Humpback populations in the Indian ocean show few common themes in their songs, indicating a limited exchange between different populations and shedding light on how whale pod culture spreads.

In the Northern hemisphere, whales in the same basin often sing songs with the same themes, while whales in the southern Indian ocean sing completely different songs.

Scientists are still not sure what explains the anomaly, but it is possible the difference in songs reflects an exchange of individuals between oceans unique to the southern hemisphere.