aid digestion, make vital nutrients, and crowd out harmful
invaders. Upon investigation, Parker and his colleagues found that in humans,
the greatest concentration of biofilms was in the appendix; in rats and
baboons, biofilms are concentrated in the cecum, a pouch that sits at the same
location.
The shape of the appendix is perfectly
suited as a sanctuary for bacteria: Its narrow opening prevents an influx of
the intestinal contents, and it’s situated inaccessibly outside the main flow
of the fecal stream. Parker suspects that it acts as a reservoir of healthy,
protective bacteria that can replenish the intestine after a bacteria-depleting
diarrheal illness like cholera. Where such diseases are rampant, Parker says,
“if you don’t have something like the appendix to harbor safe bacteria, you
have less of a survival advantage.”
Women who have struggled through a
miscarriage are often desperate for clues to what went wrong, and what they can
do differently the next time. But doctors seldom have solid answers.
The latest research seems only to
muddy the picture. A study by Kaiser Permanente in the American Journal of
Obstetrics and Gynecology this week reports that women who consumed the equivalent
of two cups of coffee or more daily had twice the miscarriage rate as those who
avoided caffeine. Yet a study from Mount Sinai School of Medicine, in the
journal Epidemiology this month, found that drinking more moderate amounts of
caffeine didn't increase a woman's risk of miscarrying.
Either way, caffeine consumption is just
one small piece of this heartbreaking puzzle for many couples. A host of other
problems can sabotage a developing fetus, and if patients are aware of their
options, they might be able to fill in at least a little of that puzzle.
Roughly one million pregnancies in the
U.S. end in miscarriage every year, according to the National Center on Health
Statistics. Most miscarriages occur in the first trimester, and some 60% are
thought to be due to a random genetic error in the egg or the sperm or the
first crucial cell divisions. No amount of prenatal care or dietary precautions
will make a difference in these cases.
Even if the baby is genetically
normal, other problems can doom the pregnancy. Some can be tested for, and
treated, if doctors investigate. But they seldom do. The American College of
Obstetricians and Gynecologists now recommends looking into possible causes
after a woman has had two consecutive miscarriages. But because miscarriages
are so common and so often thought to be genetically based, many OB/gyns still
don't look for other explanations unless a woman has had at least three. And
many insurers won't pay for tests to investigate "recurrent
miscarriage" until a woman has had three.
In the meantime, the admonition is to
"just try again" -- which can be very frustrating for couples to
hear, particularly if they postponed childbearing and had trouble conceiving.
And the chance of miscarrying gets higher after the mother reaches 35.
"You almost want something to be
wrong so you can treat it," says Kelly Maguire, a counselor for Resolve, a
support group for fertility issues, who had four miscarriages before having two
healthy babies. "My experience is, it's all up to you and how much you
push your doctor."
Among the things women can do to find
explanations is to press for a genetic analysis of the miscarried tissue, if
it's feasible to save. If it's abnormal, that alone will explain the
miscarriage. But it's a good idea to seek genetic tests of both parents that
could reveal whether the problem is likely to recur.
After a second miscarriage the mother
should be tested for imbalances of hormones, including thyroid, prolactin and
progesterone, as well as for polycycstic ovarian syndrome. Some are easily
treatable. Autoimmune disorders such as antiphospholipid antibodies can cause
blood clots that clog vessels in the placenta. Those may be treatable with baby
aspirin and blood thinner. Bacterial infections, including some that linger for
years with no symptoms, can also thwart pregnancy, and can be treated with
antibiotics. A uterine abnormality may limit the space for the fetus. That can
be seen on a sonogram, and in some cases, corrected by surgery.
To be sure, many recurrent
miscarriages remain a mystery even after lengthy investigations. But that
number is getting smaller all the time, says Jonathan Scher, a Manhattan OB/gyn
who treats patients with recurrent pregnancy loss. "Patients who miscarry
back to back should not take no for an answer. It's very old fashioned to
accept 'it's nature way,' " he says. "Miscarriage doesn't always have
to happen. Today, we can find answers in many cases, and in many cases,
treatment is available."
In some cases, Dr. Scher even works
with perinatal pathologists to seek clues from a patient's prior miscarriages if
tissue from a D&C was sent to a pathology lab. Some states require such
slides to be saved for years, and they can reveal traces of clotting problems
or infection, as well as genetic problems.
How environmental agents might fit in
is less well understood. But most OB/gyns have been telling pregnant women for
years to go easy on caffeine, as well as to quit smoking and drinking alcohol
and to avoid other hazards, such as cat litter and undercooked meat. As a
result of the Kaiser study, the March of Dimes has lowered its recommended
caffeine limit to 200 mg from 300 mg daily.
"Reducing caffeine won't prevent
a miscarriage that's destined to happen," says Tracy Flanagan, Kaiser's
director of women's health in Northern California. "But this does give
women the opportunity to do something that may reduce their risk."
The structure of DNA, the molecule of
life, was discovered in the early months of 1953. Nine years later, three men
were jointly awarded a Nobel Prize for this achievement, which has proved to be
one of the most consequential in the history of science. James Watson and
Francis Crick, who worked at the Cavendish Laboratory, in Cambridge, England,
came up with the famous double-helix structure. The third man honored, Maurice
Wilkins, was a scientist in London; although he worked at a rival lab, he did
make available to Watson and Crick some of the experimental evidence that
helped them clinch their discovery. The person actually responsible for this
evidence, however, was not Wilkins but an estranged colleague of his named
Rosalind Franklin, who had died four years before the prize was awarded.
For a decade after her death, Rosalind
Franklin remained little known beyond the world of molecular biology. Then, in
1968, Watson published "The Double Helix," his rambunctious,
best-selling account of the race to solve the structure of DNA. In its pages,
Rosalind Franklin becomes Rosy, a bluestocking virago who hoards her data,
stubbornly misses their import, and occasionally threatens Watson and others
with physical violence—but who might not be "totally uninteresting"
if she "took off her glasses and did something novel with her hair."
Friends and colleagues of hers mounted
a counter-offensive, which was soon joined by feminist historians of science.
Why did Watson create Rosy the Witch? Out of guilt for having used her
evidence, which Wilkins showed him without her knowledge. Neither Watson nor
Crick ever admitted to Franklin that they had relied crucially on her research;
neither so much as mentioned her in his Nobel acceptance speech. Moreover,
Franklin herself had made great progress toward identifying the structure of
DNA. Had she not been the rare woman laboring in a patriarchal scientific
establishment that limited her opportunities and stifled her talents, the
triumph might well have been hers. So her partisans have contended.
http://louis-j-sheehan.us/ImageGallery/CategoryList.aspx?id=a1206a74-5f7f-443f-97f5-9b389a4d4f9e&m=0
"Since Watson's book, Rosalind
Franklin has become a feminist icon, the Sylvia Plath of molecular biology, the
woman whose gifts were sacrificed to the greater glory of the male,"
Brenda Maddox writes in "Rosalind Franklin: The Dark Lady of DNA"
(HarperCollins; $29.95). This mythologizing, Maddox thinks, has done Rosalind's
memory a disservice. One wouldn't guess from the "doomed heroine"
caricature, for instance, that Rosalind enjoyed an international reputation in
three different fields of research. Nor would one guess from Watson's depiction
that, far from being frumpier than the average Englishwoman, she had actually
brought with her to London elements of Christian Dior's New Look that she had
picked up during her years in Paris. Maddox, who has previously written lives
of D. H. Lawrence and Nora Joyce, tells Rosalind's story engagingly. We get a
vivid picture of her scientific prowess, the complexity of her character, and
the stoicism with which she pursued her research during her final months even
as she was dying of ovarian cancer. Inevitably, though, it is her part in the
DNA drama which commands the most interest. Did she really play an
indispensable role in the great 1953 discovery, as Maddox finally joins so many
others in suggesting? Was she cheated of the credit due her because she was a
woman?
Rosalind Franklin was born in London
in 1920 to a prominent Anglo-Jewish family. (Her great-uncle had been installed
by the British as the first High Commissioner of Palestine.) The one indulgence
of her "frugal rich" parents was foreign travel; they favored
vigorous mountain hiking trips—an activity that became a Wordsworthian passion
for Rosalind. At sixteen, she chose science as her subject, selecting the
"hard" areas of physics, mathematics, and chemistry rather than the
botany and biology courses usually taken by girls. She avoided the social
whirl. At the age of twenty-one, after three years of study at wartime
Cambridge, she confessed to a cousin that she had never been kissed and did not
know how the human ovum was fertilized. In 1945, she submitted a Ph.D. thesis
on how the porosity of carbon was affected by heat, a subject she mockingly
described as "the holes in coal."
In fact, Rosalind's research
predilections centered on something very beautiful, the idea of a crystal. To a
mathematician, a crystal is a regular system of points that, if repeated indefinitely,
will fill all of space. For a crystal in nature, such as table salt, these
points are invisibly tiny atoms that are held in place by chemical bonds. In
the early twentieth century, it was found that the wavelength of X rays is
about the same as the space between atoms in crystalline matter. As X rays
penetrate a crystal, they are deflected by the rows of atoms. This causes
interference among them: some of the waves reinforce one another, while others
cancel one another out. If a photographic plate is placed on the other side of
a crystal being bombarded with X rays, a pattern of bright and dark spots
eventually appears—a pattern that, in principle, would allow one to infer the
molecular architecture of the crystal.
Rosalind eagerly absorbed the theory
of crystallography, and so joined, as Maddox puts it, "the small band of
the human race for whom infinitesimal specks of matter are as real and solid as
billiard balls." Upon finishing her doctoral work, she got the offer of
her dreams: a job at a crystallography lab on a quai up the river from Notre
Dame. The four years that she spent in Paris, from 1947 to 1950, were evidently
the happiest time of her life. Living in a garret in the Faubourg
Saint-Germain, speaking almost accentless French, and working with a congenial
and cultured group of scientists, she felt at home in a way she never had in
England. The head of her labo was a dashing and brilliant Russian-born Jew
named Jacques Mering, whose specialty was the study of "disordered matter"—crystals
whose molecular arrangement was in some disarray. Rosalind picked up
crystallographic expertise from Mering, and she also seems to have developed
romantic feelings for him, even though he was already equipped with a wife and
a mistress. Maddox speculates that Mering "made advances of some
sort" to Rosalind, and that "she allowed herself to be tempted
farther than was usual for her but eventually, incapable of a casual liaison,
drew back." If so, it was probably the closest brush she ever had with
carnal knowledge. As one of her fellow-chercheurs later put it, she was
"like Queen Victoria about men."
Despite the pleasures of her life and
work in Paris, Rosalind had always planned to return to London. In England, as
in America, chemists and physicists were discovering a new research vista:
life. The cells that make up an organism, after all, consist of atoms and
molecules, which must obey the laws of physics and chemistry. It made sense,
therefore, to try to bring the concepts and methods of the physical sciences to
bear on biological mysteries. (After the creation of the atomic bomb,
physicists found the prospect of escaping from the science of death to the
science of life especially appealing.) Rosalind, though avowedly "ignorant
about all things biological," applied for a position at the biophysics
laboratory of King's College, London, and was accepted. Her arrival there, in
1951, marked the beginning of what Maddox calls "one of the great personal
quarrels in the history of science."
The man who gave Rosalind the job in
London, J. T. Randall, was something of a war hero in Britain because of his
role in the development of radar. He was also happily out of step with the
misogyny that prevailed in the scientific establishment at the time. Randall
put women into more than a quarter of the positions in his lab and had a
reputation for creating a helpful environment for them. The task he offered
Rosalind was to investigate the structure of "certain biological fibres in
which we are interested"—namely, DNA. This could scarcely have been a more
important assignment. But the setting in which she was to carry it out filled
her with gloom. King's College was dominated by clerics ("hooded
crows," she called them) who trained students for the Anglican priesthood.
The scientists were relegated to a cellar laboratory on the Strand, built
around a bomb crater from the war. The atmosphere struck Rosalind as coarse and
schoolboyish. Worse, her new colleagues were intellectually mediocre. As she
wrote to a friend in Paris, "There isn't a first-class or even a good
brain among them—in fact nobody with whom I particularly want to discuss
anything, scientific or otherwise." The greatest indignity came when she
found that she was expected to share the DNA project with the lab's deputy
director, Maurice Wilkins, whom she soon decided she could not abide.
Wilkins was a New Zealand-born
physicist who had worked on the Manhattan Project during the Second World War.
He was unmarried and in his mid-thirties when Rosalind encountered him—tall,
gauntly handsome, and attractive to women. His mild temperament, a little
old-maidish perhaps, contrasted with Rosalind's brusque combativeness. She
found him "middle class" and unworthy of being her collaborator.
Wilkins made little gestures to win her favor, like buying her chocolates, but
to no avail. When he gave a progress report on his own crystallographic
research on DNA, Rosalind peremptorily ordered him to abandon X-ray work and
stick to his optical studies. "Go back to your microscopes" is how he
recalls her putting it.
What Wilkins described on that
occasion was evidence he had obtained which suggested that DNA had the form of
a helix, rather like a spiral staircase. Helices were very much in the air at
that moment. Only a few months earlier, Linus Pauling had published his
discovery that certain proteins had a helical form. Pauling, who was working at
Caltech, in Pasadena, was the foremost chemist of his time. Since he had
discovered the structure of one important kind of biological molecule, it was
natural for him to start thinking about DNA. Meanwhile, in Cambridge, at the
Cavendish Laboratory, a thirty-five-year-old physicist named Francis Crick was
becoming friends with a twenty-three-year-old American biologist named James
Watson. Watson knew genetics; Crick knew X-ray crystallography. Impressed by
Pauling's achievement, and having heard from Wilkins what the King's College
lab was up to, they also turned their attention to the structure of DNA.
The stage was set for a three-way
competition among London, Cambridge, and Pasadena. London, however, had an
enormous advantage: a jam jar containing the best sample of DNA in the world.
The gooey gel could be stretched out into long, fragile strings. "It's
just like snot!" Wilkins exclaimed. Rudolf Signer, a Swiss scientist who
had isolated the sample from the thymus glands of calves, had generously given
it to Wilkins at a scientific meeting. How Signer managed to get DNA in such a
pristine form is a mystery; he never fully explained his recipe. But it soon
became clear that his gel could yield beautifully crisp diffraction patterns.
Upon Rosalind's arrival at King's
College, the Signer DNA was turned over to her. Using state-of-the-art
equipment, she began to get superb X-ray photographs. She also found that the
Signer DNA fibres could be made to assume two distinct forms: a longer
"wet" form, and a more compact "dry" one. All earlier X-ray
photographs of DNA had been a confusing blur of the two. But when Wilkins
pointed out that her patterns, too, were consistent with a helical structure,
Rosalind snapped, "How dare you interpret my data for me?" His
proposal of collaboration was angrily rejected. The atmosphere in the lab
became so poisonous that Randall had to intervene, setting out a formal
division of labor. Rosalind got all the Signer DNA and the new X-ray cameras.
Wilkins was left with the old equipment and an inferior sample of DNA. And that
was more or less the end of any communication between them.
Maddox does not hesitate to assign
blame for all this. "The rift was Randall's doing," she writes. In
inviting Rosalind to the King's College lab, he had sent her an ambiguous
letter leading her to believe that she would be in exclusive command of the DNA
project; it was understandable, the author implies, that she should resent
Wilkins's continued involvement. Wilkins was not the only object of her
animosity in the lab, however. "She nearly terrified the living daylights
out of me," one graduate student recalled. Maddox attributes Rosalind's
rebarbativeness to the patriarchal atmosphere of London: "In Paris she was
confident, admired, independent. Now she was a daughter again." That may
be; but it is also true that, less than a year after her return to England,
Rosalind found herself in sole custody of all the experimental means needed to
discover the structure of DNA.
In Cambridge, Watson and Crick had
none of that. They did, however, enjoy a remarkable personal affinity.
"Neither had an ounce of depression in him, while Rosalind and Maurice, in
their very different ways, were prey to melancholy," Maddox writes. Watson
and Crick's approach to the structure of DNA was inspired by the method that
Linus Pauling had used so successfully with proteins: model-building. Guided by
the rules of chemistry, they would make an educated guess about how DNA was put
together, and construct a model out of metal rods and wires and colored plastic
balls. No need to mess around with any snotlike gel. Rosalind had nothing but
scorn for this speculative approach. Even if one managed to slap together a
model that satisfied the X-ray data, how could one be sure that it was the only
model that would do so? How would one know, she wondered, whether it was
"the solution or a solution"?http://louis-j-sheehan-esquire.us/
What everyone at the time did know
about DNA was that it consisted of a sequence of four different bases attached
to a sugar-phosphate chain. These bases were adenine, guanine, thymine, and
cytosine (usually abbreviated A, G, T, and C). The precise sequence presumably
encoded the genetic information. As for the over-all architecture, it seemed
reasonable to start by assuming that DNA was a helix. Pauling had already shown
that a helical structure could lend stability to large biological molecules,
and the preliminary X-ray evidence for DNA jibed with this hypothesis. But what
kind of helix? And would its structure shed light on the molecule's singular
function—self-reproduction?
In late 1951, Watson went down to
listen to the London team talk about what they had learned so far, and he
returned to Cambridge with a slightly garbled memory of their data. A week
later, he and Crick had come up with a model for DNA. It was a triple helix,
with the bases facing outward, so that they could interact with proteins. They
invited the King's College group up to see their handiwork. It got a withering
reception. Rosalind—who, unlike Watson and Crick, was actually a
chemist—pointed out that the molecule as they had constructed it would not even
hold together. Maddox reports that Rosalind was "jubilant" on the train
back to London: "She had not expected the model to be right. The whole
approach was unprofessional." Watson and Crick tried to salvage matters by
suggesting that the two groups join forces, but Rosalind wanted nothing to do
with them. After this debacle, the director of the Cavendish lab, Sir Lawrence
Bragg, ordered Watson and Crick to leave the investigation of DNA to King's. As
a token of compliance, the pair even sent their model-making jigs down to
London, where they remained idle.
Rosalind, who now had the field pretty
much to herself, was intent on deducing the molecular structure of DNA directly
from the spots on the X-ray pictures, without any imaginative guesswork. Such a
deduction would entail endless rounds of laborious calculation. Undeterred,
Rosalind plunged in. She and her assistant also continued with their X-ray
photography, taking long exposures—some lasting a hundred hours—of a single
fibre of DNA. Sometime in the spring of 1952, she obtained the most stunning
pattern yet for the wet form: a stark, X-shaped array of black stripes
radiating out from the center. It fairly shouted helix. Rosalind numbered it
Photograph 51 and put it aside. She was more interested in the dry-form photos,
which contained the complex detail that, with fastidious measurement, might
enable her to compute the form of DNA. And this detail did not point to a
helical structure. That July, in an uncharacteristic prank, she even conducted
a mock funeral for the helix. She spent the next few months with her slide rule,
buried in books of numerical tables.
Maddox finds her earthbound approach
understandable, given what she sees as the "hostile environment" in
which Rosalind found herself: "If she had felt very confident and
supported, she might have been able to make outrageous leaps of
imagination." Maybe, though, she sensed little urgency to do so. Watson
and Crick had been banned from investigating DNA. Pauling was still finishing
up his work on proteins; and, in any case, as Rosalind knew, the only DNA photographs
he had were old ones in which the two forms were deceptively superimposed. As
for Wilkins, next door, he was too cowed to ask Rosalind for her data, much
less for some of the precious DNA sample that had originally been his.
Watson and Crick, as it happened,
could also afford to be patient. They were confident that Rosalind, in
rejecting the helix, had headed up a blind alley. Crick saw how she had been
misled by her painstaking measurements: the supposed anti-helical features in
her photographs, he realized, were actually distortions that arose in the DNA
helix when it coiled up into the dry form. Watson and Crick's method was the
opposite of Rosalind's: trust no datum until it has been confirmed by theory.
They were determined to solve the structure of DNA with as few empirical
assumptions as possible.
Besides, what real data did they have
access to? Rosalind was not publishing her X-ray photographs of DNA. Watson and
Crick had heard about them from Wilkins, but not even he had seen the
extraordinary Photograph 51. In May of 1952, Pauling was to be the guest of
honor at a Royal Society meeting on proteins in London. Had he attended, he
might well have been shown Rosalind's photographs and picked up from them what
he needed to solve the structure of DNA. But the trip was aborted; because of
McCarthyist suspicions about Pauling's political sympathies, the United States
State Department had refused to issue him a passport.
Pauling pressed ahead with his
model-building all the same, relying on his unrivalled grasp of the geometry of
chemical bonds. At the end of 1952, Watson and Crick were devastated by the
news that Pauling had worked out a structure for DNA. They awaited his paper
with trepidation, but when it arrived, on January 28, 1953, they were delighted
to find that Pauling had made the same blooper they had more than a year
earlier. Like their old model, his was a chemically defective three-stranded
helix with the bases on the outside. Watson and Crick knew that Pauling's
errors would be pointed out to him, and that, given a second crack at the DNA
problem, he would probably solve it. They figured they had, at most, six weeks.
That same day, Rosalind was giving her
final seminar at King's College. She had had enough of that basement full of
"positively repulsive" mediocrities, and had accepted an invitation
from the great crystallographer J. D. Bernal to join his lab in London, at
Birkbeck College. She would leave off DNA research and apply her X-ray skills
to the study of viruses. Summarizing her work at King's, she neither referred
to the wet form of DNA nor showed the splendid photographs she had taken of it.
Instead, she concentrated on her supposed evidence that the dry form of the
molecule was not helical.
A couple of days later, Watson turned
up in her lab unbidden, offering to show her Pauling's model. When she
countered with her anti-helical evidence, Watson, by his own account in
"The Double Helix," decided to "risk a full explosion" by
implying that she was incompetent in interpreting her own X-ray pictures:
"Suddenly Rosy came from behind the lab bench that separated us and began
moving toward me. Fearing that in her hot anger she might strike me, I grabbed
up the Pauling manuscript and hastily retreated to the open door." Watson
then encountered Wilkins, who, he claimed, told him that some months earlier
"she had made a similar lunge toward him." Wilkins proceeded to do
something that has widely been deemed unethical: he showed Watson one of
Rosalind's photographs—probably Photograph 51. "The instant I saw the
picture my mouth fell open and my pulse began to race," Watson recalled.
On the train back to Cambridge, he sketched from memory, in the margin of a
newspaper, the pattern he had seen.
From this point on, Watson and Crick
needed only one month to wrap up the matter. Bragg authorized the two to resume
their model-building, with jigs to be turned out by the machine shop. Watson
plumped for a helical structure with two chains. "Francis would have to
agree," he later wrote. "Even though he was a physicist, he knew that
important biological objects come in pairs." Then they had a couple of
lucky breaks. Crick noticed a symmetry in DNA that had eluded Rosalind and her
colleagues: the crystal had the same form when it was turned upside down. As he
immediately realized, this meant that the two chains that made up the helix
must run in opposite directions, like up and down escalators. Their second
break came when an off-the-cuff remark made by a new lab mate (a former student
of Pauling's, as it happened) supplied the necessary clue to how the two chains
of the helix held together. As they'd begun to suspect, it was the bases that
bonded. Whenever A occurred on one chain, T was invariably paired with it on
the other;
the two fit snugly together because of
their shapes. Ditto for C and G. Therefore, one chain of the double helix was
an upside-down negative of the other. When separated, each might serve as a
template on which a new, complementary chain could be assembled with exactly
the same information as the old. That, Watson and Crick realized, was how the
molecule reproduced itself, and how nature, for the last four billion years,
had counteracted the tendency of matter to become disordered. At lunchtime on
February 28, 1953, Watson recounted, his partner "winged into The
Eagle"—a Cambridge pub—"to tell everyone within hearing distance that
we had found the secret of life." That April, the two presented their
model, in a nine-hundred-word prose poem, in the scientific journal Nature. The
elegance with which the DNA structure merged form and function seemed to
guarantee its truth. "It has not escaped our notice that the specific
pairing we have postulated immediately suggests a possible copying mechanism
for the genetic material," the authors demurely noted.
Rosalind was not bowled over by Watson
and Crick's model. "It's very pretty, but how are they going to prove
it?" was her reaction. Rosalind, Maddox writes, "had been trained, as
a child . . . as an undergraduate, as a scientist, never to overstate the case,
never to go beyond hard evidence." Had Rosalind been a man, the author
suggests, she might have been encouraged to be more audacious. Yet a knack for
guessing at an answer ahead of the evidence is one of the things that
distinguish a great scientist from a good one, regardless of gender. Perhaps
Rosalind was merely a very good scientist, not a great one. Or, perhaps, given
a little more time, she would have discovered the structure of DNA herself.
Crick has generously ventured that she was three months away, but it is
doubtful that Rosalind realized it, given her decision to leave the
investigation of DNA to take up the crystallographic study of viruses.
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