An Investigation of the Factors Driving Cognition in Darwin's finches

Abstract

Tool-use in the animal kingdom is more common than previously believed. The cognition associated with this remarkable behaviour and the evolutionary dynamics between cognition and tool-use remain a mystery in the case of most animal tool-users. I investigated the cognitive evolution of a tool-using bird species, the woodpecker finch (Cactospiza pallida). My main expectation was that cognition might have co-evolved with tool-use to improve the development of this behaviour and/or tool-deployment in this species. Specifically, I asked whether tool-use evolved in conjunction with enhanced cognitive abilities in woodpecker finches, and if so, whether these cognitive adaptive specializations are restricted to the domain of tool-use or rather are more general cognitive adaptations. I was also interested in examining potential pre-conditions that might have facilitated the evolution of this unusual behaviour.I compared the performance of tool-using woodpecker finches with a closely related non-tool-using species, the small tree finch (Camarhynchus parvulus) in general learning tasks and also I tested their tool-related physical cognitive abilities. Physical cognition refers to the ability to use physical forces and related events in the environment to form general rules. I found no evidence supporting an enhancement of physical cognitive abilities in woodpecker finches. Indeed, the high flexibility of small tree finches in the reversal learning task and their proficient performance in the physical tasks suggests that the cognitive abilities necessary for woodpecker finch tool-use might have preceded the evolution of this behaviour. In the last chapter I review evidence relevant to this idea, in particular, I consider whether a highly flexible stem species of Darwin’s finches might form a plausible explanation for their rapid and extensive radiation.