Asked to participate in a reflexion of primatologists on what has shaped their discipline over the past half-century, the paper offers an alternative account to the optical metaphors of biases, paradigms and points of views. It is trying to define an other demarcation criterion which does not rely on what is scientific and what is not scientific, on what is inside or outside, but on the risk taken by the scientists and their objects of study. It is thus an experiment in offering to the scientists themselves an account of "what is good science that satisfies their own constraints and not those of scientists observers