Thursday, May 01, 2025

Rhythmically trained sea lion returns for an encore—and performs as well as humans

Ronan, the only non-human mammal to demonstrate highly precise beat keeping, continues to challenge our understanding of biomusicality

University of California - Santa Cruz

Ronan the rhythmically trained sea lion — image:
California sea lion Ronan at UC Santa Cruz’s Long Marine Laboratory.
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Credit: Photo by Colleen Reichmuth; NOAA/NMFS 23554

Santa Cruz, Calif.—Animal research on biomusicality, which looks at whether different species are capable of behaving in ways that show they recognize aspects of music, including rhythm and beat, remains a tantalizing field at the intersection of biology and psychology. Now, the highly trained California sea lion at UC Santa Cruz who achieved global fame for her ability to bob her head to a beat is finally back: starring in a new study that shows her rhythm is just as precise—if not better—than humans.

Ronan first shimmied onto the world stage in 2013, when researchers at the university’s Long Marine Laboratory reported that, not only could she bob her head to a beat, but adjust her nods to tempos and music she hadn’t heard before. In this new study, to be published on May 1 in the Nature journal Scientific Reports, Ronan’s research team showed that her synchronization was as good or better than humans—and that her consistency in performing the beat-keeping task was better than that of humans.

To best match Ronan’s way of responding to a beat, a head bob, researchers asked 10 UC Santa Cruz undergraduates to move their preferred arm in a fluid, up-and-down motion to the beat of a percussive metronome. Three tempos were played—at 112, 120, and 128 beats per minute—with Ronan not previously exposed to 112 and 128 bpms.

At 120 bpm, Ronan’s most practiced tempo, she on average hits within 15 milliseconds of the beat, according to the new study’s lead author, Peter Cook, a longtime researcher with UC Santa Cruz’s Institute of Marine Sciences. Ronan’s variability in timing beat-to-beat is also around 15 milliseconds. By contrast, the blink of a human eye takes about 150 milliseconds.

“She is incredibly precise, with variability of only about a tenth of an eyeblink from cycle to cycle,” said Cook, also a comparative neuroscientist at the New College of Florida. “Sometimes, she might hit the beat five milliseconds early, sometimes she might hit it 10 milliseconds late. But she's basically hitting the rhythmic bullseye over and over and over again.”

The researchers emphasize that Ronan is in complete control of her participation. She is not deprived of food nor punished for choosing not to engage, and her training structure reflects this autonomy: She begins each session by climbing onto a designated ramp station, where she relaxes while waiting for the experiment to begin. Once ready, she positions herself and signals her readiness to start. If she chooses to disengage at any point, she is free to return to her pool without any negative consequences.

Recapping Ronan’s career

Ronan was born in the wild in 2008, but stranded repeatedly due to malnutrition. After three such strandings, and being spotted walking down Highway 1 in 2009, regulatory agencies finally deemed her to be non-releasable. So UC Santa Cruz adopted her in 2010 and she became a permanent member of the Pinniped Lab.

The lab, led by UC Santa Cruz research scientist and adjunct professor Colleen Reichmuth, uses cooperative training methods to study behavior and physiology in marine mammals. Resident research animals, including Ronan, participate in a wide range of projects that help teams explore their amphibious subjects’ inner worlds. Examples include studies on learning and memory, sensory biology, and diving physiology.

In other words, Ronan isn’t just working on her rhythm everyday in the lab. The team estimates that, over the past 12 years, she has participated in about 2,000 rhythm exercises—each lasting just 10 to 15 seconds. And sometimes, years went by between these sessions while she focused on other areas of research.

“She definitely wasn’t overtrained,” Cook said. “Realistically, if you added up the amount of rhythmic exposure Ronan has had since she’s been with us, it is probably dwarfed by what a typical 1 year old kid has heard.”

Ronan’s original rhythm study was inspired by work by Ani Patel, at Tufts University, along with colleagues who studied intermittent beat keeping in Snowball, a pet cockatoo who spontaneously “danced” to the Backstreet Boys. Because humans and cockatoos are both vocal mimics, the parrot work led to a theory that brain changes to support vocal learning were required for moving in time to music.

Sea lions haven’t shown the ability to learn new vocalizations, so Ronan’s 2013 study made a huge splash because it challenged the vocal-learning theory of rhythm. But in the study’s wake, some prominent theorists in biomusicality claimed that her performance was not as precise and reliable as human performance.

They suggested that Ronan might not be doing exactly what humans were, and that, therefore, she could not rely on the same biological mechanisms for perceiving and moving in time to rhythm. That prompted Cook and Reichmuth to test Ronan again to see if she had improved, and to compare her performance to people performing a similar task with the same sounds.

What they found, as reported in today’s new study, is that Ronan was more precise and consistent at every tempo they tested. And in a head-to-head battle of the beats with the UC Santa Cruz students, she more than held her own. The study’s authors then used the students’ performance to model the theoretical performance of 10,000 humans conducting the same rhythmic behavior.

Based on that model, Ronan was in the 99th percentile for beat-keeping reliability.

Now, at 170 pounds and age 16, the team says Ronan is “grown up and in her prime” for a female sea lion in managed care. Being with her day in and day out, over more than a decade, the researchers have become extremely attuned to Ronan. They know she is intelligent, but also exuberant. And just like us, her performance gets better with practice.

“One of the most important outcomes of the study is the fact that maturation and experience matter,” Reichmuth said. “ It's not just a test of rhythmic performance. It reflects her cognitive behavior and her ability to remember and refine it over time.”

Another thing: Ronan also wants to perform well. Everytime she mounts her test platform, it’s because she wants to, Reichmuth explained. If Ronan’s not feeling it, there’s no test that day. “She's motivated. To her, it's a game she knows how to win,” Reichmuth said, “and she likes the fish that come with it.”

Ronan’s ripple effect

Ronan’s research progression has had far-reaching impacts in the scientific community, contributing to a growing body of work in comparative cognition. Her journey from an eager and curious orphaned sea lion to a key figure in rhythm-perception studies has exceeded all expectations. Her abilities challenge existing paradigms about which species can perceive and produce rhythm, opening new doors for research on the cognitive capacities of animals.

The team’s 2013 paper inspired follow-up studies across various species, including primates, elephants, birds, and yes, humans. As UC Santa Cruz researchers continue to analyze and share findings, they remain committed to fostering a broader understanding of rhythm perception across species—and Ronan’s recent work will further that goal.

Not a fluke

Ronan’s story is not just about one sea lion. A question Cook says he often hears is why can’t dogs dance. Our canine companions are frequently exposed to music, and yet, they don’t seem to respond with rhythmic movements like Ronan. Cook responds by asking his own question: How many people try to train their dog to dance in an explicit rhythm-based way?

The answer: not many. “If you're going to say dogs can't dance, you have to empirically assess that—really give the dog many opportunities to receive very precise feedback on rhythmic movement and see how they do,” Cook said. “I would be very surprised if you couldn't get a border collie to do something like what Ronan does if you spend enough time on it.”

But this isn’t about teaching animals a cool party trick for fun. What Cook and researchers like him around the globe seek to better understand are the evolution of cognition, the universality of pattern recognition, and the intricate ways in which brains—both human and non-human—process the world around them.

“Ronan’s new study highlights the importance of experience, maturity, and really fine-grained training in a controlled laboratory setting to assess these questions,” Cook concludes.

Other co-authors of the paper include researchers Carson Hood and Andrew Rouse, who are also jointly affiliated with UC Santa Cruz’s Institute of Marine Sciences and the New College of Florida.

# # #

Additional information:

Videos explaining and demonstrating findings from current study:
- https://youtu.be/oen67G5w5S0
- https://youtu.be/1zZc18B8ZW0

Study co-authors Andrew Rouse, Peter Cook, and Carson Hood with Ronan.

Credit

Photo by Colleen Reichmuth; NMFS 23554

Journal

Scientific Reports

DOI

10.1038/s41598-025-95279-1

Method of Research

Observational study

Subject of Research

Animals

Article Title

Sensorimotor synchronization to rhythm in an experienced sea lion rivals that of humans

Article Publication Date

1-May-2025

Sex- and race-specific prevalence of hearing loss across the adult lifespan and associated factors

JAMA Otolaryngology–Head & Neck Surgery

About The Study: The prevalence and degree of hearing loss were highest among white male individuals and lowest among Black female individuals in this cohort study of 1,787 adults. Some factors associated with hearing loss, including noise exposure, differed across sex-specific and race-specific groups. Hearing loss is an important public health concern that could be addressed through tailored interventions to reduce its risk across populations.

Corresponding Author: To contact the corresponding author, Lauren K. Dillard, PhD, AuD, email dillalau@musc.edu.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamaoto.2025.0534)

Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.

# # #

Embed this link to provide your readers free access to the full-text article This link will be live at the embargo time https://jamanetwork.com/journals/jamaotolaryngology/fullarticle/10.1001/jamaoto.2025.0534?guestAccessKey=7e9e17db-be00-46c2-b18e-e218cf32651a&utm_source=for_the_media&utm_medium=referral&utm_campaign=ftm_links&utm_content=tfl&utm_term=050125

Journal

JAMA Otolaryngology–Head & Neck Surgery

Designer microbe shows promise for reducing mercury absorption from seafood

UCLA and UCSD research suggests a probiotic could one day increase the benefits of eating fish

University of California - Los Angeles

Key takeaways

· UCLA and UCSD scientists inserted DNA-encoding methylmercury detoxification enzymes into the genome of an abundant human gut bacterium. The engineered bacterium detoxified methylmercury in the gut of mice and dramatically reduced the amount that reached other tissues, such as the brain and liver.

· Mice given an oral probiotic containing the engineered microbe and fed a diet high in bluefin tuna had much lower methylmercury levels than expected, suggesting that a probiotic might eventually make it safer for people to consume fish.

· Researchers performed the tests using pregnant mice and found lower levels of methylmercury in both maternal and fetal tissues, and lower signs of mercury toxicity in the fetal brain.

UCLA and UCSD scientists inserted DNA-encoding methylmercury detoxification enzymes into the genome of an abundant human gut bacterium. The engineered bacterium detoxified methylmercury in the gut of mice and dramatically reduced the amount that reached other tissues, such as the brain and liver.

Mice given an oral probiotic containing the engineered microbe and fed a diet high in bluefin tuna had much lower methylmercury levels than expected, suggesting that a probiotic might eventually make it safer for people to consume fish.

Researchers performed the tests using pregnant mice and found lower levels of methylmercury in both maternal and fetal tissues, and lower signs of mercury toxicity in the fetal brain.

An engineered gut microbe can detoxify methylmercury, reducing the amount that passes into the brain and developing fetuses of mice fed a diet rich in fish, UCLA and UC San Diego’s Scripps Institution of Oceanography scientists have discovered.

“We envision the possibility that people could take a probiotic to offset the risk of consuming too much methylmercury, especially when pregnant,” said UCLA associate professor and director of the UCLA Goodman-Luskin Microbiome Center Elaine Hsiao, who is the senior author of a paper describing the research in the journal Cell Host & Microbe.

Mercury is a pollutant that enters water from several sources, the largest of which are human activities such as coal burning, artisanal gold mining and smelting, and wastes

from consumer products. In the ocean, mercury transforms into a toxic form called methylmercury. It also biomagnifies, meaning that methylmercury concentrations in animal tissues increase up the food chain from algae-eaters to top predators like humans.

This means that all the methylmercury in something an organism eats goes into its tissues and is passed on to whatever eats it. Organisms near the top of their food chains, like bluefin tuna and humans, acquire all the mercury accumulated by the previous links in the chain. Thus, people who primarily eat food containing high mercury levels are at higher risk of mercury poisoning and birth defects.

“Despite global efforts to reduce mercury emissions and its accumulation in fish, methylmercury levels in seafood are not expected to decline anytime soon. Fish remains a major and culturally important part of the diet for many people around the world and we hope it continues to be,” said co-senior author and Scripps associate professor of marine biogeochemistry Amina Schartup.

Researchers modified Bacteroides thetaiotaomicron, a naturally abundant bacterium in the human digestive tract, by inserting DNA-encoding mercury detoxification enzymes from a mercury-resistant soil bacterium. After confirming that the engineered bacteria could clear methylmercury in a test tube, they replaced the natural gut microbiomes of mice with the modified bacteria and orally administered a large amount of methylmercury all at once. The mice had lower levels of methylmercury in their intestines just three hours after, and the level continued to fall for four days, showing that the bacteria helped to effectively eliminate the methylmercury in the intestine.

They next asked whether the engineered bacteria would be effective at decreasing tissue methylmercury levels when exposure occurs gradually through routine dietary intake. To test this, the researchers fed the mice diets containing bluefin tuna over a period of days and found that not only did the bacteria reduce mercury in the intestine just as well, but less entered the brain and liver, too.

They then tested pregnant mice and found lower levels of methylmercury in both maternal and fetal tissues, and lower signs of mercury toxicity in the fetal brain.

“By reducing dietary methylmercury in the intestine, the gut bacteria helped to eliminate it from the body before it could enter the maternal bloodstream and access the developing offspring,” said first author and UCLA research scientist Kristie Yu.

Co-author and UCLA researcher Franciscus Chandra said that the lowered signs of toxicity in the fetal brain showed that the bacterium works at levels that are biologically meaningful.

When the team repeated the experiments with salmon, which contains lower levels of methylmercury than in bluefin tuna, the bacterium was also effective.

Finally, they fed the bacteria as an oral probiotic to mice with intact microbiomes and fed them the same bluefin tuna diet as the mice in the previous experiment. Under these conditions, the engineered bacteria were also remarkably effective at minimizing the amount of methylmercury that entered tissues, suggesting that one day, a probiotic could be developed to reduce the risks of a fish-based diet.

The researchers were supported by funds from the Eunice Kennedy Shriver National Institute of Child Health and Human Development; the National Institute of Environmental Health Sciences; the National Science Foundation; the Research Corporation for Science Advancement; the Simons Foundation; and the Packard Foundation.

Hsiao and Schartup are working on improving the efficacy of the bacterium and moving closer to translation to humans, an endeavor for which continued federal funding is critical.

Journal

Cell Host & Microbe

Ptero firma: Footprints pinpoint when ancient flying reptiles conquered the ground

Study led by the University of Leicester links fossilised flying reptile tracks to animals that made them

University of Leicester

Skeletal reconstruction — image:
A skeletal reconstruction of a comb-jawed pterosaur walking across an ancient mudflat, its posture and movement informed by fossil trackways.
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Credit: Source: University of Leicester

Fossils of footprints over 160 million years old have helped palaeontologists at the University of Leicester to narrow down when pterosaurs adapted to live on the ground.

These awe-inspiring flying reptiles of the Mesozoic era are often imagined soaring over the heads of dinosaurs. But new research shows that some of these ancient creatures were just as comfortable walking on the ground.

In a groundbreaking new study published today in Current Biology (1 May), scientists at the University of Leicester have successfully linked fossilised footprints to the types of pterosaurs that produced them. By using 3D modelling, detailed analysis, and comparisons with pterosaur skeletons, the team has shown that at least three different types of tracks match up with distinct groups of pterosaurs.

The new study supports the idea that pterosaurs underwent a major ecological shift during the middle part of the Age of Dinosaurs, about 160 million years ago, with several groups becoming more terrestrial.

Lead author Robert Smyth, a doctoral researcher in the in the Centre for Palaeobiology and Biosphere Evolution (School of Geography, Geology and the Environment at the University of Leicester), explained: “Footprints offer a unique opportunity to study pterosaurs in their natural environment. They reveal not only where these creatures lived and how they moved, but also offer clues about their behaviour and daily activities in ecosystems that have long since vanished.”

The study uncovered three distinct types of pterosaur footprints, each shedding light on different lifestyles and behaviours. By linking footprints to specific groups, scientists now have a powerful new way to study how these flying reptiles lived, moved, and adapted to different ecosystems across time.

Co-author Dr David Unwin from the School of Museum Studies, University of Leicester explained: "Finally, 88 years after first discovering pterosaur tracks, we now know exactly who made them and how."

Perhaps the most striking discovery comes from a group of pterosaurs called neoazhdarchians which includes Quetzalcoatlus, with a 10 m wingspan one of the largest flying animals ever to have existed. Their footprints have been found in coastal and inland areas around the world, supporting the idea that these long-legged creatures not only dominated the skies but were also frequent ground dwellers, inhabiting the same environments as many dinosaur species. Some of these tracks are present right up until the asteroid impact event, 66 million years ago, which led to the extinction of both pterosaurs and dinosaurs.

One group of pterosaurs, ctenochasmatoids, known for their long jaws and needle-like teeth, left behind tracks most commonly found in coastal deposits. These animals likely waded along muddy shores or in shallow lagoons, using their specialised feeding strategies to catch small fish or floating prey. The abundance of these tracks suggests that these coastal pterosaurs were far more common in these environments than their rare bodily remains indicate.

Another type of footprint was discovered in rock layers that also preserve the fossilised skeletons of the same pterosaurs. The close association between the footprints and skeletons provides compelling evidence for identifying the print makers. Known as dsungaripterids, these pterosaurs had powerful limbs and jaws, with toothless, curved beak tips designed for prising out prey, while large, rounded teeth at the back of their jaws were perfect for crushing shellfish and other tough food items.

Smyth explains: "Tracks are often overlooked when studying pterosaurs, but they provide a wealth of information about how these creatures moved, behaved, and interacted with their environments. By closely examining footprints, we can now discover things about their biology and ecology that we can't learn anywhere else."

Pterosaur tracks meet their match. Where ancient footprints meet their maker. A side-by-side comparison of a pterosaur’s hand and foot with 155-million-year-old tracks from Wyoming, USA. The false-colour depth map reveals the shape and pressure of each step, showing that these creatures bore more weight on their hands while walking.