Learning through observing the behaviour of another individual is adaptive, as it provides a shortcut to finding a solution, and so avoids the costly process of trial and error learning. There is evidence that group-living mammals (
Heyes & Galef 1996;
Whiten et al. 2005;
Huber et al. 2009), birds (
Zentall 2004), fishes (
Schuster et al. 2006) and insects (
Leadbetter & Chittka 2009) can learn socially, however, very little is known about the evolutionary origins of this behaviour despite its prevalence. An almost implicit assumption in the literature is that living in social groups favours the evolution of social learning; this logically leads to the idea that social learning is an adaptation for social living (
Klopfer 1961;
Templeton et al. 1999). The experimental support for this hypothesis, however, is not compelling. The majority of studies investigating the link between social living and social learning have examined social learning abilities in closely related species that differ in sociality. Positive findings (with the exception of
Templeton et al. 1999) are frequently confounded by species differences in individual learning; those social species that perform better in social tasks also perform better in non-social tasks (see
Reader & Lefebvre 2001).
To avoid this problem, we approached the question from a different angle, asking whether a non-social animal could learn to solve a task by observing the actions of a conspecific. The adaptive specialization hypothesis predicts that they could not. However, an alternative hypothesis, which has received little attention in the literature, is that the ability of an animal to learn socially is simply a reflection of an animal's general ability to learn. Any animal with the capacity to learn is likely to be able to use a wide variety of salient stimuli as cues (
Heyes 2003); in this context, social cues can be considered similar to other environmental cues and can thus be learned through associative processes. This hypothesis would predict that any species that has had extensive exposure to a conspecific should be able to learn socially.
Using a non-social species provides an ideal scenario for testing the hypothesis that sociality is directly linked to social learning abilities in animals. Truly solitary species within the mammalian and avian classes, however, remain elusive as those that are solitary in their adult life still receive extensive parental care as infants (
Galef & Laland 2005). It is therefore unsurprising that only one study has previously used this approach.
Fiorito & Scotto (1992) found evidence of social learning in the solitary common octopus (
Octopus vulgaris). Though apparently compelling, this study has been widely criticized for failing to control innate species-specific behaviour (e.g.
Biederman & Davy 1993).
Social learning has never been previously studied in reptiles. Moreover, some species of reptiles are solitary and exhibit no parental care (
Wilson 1998), making them ideal subjects for this experiment. To this end, we examined the social learning abilities of the red-footed tortoise (
Geochelone carbonaria), a naturally solitary species that inhabits the margins of tropical forests in Central and South America (
Strong & Fragoso 2006). Though they may naturally interact with conspecifics (e.g. mating opportunities;
Auffenberg 1965), they do not form permanent groups. Indeed, parental care has not been observed in tortoises (
Burghardt & Layne 1995): eggs are laid in holes and then left. Once the infants hatch, they dig themselves out of the hole and disperse. Despite their solitary nature, there is evidence that this species possesses a sensitivity to visual social cues (
Auffenberg 1965;
Wilkinson et al. in press). This makes the red-footed tortoise an ideal subject for examining whether a solitary species can use the behaviour of a conspecific to reach a goal.
Eight socially housed red-footed tortoises were presented with a detour task. By presenting this task to both non-observer (control) animals, who had to solve the task through individual learning, and to animals who were able to watch a conspecific demonstrator solve the task before they attempted it themselves, we were able to examine the role that social and individual learning plays on solving a task in this species.
This article has been 
