Robert May, an Australian-born scientist whose mathematical insights blazed new paths in fields as diverse as ecology, epidemiology and the structure of financial systems, died on April 28 in a nursing home in Oxford, England. He was 84.
His wife, Judith May, said in an email that his death certificate cited “frailties of old age, Alzheimer’s disease and pneumonia.”
The breadth of Dr. May’s work across three continents and at institutions like Princeton University, Oxford University and Imperial College London dazzled scientists in the varied fields that his intellect touched. “He had many careers, one piled on top of the other,” said John Terborgh, an emeritus professor of environmental science at Duke University, “and absolutely extraordinary in all of them.”
Dr. May once put it less grandly. “I have a short attention span,” he told APS News, a publication of the American Physical Society. “If you have a good background in theoretical physics, you can do anything.”
Of course it was more than that. “Science is full of people who do great work in their areas, but don’t see what we lay people call the big picture,” the author James Gleick said. “Bob May definitely did.”
Mr. Gleick featured Dr. May in his book about the study of complexity, “Chaos: Making a New Science” (1987). In an interview, he called Dr. May “one of the very small handful of seminal figures in that field.”
Dr. May showed an uncanny knack for identifying key problems in the fields of study he focused on and for developing simple mathematical models that could deepen understanding of them. When he came to ecology in the 1970s, the discipline was largely built on empirical observation in the field, and conventional wisdom held that a rich, complex ecosystem was inherently more stable than one with fewer organisms. Dr. May’s models suggested the opposite: The larger the number of species, the less stable the environment might be, with potentially wild population swings.
The power of the models lay, in turn, in their reliance on information from the empiricists. “Bob had a respect for the muddy-boots types,” Dr. Rubenstein said. “Anybody can build a model, but if you don’t tune it with realistic parameters, it’s not going to be helpful.”
From ecology, Dr. May moved to the study of infectious diseases, embarking on a fruitful collaboration with Roy Anderson, a professor of epidemiology at Imperial College London. They would write more than 80 papers together.
In an interview, Dr. Anderson said that Dr. May’s gift for translating exceedingly difficult problems into useful equations relied in part on his physics background. He “wasn’t afraid to make approximations to get some analytical insight,” Dr. Anderson said. A pure mathematician might have required greater precision.
Together Dr. May and Dr. Anderson focused on mad cow disease — bovine spongiform encephalopathy. They created models projecting the spread of H.I.V. in the sub-Saharan region of Africa, arriving closer to the mark than more optimistic estimates by the World Health Organization. And they helped define the variable known as R0 (pronounced R-naught) in estimating the number of new infections that would spread from a single case of an illness.
Such work resonates with today’s new coronavirus, said John Krebs, an Oxford colleague of Dr. May’s. “Their analytical models helped to highlight the crucial importance of this variable,” he said.
Dr. May cast his net even wider in 1976 in a groundbreaking paper, “Simple Mathematical Models With Very Complicated Dynamics,” suggesting that the kinds of equations he had been working on “arise in many contexts in biological, economic and social sciences.” Mr. Gleick called it a rallying cry to scientists in those fields, telling them: “You might use a simple model and find weird behavior and ignore it. But you shouldn’t ignore it, because that very weirdness is significant.”
After the financial collapse of the late 2000s, he collaborated with Andrew G. Haldane, the Bank of England’s chief economist, on another seminal paper, “Systemic Risk in Banking Economics” (2011), showing that once again “too much complexity implies instability.”
Colleagues recalled that throughout his career, tact was not among Dr. May’s strong points. Prof. Georgina Mace, an ecologist and conservation scientist at University College London and a former colleague of Dr. May’s, recalled in an article after Dr. May’s death, “It was both inspiring and terrifying to face his penetrating analyses and not always gentle critiques.”
She added, however, that he showed great generosity and encouragement. “His general support to women in science has benefited many of us,” she said.
Dr. May was elected a fellow of the Royal Society in 1979 and was its president from 2000 to 2005. He accepted joint posts at Oxford and Imperial College in 1988. He was knighted in 1996 and became a peer, Baron May of Oxford, in 2001. From 1995 to 2000 he was chief scientific adviser to Prime Ministers John Major and Tony Blair.
As science adviser to 10 Downing Street he took what had been a low-profile post and made it a soapbox for sound science, “speaking very clearly and bluntly,” said Dr. Krebs, who also served in government. Dr. May became a vocal proponent of taking urgent action on climate change, a topic he pursued as a founding member of Britain’s independent Committee on Climate Change, serving on it from 2008 until 2016.
“Bob May was one of the most outspoken and capable defenders of the role of scientific expertise — something that is now widely questioned,” said the author Edward Tenner, a former colleague at Princeton and now a visiting scholar at the Institute for Advanced Study in Princeton, N.J. “Bob had the personality to stand up to people who challenged science on ideological grounds.”
Robert McCredie May was born on Jan. 8, 1936, in Sydney to Henry W. and Kathleen M. (McCredie) May. His father was a barrister and an alcoholic who left the family when Robert was young; his mother raised him and his younger brother, Ronald.
He attended the University of Sydney, earning a bachelor’s of science in physics and mathematics in 1956 and a Ph.D. in physics in 1959, focusing on superconductivity. He did postdoctoral work at Harvard University, where, on a blind date, he met Judith Feiner, an undergraduate at Brandeis University. They married in August 1962 and had a daughter, Nome. Both survive him, as does Ronald May.
Dr. May was an avid runner and hiker, organizing group walks with colleagues in the mountains of England and Wales as well as weekslong mountain treks in Europe. He could be voraciously competitive.
One friend recalled that during one hiking trip, with his party snowed in, “Bob went off to play chess with a 10-year-old.”
As the world-famous scientist walked back into the room, he announced, “I won.”