Death announcements arrive at odd moments. In this case, the news came during the planning of new field experiments with vervets in South Africa; ideas were flowing, enthusiasm brewing: the happy moments of science in the making. Then the phone rang: Hans Kummer, the great scientist, is no more.

Kummer was an ethologist whose pioneering advances with research on primates created some of the fundamental building blocks of behavioral science. His findings have not only revolutionized our understanding of the mechanisms and evolution of social behavior and organization, but they have also changed how we think about the cognitive capacities of our closest animal relatives.

During his field research Kummer quickly realized that animal behavior can be studied only with the tools of an exact science and that scientific problems cannot always be answered with field observations alone but need systematic experiments to uncover the invisible causal relationships. This, he argued, often requires research both in the laboratory and in the wild. With his methodological rigor, Kummer thus demonstrated how to unravel the mysteries of the world of primates and how to get a glimpse of the world through their eyes.

At conferences and among colleagues he fought fearlessly for the highest scientific standards. He warned of the dangers of overinterpretation and against the abuse of single observations, and he cautioned against vulgarizing reality. In doing so he helped to create an extremely successful and respected branch of modern science, now taught at universities around the world with a tremendous influence on our understanding of ourselves as human beings.

As a professor at the University of Zurich he took us students along on his mental travels to places we had never been. He transformed our worlds without really intending to. He showed us how evolution takes place, how to read its tracks, and how it has created our social behavior and cognition. He helped us to understand who we are: remarkable primates with an overpowering culture and an oversized brain.

Hans Kummer was a visionary, far ahead of all, with his clarity, his intuition, his knowledge, and his ability to ask deep questions. A disease began to take away these cognitive powers and he decided he could not let that happen. To us, his survivors, is left despair, anger, and grief. But again he has led us to consideration and thought – about individual decisions, morality, and human life.

We are deeply grateful to him.