Male humpbacks sing complex displays that are learned rather than inherited, and a population will sometimes abandon its song outright and adopt a new one wholesale. That kind of upheaval needs contact: somebody has to hear the new song and carry it. Where that contact happens has stayed uncertain. Owen and colleagues compared recordings from a newly discovered stopover against several South Pacific . Where do the songs meet?
At a stopover on the way. Songs recorded at the Kermadec Islands shared themes with wintering grounds spread from New Caledonia across to the Cook Islands. That marks the place as a conduit for song passing eastward across the South Pacific. turned up too, meaning learning was happening on the spot. Wintering grounds, acoustically isolated from each other, then allow the versions to converge culturally.
Male humpback whales perform long, structured songs that are learned from other whales. The song changes evolutionarily, through accumulated small modifications. are the other mode, where a population rapidly abandons its song and adopts a novel one from elsewhere.
The coordination behind such a switch is what makes it interesting. For an entire population to change, the new song has to arrive and spread, which means whales from different populations must hear each other somewhere. Migratory routes are the obvious candidate, and the specific places of acoustic contact have remained uncertain.
Owen and colleagues recorded song at the Kermadec Islands, a migratory stopover identified only recently, and compared it against multiple wintering grounds across the South Pacific. Themes from the Kermadecs resembled those from locations stretching from New Caledonia to the Cook Islands.
That points to the islands as a conduit for of song eastward across the South Pacific. Hybrid songs in the recordings indicate active song learning taking place there rather than a simple overlap of two populations. Afterwards the whales disperse to wintering grounds, acoustically isolated from one another, where the versions can converge. The migration patterns, as the authors put it, are written into the songs.
wat. The migration route is written into the song, because the song is what the whales exchange along it.
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A cultural trait moving along a migration route is the same pattern anthropologists trace in human language, and here the route can be mapped from the songs themselves.
How do we know?
Owen and colleagues compared humpback songs recorded at the Kermadec Islands, a recently discovered migratory stopover, against recordings from multiple South Pacific wintering grounds.
What is still unknown
Shared themes show contact is plausible at this location, not that any particular song upheaval started there. The recordings cover limited seasons and a limited set of grounds.
Learn something?
Where to next
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