Male humpback whales produce some of the most structured non-human sound sequences known to science: long, repeating patterns of moans, cries, and pulses organised into phrases, phrases into themes, and themes into a full song that can last 30 minutes and then repeat, sometimes continuously, for hours. What makes humpback song more than an evocative curiosity is that it changes. Every whale in a given population sings a version of the same song at any point in time, and that shared song gradually evolves over months and years, with new phrases appearing and spreading through the entire population in a pattern researchers describe as one of the largest known examples of cultural transmission in a non-human species.
A Song That Travels the Ocean
Low-frequency whale calls can travel extraordinary distances underwater, aided by a phenomenon called the SOFAR channel — a layer of ocean at a specific depth where temperature and pressure combine to trap and carry sound with unusually little loss. Under the right conditions, some baleen whale calls are believed capable of travelling hundreds, potentially over a thousand, kilometres before becoming undetectable. This means whale populations separated by enormous distances may, at least in principle, be able to hear signals from animals they will never physically encounter — an acoustic environment with no real equivalent in terrestrial animal life, where sound rarely travels more than a few kilometres before fading.
How a Song Spreads Across an Ocean
One of the most striking documented cases of song transmission involved a new song type that appeared in a whale population off eastern Australia and, over a small number of years, was recorded progressively further east across the Pacific, eventually appearing in populations as far away as French Polynesia — a spread researchers interpreted as evidence of the song being learned and passed between populations that have some degree of seasonal overlap, rather than evolving independently and coincidentally in multiple places. This kind of rapid, population-wide cultural replacement, where an old song is essentially abandoned in favour of a new one within a few breeding seasons, has no clearly identified equivalent in birdsong or any other well-studied animal communication system.
What the Song Might Be For
Only male humpbacks sing, and singing occurs predominantly during the breeding season, which has led most researchers to treat song as serving some combination of mate attraction and male-to-male signalling, similar in broad function to birdsong even though the underlying mechanism is entirely different. But this explanation remains incomplete: females have rarely been observed responding directly to song in ways that would confirm a simple mate-attraction function, and some researchers have proposed that song may also serve a role in spacing males apart or establishing some form of social ranking, a question that remains genuinely open despite decades of dedicated study.
A Communication System Still Being Decoded
Modern bioacoustic research, including long-term monitoring efforts supported by organisations such as Whale and Dolphin Conservation, increasingly uses machine learning to analyse decades of accumulated recordings, searching for structural patterns in whale song that might resemble the hierarchical structure linguists look for in human language — nested units built from smaller repeating parts. No consensus yet exists on whether whale song constitutes anything resembling language in a linguistic sense, but the structural complexity is not in serious dispute. What is clear is that somewhere in the deep ocean, whale populations are maintaining a shared, evolving cultural tradition passed between individuals across vast distances, using a communication channel humans only began to seriously study within the last century.
Rising ocean noise from shipping traffic, sonar, and offshore construction is now a growing concern for researchers studying whale communication, since many of these anthropogenic sounds overlap with the same low-frequency range whales use to call across long distances. Some studies have found whales in noisier waters shortening their calls or shifting frequency to compensate, changes that may reduce how far a signal can travel or how much information it carries. A communication system this old, this widespread, and this poorly understood is also, as a result, one that is being altered by human activity before scientists have finished working out how it functions in the first place.