The Latin phrase ‘tabula rasa’ refers to the idea that people are born as empty slates, filled in by experience and perception. Of course now, the power of genetics is widely known and so is the moulding power of cultural experience. There is little agreement on the characterization of culture in human society, however in order to understand similar patterns in animals a definition of behaviours resulting from socially learned and transmitted information has been suggested. In these terms, animal cultures are evident when examining behaviours ranging from vocal dialects in bird or cetacean (whales and dolphins) song, to tool-use in primates. Yet there has been little work done to identify the mechanisms through which social learning spreads through a population. Indeed such studies can prove tricky to undertake, particularly in wild communities. Earlier this week a team of scientists published a paper describing social learning of novel foraging techniques, in a controlled experiment on wild populations of the great tit Parus major.
Birds have been some of the most popular subjects of behavioural studies, with numerous publications describing how British birds exhibited interesting behaviour , piercing milk bottles and feeding on the cream. Great tits in particular are ideal test subjects; demonstrating innovation, opportunity and the ability to use social information in a wide range of contexts.
In this case, the team devised a puzzle box that rewarded birds with meal worms when they provided a solution. The box consisted of a perch, surrounded by a cage to exclude larger birds and squirrels; a feeder with peanut granules to originally attract the great tits, and the puzzle that needed solving to provide the birds with the much more nutritious food source i.e. meal worms. By sliding a door either from right to left, moving its red side, or from left to right, moving its blue side through the use of their bill, birds got access to food. The puzzle box, in addition to rewarding the birds, recorded the identity of the visiting bird, the duration of its attempt and solution choice, whilst resetting itself after each visit.
The team captured sixteen males from eight subpopulations and trained each individual over the course of four days to open the door using one of the two strategies or, as a control, released them untrained. After the training was complete, the males were released back into the wild. The experiment was undertaken in Wytham Woods, where the birds are recorded and tracked from the very beginning as nestlings. Relatively often, mist nettings are also carried out to capture and tag migrating birds.
As expected, in subpopulations where trained males have been released, birds started solving the puzzle box significantly sooner in comparison to populations whose males were untrained. Moreover, individuals showed a preference for a particular technique, depending on what technique the resident males had been exposed to. The diffusion of their behaviour seemed to follow the patterns of independently derived social networks within the subpopulations, with the likelihood of picking up a technique increasing if an individual had interacted socially with “knowledgeable” birds. The likelihood also varied in regards to age and sex, with younger individuals and males keener to pick up the technique than their counterparts.
Of course, in all subpopulations there were individuals that initially followed the alternative strategy. However, over time the technique originally introduced by the trained birds gained popularity, signifying a strengthening of tradition as birds opted for the most commonly used strategy. Even in cases of migration from one subpopulation to another, the majority of migrants switched their strategy to mirror the most popular strategy in the community they had arrived at. The following winter, puzzle boxes were re-introduced and strategy adoption occurred much faster, both by birds previously exposed to the boxes and by individuals new to them. This demonstrates that birds remembered their original experience with the boxes and new birds rapidly adopted a strategy due to the existence of plenty of demonstrators. So it appears that conformity, a major cultural driver in human societies also plays a significant role in animal communities.
What other mechanisms might animals employ in healthy social learning?