Behavioral ecology is primarily concerned with the determination of the function, or survival value, of behavior (Krebs and Davies, 1993, p. 1). However, as should be evident from the fact that philosophers of science have devoted many volumes to debating the question of function, it is not straightforward even to define what “function” is, far less defend the validity of the various approaches used to investigate it. As it is relatively rare for behavioral ecologists, in common with most working biologists, to consider such seemingly rarefied debates, I start this chapter by examining the question of function. I place special emphasis on the development of Tinbergen's interest in the topic, but also try to draw conclusions in the light of recent treatments of the subject by philosophers and philosophically minded behavioral ecologists. I will then explore the reasons for behavioral ecologists' special interest in functional questions, and the merits of the different approaches to determining the function of behavior. Although the aims and methods of behavioral ecology are often portrayed as following the Tinbergian tradition within ethology, there are important differences. Finally, I will discuss where this has got us and, dangerous though it may be, I will attempt to forecast the future of the subject.

TINBERGEN AND FUNCTION

When Niko Tinbergen was a student at Leiden University in the late 1920s, his notion of “function” in relation to animal behavior was probably that of any layperson with an interest in natural history: the role that behavior plays in the animal's life.