SFI External Faculty Fellow Peter Schuster, one of the world’s leading theoretical chemists whose work laid the foundation for many research directions at SFI, died on June 14, 2026. He was 85. He is survived by his wife, Inge, and son, Manfred.
Based in Austria, Schuster was prominent in European scientific life, serving as the Austrian Academy of Science’s Vice President from 2000–2003 and President from 2006–2009 and leading the Institute for Theoretical Chemistry at the University of Vienna for several decades. He was a prolific author, with nearly 400 scientific papers and 15 books to his name, and contributed as an editor to multiple journals, including Complexity, where he served as Editor-in-Chief from 2002–2016 and contributed more than 30 essays since the journal's launch in 1995. Inge, who is also a chemist, has shared many of these on her ScienceBlog and plans to turn them into a book. "They give an easily understandable overview on Peter's work and concepts," she says.
Early in his career, Schuster was a postdoctoral fellow at the Max Planck Institute for Physical Chemistry in Göttingen, Germany, where Manfred Eigen was director. Eigen had just won a Nobel Prize in chemistry for techniques to measure extremely fast chemical reactions — techniques that would help propel the field of molecular biology. Schuster and Eigen began a collaboration that continued for years after Schuster’s postdoc ended, and they “began to develop a dynamic theory of the self-organization of matter,” writes Inge in her obituary for Peter.
Together, Eigen and Schuster expanded on Eigen’s mathematical formulation of hypercycles — self-replicating molecules like RNA that are connected through self-sustaining, autocatalytic reactions — in their 1979 book The Hypercycle. And in 1989, Eigen, Schuster, and John McCaskill provided a rigorous and fairly complete mathematical understanding of the idea of a molecular quasi-species — a “cloud” of related, but mutated, genotypes — posing a chemical–kinetic theory for the origin of life. Hypercycles and quasi-species would become the foundation for novel ways of thinking about biological evolution, robustness, and life itself.
While Schuster’s work led to new understandings of how life evolves, his ideas have themselves evolved among students he taught directly and those influenced by his work, says SFI External Professor Aviv Bergman (Albert Einstein College of Medicine). “[His students] have carried Peter’s intellectual tradition into very different territories. The ideas have taken on a life of their own, mutating, traveling through generations, and finding new expression in those who inherit them.”
Walter Fontana (Harvard Medical School), a former SFI Resident and later, External Professor, who met Schuster while pursuing his Ph.D. at the University of Vienna, is one of those students. The German term for a Ph.D. advisor is Doktorvater — essentially, doctorate father — calling to mind notions of family, and reflecting the close relationship between supervisor and student, much like a master craftsman and an apprentice. “As an academic father, Peter was not merely a professional mentor; he was also a patron, a witness, an advocate, and someone who opened doors for my academic career,” says Fontana.
During a postdoctoral fellowship at Los Alamos National Laboratory in the lab of Doyne Farmer (now an SFI External Professor based at Oxford University) in 1989, Fontana spent significant time “down the hill” at SFI’s offices, eventually pursuing a second postdoc at SFI. “It was fairly natural that I would help connect SFI to my Viennese network. Peter began visiting with some regularity, and so did [now SFI External Professor] Peter Stadler.” In 1991, Schuster became a Researcher in Residence, and in 1992, joined SFI’s External Faculty.
In one of their foundational collaborations, Schuster and Fontana worked to expand on Eigen and Schuster’s quasi-species theory to model a fitness landscape based on RNA folding. “This might have been the first computational model of a biophysically anchored genotype-to-phenotype map,” says Fontana; their work modeled how various RNA molecules, each with one or two mutations from the others, might produce the same folded protein or catalyze the same chemical reactions. In their 1994 paper “From sequences to shapes and back: a case study in RNA secondary structures,” Fontana, Schuster, Stadler, and Ivo Hofacker modeled a network of these related molecules such that any individual was separated by one or two mutations, spreading across what they called a “neutral network.”
For SFI External Professor Andreas Wagner (University of Zurich), this work had profound consequences for understanding how evolution can explore a genotype space, “because it can lead to astronomical numbers of different genotypes while preserving a phenotype, and some of those genotypes might be close to novel molecules that do useful and new things.” In 1993, Wagner was a Ph.D. student at Yale when he heard Fontana present this work, just before its publication. This opened a path for Wagner and others to understand how organisms may find a variety of evolutionary solutions to the same problem. “Until this point, mainstream evolutionary biology was dominated by an interpretation of the world that had been established in the 1920s. Peter Schuster’s take on evolution was completely different. It came not from biology, but from biophysics and biochemistry, and that opened completely new horizons.”
Schuster’s work researching the origins of life from a physics-inspired minimal-model approach fit well with SFI’s early work, says Stadler (University of Leipzig), who was among Schuster’s Ph.D. advisees at the University of Vienna. While notions about complexity and interdisciplinary work have evolved since the early ‘90s — a time when complexity science was understood primarily as transferring methodology from physics onto other fields — the cross-disciplinary conversations happening in Santa Fe were nonetheless unusual in academia, says Stadler. “Being part of SFI was very important to my scientific socialization, and this goes back to what I learned from Peter — you know, ‘this is not my field’ is not an argument. Nature doesn’t care how universities organize departments, and you have to use whatever tools are available to solve the problem you are working on.”
Fontana agrees. As he sees it, Schuster’s influence on SFI was an inevitability. “Peter had to become an important presence in the early days of SFI because of how he contributed to and fit into the prevailing paradigms,” says Fontana. “The quest for understanding what complexity is about has, I believe, barely begun. Beyond the feat of solving well-posed problems, the foundations that Peter and others laid at the dawn of SFI provide a firm ground from which we can better frame the questions that lie ahead.”
Read Ivo Hofacker’s obituary for Schuster through the University of Vienna: https://chemie.univie.ac.at/wissensaustausch/news/detail/news/in-memoriam-peter-schuster-1941-2026/