Obituary of Manfred Eigen

Manfred Eigen was a German chemical physicist who made seminal contributions to chemical kinetics, biophysics, and molecular evolution. He died on 6 February 2019 at age 91.

Eigen was born in Bochum on 9 May 1927. His formal studies were interrupted by World War II. But he was able to resume his education immediately after the war, joining the University of Göttingen right at the time the institution reopened its doors.

Eigen’s career took a meteoric rise when in the early 1960s he showed the world how to measure ultrafast chemical reactions, occurring in submicrosecond or even nanosecond timescales. Eigen took up what at the time was regarded as a major challenge, since those reactions were faster than the mixing timescale required for the reactants to be fully combined and thus were deemed essentially unmeasurable. Particularly opaque were the proton transfer reactions in aqueous media, which are ubiquitous in biochemical processes. In a brilliant turn, Eigen let the reaction achieve equilibrium and perturbed this state with an ultrafast sonic or light pulse, monitoring the system’s relaxation back to equilibrium. Thus, the relaxation parameters provided the necessary information to obtain the reaction rates and even provided mechanistic insights on how the reactions took place. Eigen presented this research in 1964 at the Faraday Society in London and achieved instant fame as one of the foremost experimentalists of his day. That same year he became head of the Max Planck Institute in Göttingen, later to become the Max Planck Institute for Biophysical Chemistry. In 1967, Eigen was awarded, along with Ronald Norrish and George Porter, the Nobel Prize in Chemistry for his work on ultrafast reaction measurements.

In the 1970s Eigen’s research took a different direction. He became more involved in the field of molecular evolution. Eigen built a kinetic scheme known as hypercycle that he believed would capture the essential features of self-organization in prebiotic systems at molecular scales and would contribute to provide a cogent explanation for the emergence of biological information. Novel concepts like the quasispecies arose from such forays into molecular evolution. This research became inspirational to a generation of researchers, including Nobel laureate Frances Arnold, who decided to test Darwinian scenarios at the molecular level. It also fostered multidisciplinary efforts that became the hallmark of the Max Planck Institute under Eigen’s leadership.

On the personal side, Eigen was inspirational and humorous, with a deep sense of irony. As a former researcher in his biophysical chemistry division at the Max Planck Institute, I recall once giving a complicated mathematical presentation on a scenario for the origin of biological information, with Eigen and his group in full attendance. As my derivations were getting more and more convoluted, Eigen politely interrupted me and said: “Ariel, if you want to go to Stockholm, never get past the linear approximation.”