Network-Based Diffusion Analysis Reveals Cultural Transmission of Lobtail Feeding in Humpback Whales

Animal Culture Cultural transmission of information occurs when individuals learn from others with more experience or when individuals come to accept particular modes of behavior as the local norm. Such information transfer can be expected in highly social or long-lived species where contact and time for learning are maximized and are seen in humans (see the Perspective by de Waal). Using a network-based diffusion analysis on a long-term data set that includes tens of thousands of observations of individual humpback whales, Allen et al. (p. 485) show that an innovative feeding behavior has spread through social transmission since it first emerged in a single individual in 1980. The “lobtail” feeding has passed among associating individuals for more than three decades. Van de Waal et al. (p. 483), on the other hand, used a controlled experimental approach in vervet monkeys to show that individuals learn what to eat from more experienced individuals within their social group. Not only did young animals learn from observing older animals, but immigrating males switched their food preference to that of their new group. Whales have learned from their peers how to use their tails to herd prey. [Also see Perspective by de Waal] We used network-based diffusion analysis to reveal the cultural spread of a naturally occurring foraging innovation, lobtail feeding, through a population of humpback whales (Megaptera novaeangliae) over a period of 27 years. Support for models with a social transmission component was 6 to 23 orders of magnitude greater than for models without. The spatial and temporal distribution of sand lance, a prey species, was also important in predicting the rate of acquisition. Our results, coupled with existing knowledge about song traditions, show that this species can maintain multiple independently evolving traditions in its populations. These insights strengthen the case that cetaceans represent a peak in the evolution of nonhuman culture, independent of the primate lineage.