SYDNEY, Nov. 21 (Xinhua) -- An analysis of humpback whale songs on the east coast of Australia has revealed "revolution" events where the tunes of male populations, which have gradually evolved over time, will suddenly change entirely.
The University of Queensland study, released on Wednesday, analyzed recordings from a 13 year period, revealing that over the time, the complexity of the whales' songs oscillated in a clear pattern.
"Humpback whale songs generally change gradually from one year to the next, and you can sort of see the similarities in the songs," study author Jenny Allen told Xinhua.
"But in the South Pacific every couple of years you get a revolution event which is where the entire song is completely replaced."
Allen and her colleagues noticed that when the small gradual changes were occurring, the songs were getting more complicated, however when the revolution events occurred, the new song was simpler than the one it replaced.
"It was this really clear oscillating pattern where the songs would get gradually more complex, there'd be a revolution, the song would simplify and then it would get more complex again, and so on," Allen said.
It is not known why whales sing, although it is observed to only be the males that do, and only while at breeding grounds or on the passage to and from breeding grounds.
This has led scientists to speculate that the songs have something to do with attracting a mate, or competing with other males, or a combination of both.
