Why study reptiles?

Reptiles, birds and mammals have all evolved from a common amniotic ancestor, and as such they are likely to share both behavioural and morphological traits. However, this common ancestor lived around 280 million years ago and so it is equally as likely that different traits and abilities may have emerged. Despite their clear importance for the study of cognitive evolution, very little research has investigated the learning abilities of reptiles. The few studies that have been conducted with reptiles found little evidence of impressive cognitive skills. However, many of these studies took place in unsuitable environments for the species tested (e.g. a cold room for a tropical reptile). As reptiles are ectothermic (cold-blooded) it is essential to provide them with an environmental temperature similar to that which they would experience in their natural habitat. Only then can their true cognitive abilities be tested. The cold-blooded cognition group is interested in all aspects of reptile cognition and studies their behaviour in the context of the behavioural ecology of the specific species tested.

Spatial Perception

We are currently working on a project investigating spatial perception in the red-footed tortoise and other reptiles. We have recently examined the spatial abilities of the red-footed tortoise in a radial arm maze and found a similar level of performance to mammals; however the mechanisms controlling the behaviour appear to be quite different. We are currently working on elucidating exactly how tortoises navigate and under what conditions their behaviour differs from mammals. Further, we are also investigating whether the differences observed between our tortoises and mammals are common to all reptiles, or specific to our study species. As such we are running the tortoises and our jewelled lizards on identical tasks. Similarities and differences in behaviour can inform us about the evolution of the mechanisms underlying spatial navigation in reptiles.

Social Learning

Reptiles are not very social animals. The red-footed tortoise is naturally solitary, exhibits no parental care and has little social interactions with conspecifics (other than mating). This makes this species ideal subjects to test hypotheses regarding the evolution of social learning. It has been suggested that social learning is an adaptive specialisation for social living and also that social living causes a general increase in cognition which allows an animal to learn from another’s actions. Both of these hypotheses suggest that a solitary species would be unable to learn from observing another’s actions. However, it is equally likely that an animal’s ability to learn socially is merely a reflection of that animal’s general ability to learn, irrelevant of its social environment. If this is the case then we would expect that the tortoises would be able to learn by observing the actions of a conspecific, and that is exactly what we found. This very exciting finding is the first evidence of social learning in a solitary species and suggests that social learning may merely be a reflection of an animal’s general learning ability.

Visual Perception and categorisation

Categorisation is probably the most fundamental component of cognition. It allows animals (and humans) to reduce the vast amount of information that is perceived daily, and takes advantage of the fact that objects within the same category share many properties and behaviours, and thus require similar responses (to flee, to hunt etc.). Most experiments investigating categorisation use photographic stimuli (see pigeon section). However, before embarking on these type of experiments with the tortoises, it is essential to question whether they are able to recognise the equivalence between real entities, and pictures of them. As such, the tortoises were trained to choose a piece of food over a non-food object (it did not take much training) and were then tested with photographs of the food vs. photographs of the object to see if they could still make this discrimination. We found that they could, later tests revealed that they did not see an equivalence between the real fruit and the photograph of the fruit, but actually perceived them in the same way.

The others
We have run projects with frogs and plan to work with newts in the future too.

Projects

Effects of physical changes on memory processes
Amphibians, more than any other vertebrate go through enormous physical changes during their life cycle. The hormones that control the changes that the animals go through during metamorphosis also change the brain. However, little is known about how this affects their memory. We are working on a series of experiments examining the effects of metamorphosis on memory retention in the frog. In a similar vein we are running a set of experiments examining the effects of hibernation on memory retention in salamanders. The salamanders will be taught two tasks and then we will examine whether they can remember how to solve these tasks post-hibernation.