Since Krebs and Davies’s (1978) landmark publication, it is acknowledged that behavioural ecology owes much to the ethological tradition in the study of animal behaviour. Although this assumption seems to be right—many of the first behavioural ecologists were trained in departments where ethology developed and matured—it still to be properly assessed. In this paper, I undertake to identify the approaches used by ethologists that contributed to behavioural ecology’s constitution as a field of inquiry. It is my contention that the current (...) practices in behavioural biology owe ethology something much subtler than the simple transposition of Tinbergen’s Four Problems for heuristic purposes. Demonstrating what ethology inherited from the long naturalist tradition shows the tensions that strained the field and that later led to the loss of both its unity and its specificity. It also allows for a precise delineating of what behavioural ecology picked up from the ethological practice, and it helps to cast some light on the introduction of economical thinking in behavioural sciences. (shrink)