Like any fad, the songs of humpback whales don’t stick around for long. Every few years, males swap their chorus of squeaks and groans for a brand new one. Now, scientists have figured out how these “cultural revolutions” take place.
All male humpbacks in a population sing the same song, and they appear to learn new ones somewhat like people do. Males in the eastern Australian population of humpbacks, for example, pick up a new song every few years from the western Australian population at shared feeding grounds or while migrating. Over the next few years, the songs spread to all South Pacific populations.
To understand how the whales learn the novel ballads, scientists analyzed eastern Australian whale songs over 13 consecutive years. Using spectrograms of 412 song cycles from 95 singers, the scientists scored each tune’s complexity for the number of sounds and themes, and studied the subtle variations individual males can add to stand out. Complexity increased as the songs evolved (as heard in the video below), the team reports today in the Proceedings of the Royal Society B. But after a song revolution, the ballads became shorter with fewer sounds and themes.
The revolutionary songs may be less complex than the old ones because the whales can only learn a certain amount of new material at a time, the scientists conclude. That could mean that although humpback whales are still the crooners of the sea, their learning skills are a bit limited.