1. Overview
Melvin Ellis Calvin was a prominent American biochemist renowned for his groundbreaking work in understanding photosynthesis, particularly the Calvin cycle, which elucidates the process of carbon fixation in plants. For this pivotal discovery, made in collaboration with Andrew Benson and James Bassham, he was awarded the Nobel Prize in Chemistry in 1961. Calvin dedicated over five decades of his career to the University of California, Berkeley, where he not only conducted pioneering research but also established and directed key scientific institutions. His contributions extended beyond photosynthesis to include significant investigations into chemical evolution, the potential of oil-producing plants as renewable energy sources, organic geochemistry, and studies related to cancer and lunar samples. Throughout his life, Calvin also engaged in extensive public service, advising various government bodies and leading major scientific organizations, reflecting his commitment to applying scientific knowledge for broader societal benefit. While his scientific achievements are widely celebrated, his career also faced scrutiny, notably concerning the recognition of his collaborators' contributions to the Calvin cycle.
2. Early life and education
Melvin Calvin's early life and academic pursuits laid the foundation for his distinguished scientific career, marked by a deep curiosity and a rigorous educational path.
2.1. Birth and family background
Melvin Calvin was born on April 8, 1911, in St. Paul, Minnesota. He was the son of Elias Calvin and Rose Herwitz, who were Jewish immigrants from the Russian Empire, specifically from areas now known as Lithuania and Georgia. At a young age, his family relocated to Detroit, Michigan, where his parents operated a grocery store. Calvin's early curiosity was evident as he often explored the various products stocked on their shelves.
2.2. Education
Calvin's academic journey began after he graduated from Central High School in 1928. He then enrolled at Michigan College of Mining and Technology, now known as Michigan Technological University, where he earned the institution's first Bachelor of Science degree in chemistry in 1931. He continued his studies at the University of Minnesota, completing his Ph.D. in chemistry in 1935. Under the guidance of George Glocker, his doctoral thesis focused on the electron affinity of halogens. Following his doctoral work, Calvin was invited to join the laboratory of Michael Polanyi as a postdoctoral researcher at the University of Manchester in England. He spent two years there, from 1935 to 1937, concentrating on the study of the structure and behavior of organic molecules.
3. Career
Melvin Calvin's professional life was predominantly spent at the University of California, Berkeley, where he made his most significant scientific discoveries and established influential research institutions.
3.1. Joining UC Berkeley and Professorships
In 1937, Joel Henry Hildebrand, the director of the University of California Radiation Laboratory, invited Calvin to join the faculty at the University of California, Berkeley as an instructor. This appointment was notable as Calvin was the first non-Berkeley graduate hired by the chemistry department in over 25 years. Hildebrand encouraged Calvin to advance research in radioactive carbon, emphasizing the timeliness of such work. Calvin's initial research at UC Berkeley built upon the discoveries of Martin Kamen and Sam Ruben regarding the long-lived radioactive isotope carbon-14 in 1940.
In 1947, Calvin was promoted to Professor of Chemistry and appointed director of the Bio-Organic Chemistry group within the Lawrence Radiation Laboratory. His team included key collaborators such as Andrew Benson and James Bassham, among others. In 1963, Calvin received the additional title of Professor of Molecular Biology, reflecting the interdisciplinary nature of his expanding research.
3.2. Establishment and Direction of Research Laboratories
Calvin was the founder and first Director of the Laboratory of Chemical Biodynamics, widely known as the "Roundhouse" due to its distinctive circular design. This unique architectural choice was intended to foster collaboration and open scientific discussion among students and visiting scientists, reflecting Calvin's belief in the benefits of cross-disciplinary interaction. He actively brought in postdoctoral students and guest scientists from around the world to create a vibrant community where diverse minds and knowledge could converge. His management skills were highly regarded, with many contemporary creative scientific outlets modeling their approaches after his. Simultaneously, he served as the Associate Director of the Berkeley Radiation Laboratory, where he conducted a significant portion of his research until his retirement in 1980.
3.3. Discovery of the Calvin cycle
Calvin's most celebrated achievement was the elucidation of the carbon fixation pathway in photosynthesis, a process now universally known as the Calvin cycle.
3.3.1. Background and Methodology
The quest to understand carbon fixation began by building on the foundational research of Sam Ruben and Martin Kamen concerning the carbon-14 isotope. Their work was interrupted by Ruben's accidental death in the laboratory and Kamen's issues with the FBI and Department of State. Despite these setbacks, Ernest Lawrence, the Radiation Laboratory director, and Wendell Latimer, the Dean of Chemistry and Chemical Engineering, recognized the importance of their work and recruited Calvin in 1945 to further the research.
Initially, the lab's focus was on applying carbon-14 in medicine and synthesizing radio-labeled amino acids and biological metabolites for medical research. Calvin diligently assembled a team of skilled chemists from across the country. He then recruited Andrew Benson, who had prior experience with Ruben and Kamen on photosynthesis and carbon-14, to lead this specific research aspect within the lab. The prevailing scientific theory at the time suggested that the production of sugars and other reduced carbon compounds in photosynthesis was exclusively a "light" reaction. Benson's investigations began by attempting to isolate the product of dark carbon dioxide (CO2) fixation, aiming to crystallize radioactive succinic acid. He also conducted experiments where algae were exposed to light without CO2 and then immediately transferred to a dark flask containing CO2. The observation that radioactive sucrose was still formed at the same rate as during photosynthesis in pure light provided definitive evidence of a non-photochemical reduction of CO2.
3.3.2. Mapping Carbon Fixation
A critical challenge remained: identifying the first product of CO2 fixation. To achieve this, Calvin's team adopted paper chromatographic techniques, which had been pioneered by W.A. Stepka. This method enabled them to determine that the initial product of CO2 fixation was 3-carbon phosphoglyceric acid (PGA), a compound previously identified as a product of glucose fermentation by Ruben and Kamen.
This discovery, however, faced immediate challenge. A competing laboratory at the University of Chicago was unable to confirm Calvin's findings, leading to a strong critique of Calvin's published literature. This dispute culminated in a symposium sponsored by the American Association for the Advancement of Science, convened to resolve the conflicting claims. Despite initial resistance at the conference, Calvin and Benson successfully presented their evidence, convincing the audience of their position and dismissing the attack.
Following the identification of PGA, most other components of the glycolytic sequence were identified based on their chemical behavior, with the exception of two unknown sugars. Benson, observing their separation on paper chromatograms and examining their reactivities, recognized them as ketoses. Through the collaboration of James A. Bassham, these compounds were subjected to periodate degradation. The detection of 14% activity in the carbonyl carbon of one of the sugars led Bassham to investigate seven-carbon sugars. Despite further tests, the exact identities of these two sugars remained elusive for a time.
3.3.3. Key Findings and the Calvin-Benson-Bassham Cycle
Further experimentation revealed that restricting the uptake of CO2 led to an increase in the level of ribulose bisphosphate. This observation strongly indicated that ribulose bisphosphate was the acceptor molecule for CO2, a crucial step in the carbon fixation process. Although the precise mechanism for this was not immediately apparent, Calvin later elucidated a novel carboxylation mechanism, which led to the complete mapping of the cycle by 1958.
Using the carbon-14 isotope as a tracer, Calvin, Andrew Benson, and James Bassham meticulously mapped the entire route that carbon traverses through a plant during photosynthesis. This process begins with the absorption of atmospheric carbon dioxide and culminates in its conversion into carbohydrates and other organic compounds. Their work demonstrated that light energy acts on chlorophyll to fuel the production of organic compounds, rather than directly on carbon dioxide as previously believed. The cycle was formally named the Calvin-Benson-Bassham Cycle, acknowledging the indispensable contributions of Melvin Calvin, Andrew Benson, and James Bassham. For this monumental discovery, Calvin was awarded the 1961 Nobel Prize in Chemistry. His profound impact on the field led to him being dubbed "Mr. Photosynthesis" by Time magazine in 1961.
3.4. Other Research Areas
Beyond his seminal work on the Calvin cycle, Melvin Calvin pursued a diverse range of research interests that significantly impacted various scientific fields. He spent many years investigating the chemical evolution of life, a subject on which he authored a seminal book titled Chemical Evolution: Molecular Evolution Towards the Origin of Living Systems on the Earth and Elsewhere, published in 1969.
Calvin also dedicated considerable effort to exploring the use of oil-producing plants as sustainable and renewable energy sources, particularly in his later years of active research. His work extended into organic geochemistry, where he analyzed the chemical composition of geological samples. Furthermore, he conducted studies related to the chemistry of cancer and contributed to the analysis of lunar samples brought back from space missions, demonstrating the breadth of his scientific curiosity and expertise.
4. Public service
Throughout his career, Melvin Calvin was deeply committed to public service, holding numerous advisory and leadership positions within both government and scientific organizations.
4.1. Government Advisory Roles
Calvin served the United States government in several key advisory capacities. He was a member of the President's Science Advisory Committee from 1963 to 1966, under Presidents John F. Kennedy and Lyndon B. Johnson. He also served on the Energy Research Advisory Board, the top advisory body for the United States Department of Energy.
A significant area of his public service involved his collaboration with NASA. He played a crucial role in developing plans to safeguard the Moon from biological contamination originating from Earth, and conversely, to protect Earth from potential contamination from lunar samples during the Apollo missions. Additionally, he contributed to strategies for the safe return of lunar samples and for the detection of biological life on other planets.
4.2. Leadership in Scientific Societies
Calvin held leadership roles in several prominent scientific organizations. He served as president of the American Chemical Society, the American Society of Plant Physiology, and the Pacific Division of the American Association for the Advancement of Science. He also chaired the Committee on Science and Public Policy for the National Academy of Sciences.
His influence extended to international scientific committees and organizations, including the Joint Commission on Applied Radioactivity of the International Union of Pure and Applied Chemistry, the U.S. Committee of the International Union of Biochemistry, and the Commission on Molecular Biophysics of the International Organization for Pure and Applied Biophysics. His contributions were recognized through his election to prestigious bodies such as the National Academy of Sciences, the Royal Society of London, the Royal Netherlands Academy of Arts and Sciences, the American Academy of Arts and Sciences, the German Academy of Sciences Leopoldina, and the American Philosophical Society.
5. Controversy
Despite his significant scientific achievements, Melvin Calvin's career was not without controversy, particularly concerning the appropriate attribution of credit for the discovery of the Calvin cycle.
5.1. Dispute over Credit with Andrew Benson
A notable dispute arose regarding the recognition of contributions to the Calvin cycle, primarily involving his collaborator, Andrew Benson. In a 2011 television history of Botany for the BBC, Timothy Walker, who was the Director of the University of Oxford Botanic Garden, openly criticized Calvin's treatment of Benson. Walker alleged that Calvin had taken undue credit for Benson's work after dismissing him from the laboratory. Furthermore, Walker pointed out that Calvin failed to acknowledge Benson's significant role when writing his autobiography, Following the Trail of Light, decades later.
Andrew Benson himself corroborated these claims. In an interview transcript from 2012, Benson confirmed that he was indeed "fired" by Calvin. He also expressed his disappointment about being omitted from Calvin's autobiography, stating that while the book was beautifully titled and focused on Calvin's path to the Nobel Prize, it made no mention of Benson. Benson noted that in one of Calvin's very last publications, he briefly mentioned "Dr. Benson and some graduate students were involved," but this was a minimal acknowledgment. This controversy highlights a critical perspective on how contributions in collaborative scientific endeavors are sometimes attributed and recognized.
6. Personal life
Melvin Calvin's personal life was centered around his family.
6.1. Marriage and Family
In 1942, Melvin Calvin married Marie Genevieve Jemtegaard. Together, they had four children: three daughters named Elin, Sowie, and Karole, and a son named Noel.
7. Honours and Legacy
Melvin Calvin received numerous awards and honors throughout his career, cementing his legacy as one of the most influential biochemists of the 20th century.
7.1. Major Awards and Recognition
Calvin's most significant accolade was the Nobel Prize in Chemistry, awarded to him in 1961 for his research on the assimilation of carbon dioxide in plants. Beyond the Nobel Prize, he received a multitude of other prestigious awards:
- 1954: Elected to the National Academy of Sciences (United States)
- 1955: Awarded the Centenary Prize by the Royal Society of Chemistry
- 1957: Awarded the Remsen Award
- 1958: Elected a foreign member of the Royal Netherlands Academy of Arts and Sciences
- 1958: Elected to the American Academy of Arts and Sciences
- 1959: Elected a Member of the German Academy of Sciences Leopoldina
- 1960: Elected to the American Philosophical Society
- 1964: Awarded the Davy Medal of the Royal Society
- 1965: Awarded the Bakerian Medal of the Royal Society
- 1971: Received an Honorary Doctor of Laws (LL.D.) degree from Whittier College
- 1977: Awarded the Willard Gibbs Award by the American Chemical Society
- 1978: Received the Priestley Medal of the American Chemical Society
- 1979: Awarded the American Institute of Chemists Gold Medal
- 1989: Awarded the National Medal of Science
In addition to these, Calvin was granted 13 other honorary degrees from various institutions worldwide.
7.2. Scientific Impact and Legacy
Melvin Calvin's research had an enduring influence on several scientific disciplines. His elucidation of the Calvin cycle fundamentally transformed the understanding of photosynthesis, providing a detailed biochemical pathway for carbon fixation. This work laid the groundwork for countless subsequent studies in plant physiology, biochemistry, and molecular biology. His pioneering investigations into chemical evolution significantly contributed to theories on the origin of life on Earth and potentially elsewhere in the universe. Furthermore, his later work on utilizing oil-producing plants as renewable energy sources underscored his foresight in addressing global energy challenges and continues to inspire research in biofuels and sustainable energy. His contributions to organic geochemistry, the chemistry of cancer, and the analysis of lunar samples further demonstrate the breadth and depth of his scientific curiosity and impact.
7.3. Commemorations
In recognition of his monumental achievements, Melvin Calvin was honored on a United States postage stamp in 2011. He was featured in the "American Scientists" collection of U.S. postage stamps, alongside other distinguished scientists such as Asa Gray, Maria Goeppert-Mayer, and Severo Ochoa. This was the third volume in the series, with previous volumes released in 2005 and 2008.
8. Death
Melvin Calvin passed away on January 8, 1997, at the age of 85. His death was attributed to heart failure.