Whale songs can travel nearly 5000 miles between never met groups
A multinational group of collaborators has found similarities in songs sung by whales in eastern Australia to those sung by those in French Polynesia, even though the two geographies are nearly 5,000 miles (8,000 km) away, New Scientist reported.
Male humpback whales sing a repetitive song that is learned socially. It consists of structures that are similar to notes and symphonies of classical music. The song is also a part of cultural transmission that has been observed in these mammals, and most males within a population will sing the same song.
Over the years, the songs do evolve, but the pace of evolution is slow and measured. Researchers, however, noticed song revolutions in the South Pacific, where the whale groups have completely and rapidly changed their songs.
Song revolution in humpback whales
To understand what exactly was causing this phenomenon, researchers started analyzing whale songs from different areas in the South Pacific. In 2011, Ellen Garland, of the Scottish Oceans Institute at the University of St. Andrews found that distinct themes related to mating that was recorded off the coast of Australia were heard again in French Polynesia, some 3,700 miles (6,000 km) away.
To determine if these themes or songs had traveled further, she teamed up with researchers at the Universidad San Francisco de Quito in Ecuador and collected sound data from the region as well as from French Polynesia between the years 2016 and 2018. They then performed similarity analyses on these recordings to determine how alike the two songs were.
To their surprise, the researchers found that three separate songs appeared in Polynesia waters in 2016 and then in Ecuador in 2018, suggesting that the songs were traveling eastwards.
Why is this so important?
"These new song types are just so completely different – [they are] composed of the same sounds, but the arrangement is so different, they just literally jump off the computer screen and out of the headphones to us," Garland told New Scientist. "These really rapid cultural changes are not seen in any other animal species, it’s happened so fast."
Garland and her team suggest that songs travel when neighboring groups of whales migrating between their breeding and feeding grounds pass within the acoustic range of each other.
Working with other research groups, Garland is currently exploring if song transmission can be traced further than the South Pacific basin. There is a high likelihood that it can be, paving the way for a "circumpolar Southern Hemisphere cultural transmission of song and a vocal culture," which otherwise is assumed to exist in human civilization.
Understanding whale song transmission will also help improve our understanding of the evolution of communication and speech in humans.
The research has been published in the journal Royal Society Open Science
Cultural transmission of behavior is an important aspect of many animal communities ranging from humans to birds. Male humpback whales (Megaptera novaeangliae) sing a repetitive, stereotyped, socially learned and culturally transmitted song display that slowly evolves each year. Most males within a population sing the same, slow-evolving song type; but in the South Pacific, song ‘revolutions’ have led to rapid and complete replacement of one song type by another introduced from a neighboring population. Songs spread eastwards, from eastern Australia to French Polynesia, but the easterly extent of this transmission was unknown. Here, we investigated whether song revolutions continue to spread from the central (French Polynesia) into the eastern (Ecuador) South Pacific region. Similarity analyses using three consecutive years of song data (2016–2018) revealed that song themes recorded in 2016–2018 French Polynesian song matched song themes sung in 2018 Ecuadorian song, suggesting continued easterly transmission of song to Ecuador, and vocal connectivity across the entire South Pacific Ocean basin. This study demonstrates songs first identified in western populations can be transmitted across the entire South Pacific, supporting the potential for a circumpolar Southern Hemisphere cultural transmission of song and a vocal culture rivaled in its extent only by our own.