By BERT GAMBINI
Published April 21, 2023
Eduardo Mercado III, professor of psychology, College of Arts and Sciences, has been awarded a John Simon Guggenheim Memorial Fellowship for a project that will analyze how humpback whales adjust their songs in response to their surroundings, work that radically contradicts the prevailing hypothesis suggesting why whales sing.
Guggenheim fellowships are awarded to mid-career individuals who have demonstrated exceptional creativity or productive scholarship. Since its establishment in 1925 by Simon Guggenheim and his wife, Olga, the foundation has annually awarded grants of varying amounts to over 18,000 individuals totaling nearly $400 million.
Mercado is one of 171 American and Canadian scientists and scholars in the social sciences and humanities, along with writers and artists across multiple genres, selected for fellowships from among roughly 2,500 applicants. His project — “Cognitive Flexibility in ‘Singing’ Whales” — will afford exceptional opportunities for creating diverse research teams that combine the efforts of multiple disciplines.
The findings will be published in a forthcoming book describing how singers’ capacity to flexibly produce sounds and adapt to new experiences (through brain plasticity) enable whales to create such impressive songs.
“Receiving the John Simon Guggenheim Memorial Fellowship is a remarkable achievement,” says Robin G. Schulze, dean of the College of Arts and Sciences. “Professor Mercado’s research is significantly advancing our understanding of humpback whales and neuroplasticity generally.
“I’m excited to see where his research takes him next.”
Roughly 50 years of study have led to the near universal conclusion that humpback whale song is a courtship display performed to attract a mate. Other whales are then thought to copy successful songs to increase their mating opportunities.
Mercado, however, is skeptical of this reproductive hypothesis, and isn’t hesitant about questioning these interpretations.
“I have argued that much of the observational, experimental and comparative evidence collected to date provides little support for this interpretation,” he says. “The current data accumulated through my research are better accounted for by the alternative sonar hypothesis, which speculates that humpbacks sing to actively explore the world around them.”
Previous research motivated by the sonar hypothesis has clarified the mechanisms of humpback whale sound production and perception, and has generated testable predictions.
“In recent analyses of songs, I found that singers showed the ability to flexibly control where they concentrated acoustic energy, and to structure songs in ways that minimize potential interference from overlapping echoes,” says Mercado. “The sonar hypothesis specifically predicts that whales are controlling sounds to detect and localize distant targets as far as five kilometers away.”
In other words, whale song is a form of echolocation, not a mating ritual. Changes observed in the songs are not consistent with vocal competitions, according to Mercado. The songs are so dynamic that they often change within individual sessions.
Mercado’s project will include sophisticated acoustic analysis of humpback whale song that’s publicly available through a web-based interface. Recordings of whales off the coasts of Hawaii, Colombia and California will reveal whether singers modify their songs to maximize the detectability of song-generated echoes. The Colombian recordings are cleaner, with little noise generated by human activity. Those will be compared to the other sets, where there is considerable noise from shipping traffic. Singers’ vocal reactions to each other will also be analyzed to determine how songs produced in locations where other singers are audible differ from songs produced in isolation.
It’s a unique project with the potential to also reveal insights into the origins of human cognition.
“Humpback whales and humans are the only mammals on the planet that regularly reorganize their vocal repertoires as adults,” says Mercado. “Understanding this unlikely convergence can potentially shed light not just on the nature of whale songs, but also on the neural and ecological factors that determine how vocal flexibility and cognitive skills like speech production naturally emerge.
“Comparative studies of vocal flexibility can provide new clues about why humans, but not other primates, can continuously learn to adjust the sounds they produce and use.”
The public outreach component of the project will also create awareness of oceanic noise pollution and the billions of metric tons of greenhouse gases emitted by container ships, which account for 90% of world trade.
“Shipping is contributing not only to noisier ocean soundscapes, but also to incremental shifts in the physical features of ocean environments,” says Mercado. “By increasing public awareness of these new threats to whales’ survival, this project can help galvanize members of the public to do what is necessary to reverse the course of our current trajectory.”