Remixing the old with the new: How do Humpback whales learn their song?

The song of the humpback whale is easily one of the most extravagant vocal displays in the animal kingdom and has attracted the attention of so many since first recorded in the early 1950s.

humpback whale

Humpback whales, like other cetaceans*, rely heavily on sound for communication as it travels four times faster in water than in the atmosphere and many of the other senses prove to be at a disadvantage underwater.

Within any population of whales there is a ‘song type’ which will differ to that of another population, although, it is only the males which produce the song and it is therefore considered a product of sexual selection*. The song can last anywhere from 5 – 30 minutes.

As for the song itself, it has a hierarchical organisation, meaning that it can be broken down into various ranks. The highest of these ranks is the ‘song’, this is composed of several different ‘themes’ sung in a set order. Within the themes are repeated ‘phrases’ which are made up of single sounds, termed ‘units’.

This song is constantly changing, so males must continuously add in new alterations. It is a remarkable example of the transmission of a cultural trait. To be able to see just how these songs are learned by whales’ scientists investigated the learning of hybridised songs.

Hybridised songs contain new themes and elements from the old and new song. They are particularly common where adjacent populations adopt elements of each other’s song, as seen by whale populations in the western and central Pacific Ocean.

There are two methods of hybridising songs. The singer can splice (add in) complete themes from the new song into the current song or place a single hybrid phrase at the point of transition between the old and new song.

In humans and birds segmentation (learning in segments then putting it together) has been found to be important in language and song acquisition. Scientists have found the same to be true of Humpback whales, making it a learning mechanism in cetaceans.

Humpback whales split the song into its themes which are then each learned individually. These new themes are then combined with the older themes, with any transitional phases containing sound from both the new and old song. There is also some evidence of pausing between segments giving an emphasis which is important in memorisation of the new segments, as well as rhyme like patterns aiding recall.

Intense cultural conformity means that once this new song is found in a population all the males switch to it once it’s been heard from multiple individuals and there is a progressive deletion of any old themes as the song changes.

Group of whales.jpg

It is not currently known just how long these whales can remember vocalisations for, but in bottlenose dolphins they are remembered for as long as 20years. These insights into the learning mechanisms of song in the humpback whale could be used to give a comparative view on the evolution of the human language and further information on learning mechanisms in mammals.

Their incredible ability to repeat each other’s songs and extend and change it demonstrates the complexity and size of their memory. In my eyes, this makes them deserving of being known for having one of the most beautiful and intricate vocal displays in the animal kingdom.

For anyone who’s keen to know just what whale song sounds like here’s a little clip…

Glossary
Cetaceans*
A marine mammal of the order Cetacea; a whale, dolphin, or porpoise.
Sexual Selection*
Preference by one sex for certain characteristics in individuals of the other sex. In the case of whales it is preference by the females for the male’s song.

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