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Sir Alan Lloyd Hodgkin (5 February 1914 – 20 December 1998) was a British physiology and biophysics who shared the 1963 Nobel Prize in Physiology or Medicine with Andrew Huxley and John Eccles.
Because of poor eyesight, he was unable to study medicine and eventually ended up working for a bank in Banbury. As members of the Quakers, George and Mary opposed the Military Service Act of 1916, which introduced conscription, and had to endure a great deal of abuse from their local community, including an attempt to throw George in one of the town canals. In 1916, George Hodgkin travelled to Armenia as part of an investigation of distress. Moved by the misery and suffering of Armenian refugees he attempted to go back there in 1918 on a route through the Persian Gulf (as the northern route was closed because of the October Revolution in Russia). He died of dysentery in Baghdad on 24 June 1918, just a few weeks after his youngest son, Keith, had been born.
From an early life on, Hodgkin and his brothers were encouraged to explore the country around their home, which instilled in Alan an interest in Natural History, particularly ornithology. At the age of 15, he helped Wilfred Backhouse Alexander with surveys of Heronry and later, at Gresham's School, he overlapped and spent a lot of time with David Lack. In 1930, he was the winner of a bronze medal in the Public Schools Essay Competition organised by the Royal Society for the Protection of Birds. Protection of Birds Measures Urged By Royal Society in The Times, Saturday, 29 March 1930; pg. 14; Issue 45474; col C
Between school and college, he spent May 1932 at the Freshwater Biological Station at Wray Castle based on a recommendation of his future Director of Studies at Trinity, Carl Pantin. After Wray Castle, he spent two months with a German family in Frankfurt as "in those days it was thought highly desirable that anyone intending to read science should have a reasonable knowledge of German." After his return to England in early August 1932, his mother Mary was remarried to Lionel Smith (1880–1972), the eldest son of A. L. Smith, whose daughter Dorothy was also married to Alan's uncle Robert Howard Hodgkin.
In the autumn of 1932, Hodgkin started as a freshman scholar at Trinity College where his friends included Classics John Raven and Michael Grant, fellow-scientists Richard Synge and John H. Humphrey, as well as Polly and David Hill, the children of Nobel laureate Archibald Hill. He took physiology with chemistry and zoology for the first two years, including lectures by Nobel laureate Edgar Adrian. For Part II of the tripos he decided to focus on physiology instead of zoology. Nevertheless, he participated in a zoological expedition to the Atlas Mountains in Morocco led by John Pringle in 1934. He finished Part II of the tripos in July 1935 and stayed at Trinity as a research fellow.
During his studies, Hodgkin, who described himself as "having been brought up as a supporter of the British Labour Party" was friends with communists and actively participated in the distribution of anti-war pamphlets. At Cambridge, he knew James Klugmann and John Cornford, but he emphasised in his autobiography that none of his friends "made any serious effort to convert me to, either then or later." From 1935 to 1937, Hodgkin was a member of the Cambridge Apostles.
After his return to Cambridge he started collaborating with Andrew Huxley who had entered Trinity as a freshman in 1935, three years after Hodgkin. With a £300 equipment grant from the Rockefeller Foundation, Hodgkin managed to set up a similar physiology setup to the one he had worked with at the Rockefeller Institute. He moved all his equipment to the Plymouth Marine Laboratory in July 1939. There, he and Huxley managed to insert a fine cannula into the giant axon of squids and record action potentials from inside the nerve fibre. They sent a short note of their success to Nature just before the outbreak of World War II.
Providing a readable account of the little-known piece of military history that he was a part of during World War II was a main motivation for Hodgkin to write his autobiography Chance and Design: Reminiscences of Science in Peace and War.
After being released from military service in August 1945 upon Edgar Adrian request, Hodgkin was able to restart his experiments in collaboration with Bernard Katz and his pre-war collaborator Andrew Huxley. They spent the summers of 1947, 1948, and 1949 at the Plymouth Marine Laboratory where they continued to measure resting and action potentials from inside the giant axon of the squid. Together with Katz, he provided evidence that the permeability of the neuronal cell membrane for sodium increased during an action potential, thus allowing sodium ions to diffuse inward. The data they had obtained in 1949 resulted in a series of five papers published in The Journal of Physiology that described what became later known as the Hodgkin–Huxley model of the action potential and eventually earned Hodgkin and Huxley the Nobel Prize in Physiology or Medicine. Building on work by Kenneth S. Cole they used a technique of electrophysiology, known as the voltage clamp to measure ionic currents through the membranes of squid axons while holding the membrane voltage at a set level. They proposed that the characteristic shape of the action potential is caused by changes in the selective permeability of the membrane for different ions, specifically sodium, potassium, and chloride. A model that relies on a set of differential equations and describes each component of an excitable cell as an electrical element was in good agreement with their empirical measurements.
The cell membrane depolarisation sequence where a small depolarization leads to an increase in sodium permeability, which leads to influx of sodium ions, which in turn depolarizes the membrane even more is now known as the Hodgkin cycle.
In addition, Hodgkin and Huxley's findings led them to hypothesize the existence of on cell membranes, which were confirmed only decades later. Confirmation of ion channels came with the development of the patch clamp leading to a Nobel prize in 1991 for Erwin Neher and Bert Sakmann, and in 2003 for Roderick MacKinnon.
After establishing ion movements across a selectively permeable cell membrane as the mechanism of the action potential, Hodgkin turned his attention to how the ionic interchange that occurs during the action potential could be reversed afterwards. Together with Richard Keynes he demonstrated that in addition to the changes in permeability that lead to an action potential, there is a secretory mechanism that ejects sodium and absorbs potassium against the electrochemical gradients. A few years later, the Danish scientist Jens Christian Skou discovered the enzyme Na+/K+-ATPase that uses ATP to export three sodium ions in exchange for two potassium ions that are imported, for which he received the Nobel Prize in Chemistry in 1997.
Hodgkin was nominated for the Nobel Prize in Physiology or Medicine in 1953 by Edgar Adrian. In October 1961, he was told by Swedish journalists that he, Andrew Huxley, and Eccles had been awarded the Nobel Prize. This turned out to be a false alarm, however, when shortly thereafter it was announced that the 1961 Prize was awarded to Georg von Békésy. It was only two years later that Hodgkin, Andrew Huxley, and Eccles were finally awarded the Prize "for their discoveries concerning the ionic mechanisms involved in excitation and inhibition in the peripheral and central portions of the nerve cell membrane". During the Nobel Banquet on 10 December 1963, Hodgkin gave the traditional speech on behalf of the three neurophysiologists, thanking the king and the Nobel Committee for Physiology or Medicine for the award. Incidentally, Hodgkin and his wife attended the Nobel Prize ceremony a second time, three years later, when Hodgkin's father-in-law, Francis Peyton Rous, was awarded the 1966 Nobel Prize in Physiology or Medicine.
From 1970 to 1975 Hodgkin served as the 53rd president of the Royal Society (PRS). During his tenure as PRS, he was knighted in 1972 and admitted into the Order of Merit in 1973. From 1978 to 1985 he was the 34th Master of Trinity College, Cambridge.
He served on the Royal Society Council from 1958 to 1960 and on the Medical Research Council from 1959 to 1963. He was foreign secretary of the Physiological Society from 1961 to 1967. He also held additional administrative posts such as Chancellor, University of Leicester, from 1971 to 1984
A portrait of Hodgkin by Michael Noakes hangs in Trinity College's collection.
Their first daughter, Sarah, was born in April 1945, shortly before the Hodgkins moved back to Cambridge. They had three more children: Deborah Hodgkin (born 2 May 1947), Jonathan Hodgkin (born 24 August 1949), and Rachel Hodgkin (born June 1951). Marni became a Children's Book Editor at Macmillan Publishing Company and a successful writer of children's literature, including Young Winter's Tales and Dead Indeed. Jonathan Hodgkin became a molecular biologist at Cambridge University. Deborah Hodgkin is also a successful psychologist.
Thomas Hodgkin (1798–1866), who first described Hodgkin's lymphoma, was Alan Hodgkin's great-uncle.
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