Bob May at the Santa Fe Institute

Robert McCredie May, OM, the Lord May of Oxford, and a leading figure of theoretical ecology, died on April 28, 2020. Bob, as he was known to his many friends and colleagues, was 84 years old.

May referred to himself as an r-selected scientist: an early-stage person who liked to work in fields where he could do “nice, simple things that are important.” This self-assessment understates May’s prodigious works but aptly summarizes a career in fundamental and applied research that boasted contributions to physics, astrophysics, theoretical ecology, population biology, host-parasite and infectious disease dynamics, biodiversity, and finance.

“Bob was driven by finding grand unifying theories of ecological systems,” says Simon Levin, a member of SFI's science board and the James S. McDonnell Distinguished University Professor in Ecology and Evolutionary Biology at Princeton University, and a collaborator of May. “He was driven by the view that there were similarities among systems, and that those similarities can help us develop unifying theories.”

This commitment to understanding complex systems helped May work across fields and transcend disciplines. Jennifer Dunne, the Vice President for Science at the Santa Fe Institute, noted that while May was not one of the founders of SFI, “he helped to create the intellectual landscape that led to SFI.” May was a longtime member and past Chair of the Santa Fe Institute Science Board and the featured speaker of SFI’s 2012 Stanislaw Ulam Memorial Lecture Series.

“He was hugely supportive of the Institute, always a man of strong opinions and a breath of fresh air liberally sprinkled with appropriate expletives,” said Distinguished Shannan Professor and Past President Geoffrey West, who regards May as part of a “second wave of founding fathers” at SFI. “I will miss his feisty dialogues and friendship. A tremendous loss."

The brilliance of his contributions, combined with May’s dedication to service, garnered him countless accolades and titles. May was named Knight Bachelor in 1996, Companion of the Order of Australia in 1998, and to the Order of Merit (OM) of 2002. In his distinguished career, he received, among others: the Royal Swedish Academy’s Crafoord Prize, ecological science’s equivalent of a Nobel Prize; the Swiss-Italian Balzan Prize for “seminal contributions to understanding biodiversity”; the Japanese Blue Planet Prize “for developing fundamental tools for ecological conservation planning”; and the Royal Society’s Copley Medal, its oldest and most prestigious award given annually for outstanding achievements in research in any branch of science.

May was President of The Royal Society, Chief Scientific Adviser to the United Kingdom Government, Head of the United Kingdom Office of Science and Technology, a Fellow of Merton College at Oxford, a Fellow of the Australian Academy of Sciences, and a Foreign Associate of the U.S. National Academy of Sciences.

Inspired by his high school chemistry teacher, May studied Chemical Engineering at the University of Sydney (BSc, 1959), where he later completed a Ph.D. in theoretical physics (1959). It was May’s work in ecology, however, that earned him international recognition from the scientific community.

An admitted “accidental ecologist,” May’s first foray into the ecological sciences yielded one of the most significant achievements of his career. Intrigued by the popular idea at the time that complicated ecosystems are inherently more stable, May challenged the stability paradigm in a 1972 article in Nature entitled, “Will a Large Complex System be Stable?” In the article, May used a corollary of Wigner’s Theorem on the eigenvalues of block random matrices to mathematically demonstrate that, in model ecosystems, stability actually decreases with the number of species in a community. The Nature article served as a precursor to May’s seminal 1973 work, “Stability and Complexity in Model Ecosystems,” in which he further delved into the mathematical modeling of ecosystems. The results suggested that the relationship between complexity and stability was not as straightforward as earlier studies had argued. The significance of the work was such that May’s name is now coupled to the May-Wigner stability theorem. The book immediately became, as one reviewer wrote, “an authoritative summary of the efforts of mathematical ecologists” to simulate ecosystems.

External Professor Andrew Dobson, a professor of ecology and evolutionary biology at Princeton University and a friend and colleague of May’s, noted that the book, “set the agenda [for theoretical ecology] for more than 25 years after its publication.”

May’s work on ecological stability eventually shepherded him into the study of infectious diseases. While at a meeting on ecological stability at York University, in 1975, May met Roy Anderson, a professor of infectious disease epidemiology at Imperial College. Over the next 20 years, the pair pioneered much of the mathematical theory that shapes our understanding of how infectious diseases operate at the population level and how best to define optimal control strategies for infections of humans. May and Anderson’s work informed many aspects of public health including vaccination control strategies for common childhood infections like measles, mumps, and rubella to vector-borne diseases like malaria that afflict millions of people around the world. Their 1992 book, “Infectious Diseases of Humans,” remains an essential read for public health students and professionals.

May and Anderson published timely and impactful research. Widespread outbreaks in the United Kingdom inspired their work on Bovine Spongiform Encephalopathy (BSE, or “mad cow disease”), and they later turned an eye toward foot and mouth disease, which erupted in 2002. The pair were among the first to model the spread of HIV within human populations and between sub-groups of people with different sexual practices or use of IV-drugs. Their models of viral, bacterial, and protozoan pathogens are used to guide vaccine administration at the population level and has been used to fight African Ebola epidemics.

Toward the end of his career, May pivoted from biology and turned his attention to analyzing the stability and robustness of financial systems. In 2011, he co-authored an influential paper on “Systemic risk in banking ecosystems” with Andy Haldane, the Chief Economist at the Bank of England. A year later, May shared those insights in his public talk on “What is Stability in Today’s Complex Financial Systems?” the second of three Stanislaw Ulam Memorial Lectures on “The Many Faces of Complexity.”

Among friends, May was known for his generosity, competitiveness, and brilliance.

“If Bob didn’t think much of your work, you didn’t want to be on the other side. But if he liked what you did, he was a terrific colleague and mentor,” says Levin.

May was an avid runner and ping pong player. He prided himself for his prowess at real tennis, a predecessor to modern tennis that is primarily played in Great Britain. An oft-quoted anecdote, attributed to May’s wife, Judith, best sums up May’s competitiveness: “Bob would come home and play with the dog—but you better believe that he’d be playing to win.”

May is survived by his wife, Judith, and his daughter, Naomi. He leaves behind an adoring community of family, friends, and colleagues, as well as an outsized influence on science.

Says Dunne, “He was a towering intellect, and his loss is a loss to humanity.”

Read the obituary in The Guardian (April 29, 2020)

Read the obituary in The Australian (May 2, 2020)