PH Gouyon is a biologist, one of the most brilliant specialists in evolutionary science, genetics and ecology. A researcher and professor at the Museum of Natural History, he is particularly known for his work Le Principe de précaution (The Precautionary Principle”), published in 2000.
JL Dessalles is a researcher in artificial intelligence and cognitive science. He is particularly known for his original contribution to the theory of simplicity and the origin of language.
Cédric Gaucherel is an astrophysicist, a member of INRA, and a specialist in the study of ecosystems, dynamics of populations and landscapes. He is Director of the Department of Ecology at the Institut Français de Pondicherry.


What is life made of? What is the substance of it? When a living thing dies, what endures and continues among the living? What makes an ecosystem, an animal population, a human culture, have a memory that far exceeds the duration of the lives that compose it? To these fundamental questions, this book provides an original scientific answer: the thread of life, the one that runs through all beings, from our distant amphibian ancestors to us modern human beings, is not material: it is a message. An inherited message that is built up from generation to generation, whose imprint is on the DNA of our chromosomes but which is also expressed through the way we live and talk.
Although not material, this thread of life affects our existence and that of our descendants; it evolves and changes. It is the very structure of the living, the warp threads on which are woven our lives.