Humpback whales are famous for their extraordinary songs, which are amongst the most complex in the animal kingdom. Now researchers from the University of Queensland have revealed that multiple song types spread rapidly and repeatedly like cultural waves, eastward across the Pacific Ocean.
Although both males and females vocalize, only males produce the loud complex “songs” that may continue for hours on end. Each song consists of lots of different sounds, such as low frequency moans, groans and growls, higher cries and shrieks, and all variations of ascents and descents, which are repeated in patterns. Interestingly, in each population all singers sing virtually the same song at any point in time. Furthermore, the song is constantly evolving, sometimes rapidly, from year to year.
By studying hours and hours of whale songs recorded from populations across the Pacific over a decade, the researchers found the striking pattern of cultural tranmission, the social learning of information or behaviours from members of the same species, as whale songs spread from Australia to French Polynesia, almost 6000km away. Although cultural transmission is believed to occur in a number of groups of non-human animals, including primates, cetaceans, and birds, it has never been documented at such a broad scale and wide population level.
It is striking that the songs were almost exclusively passed on from west to east. The researchers think the whales in the South Pacific may hear and learn songs during their annual migration to their feeding grounds in Antarctica. Since the East Australian population is the largest in the region, these whales may have more influence on what songs become top hits.
Interestingly the reason why male humpbacks sing is still not completely understood. Although most scientists agree it is likely a mating display, it is unclear whether the main effect is to attract females or to repel rival males.
It is fascinating scientists have now discovered these large-scale cultural changes in whale song. Not only because we can start to understand why humpback whales have evolved to change their complex songs in such a flexible and conforming way, but especially since investigating its underlying mechanisms may yield powerful insights into cultural evolution and the transmission of traits.Garland, E., Goldizen, A., Rekdahl, M., Constantine, R., Garrigue, C., Hauser, N., Poole, M., Robbins, J., & Noad, M. (2011). Dynamic Horizontal Cultural Transmission of Humpback Whale Song at the Ocean Basin Scale Current Biology DOI: 10.1016/j.cub.2011.03.019