Features
Ditwah: A Country Tested, A People United
When Cyclone Ditwah roared across the island on November 27 and 28, 2025, it left behind a landscape scarcely recognisable to its own inhabitants—homes reduced to rubbles, vital infrastructure torn apart and entire communities engulfed by floodwaters that surged with terrifying speed. The storm’s ferocity carved deep scars into the island’s social and economic fabric, displacing thousands and severing lifelines that families had relied upon for generations. In its aftermath, the air hung heavy not only with the scent of mud and debris, but also with a palpable collective grief—a profound sense of loss etched on every face. As of December 9, the day of writing, the death toll had reached 635, with an additional 192 individuals reported missing. In Kandy alone, one of the most severely affected districts, 234 lives were lost. Island-wide, 12,123 families—amounting to 1,776,103 people—were displaced.
As a small island situated in the monsoon-fed waters of the Indian Ocean, Sri Lanka has long lived in intimate coexistence with hydro-meteorological hazards. For centuries, the monsoon winds that swept across the island brought not only life-giving rains to nourish paddy fields, forests, and communities, but also shaped the rhythms of daily life, agriculture, culture and even the island’s civilisation itself. Yet this same monsoon—when delayed, intensified, or disrupted—has had the power to unsettle entire ways of life and inflict widespread human suffering. Over generations, communities learned to read the sky and the sea, developing localised knowledge systems and adaptive skills to cope with the uncertainties of winds and waves. This reservoir of traditional wisdom fostered a form of social resilience deeply embedded in the island’s cultural fabric. At present, however, this traditional resilience is increasingly tested by the new realities of climate change and the growing frequency of severe cyclones.
When Cyclone Ditwah struck on November 27, 2025, it unleashed a force so violent that it reshaped many districts within hours, leaving behind a trail of destruction that stretched as far as the eye could see. Whole neighborhoods were crushed under winds that tore roofs from their foundations, while surging floodwaters swept through villages, carrying away homes, livelihoods, and the fragile sense of security people had built over generations. Roads lay fractured, communication lines collapsed, and families found themselves cut off in pockets of isolation marked by debris and despair. In the storm’s wake, the silence was haunting—broken only by the cries of survivors searching for loved ones and the distant hum of rescue teams navigating the ruins. The scale of the devastation was overwhelming, a human and infrastructural tragedy so profound that it demanded not just an emergency response, but a coordinated, compassionate, and deeply human-centered approach to crisis management.
The most devastating natural disaster Sri Lanka has experienced in recent history remains the 2004 Indian Ocean tsunami, which claimed over 35,000 lives and displaced nearly a million people. Sweeping across two-thirds of the nation’s coastline—more than 1,000 kilometers—it affected approximately 234,000 families and destroyed over a million houses. More than two-thirds of the country’s fishing fleet was obliterated. Beyond the immense human suffering, the tsunami exposed profound gaps in preparedness and underscored the urgent need for a systematic, coordinated approach to disaster risk management.
Over the last decade, Sri Lanka has increasingly confronted hydro-meteorological hazards driven by the accelerating impacts of climate change. Cyclones such as Roanu (2016), Mora (2017), Burevi and Amphan (2020), and Yaas (2021) highlight the growing frequency and severity of extreme weather events. According to the Sri Lanka – Disaster Management Reference Handbook, Cyclone Roanu brought the highest recorded rainfall in more than 18 years, triggering floods in 24 of the country’s 25 districts. Covering 1,400 square kilometers, the flooding affected nearly half a million people and inflicted damages estimated at US$600 million. Just a year later, Cyclone Mora caused severe flooding across 15 southern districts and unleashed landslides that further compounded human and infrastructural losses.
These climate-induced pressures have been accompanied by increasingly destructive monsoon-related disasters. In May 2016, the Aranayake landslide wiped an entire village off the map, killing 144 people, leaving 96 missing, and rendering hundreds homeless as their dwellings were buried under rubble. The following year, unprecedented monsoon rains caused flash floods and landslides that killed more than 210 people and displaced 630,000 across 15 districts. Subsequent monsoon seasons delivered similar devastation: in 2018, floods and landslides resulted in 24 deaths and affected 170,000 people; in 2019, heavy rains left 16 dead and displaced more than 7,000. Even in 2020, despite the successful evacuation of more than 75,000 residents ahead of Cyclone Burevi—an example of improved preparedness—post-cyclone flooding still affected over 100,000 people and destroyed or damaged nearly 4,000 homes.
Compounding this pattern of extreme rainfall and flooding is the paradoxical increase in drought conditions, another manifestation of climate variability. The worst drought in four decades struck between October 2016 and October 2017, affecting 2.2 million people across the North Western, North Central, Northern, and Eastern Provinces. From March to May 2020, another severe drought impacted more than 500,000 individuals in 14 districts, forcing the government to implement emergency drinking water distribution across six provinces. These cycles of excess and scarcity are further aggravated by the seasonal rise in vector and rodent-borne diseases—most notably dengue fever and leptospirosis—adding another layer of complexity to Sri Lanka’s disaster management landscape.
Societal Resilience in Disaster Management
As these converging crises demonstrate, Sri Lanka’s vulnerability to climate-driven disasters is no longer episodic but structural—woven into the lived reality of communities across the island. Yet amid repeated cycles of loss and recovery, what stands out most is not only the scale of devastation but the remarkable capacity of ordinary people to adapt, support one another, and rebuild their lives. This enduring strength points to a deeper truth: effective disaster management cannot rely solely on institutions or technologies; it must draw upon—and reinforce—the social resilience embedded within communities themselves.
Having lived under the influence of monsoons for generations, traditional communities developed sophisticated knowledge and skills to cope with nature’s unpredictability. Long before formal disaster management systems existed, villagers relied on environmental cues and collective action to prepare for seasonal threats. In the upstream and valley areas of the Kalu Ganga, for example, older generations still recall how communities repaired boats and rafts through shramadana well before the rainy season began. They observed the behavior of birds, animals, and changes in wind patterns to decode early warning signs that modern meteorology would later confirm.
Such practices demonstrate that traditional communities were not merely passive recipients of natural hazards; they were active interpreters of their environment. Their resilience stemmed from a deep ecological intimacy, a lived knowledge system refined through experience. Today, there is immense value in unpacking this traditional knowledge and synergising it with modern technology—not to romanticise the past, but to strengthen contemporary preparedness.
The Role of Community and the Political Domain
Building societal resilience requires more than cultural memory; it demands structured collaboration between communities and the political system. While communities are often the first responders in any disaster, the political domain plays a crucial role in mobilising, legitimising, and coordinating their efforts. Transforming political will into national will requires an organic articulation between civil society and political leadership—a partnership where both domains reinforce one another rather than operate in isolation. Within this broader framework, disaster management encompasses three equally critical components:
Disaster Risk Management
In each of these, the state has a vital role—from policy formulation to resource allocation, coordination, and accountability. Yet, the effectiveness of state-led initiatives ultimately hinges on the strength of the relationship between institutions and the communities they serve.
Beyond Culture: Technology and Institutions as Pillars of Resilience
While socio-cultural resilience forms an indispensable foundation, it is no longer sufficient on its own, given the scale and complexity of contemporary climate-induced hazards.
Modern disaster risk management relies on a robust interface between technology, institutional networks, and community participation. Advanced and accessible communication technologies—early-warning systems, mobile alerts, satellite data, and community-level dissemination platforms—play a crucial role in transforming timely information into effective action.
But technological tools reach their full potential only when supported by strong institutional structures, in both formal and informal, capable of mobilising people and resources rapidly and equitably. Thus, societal resilience can be understood as a system supported by three interdependent pillars.
Societal Resilience
When these elements function in harmony, the collective capacity to withstand and recover from disasters is significantly enhanced. Ultimately, social resilience is not merely the ability to endure shocks—it is the ability to recover with dignity. A humane disaster management system recognizes the agency, knowledge, and lived experiences of affected communities. It integrates cultural wisdom with modern capabilities, fosters trust between citizens and institutions, and ensures that every step of the disaster cycle reflects empathy, inclusion, and respect. 
Immediate Community and Government Responses to the Crisis
Within ten days of the Ditwah disaster, the Sri Lankan government succeeded in rapidly mobilizing the security forces, key institutional structures, political leadership, and community organisations to confront the crisis. Given the scale and depth of the devastation, meeting the challenge and mitigating its effects seem to be a formidable task. The armed forces and government departments, supported by unaffected communities, provided exceptional assistance to meet the initial challenge. People in the South—often guided directly or indirectly by local political/community leadership—volunteered in large numbers, travelling to the hills to support recovery efforts. Much of the initial work of clearing debris and cleaning homes was carried out through community participation. Infrastructure repairs, particularly the restoration of roads, water supply, and electricity, were undertaken through coordinated action by relevant government agencies who worked tirelessly day and night. As a result, nearly 80 per cent of essential infrastructure was restored within ten days, with the exception of the severely damaged railway network, which requires longer-term reconstruction.
In the immediate aftermath, the government declared a nationwide state of emergency under the Public Security Ordinance, enabling the rapid deployment of resources across sectors. Through the Disaster Management Centre (DMC) and relevant ministries, authorities activated emergency operations: evacuation orders were issued in high-risk flood and landslide zones, shelters were established across the country, and search-and-rescue missions commenced immediately after landfall.
Concurrently, the government announced a comprehensive relief and recovery package. Affected households received allowances for cleaning and resettlement, support for temporary accommodation, and financial assistance for the repair or reconstruction of damaged homes. Immediate access to financial resources—including a Rs. 30 billion contingency allocation that did not require prior parliamentary approval—enabled swift implementation. The declaration of this extensive and unprecedented relief package played a key role in restoring hope and strengthening the self-confidence of affected communities.
Recognizing the magnitude of the crisis, the government established a special recovery fund that brings together public and private sector contributions to support long-term reconstruction, infrastructure repair, and livelihood restoration. Involving prominent private sector leaders—including those who are not aligned with the ruling administration—alongside government officials and key ministers is intended to build trust within the business community and reinforce transparency in the fund’s management. The substantial international assistance received and pledged reflects a renewed confidence among external partners in the government’s ability to manage funds transparently and ensure that aid reaches intended beneficiaries. Sri Lanka further collaborated closely with international and humanitarian agencies to scale up multi-sector support. Organizations such as the World Food Programme (WFP), International Organization for Migration (IOM), and World Health Organization (WHO) mobilized food, water, medical supplies, shelter materials, and rapid-response teams—often in coordination with government efforts—to reach displaced persons and vulnerable populations, particularly in remote and landslide-prone areas.
During this ten-day period, the President personally attended the district coordinating committee meetings in all cyclone- and flood-affected areas. These meetings brought together political leaders—both from the ruling party and the opposition—along with key administrative officers and representatives from the relevant line ministries to review disaster response, mitigation measures, and recovery needs. The manner in which the President raised issues, sought clarification, and directed action demonstrated a high level of preparation and a clear understanding of the scope and complexity of the damage. His engagement signaled a proactive and informed approach to crisis governance, contributing to more coordinated and timely interventions across affected districts.
Thus far, these measures largely pertain to confronting the immediate challenge and mitigating its impacts. Yet effective mitigation must ultimately lead into long-term recovery planning and strengthened preparedness for future climate-induced crises. Ditwah is not the first or the last. Climate change has altered the frequency, scale, and unpredictability of extreme weather events, making it clear that Sri Lanka must now learn to live with recurring climate hazards as a structural condition rather than an episodic disruption. This requires a sustained investment in resilient infrastructure, risk-sensitive development planning, and community-level adaptive capacity. In this sense, the response to Cyclone Ditwah should not only be understood as an emergency undertaking, but also as a critical moment to embed long-term climate resilience into national policy and institutional practice.
Lessons learned
The devastation wrought by Cyclone Ditwah has once again tested Sri Lanka’s institutional capacity, the NPP political leadership and peoples’ resilience. Since the 2004 Tsunami, the country has made significant progress in establishing organisational structures and policy frameworks for disaster management, making it a central domain of contemporary statecraft. Yet, the experience of Ditwah underscores the need for further strengthening in four key areas. First, given the multiplicity of ministries and agencies involved—from the Ministry of Disaster Management and the National Council for Disaster Management to the Disasters Management Center, the Meteorological Department and the National Disaster Relief Services Centre—clear mechanisms are essential to avoid overlap and ensure coherent, efficient action.
Second, disaster preparedness and response must harness the collective capacities of state institutions, NGOs, and community-based organisations, whose collaboration is indispensable for effective disaster risk governance. Third, the integration of traditional knowledge systems—rooted in long-standing practices of environmental stewardship and community resilience—should inform planning and implementation, complementing modern technology and institutional expertise. Finally, in a multi-ethnic, post-conflict society, sensitivity to ethno-political dynamics is imperative across all three phases of disaster management: preparedness, emergency response, and post-disaster recovery.
Ultimately, Cyclone Ditwah revealed both the vulnerabilities and strengths of the nation—demonstrating that while Sri Lanka’s systems were tested, its people were united in response, reaffirming the country’s capacity to confront adversity through collective resolve. The spontaneous networks of support that emerged in the cyclone’s aftermath demonstrated that unity is not merely an aspiration but an operational force in moments of crisis. In reaffirming the country’s capacity to confront adversity through collective resolve, the response to Ditwah offers a powerful reminder that the resilience of the people remains Sri Lanka’s most reliable foundation for future challenges.
by Prof. Gamini Keerawella ✍️
Features
‘A remarkable time capsule’: The enchanting history of Oxford University’s 750-year-old medieval library
Predating the Aztec Empire, Merton College Library in Oxford has been used by everyone from celebrated 14th-Century mathematicians to JRR Tolkien. In an exclusive interview with the BBC for its 750th birthday, its librarian describes what makes it so special.
At Merton College in Oxford, there is an antique chest. In the Middle Ages, three key-holders had to be summoned to reveal the riches within. But this treasure wasn’t gold or jewels. It was books.
Such strict security may sound overly cautious for mere parchment. But in an era before the printing press, books were a valuable commodity. They could take months to produce, as the entire text had to be painstakingly written out by hand. So, just as universities solicit cash from their alumni today, Merton College insisted its 13th-Century fellows donated books.
“There’s no single definition of a library” – Prof Teresa Webber
The Archbishop of Canterbury issued a decree in 1276 introducing this requirement, which marked the beginning of the library at Merton College. It has been running continuously ever since. To put that length of time in context, Merton’s library predates the Aztec Empire. Its unbroken history stretches from before the Black Death to beyond the Covid-19 pandemic. And its users have encompassed everyone from famous 14th Century mathematicians to Lord of the Rings author JRR Tolkien.
This month marks the library’s 750th anniversary. It’s a major milestone. But Merton’s extraordinary lifespan has been recognised since the Victoria era, when it was routinely described as the oldest library in England.
In the 20th Century, writers like Rudyard Kipling and John Buchan referenced it in works of historical fiction, bolstering its reputation as a particularly venerable library. As the cultural recognition of “the famous Merton Library” grew, claims about its longevity became exaggerated. Some overzealous Oxonians even declared it the oldest library in the world.
The origins of the historic library
Historians today are more careful about making such bold declarations. “It’s a complicated question,” says Prof Teresa Webber from the University of Cambridge. “There’s no single definition of a library. And there were all sorts of stages in the development of what we think of today as a library.”

The origins of the library at Merton are certainly different from how we think of such institutions now. There was no librarian and there were no shelves for browsing. “There was a system of loaning and returning books from the chest,” Merton’s librarian, Dr Julia Walworth tells the BBC. “It would have been a formal thing. Rather than just saying, ‘Oh, go rummage and find the books you need,’ the whole community would come together to open the chest.”
“Horizontal shelves were installed for placing books upright. Merton is the first recorded use in Britain of this method of storing books” – Dr Julia Walworth
Merton’s collection started evolving into a modern library quite quickly. Just a few years after the Archbishop’s decree, several books were stored outside the chest for the first time. They were chained to a table in the college, making them available at any time. According to Walworth, this innovation “anticipates the modern distinction between loan and reference library collections”.
Merton’s book treasury moved closer to becoming a modern library in the 1370s, when a purpose-built room was constructed to house the growing collection. It was here that Merton introduced a vital improvement in book storage. “Horizontal shelves were installed for placing books upright,” Walworth says. “Merton is the first recorded use in Britain of this method of storing books.”
Curiously, Merton’s books were shelved with their spines inwards and their titles inked on the paper facing out. This was due to the continued use of chains, which were clipped on the fore-edge of each book’s cover. “The fellows were aware that chained books had a better chance of survival than books that went out on loan,” Walworth explains.

Today, just a few volumes in the library are chained – purely for display purposes. And the remaining books are now placed in the modern fashion with their spines out. But otherwise, the medieval room remains a remarkable time capsule of the library’s history. Near the entrance, visitors can even see the 13th-Century chest, which Walworth believes is the original. During term time, the historic library room is still used by students. And this ongoing use is a major factor in the superlatives that are often applied to the age of Merton’s library. “It’s hard to think of an earlier library room that’s been in continuous use,” Webber says.
Claims about Merton’s longevity first gained traction in the Victorian era, as it became more of a tourist destination. Visitors would marvel at its stained-glass windows, as well as rare books like its 15th-Century edition of The Canterbury Tales. “It’s one of the earliest books printed in England,” Walworth explains. “What’s unique about Merton’s copy is the hand-illuminated borders.” Among those who visited the library was American writer Ralph Waldo Emerson, who mentioned it in his 1856 travelogue English Traits. In 1884, a young Beatrix Potter visited, describing the library’s “beautiful oak roof” and “ancient, dusty smell” in her diary.
By this time, books and magazines were increasingly describing the library in record-breaking terms. An 1878 guide to Oxford called Merton’s library “the most ancient now in England”. The 1885 edition of the Encyclopaedia Britannica described it as “the oldest existing library in England”. Gradually, these claims were inflated. A 1928 article in The Times recounted an event held by the Oxford Preservation Trust in which it was declared “the oldest library in the world”.

This growing perception of Merton’s longevity was even referenced in F Scott Fitzgerald’s classic novel The Great Gatsby. In the book, the multi-millionaire title character fills his mansion with imitations of history’s most prestigious rooms. So, it’s only natural that his books live in a recreation he refers to as “the Merton College Library”. As Walworth puts it, “Merton’s library had become a byword for the ‘best’ ancient library” by that time. She even points out that Fitzgerald’s fictional scenario had roots in reality. “The dining clubs at Princeton University have historical imitation rooms. One of them is based on the Merton College Library.”
But today, Walworth rebukes any suggestion that Merton’s library is the world’s oldest. She prefers to describe it with several qualifiers, calling it “one of the oldest still-functioning academic libraries in Europe”. That more measured description recognises that not all historic libraries can be categorised in the same bucket – monastic libraries functioned very differently from private subscription libraries, for instance. But it also acknowledges ancient institutions around the globe. “It’s not that people weren’t aware of other parts of the world in the past,” Walworth says. “But there was a tendency for people to think of their own world as having primacy. Our outlook tends to be more global now, quite rightly.”
The debate over the world’s oldest library
Among these global institutions, there are several candidates for the contested title of world’s oldest library. When the Al-Qarawiyyin library in Morocco underwent a major restoration in 2016, it was described by several media outlets as “the oldest library in the world”. But Guinness World Records cites Saint Catherine’s Monastery in Egypt as the oldest continuously operating library.

In both cases, it’s difficult to establish an exact starting date. For the Al-Qarawiyyin library, some scholars have cast doubt on the library’s claims of Ninth-Century origins, saying the “story has much myth about it”. In the case of Saint Catherine’s Monastery, the building was constructed in the Sixth Century. But ancient writings suggest that the library’s collections could date from two centuries earlier. “It depends how you count it,” Walworth says. “When are you going to start the timeline? What is the beginning of a library?”
However, Prof Richard Gameson from Durham University tells the BBC that the library at Saint Catherine’s Monastery “is probably the one with the longest continuous history”. But he caveats this by adding that “the nature of the ‘library’, how it was used and how it was understood changed over time”. So, any claim to be “the oldest” needs to be accompanied by an appropriate explanation of what a library is. Finding a single definition that allows for one conclusive record-holder seems a near-impossible task.
“You can think of the oldest library as the oldest coherent collection of books that stayed together,” says Webber. “Or you can think of it in terms of the survival of the physical space. Or you could ask, ‘What’s the oldest space and collection of books which has been there continuously?'”
She offers the Dunhuang Library Cave in China as an example. This secret chamber was filled with manuscripts and sealed sometime around the 11th Century. It was only opened again after its rediscovery in 1900. “But the books were still in continuous storage there,” Webber says.

Finding a common definition of a library will only become more challenging now, as digital institutions offer physical spaces that do not even contain any books. “The definition of what a library is has always needed to be a capacious one,” says Webber. “The introduction of new technology is simply a continuation of that. But I don’t think the library as a physical space will disappear.”
Walworth is similarly optimistic, as she embarks on a project to digitise Merton’s manuscripts. “People will be able to access them anywhere. But I think they will still want to come and see the library and understand how people used books in the past.”
Reflecting on the 750-year span of Merton’s library, this digital phase seems like just another step in a long evolution. Just as the books moved from the Archbishop’s chest to chained desks to horizontal shelves, now they will enter the virtual realm. “I suppose that’s why I now find it less useful to talk about libraries as ‘the oldest’,” Walworth says. “For me, the story is not about how long a library has been running. It’s more about the sense of community.”
She points out that the tradition of donating books introduced by the Archbishop of Canterbury in 1276 persists to this day. “What started when he laid down those injunctions was the idea of a common collection built by the people. So, it’s just remarkable that for 750 years people have maintained this connection with an institution and its books.”
Perhaps that proves that books really are the most durable treasure – whether they are handwritten on parchment and sealed in an antique chest or distributed as pixels in the cybernetic ether.
[BBC]
Features
Discovery of molecular structure of primary genetic material of life
World DNA Day falls on 25 April:
On 25 April 1953, Watson and Crick published an article, in the acclaimed journal “Nature” titled “Molecular structure of nucleic acids: A structure for deoxyribonucleic acid”.
The one-page article largely based on theoretical arguments and the previous work of Rosalind Franklin who examined DNA using X-rays, changed the world forever by explaining how genetic information is copied and transmitted.
Everyone concerned with promoting science in the country should be aware of the story behind the discovery of DNA and tell it to their children and students and remind the policymakers.
The world commemorates the transformative event on 25th April every year. An example vividly illustrates how intense curiosity and imagination, rather than mere indulgence in technologies, leads to groundbreaking discoveries.
DNA Day is also intended to celebrate the completion of the Human Genome Project in 2003. Genome means the entire set of genetic information characterising an organism.
Heredity and inheritance
Heredity is the cause of transferring traits from parents to their offspring. The closely related word “inheritance “refers to the specific nature of the transmitted trait. For example, we say intelligence is hereditary in their family and he inherited his father’s intelligence.
The resemblance of progeny to parentage was common knowledge, taken for granted and considered a blending of maternal and paternal traits. Philosophers of antiquity proposed several theories to explain the inheritance of parental traits by the offspring. Hippocrates believed the essence of all body parts of the parents are incorporated into the male and female germinal essence and therefore the offspring display characteristics as a proportionate blend. Aristotle offered a different explanation. He argued that the active principle is in the male seminal fluid and the mother’s blood provided the original body material. The inaccuracy of these theories was apparent. Sometimes children possess qualities akin to grandparents rather than parents. Fathers or mothers of humans and animals, deformed by accidents or disease, gave birth to normal children- a clear proof that the acquired characters are not inherited. Children of a blue-eyed mother and a brown-eyed father have either blue or brown eyes but not a blend of blue and brown.
Two golden sayings in our culture, “Arae gathi nare” and “Jammeta wada lokuei purrudha” (“Hereditary characters persist” and “Habits overtake heredity “), agree more with modern genetics, than the views of Hippocrates and Aristotle.
Gregor Mendal’s groundbreaking experiment
The Austrian mathematician cum botanist, Gregor Mendel was the first to conduct a systematic investigation to understand the cause of heredity. Being unconvinced of the traditional explanations, he carried out a series of experiments lasting eight years to determine how the traits (plant height, seed color, flower color etc.) of pea plants are transmitted from generation to generation. When Mendel cross pollinated tall and short plants, he found that the progeny was entirely tall. However, when first generation tall plants were allowed to self-pollinate, the missing short trait reappeared at a statistically significant probability of 25 percent. Mendel’s work provided an unequivocal proof that traits do not blend but exist as unique entities, manifested from generation to generation following a predictable mathematical pattern.
Mendel’s finding remained unrecognized for more than 30 years. His ideas were too far ahead of time and biologists were shy of mathematics. In the early 1900s several European botanists arrived at the same conclusion based on independent experiments. With the advancement of microscopy, a great deal of information about plant and animal cells was gathered. A key finding was the presence of colored bodies in the cell nucleus named chromosomes, seen separating during cell division, leading to the hypothesis that Mendel’s genetic units (genes) should be physical entities present in the chromosomes.
Chemists and biologists wondered what the genetic material in chromosomes made off. Is it a protein, carbohydrate or a lipid? Most biological materials are constituted of these substances.
Discovery of DNA
Great discoveries are made by unusual people. The Swiss Friedrich Miescher belonged to a clan of reputed physicians. Following family tradition, he qualified as a doctor but did not engage in profitable practice of medicine. He decided to do research to understand the foundations of life. In search for new biological substances, he experimented with pus deposited in bandages and extracted a substance rich in phosphates but very different from proteins. The new substance called “nuclein” was indeed DNA. Later, the German biochemist Albrecht Kossel following the Miescher’s work, showed that DNA contains four crucial compounds, adenine (A), cytosine (C), guanine (G) and thymine (T), known as nucleotide bases.
Avery – MacLeod – McCarthy Experiment
The flu pandemic of 1918 killed an estimated 50 million people worldwide due to the pneumonia that followed the viral infection. Pneumonia was caused by the virulent bacterium Streptococcus pneumoniae. The British bacteriologist, Frederick Griffith attempting to find a vaccine for pneumonia, worked with two strains of Streptococcus pneumoniae, one virulent causing pneumonia in mice, and the other avirulent to them. He found that neither the virulent strain denatured by heating nor the live avirulent strain injected into mice caused the disease, whereas a mixture of the denatured virulent strain and the live avirulent strain was deadly to mice just as the virulent one. He concluded that some chemical compound present in the virulent strain – a transforming principle – has changed the avirulent strain to the virulent strain.
In 1944, Oswald Avery, Colin MacLeod and Maclyn McCarty working at the Rockefeller University, United States, continued the work of Frederick Griffith to identify the transferring principle and found that it is not protein as widely believed, but deoxyribonucleic acid (DNA). Their result pointed to the conclusion that DNA is the carrier of genetic information.
A book by a physicist that triggered a transformation in biology
The insights of brilliant brains engaged in fundamental inquiry have opened the way for major scientific discoveries and technological innovations. In 1944, the Austrian theoretical physicist Erwin Schrodinger, one of the founders of quantum mechanics, published a book titled “What is life? The physical aspect of the living cell “. The American biologist Maurice Wilkins said he was so inspired by Schrodinger’s book and after reading it, he decided to switch from ornithology to genetics. While physicist Maurice was influenced to take up biology. Francis Crick was a physicist working on magnetic mines for the British Admiralty during the war. After reading “What is life” he thought a physicist could find treasures in biology and joined the Cavendish Laboratory in Cambridge to pursue a Ph.D.
Structure of the DNA molecule
When DNA was shown to be the molecular entity that encodes genetic information, chemists rushed to determine its structure.
The pattern formed when X-rays passing through a material cast an image on a screen, provides information about its molecular structure. In 1938, the English physicist William Astbury examined DNA using x-rays and concluded that the molecule has a helical structure. Having heard a group in the United Kingdom was attempting to unearth the structure of DNA, the American theoretical chemist, Linus Pauling, adopted Astbury’s data and proposed a model for the structure of DNA, publishing the results in the journal “Nature” in January 1953.
There was an obscure but remarkably talented person, Rosalind Franklin, pursuing x-ray diffraction studies on DNA at King’s College London. After a painstaking effort, she obtained accurate x-ray diffraction images of DNA. Her colleague, Maurice Wilkins, working in the same laboratory, passed the images to Francis Crick and James Watson at Cavendish Laboratory.
Crick and Watson were more insightful and theoretical in their approach to elucidating the structure of DNA. They, inspired by Erwin Schrodinger’s hypothesis, that the entity accounting for heredity should be an aperiodic molecular entity in cells, arrived at the double helix model, showing that Linus Pauling’s model was erroneous. The Crick – Watson model explained how DNA stores information and replicates during cell division. Their assertions were subsequently confirmed rigorously by experimentation. Crick, Watson and Wilkins received the Nobel Prize for Physiology and Medicine in 1962.
The work following the Crick – Watson model, firmly established that the DNA is a polymer string constituted of two strands made of a sugar- phosphate backbone, connected to each other by linkage nucleotide bases A, T, G, C. The base A links base T and G to C. When one strand is defined by the arrangement of bases, the complementary strand is defined. The arrangement bases store information analogously to a four-letter alphabet. Each individual in a species has a unique sequence of arrangement base pairs. The variation within the species is generally a fraction of a percent.
The Watson-Crick model also explained how the DNA molecule replicates. The two strands unwind and separate, and two complementary strands are inserted. The detailed dynamics of the replication process are not fully understood.
‘DNA is a cookbook’
DNA functions like a multiple – volume cookbook, written in a four-letter alphabet. The volumes are kept in a rack in the kitchen. The rack is the nucleus and volumes on it are the chromosomes, and the cell is the kitchen. A paragraph giving a recipe is a gene. Enzymes act as chefs, who read recipes and give instructions to cell machinery to prepare the dishes, which are proteins. The system is so complex; a complete macroscopic analogy would be impossible.
The significance of the Crick- Watson work
Until Charles Darwin proposed the idea of evolution, biology lacked a theoretical foundation. Darwin hypothesized, when organisms reproduce, the progeny inherit parental characters, but there are variations. The variants, though similar to the parents, have some new or altered characters. If these characters, originating from mutations or cross – breeding are favorable for survival in the environment, they dominate in the population, inheriting advantageous traits. Thus, random generation – to – generation, advancements of living organisms, become possible – a way of improving the design of things in a production process without a designer. Living systems store information and progeny retrieve them, when required. A bird hatched from an egg when matured, knows how to fly.
The discovery of DNA and understanding how it stores genetic information, replicates and mutates explained Darwinian evolution. A mutation is a change in the ordering of base pairs, accidentally during replication or due to external chemical or physical causes. In sexual reproduction, the offspring gets nearly half of its DNA from each parent. Consequently, the offspring does not have DNA identical to one parent. It mixes up DNA in the species. However, mutations generate new genes, driving evolution. Sexual reproduction and mutation acting in concert introduced the diversity of life on earth we see today.
Once science becomes explanatory and predictive, it opens the way for innovations. Theories of mechanics and electromagnetism formulated in the late 19th and early 20th centuries brought forth modern engineering, transforming it from an empirical craft to a scientific technological discipline. Before the discovery of DNA structure and its function, biological innovations were largely empirical. Today we have genetic engineering – genes in organisms can be manipulated. The goal of more advanced genetic engineering, referred to as synthetic biology, aims to induce major genetic changes to organisms by incorporating several genes to alter biochemical, physiological and anatomical functions. Gene technology is rapidly transforming medicine, agriculture and biotechnology. Cures have been found for diseases formerly branded incurable.
How did DNA come into existence
Life is believed to have originated in prebiotic oceans enriched with carbon and nitrogenous substances. How did DNA originate there? Today, chemists can synthesize DNA in minutes, via selective procedures, only humans can do with their knowledge. Even in a vast ocean containing trillions of times more molecular ingredients than in a test tube, a molecule as complex as DNA is most unlikely to be created by random events during the largest possible time scales of the universe. A plausible scenario would be DNA evolving from simpler self-replicating molecules such as RNA (a single strand of DNA) precursors. Unlike RNA, DNA is highly stable and good stability is necessary for the evolution of advanced forms of life.
Epigenetics
Earlier we pointed out there are two golden sayings in our culture: “Arae gathi nare” and “Jammeta wada lokuei purudha (“Hereditary characters persist” and “Habits overtake heredity “). The first is a consequence of our genetic predisposition determined by DNA and explicit genes. However, the character of an individual is also influenced by the physical, social and cultural environment. Although completely non-genetic, our children frequently follow habits we indulge in. Again, the behavior of an individual is also influenced by the physical, social and cultural environment.
The environmental factors also trigger or silence genes. The study of this important genetic effect, which does not alter the sequence of base pairs, is referred to as epigenetics. Epigenetic effects could be deleterious or beneficial. Sometimes, chronic stress causes disease, including cancer. Research suggests engagement in creative and imaginative activities, and establishes favorable epigenetic changes in the brain. Inheritance is dictated mainly by the arrangement of base pairs in DNA. Epigenetic changes involve chemical changes in DNA without altering the sequence. These alterations are erasable but allow transmission to subsequent generations.
Conclusion: World DNA day message to lawmakers
The discovery of the structure of DNA stands as one of the most significant scientific discoveries in human history. It is a lesson to all those involved in research and education, telling how great discoveries originated. It is intense curiosity, imagination and preparation rather than mere indulgence in technologies that clear the path for discovery and innovation. A society that advocates policies conducive to discoveries, also develops new technologies that follow. If we just borrow technologies from places where they originated, hoping for quick economic returns, the effort would be a gross failure. Students, determined to be the best judging from exam performance, engage in professional disciplines and perform exceptionally. Why are we short of discoveries and innovations in those disciplines? Will our lawmakers ever realize the issue? They need to wonder why we are weak in science and poor in innovation. Right policies can even reverse adverse epigenetic attributes propagating in a society!
By Prof. Kirthi Tennakone
ktenna@yahoo.co.uk
National Institute of Fundamental Studies
Features
Death of the Sperm Whale
REVIEWED BY Prof. Rajiva Wijesinha
Earlier this year, I sent her most recent book by an old friend, Kamala Wijeratne. Death of the Sperm Whale is her first book of poetry in four years, though in between she has published fiction, two books though both of them too were slim volumes. I am full of admiration for her in that she keeps going, the last of the poets whom I helped to a wider readership in the eighties, when I championed Sri Lankan writing in English, something hardly any academic was prepared to do in those conservative days.
Kamala’s subjects are those she has explored in the past, but the use of the plural indicates that her range is expansive. She dwells much on nature, but she deals also with political issues, and engages in social criticism. There are several poems about Gaza, the multiple horrors occurring there having clearly affected her deeply. She repeatedly draws attention to the slaughter of children, the infants sent by God only to be taken back. And she deals with the destruction of the life of a doctor, after his healing, a theme that has kept recurring in the ghastly world which is subject to the whims of the incredibly nasty Netanyahu.
The title poem is about a whale destroyed by ingesting plastic, a tragedy to which we all contribute, though those who ‘loll on the beach, their senses dulled by the burgers they eat’ could not care less. More immediate is the simple account of a friend whose infant had died in hospital, when they diagnosed pneumonia too late.
Contrasting with these urgent statements are Kamala’s gentle perceptions, as when she writes of her son supporting her as she walks, while she thinks back to the days she supported him; of a marigold growing in a crack in a shrine, offering obeisance with its golden flowers to the Noble One; of birds investigating her dining room and deciding not to build there, the male lingering ‘confused and irritated’ but eventually following the female through the window for ‘She was mistress after all.’
She is deeply interested in the passing of time, and its impact on our perceptions. The first poem in the book is called ‘First Poem of 2024’ when she ‘heard the weeping of the dying year’, and went on to meditate on how we have categorised the passing of time, while the universe moves on regardless.
She welcomes the return of the Avichchiya, the Indian Pitta, a bird that has figured previously in her poetry, after six months, but this time she spares a thought for his case against the peacock, which stole his plumes.
There are two personal poems, one about a former student who turned her back on her when she had achieved success, the other about being nominated for a literary award, but not getting it after the excitement of attending the Awards Ceremony. Swallowing her disappointment, she congratulates the winner, noting that she will not go into ecstasies the next time she is nominated.
Paraphrase cannot do justice to Kamala Wijeratne’s gentle touch, which has expanded its reach over the years. So,A I will end by quoting from her tribute to Punyakante Wijenaike, another of the distinguished ladies whose work I promoted, the one before the last to leave us. The tribute ends, recalling her most impressive work Giraya,
Like the nutcracker
That makes a clean cut
You cut the human psyche
To reveal its darkest depths
by Kamala Wijeratne
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