Marc is a biologist, ethologist, behavioural ecologist and writer. He is Professor Emeritus of Ecology and Evolutionary Biology at the University of Colorado, Boulder. He is the co-founder, with Jane Goodall, of Ethologists for the Ethical Treatment of Animals, a fellow of the Animal Behavior Society and a former Guggenheim fellow. He lectures internationally on animal behavior, cognitive ethology (the study of animal minds), and behavioral ecology, and writes a science column about animal emotion for Psychology Today. He is an advocate for the compassionate conservation movement that aims to improve environmentalism by embedding a moral concern for individual sentient animals. In 1986 Marc won the Master's age-graded Tour de France. Marc is a vegan and has a naturalistic worldview.