Singing humpbacks are exploring, not courting, UB researcher says

Psychology professor Eduardo Mercado III wasn’t impressed as a young researcher in the 1990s when he first heard humpback whales singing. 

A groundbreaking expert on whale song, Mercado is a cognitive scientist and a 2023 fellow of the Guggenheim Foundation. He knows how certain sounds, such as whale song, can release neurochemicals in listeners that produce feelings of pleasure, accounting, in part, for why the songs appeal to so many people. Mercado, at least initially, didn’t include himself among the enchanted.

That lackluster first impression soon became a driven scientific curiosity when Mercado, a professor in the Department of Psychology, encountered a few pages of text in a book discussing echolocation that caused him to think differently and more deeply about singing whales. He has since published years’ worth of innovative research on whale song in leading journals, producing a body of work that upends more than 50 years of established science on the singing behavior of humpback whales, most of which concludes that whales sing as a courtship display, like songbirds, or peacocks spreading their tail feathers to attract a mate.

Not so, according to Mercado.

His new book, “Why Whales Sing?” (Johns Hopkins University Press), available Nov. 4, is a persuasive and accessible explanation that challenges the scientific consensus while introducing its readers to previously unimagined and fascinating dimensions of whale behavior.

“What I’m arguing in this book is that singing whales aren’t performing; they’re exploring,” he explains. “They’re not ‘singing’ to serenade a potential mate but are instead vocally scanning to ‘see’ what’s going on for miles around them, using their songs as a kind of sonar.

“Whales see with song.”

This type of auditory scene analysis by whales is known as the sonar hypothesis, which directly opposes the nearly universally embraced reproductive hypothesis.

“In my mind, singing humpback whales are like submerged megaspiders laying out an acoustic web all around them,” he says. “The evidence needed to support the reproductive hypothesis just isn’t there.”

Researchers in the 1970s first proposed that some sounds produced by humpbacks might be used for echolocation, but their songs were nevertheless related to reproductive fitness. Those observations were ignored. Since whale song sounded nothing like the clicks used by dolphins, Earth’s most prominent underwater echolocators, scientists didn’t see the songs as sonar.

Mercado thought otherwise, and he has emerged as the leading and most diligent researcher exploring the sonar hypothesis. His book has been 20 years in the making. His first two attempts to interest a publisher failed, mainly because other whale experts opposed the publication of his revolutionary findings. But multiple studies on the topic created enough momentum to counteract critics’ complaints.

“Thirty years ago, when I first proposed that whale songs might be sonar, I was verbally stoned by many whale researchers for suggesting the possibility,” says Mercado. “I attempted to abandon the topic but failed because new evidence kept popping up indicating that singing humpbacks are echolocating.”

Evidence like the amount of interest female whales show in singing males. Mercado says it’s “essentially none.” In fact, females tend to actively avoid singers. In addition, contrary to male behavior in the courtship displays of other animals, singing males have no problem with other males approaching them. Singers rarely react aggressively to these “intruders” and sometimes swim off with them.

“I feel like the early scientific consensus that whale songs are love songs was a rush to judgment, like how people once portrayed gorillas as blood thirsty before more detailed observations revealed that they lived in peaceful families,” says Mercado.

Mercado says many novel scientific ideas, like evolution through natural selection, have at first been dismissed, but that has only served to encourage his continued work in the field of whale song.

“I think Max Planck got it right when he suggested science progresses one funeral at a time,” says Mercado. “And it’s time to put the reproductive hypothesis to rest.”