George Karreman (1921–1997) was a seminal figure in the mid-20th-century movement to transform biology from a purely descriptive discipline into a rigorous, predictive science. As a mathematical biophysicist, Karreman applied the tools of theoretical physics and quantum mechanics to the complexities of living systems, leaving an indelible mark on our understanding of cardiovascular dynamics and cellular physiology.
1. Biography: From Leiden to the Vanguard of Mathematical Biology
George Karreman was born on November 19, 1921, in Goudriaan, the Netherlands. His early intellectual development was shaped by the rigorous European tradition of theoretical physics. He began his higher education at the University of Leiden, a historic center for physics research. However, the disruptions of World War II eventually led him to the United States, where he would spend the remainder of his career.
In the late 1940s, Karreman joined the University of Chicago’s Committee on Mathematical Biology, the world’s first formal program dedicated to the field, founded by the visionary Nicolas Rashevsky. Under Rashevsky’s mentorship, Karreman earned his Ph.D. in 1951.
His academic trajectory took him from Chicago to the University of Pennsylvania (UPenn) in the late 1950s. At UPenn, he served as a Professor of Physiology at the School of Medicine and held a senior research position at the Bockus Research Institute. He remained a fixture at UPenn for decades, bridging the gap between the medical school and the physics department until his retirement. Karreman passed away on September 30, 1997, in Pennsylvania.
2. Major Contributions: The Physics of Life
Karreman’s work was characterized by an attempt to find the mathematical "laws of motion" for biological entities. His contributions span three primary areas:
Mathematical Hemodynamics
Karreman was a pioneer in modeling the cardiovascular system. He developed sophisticated differential equations to describe blood flow (rheology) and the elastic properties of arteries. His models helped explain how the heart’s pulsatile energy is dissipated or preserved through the vascular tree.
Quantum Biology
Decades before "quantum biology" became a popular buzzword, Karreman was investigating the electronic aspects of biochemical reactions. He sought to understand how subatomic particle behavior—specifically electron excitation and transfer—governed the behavior of enzymes and metabolic pathways.
The Association-Induction Hypothesis
Perhaps his most significant theoretical work was providing the mathematical framework for Gilbert Ling’s "Association-Induction (AI) Hypothesis." This theory challenged the traditional "sodium pump" model of the cell, suggesting instead that the cell is a high-energy structured system where water and ions are adsorbed onto proteins in a cooperative, polarized state.
3. Notable Publications
Karreman’s bibliography is extensive, primarily appearing in the Bulletin of Mathematical Biophysics (now the Bulletin of Mathematical Biology). Key works include:
- "Contributions to the Mathematical Biology of the Heart" (1949): One of his earliest significant papers, establishing a theoretical basis for cardiac contraction cycles.
- "The Mathematical Biology of Blood Pressure" (1954): A foundational text in physiological modeling that treated the vascular system as a complex physical circuit.
- "Electronic Aspects of Biochemistry" (1964): Co-edited with Bernard and Alberte Pullman, this work was a cornerstone in the early study of quantum effects in biological molecules.
- "Cooperative Specific Adsorption" (1964): Published in Federation Proceedings, this paper provided the statistical mechanical proof for the AI Hypothesis, demonstrating how cells could switch states (like a transistor) through cooperative protein-ion interactions.
4. Awards and Recognition
While Karreman did not seek the limelight, his peers recognized him as a foundational architect of his field:
- President of the Society for Mathematical Biology (1973–1975): He served as the leader of the primary international body for his discipline.
- Fellow of the American Association for the Advancement of Science (AAAS): Elected for his contributions to the integration of physics and physiology.
- The Nicolas Rashevsky Award: He was honored for his lifetime of research and his role in sustaining the Chicago school of mathematical biology.
5. Impact and Legacy
Karreman’s legacy is found in the modern shift toward Systems Biology. He was among the first to argue that biological functions cannot be understood by looking at isolated molecules but must be viewed as "integrated systems" governed by physical constants.
His work on the AI Hypothesis remains a subject of intense interest among a subset of biophysicists who study the "structured water" theory of the cell. Furthermore, his mathematical models of the heart and circulatory system laid the groundwork for the computational hemodynamics used today in designing artificial heart valves and stents.
6. Collaborations: A Bridge Between Giants
Karreman’s career was defined by his work with other "renegade" geniuses of science:
Nicolas Rashevsky
As Rashevsky’s protégé, Karreman helped formalize the "Relational Biology" framework, which uses topology to describe life.
Albert Szent-Györgyi
Karreman collaborated with the Nobel Prize-winning discoverer of Vitamin C. Together, they explored the role of electronic conduction in proteins, a field Szent-Györgyi called "Submolecular Biology."
Gilbert Ling
Karreman was the "mathematical engine" behind Ling’s controversial theories. While Ling provided the experimental data on cellular ions, Karreman provided the rigorous statistical mechanics that made the theory scientifically viable.
7. Lesser-Known Facts
The "Cell as a Transistor"
Karreman was one of the first to suggest that biological cells might operate similarly to solid-state electronic devices. He proposed that proteins act as semiconductors and that the cell's "switch" from a resting to an active state was a physical phase transition.
A Lifelong Mentor
Despite the density of his mathematical work, Karreman was known at UPenn for his patience with medical students, often spending hours helping them understand the physics behind the physiological phenomena they were seeing in the clinic.
Philosophical Bent
Karreman was deeply interested in the philosophical implications of his work, often debating whether life could ever be fully reduced to equations or if there was a "relational" quality to living things that transcended pure physics.
George Karreman remains a towering, if sometimes overlooked, figure whose work ensured that the "soft" science of biology would eventually acquire the "hard" mathematical rigor of physics.