Scientists studying social learning in animals have shown how easy it can be to introduce a new behavior into a group and watch it spread from individual to individual. However, not nearly as many studies are devoted to following up on the establishment of new behaviors to see if those behavioral traditions persist.
In a new study,Tina Gunhold, Jorg Massen, and Thomas Bugnyar of the University of Vienna, Nicola Schiel of the Federal Rural University of Pernambuco, Brazil, and Antonio Souto of the Federal Unversity of Pernambuco, Brazil, investigated the formation and persistence of foraging traditions in wild common marmosets. The researchers took advantage of a previous study in which they established two alternative ways of obtaining fruit from a novel feeding box in family groups of wild marmosets in northeast Brazil. Marmosets could reach the treats inside the wooden box by either pushing or pulling an opaque flap door.
Gunhold and her colleagues returned to Brazil to study the seven family groups used in the original study, plus six additional family groups. First, they wanted to see if experienced marmosets still remembered the foraging technique (i.e., either pushing or pulling) that they learned two years earlier in the previous study. Second, the researchers investigated whether naive group members (marmosets who were either born or immigrated into the group since the previous study two years ago) would pick up a preference for a certain foraging technique from experienced marmosets. Finally, Gunhold and her colleagues tested if socially learned foraging techniques persisted over nine months.
“Individuals from all conditions appeared to get stuck with a given method,” Gunhold explains. “It seemed that after an individual learned a technique — triggered by the observation of a skilled family member — it formed a strong habit.” As long as an individual was successful enough with that technique, this seemed sufficient to maintain it.