On The Biomechanics of Behavior
Sanjay Sane, Tata Institute of Fundamental Research
In his influential treatise “The Discourse on Method”, Rene Descartes suggested that animals can, by and large, be viewed as automatons which follow the laws of mechanics. Their behavior is thus a consequence of a series of actions and reactions, or as chains of reflexes. Despite the many obvious counterpoints to Descartes’ view, it holds remarkable sway over how we think and conduct research on animal behavior (or ethology) down to the current day. The broad approaches of modern ethological research are best summarized in the classic review “on aims and methods in ethology” by Niko Tinbergen, who outlined the spectrum of ethological questions as ranging from function (what is it for?), causation (how does it work?), development (how did it develop?), and evolution (how did it evolve?). The modern view of animal behavior - as a product of the nervous system’s activity - incorporates approaches that involve presentation of stimuli to animals, and a recording of their responses to these stimuli. Eminent ethologists such as Niko Tinbergen and Karl von Frisch developed these approaches largely on the premise that similar stimuli lead to repeatable responses and thus animal behavior may be quantified as an output of these experiments on an “ensemble”, and quantified in terms of statistical means with standard deviations as measures of variability. In contrast to this view are many recent observations that animal behavior may not always be viewed in mechanistic terms. Indeed, according to this view, animals are capable of generating their own “spontaneous” activity in absence of stimuli. I will argue that both views are compatible depending on the time scales of behavior. In reflexive behaviors that occur on fast time scales, there is less variability in the nervous output and the importance of body mechanics is proportionately greater. This view puts in perspective the importance of mechanics in animal behavior, which we hope that it will motivate researchers to investigate the role of biomechanics as a critical component of animal behaviors.