Having good friendships may make for a healthier gut microbiome

Beneficial microbes are more abundant in more sociable rhesus macaques

Peer-Reviewed Publication

FRONTIERS

 

IMAGE: RHESUS MACAQUES ON CAYO SANTIAGO GROOMING EACH OTHER view more 

CREDIT: LAUREN BRENT

Social connections are essential for good health and wellbeing in social animals, such as ourselves and other primates. There is also increasing evidence that the gut microbiome – through the so-called ‘gut-brain axis’ – plays a key role in our physical and mental health and that bacteria can be transmitted socially, for example through touch. So how does social connectedness translate into the composition and diversity of the gut microbiome? That’s the topic of a new study in Frontiers in Microbiology on rhesus macaques, Macaca mulatta.

Lead author Dr Katerina Johnson, a research associate at the Department of Experimental Psychology and the Department of Psychiatry of the University of Oxford, said: “Here we show that more sociable monkeys have a higher abundance of beneficial gut bacteria, and a lower abundance of potentially disease-causing bacteria.”

Monkey island

The scientists focused on a single social group (with 22 males and 16 females between the ages of six and 20 years) of rhesus macaques on the island of Cayo Santiago, off the eastern coast of Puerto Rico. Macaques originally only lived in North Africa and Asia. But in 1938, a founder population of 409 rhesus macaques was moved from India to Cayo Santiago. Today, more than 1,000 macaques live on the 15.2 hectare island, divided into several social groups. They range and forage freely, although their diet gets supplemented daily with monkey chow. Researchers do behavioral observations on the monkeys each year.

Between 2012 and 2013, the authors collected a total of 50 uncontaminated stool samples from this social group. As a measure of social connectedness, they used the time each monkey spent grooming or being groomed in 2012 and 2013, and his or her number of grooming partners. 

Social grooming

Co-author Dr Karli Watson, from the Institute of Cognitive Science at the University of Colorado Boulder, explained: “Macaques are highly social animals and grooming is their main way of making and maintaining relationships, so grooming provides a good indicator of social interactions.”

Johnson, Watson et al. analyzed DNA sequence data from the stool samples to measure the composition and diversity of the gut microbial community, and looked at the relationship with social connectivity. They also took into account sex, age, season, and rank within the group’s hierarchy. They focused on microbes that have been repeatedly shown in to be either more or less abundant in people or rodents with autism-like symptoms (commonly accompanied by social disconnection) or which are socially deprived.

Sociable monkeys have more ‘good’ microbes

“Engagement in social interactions was positively related to the abundance of certain gut microbes with beneficial immunological functions, and negatively related to the abundance of potentially pathogenic members of the microbiota,” said co-author Dr Philip Burnet, a professor from the Department of Psychiatry at the University of Oxford.

For example, genera more abundant in the most sociable monkeys included Faecalibacterium and Prevotella. Conversely, the genus Streptococcus, which in humans can cause diseases such as strep throat and, pneumonia, was most abundant in less sociable monkeys.

“It is particularly striking that we find a strong positive relationship between the abundance of the gut microbe Faecalibacterium and how sociable the animals are. Faecalibacterium is well known for its potent anti-inflammatory properties and is associated with good health,” said Johnson.

Cause and effect?

But what drives the relationship between social connectedness and gut microbiome composition? Distinguishing between cause and effect isn’t easy.

“The relationship between social behavior and microbial abundances may be the direct result of social transmission of microbes, for example through grooming. It could also be an indirect effect, as monkeys with fewer friends may be more stressed, which then affects the abundance of these microbes. As well as behavior influencing the microbiome, we also know it is a reciprocal relationship, whereby the microbiome can in turn affect the brain and behavior,” said Johnson.

Co-author Dr Robin Dunbar, a professor from the Department of Experimental Psychology at the University of Oxford, said: “As our society is increasingly substituting online interactions for real-life ones, these important research findings underline the fact that as primates, we evolved not only in a social world but a microbial one as well.”

Rhesus macaques on Cayo Santiago grooming each other

Rhesus macaques on Cayo Santiago grooming each other

CREDIT

Lauren Brent

Rhesus macaques on Cayo Santiago grooming each other

CREDIT

Alyssa Arre

Rhesus macaques on Cayo Santiago grooming each other

CREDIT

Lauren Brent

The 'Monkey island' of Cayo Santiago, off Puerto Rico

CREDIT

Joyce Cohen

JOURNAL

Frontiers in Microbiology

DOI

10.3389/fmicb.2022.1032495 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Sociability in a non-captive macaque population is associated with beneficial gut bacteria

ARTICLE PUBLICATION DATE

11-Nov-2022

Study: Popular dietary supplement causes cancer risk, brain metastasis

University of Missouri researchers made the discovery while using bioluminescent imaging technology to study how nicotinamide riboside supplements work inside the body.

Peer-Reviewed Publication

UNIVERSITY OF MISSOURI-COLUMBIA

 

IMAGE: ELENA GOUN view more 

CREDIT: UNIVERSITY OF MISSOURI

While previous studies have linked commercial dietary supplements like nicotinamide riboside (NR), a form of vitamin B3, to benefits related to cardiovascular, metabolic and neurological health, new research from the University of Missouri has found NR could actually increase the risk of serious disease, including developing cancer.

The international team of researchers led by Elena Goun, an associate professor of chemistry at MU, discovered high levels of NR could not only increase someone’s risk of developing triple-negative breast cancer, but also could cause the cancer to metastasize or spread to the brain. Once the cancer reaches the brain, the results are deadly because no viable treatment options exist at this time, said Goun, who is the corresponding author on the study.

“Some people take them [vitamins and supplements] because they automatically assume that vitamins and supplements only have positive health benefits, but very little is known about how they actually work,” Goun said. “Because of this lack of knowledge, we were inspired to study the basic questions surrounding how vitamins and supplements work in the body.”

Following the death of her 59-year-old father only three months after being diagnosed with colon cancer, Goun was moved by her father’s passing to pursue a better scientific understanding of cancer metabolism, or the energy through which cancer spreads in the body. Since NR is a known supplement for helping increase levels of cellular energy, and cancer cells feed off of that energy with their increased metabolism, Goun wanted to investigate NR’s role in the development and spread of cancer.

“Our work is especially important given the wide commercial availability and a large number of ongoing human clinical trials where NR is used to mitigate the side effects of cancer therapy in patients,” Goun said.

The researchers used this technology to compare and examine how much NR levels were present in cancer cells, T cells and healthy tissues.

“While NR is already being widely used in people and is being investigated in so many ongoing clinical trials for additional applications, much of how NR works is a black box — it’s not understood,” Goun said. “So that inspired us to come up with this novel imaging technique based on ultrasensitive bioluminescent imaging that allows quantification of NR levels in real time in a non-invasive manner. The presence of NR is shown with light, and the brighter the light is, the more NR is present.”

Goun said the findings of the study emphasize the importance of having careful investigations of potential side effects for supplements like NR prior to their use in people who may have different types of health conditions. In the future, Goun would like to provide information that could potentially lead to the development of certain inhibitors to help make cancer therapies like chemotherapy more effective in treating cancer. The key to this approach, Goun said, is to look at it from a personalized medicine standpoint.

“Not all cancers are the same in every person, especially from the standpoint of metabolic signatures,” Goun said. “Often times cancers can even change their metabolism before or after chemotherapy.”   

“A bioluminescent-based probe for in vivo non-invasive monitoring of nicotinamide riboside uptake reveals a link between metastasis and NAD+ metabolism” was published in the Journal of Biosensors and Bioelectronics. Funding was provided by grants from the European Research Council (ERC-2019-COG, 866338) and Swiss National Foundation (51NF40_185898), as well as support from NCCR Chemical Biology.

Other authors on the study are Arkadiy Bazhin, Pavlo Khodakivskyi, Ekaterina Solodnikova and Aleksey Yevtodiyenko at MU; Tamara Maric at the Swiss Federal Institute of Technology; Greta Maria Paola Giordano Attianese, George Coukos and Melita Irving at The Ludwig Institute for Cancer Research in Switzerland; and Magali Joffraud and Carles Cantó at the Nestlé Institute of Health Sciences in Switzerland. Bazhin, Khodakivskyi, Mikhaylov, Solodnikova, Yevtodiyenko and Goun are also affiliated with the Swiss Federal Institute of Technology. Mikhaylov, Yevtodiyenko and Goun are also affiliated with SwissLumix SARL in Switzerland.

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JOURNAL

Biosensors and Bioelectronics

DOI

10.1016/j.bios.2022.114826 

Mysterious outbreak of bone-eating TB resembled an ancestral form

Driving force behind strange NC outbreak solved by a Duke collaboration

Peer-Reviewed Publication

DUKE UNIVERSITY

DURHAM, N.C. –  Tuberculosis is usually encountered as a disease of the lungs, but in 2 percent of cases in the U.S. it can also be found in the bones. The 9,000-year-old skeletons of some Egyptian mummies show signs of having tuberculosis infection in their bones, a painful condition that leaves the bones looking like they’ve been gnawed. 

So it was a weird puzzle when Duke physician Jason Stout M.D. encountered a Wake County TB outbreak in the mid-2000s in which the infection had spread beyond the lungs in six people. “Four out of six were in the bone,” Stout said. “That’s way more than 2 percent.”

The index case, the first person in Raleigh to have this strain of the disease, apparently contracted the bacterium in Vietnam, but he wasn’t feeling very sick and had been working around 400 people in his workplace.

“So it was prolonged exposure in a workplace,” said Stout, a Duke professor of medicine who tracked down and identified seven subsequent infections through contact tracing and health department records.

All eight people were treated with antibiotics and other co-workers received preventative care and then the strange outbreak went away. But the mystery was never really solved. “I’m an epidemiologist and clinical trial specialist and I was left scratching my head,” Stout said.

Until several years later when Stout had a chance conversation with his colleague and TB researcher David Tobin, Ph.D., an associate professor in molecular genetics and microbiology and immunology at Duke.

“We met up and we're having coffee one day, and we're talking about this,” Stout recalls. Academic medical centers like Duke routinely keep biological specimens, and Stout still had samples of the puzzling bug. “David said, ‘Well, give it to me and we'll take a look.’ And then this amazing science came from that,” Stout said.

The amazing science is that Tobin’s lab, with several colleagues at Duke, Notre Dame, and the University of Texas, figured out precisely how and why these particular TB bacteria were so mobile. Their findings appear online Nov. 9 in the journal Cell.

“Certain infections tend to go certain places,” Stout said. “And the question is always, why does it do that?” In TB strains found in the Americas and Europe, the bacteria seem more likely to stay put in the lungs. But this strain was highly mobile.

Tobin’s team, led by Joseph Saelens, Mollie Sweeney and Gopinath Viswanathan, ran genetic sequencing on the Raleigh bug and found it most resembled an ancestral strain from a group of strains called lineage 1. In the U.S. we tend to see the modern strains, lineages 2, 3, and 4, but lineage 1 is still out there, mostly in South and Southeast Asia.

Mycobacterium tuberculosis generally infects a type of white blood cell called a macrophage, a highly mobile street sweeper cell that moves around looking for invaders and then engulfs them and chews them up. (Macrophage is Latin for big eater.) One part of the pathogenic bacteria’s toolkit is a set of unique chemical signals – secreted factors -- to protect itself from the immune system and tell its macrophage host what to do.

Tobin’s team wanted to find the difference that allowed the Wake County bug’s macrophages to be more mobile and leave the lungs.

They compared genetic variants from 225 different strains of TB with particular attention to the genes for their secreted factors. What they found is a secretion factor called EsxM that was active in the Raleigh bacteria, but had been inactivated by a mutation in the modern strains.

Then, working with Craig Lowe, an evolutionary biologist and assistant professor of molecular genetics and microbiology at Duke, they looked at genetic sequencing from 3236 different strains of TB and found the pattern persisted: the modern strains have a silenced version of the EsxM secretion factor. “Over a few thousand strains, that really holds up,” Tobin said. “They’ve maintained that and presumably it’s something that’s evolutionarily advantageous to them.”

To further prove their point, the researchers put active versions of EsxM into safely attenuated versions of modern strains and watched as their macrophage hosts in a lab dish became more active and mobile. “We can see these changes in macrophage shape and structure and they become more migratory,” Tobin said. They also knocked out EsxM in a strain with the ancestral version and made the infected macrophages less mobile.

While being careful not to overstate their findings, Tobin said it would appear that the broadly distributed modern strains of TB benefit from staying within the lungs because of the way they spread through the air by breathing. Staying in the lungs would presumably give them a better launching pad to a new host.

Fortunately, the migratory TB strain hasn’t been seen again locally, Stout said, “hopefully because we did good work and got a lot of people preventative therapy.” But the mystery of its strange mobility has been solved.

“This may well have ended with me saying, ‘Wow, that was weird. There’s got to be something about the strain because all these patients had healthy immune systems,’” Stout said. “But the kind of science that I do is not the kind of science that David does. This is a wonderful example of people from different disciplines coming together to answer a really interesting clinical problem.”

This research was supported by the National Institutes of Health (AI-125517, AI-130236, AI-127115, AI-142127, AI-149147, AI-106872, 1DP2-GM146458-01, UC6-AI-058607).

CITATION: “An Ancestral Mycobacterial Effector Promotes Dissemination of Infection,” Joseph W. Saelens, Mollie I. Sweeney, Gopinath Viswanathan, Ana María Xet-Mull, Kristen L. Juric Smith, Dana M. Sisk, Daniel D. Hu, Rachel M. Cronin, Erika J. Hughes, W. Jared Brewer, Jörn Coers, Matthew M. Champion, Patricia A. Champion, Craig B. Lowe, Claire M. Smith, Sunhee Lee, Jason E. Stout, David M. Tobin. Cell, Nov. 9, 2022. DOI: 10.1016/j.cell.2022.10.019

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JOURNAL

Cell

DOI

10.1016/j.cell.2022.10.019 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Cells

ARTICLE TITLE

An Ancestral Mycobacterial Effector Promotes Dissemination of Infection

ARTICLE PUBLICATION DATE

9-Nov-2022

BEHIND CUBA

Decades-long push to lower stillbirth rate in the US has stalled, Rutgers-led research finds

A study published in The Lancet shows no progress since mid-2000s in reducing stillbirth risk.

Peer-Reviewed Publication

RUTGERS UNIVERSITY

A decades-long effort to lower the stillbirth rate in the United States has stalled, as has progress in closing a persistent gap in excess stillbirths experienced by Black women compared with White women, according to a Rutgers-led study.

“Over the last 40 years, we have reduced certain risk factors for stillbirth, such as smoking and alcohol use before and during pregnancy, but these gains have been countered by substantial increases in other risk factors, like obesity and structural racism,” said Cande Ananth, chief of Epidemiology and Biostatistics in the Department of Obstetrics, Gynecology and Reproductive Sciences at the Rutgers Robert Wood Johnson Medical School and lead author of the study published in The Lancet Regional Health – Americas.

“Our findings illustrate that past progress has now been offset by these newly identified risks,” Ananth said.

To determine how cultural and environmental factors impact stillbirths among Black and White women in the U.S., Ananth and a team of Rutgers obstetricians examined changes in stillbirth rates between 1980 and 2020.

Using data compiled by the National Center for Health Statistics of the Centers for Disease Control and Prevention and covering all 50 states and the District of Columbia, the researchers measured how maternal age, year of death (indicative of changes in prenatal and intrapartum care and other factors) and maternal birth cohorts (indicative of social and environmental elements,  such as socioeconomic status, education, nutrition and substance use at the time of the women’s birth) shaped stillbirth trends.

More than 157 million live births and nearly 711,000 stillbirths delivered at 24 or more weeks over the last four decades in the U.S. were included in the study.

Consistent with previous studies, the researchers found that total stillbirth rates in the U.S. declined steadily between 1980 and 2005, backed by advances in prenatal care and maternal health. For every 1,000 women who delivered in 1980, 10 of those pregnancies ended in stillbirth. By 2005, the figure had declined to about 5 per 1,000.

But since then, the researchers found, improvements have flatlined and the rate today is about the same as it was more than a decade ago.

Additionally, despite efforts to reduce structural racism and increase health-care access to women of color, the disparity in stillbirth rates for Black women compared with White women remained unchanged during the 40-year period. The rate for Black women was about twice the rate of White women in 1980 (17.4 versus 9.2 per 1,000 births) and remained twofold in 2020 (10.1 versus 5.0 per 1,000 births).

Unlike most previous work, which has focused primarily on risks such as age at delivery and social and environmental conditions, Ananth’s study added a third element: the birth cohort – the year the mother herself was born.

Ananth said that the data demonstrates a strong link between birth cohort and stillbirth risk.

“The cohort is a new dimension to understanding these adverse outcomes,” said Ananth. “To understand the paper’s significance, you need to view it in a three-dimensional perspective. We have age of the mother, year of delivery and the birth cohort. All three factors are time-related and intertwined.”

Several factors might explain the stalled decline in reducing stillbirth rates. One possible cause, the researchers wrote, is a national effort in 2009 to reduce elective deliveries before 39 weeks. There also may have been a slowdown in medical advances and obstetrical intervention to predict or prevent stillbirth.

The persistent gap in stillbirth disparities is more complicated and includes structural racism and biases, social inequality and a greater burden of chronic diseases and illness, Ananth said.

Taken together, Ananth said these data paint a dire health care picture that needs urgent attention at local, state and national levels.

“I am a firm believer that even one death is one too many,” he said. “Delivering a stillbirth carries so much social and emotional trauma – for the parents, and for the entire society.”

JOURNAL

The Lancet

DOI

10.1016/j.lana.2022.100380 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Evolving stillbirth rates among Black and White women in the United States, 1980–2020: A population-based study

How we experience the pain of other people?

Peer-Reviewed Publication

NETHERLANDS INSTITUTE FOR NEUROSCIENCE - KNAW

A new study from the Netherlands Institute for Neuroscience recorded from neurons of human patients to show that the pain of others is directly mapped onto neurons in the insula – a brain region critical for our own emotions.

Sharing the distress of others is considered key to empathy and our motivation to help others. With people greatly differing in their ability to empathize, and some psychiatric patients lacking the ability to empathize, understanding how our brain makes the pain of others feel painful is key to understanding the origin of these individual differences.

So far, we have had to rely on fMRI studies to identify brain regions that become activated while we perceive the pain of others. Unfortunately, fMRI cannot directly measure the activity of neurons. Instead it measures changes in blood-flow that help pinpoint brain regions that are associated with empathy. To understand where in the brain neurons help us share the distress of others, we would need to insert electrodes into the brain, and directly measure the electrical activity through which neurons process information. For obvious reasons, this is not possible in humans, or is it?

Epilepsy patients

In certain cases of epilepsy that cannot be treated using pharmacological treatments, surgeons implant electrodes directly into the brain of patients, to localize the origin of the epilepsy. The patients then have to stay in the hospital for about a week, while the surgical team records their brain activity and waits for an epileptic event to occur. To add purpose to this waiting, some patients volunteer a unique opportunity to better understand the human mind: they engage in psychological tasks while their brain activity is measured through these medical electrodes.

In a new paper published in the prestigious journal eLife, a collaboration between NIN researchers Efe Soyman, Rune Bruls, Kalliopi Ioumpa under the supervision of professors Christian Keysers and Valeria Gazzola leveraged this unique opportunity to test the notion that neurons in brain regions involved in our own pain, like the insula, contain neurons with activity that directly mirrors the pain of others. They showed patients short video-clips of a woman experiencing various levels of pain, and measured how strongly neurons in the insula – a brain region involved in the patient's own pain experiences – respond to the pain they observe the woman in the video-clip to experience. Specifically, they could measure intracranial local field potentials, which measure the activity of some hundreds of insula neurons close to the electrode, from 7epilepsy patients. In addition, they could zoom into the activity of individual neurons in the insula of 3 epilepsy patients.

Background: The insula and our own emotions

The insula, a brain region hidden inside of the brain, is known to play a critical role in our own emotions. It can sense the state of our body through input from our inner organs and skin, and integrates this information with what we see, hear and smell, and is thought to give rise to these conscious feelings we call emotions. In particular, it has also been shown to contain many neurons that respond when we experience pain in or on our own body, with the level of its activity scaling with how unpleasant we find this pain.

The novelty: coding the pain of others

The team therefore explored whether neurons in this region would also represent the level of pain experiences by others. Because the movies they showed participants varied in how much pain the actress in the movies was experiencing, the team could explore whether movies in which the patients perceived others to be in more pain would be movies in which the insular neurons would show more activity – serving as a mirror for other people’s pain. This is exactly what they found: throughout the insula, they could record electrical activity that scaled with the pain the people reported perceiving in the movies. This was true in the local field potentials, and even in individual neurons, providing the first evidence, that a brain region involved in our own pain, contains a fine-grained representation of how much pain others experience.

Using advanced data analysis methods, the team could take the level of electrical activity in the insula during each movie, and predict how the patient would respond to the question: “how intense do you think the pain was that the person in the movie experienced”. By offering the unique opportunity to directly record from their brain, the patients thus provided us with a key insight into human empathy: it really looks as though we empathize with the pain of others because our brains are wired to transform their pain into activity in regions involved in our own pain.

How do we perceive the pain of others?

The team provided further insights into how we perceive the pain of others. In half the videos, the camera was focused on the facial expression of the actress, which was seen to unfold from a neutral expression to one of varying degree of pain in a period of about one second. Analyzing the electrical responses in the insula and the muscle movements of the actress in the movies revealed that what the brain appears to use to perceive the pain of others was not the movement per se, but simply how contracted the eyes of the actress ended up being. In the other half, the camera was focusing on the hand of the actress, and showed a belt hitting the hand. In that case, the brain appeared to deduce the amount of pain from processing how much the hand was moving under the action of the belt. Together, this revealed intricate details of how flexibly the human brain transforms what we see others do into a fine-grained perception of their inner states.

While this study focused on a single brain region, the insula, that fMRI studies had suggested to be important for empathy, future research of the team will aim to combine the data from all recorded electrodes. They can then develop a map of where in the brain, the pain of others is transformed into the nuanced empathy we can have for other people’s emotions, and pinpoint the locations in which differences across individuals could account for the striking differences in empathy we can observe around us.

Acknowledgements:

This work was made possible through a tight collaboration between the members of the social brain lab that designed the tasks and analysed the data (Efe Soyman, Rune Bruls, Kalliopi Ioumpa, Laura Müller-Pinzler, Selene Gallo, Chaoyi Qin, Christian Keysers and Valeria Gazzola), clinicians at the VUmc in Amsterdam that performed the surgeries and helped in data acquisition (Elisabeth CW van Straaten, Johannes C Baayen, Sander Idema), and the team of Prof. Pieter Roelfsema and Matt Self (Matthew W Self, Judith C Peters, Jessy K Possel) that have established the link between the fundamental research at the NIN and the clinicians at the VUmc, and also helped acquire the data. We extend our warmhearted gratitude to the patients that participate and thereby made these scientific insights possible.

Source: eLife: https://doi.org/10.7554/eLife.75197

Quotes:

Christian Keysers: “As a neuroscientist, our dream is to understand how neurons make us who we are. What these patients do, by allowing us to record from these electrodes, is to make that dream come true: we could see in real time, how the pain of someone else is mirrored in the neurons of an observer. After decades of working on empathy, we could see empathy unfold in the human insula”.

Efe Soyman: “Other people’s suffering can be inferred from a variety of indicators: a painful expression, the intensity of the event that inflicts pain in them, etc. With this incredibly valuable data we collected from the patients, we see how the human insula might tune into whichever is available among these various cues when we experience the pain of other people.”

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JOURNAL

eLife

DOI

10.7554/eLife.75197 

ARTICLE TITLE

Intracranial human recordings reveal association between neural activity and perceived intensity for the pain of others in the insula

Seals’ sense of rhythm may give us answers about our own musicality

New research from Aarhus University suggests that seals can both distinguish and react differently to different rhythms. A big step forward in understanding human musicality, says Associate Professor Andrea Ravignani

Peer-Reviewed Publication

AARHUS UNIVERSITY

New research from Aarhus University suggests that seals can both distinguish and react differently to different rhythms. A big step forward in understanding human musicality, says Associate Professor Andrea Ravignani.

When a small child develops language, the language centre is not the only part of the brain that is activated; a sense of rhythm goes hand in hand with language development for us humans. The same also applies to birds. Monkeys, on the other hand, turn out to have almost no sense of rhythm. But in fact, researchers currently know very little about whether other vocally-plastic mammals, like us, also pick up on and react to rhythms.

However, a new study from the Centre for Music in the Brain at the Department of Clinical Medicine at Aarhus University and Max Planck Institute for Psycholinguistics now suggests that seal pups do not just listen to, but also react differently to sounds played in different rhythms.

Associate Professor Andrea Ravignani is behind the study, in which the researchers tested a total of 20 harbour seal pups to see if they had an understanding of rhythm. Over a period of 30 minutes, the researchers played sequences of seal calls in different rhythmic variations and tempi. Some were quick, others slow, some were rhythmic, while others were irregular. The experiment showed that the seals reacted differently, depending on which rhythm the researchers played, says Andrea Ravignani.

“We filmed the seals’ reactions to the sounds and measured how many times they turned their heads to look at where the sounds were coming from. We then examined whether there was a difference between how many times the seals turned their heads, and how long they looked towards the sound, depending on the rhythm we played. This allowed us to see whether the different rhythms produced different reactions,” says Andrea Ravignani.

The method is also known from studies of babies’ reactions to sounds and rhythms, and although it may seem strange to investigate the rhythmic sense of seals, the study, according to Andrea Ravignani, may provide not only a better understanding of the seals’ sense of rhythm, but also of human language development.

“Our study represents a significant step forward in relation to our understanding of humankind’s own musicality and language development, about which we still don’t know very much today. By showing that another vocally plastic mammal can also perceive different rhythms, we support the scientific hypothesis that the two abilities are interconnected,” he says.

“We can conclude that even very young, untrained seals can distinguish vocalisations from other seals, based on their rhythms. It shows that we are not the only mammals to show rhythmic understanding and learn vocalisations. The two abilities may possibly have developed in parallel in both seals and human beings.”

More studies on the way

According to Andrea Ravignani, the study may be the first of its kind to link a spontaneous rhythmic understanding and the development of vocalisation in a mammal other than human beings. At the same time, it is worth noting, says Andrea Ravignani, that early in life the seal pups have a robust understanding of rhythm that has not been trained. The same intuitive rhythmic understanding is seen in human infants.

The study raises more questions, which the researchers hope to be able to answer in other studies, says Andrea Ravignani.

“Can seals detect rhythms in sounds other than seal sounds, such as sounds from other animals, or abstract sounds? Can they perceive more complex rhythms? Are seals unique in this, or do other mammals also have a sense of rhythm? And what are the biological and physiological mechanisms that support this ability? These are all questions to which we now hope to find the answers.”

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Behind the research results

• Type of study: Observational study
• Partners: Comparative Bioacoustics Group, Max Planck Institute for Psycholinguistics
• External funding: Max Planck Research Group (MPRG) 
• Link to the scientific article: https://doi.org/10.1098/rsbl.2022.0316

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JOURNAL

Biology Letters

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Spontaneous rhythm discrimination in a mammalian vocal learner

Your favorite songs reveal your attachment style: New psychology research

Peer-Reviewed Publication

UNIVERSITY OF TORONTO

What does having a particular artist on repeat tell us about how to — or how not to — navigate our romantic lives, friendships and family ties? Whether it’s Adele or The Weeknd on your go-to playlist, the lyrics can say a lot about you, and it’s all related to attachment styles, or how people typically think, feel and act in relationships.

“I’m interested in the role music plays in people’s lives. Since humans started making music tens of thousands of years ago, songs across cultures have always focused on relationships — getting into one, maintaining one or breaking up — so I wondered, do people listen to music that mirrors their experiences in relationships?” says Ravin Alaei, who graduated with a PhD from the Department of Psychology in the Faculty of Arts & Science in 2019.

In a new study published in the journal Personal Relationships, Alaei and Department of Psychology professors, Geoff Macdonald and Nicholas Rule, found that people’s individual attachment styles correspond with the lyrics of their favourite songs. In other words, we tend to return to the tunes that spell out what we’re going through in a relationship, for better or for worse.

“Lyrics matter, so pay attention to them,” says Alaei, who is also a physician who earned his MD at McMaster University. “The lyrics of your favourite songs about relationships may help validate your thoughts and feelings but may also reveal things about your experiences of relationships that you might not have realized — something that you’re going through repeatedly, that you keep coming up against.”

First, a refresher on attachment styles, which can roughly be considered as four categories, says Alaei. Anxiously attached people worry about being rejected and seek a lot of reassurance about their relationships. On the other hand, avoidantly attached people respond to their negative expectations of relationships by closing off emotions and intimacy in favour of independence. People with a mixed attachment style have confused expectations, fluctuating between clingy and cold. Lastly, secure people have optimistic outlooks on relationships, and are open communicators and trust their partners.

“We asked about 570 people to tell us their favourite songs, and then coded the nearly 7,000 songs for the attachment style that their lyrics expressed. In turn, we consistently found that avoidantly attached people prefer music with avoidant lyrics,” says Alaei. “I expected to see a clear relationship between anxiously attached people and anxious songs because they are the most emotional, but surprisingly, this was the most tenuous result.”

This strong avoidant connection is reflected not only on an individual level, but on a societal one as well. In a second study, the researchers coded over 800 Billboard number-one hits from 1946 to 2015 for their attachment themes and found that lyrics have become more avoidant and less secure over time.

“Popular music lyrics are running parallel to sociological trends of social disconnection — people valuing independence over reliance on others, and feeling more isolated,” says Alaei.

If we’re listening to music that reflects our relationships back at us, is that helping or hindering our relationship skills? Alaei says this is the next step in the research.

Take Adele’s discography for example, which Alaei says tips the scale towards anxiously attached themes and was popular among participants. “Someone Like You” appeared on many playlists, with the refrain: “I hate to turn up out of the blue uninvited / But I couldn’t stay away, I couldn’t fight it / I had hoped you’d see my face and that you’d be reminded / That for me it isn’t over.”

If someone is an anxiously attached person, will listening to “Someone Like You” on repeat cause more harm than good? According to Alaei, it all starts with self-awareness of your own attachment style.

“As an anxious person, you should recognize that you’re vulnerable to a negative feedback loop, and your emotions snowballing,” says Alaei. “Music can be a very powerful exacerbator of that because it can stimulate deep emotions and memories, ultimately reinforcing your worries.”

Adele fans may be having very different relationship experiences compared to those listening to The Weeknd’s “Heartless.” With lyrics like “Tryna be a better man but I'm heartless / Never be a wedding plan for the heartless / Low life for life 'cause I'm heartless,” it’s a prime example of an avoidant song, says Alaei.

His advice: “Listen to the song a few times to help you process what you’re going through and express your thoughts and feelings. You can decide whether listening to songs that reflect your experiences back at you is either helping you or reinforcing destructive behaviours for yourself. At some point, you may find it more productive to listen to music that provides a sense of security.”

A popular throwback among participants was Sonny & Cher’s “I Got You Babe”: “Then put your little hand in mine / There ain’t no hill or mountain we can’t climb.”

“It’s pretty much a manual on how to be securely attached,” says Alaei.

What do your favourite songs about relationships reveal about your attachment style? Here are some of the tunes that research participants chose for their playlists:

Avoidant songs:

• Beyoncé, Irreplaceable
• Chris Brown, Say Goodbye 
• N'Sync, Bye Bye Bye
• Michael Jackson, Billie Jean
• TLC, Scrubs
• Rihanna, Take a Bow
• The Weeknd, The Hills; Heartless

Anxious songs:

• Adele, Someone Like You
• The Police, Every Breath You Take
• Miley Cyrus, Wrecking Ball
• Adele, Hello
• U2, One
• Seether, Broken
• No Doubt, Don't Speak
• Bruno Mars, When I Was Your Man
• Drake, Hotline Bling

Secure songs:

• Sonny & Cher, I Got You Babe
• Whitney Houston, I Will Always Love You
• The Beatles, Love Me Do
• Ed Sheeran, Thinking Out Loud
• Plain White Ts, I Love You 
• John Legend, All of Me
• Michael Bublé, Haven't Met You Yet
• Beach Boys, Wouldn't It Be Nice
• Bryan Adams, (Everything I Do) I Do It for You
• Etta James, At Last
• Justin Bieber, Holy

Anxious-Avoidant (mixed) songs:

• Carrie Underwood, Before He Cheats
• Gotye, Somebody that I Used to Know
• Taylor Swift, Bad Blood
• Sam Smith, I'm Not the Only One
• Ne Yo, So Sick
• Bonnie Raitt, I Can't Make You Love Me
• Adele, Rolling in the Deep
• Rihanna ft. Drake, Work
• Eminem ft. Rihanna, Love the Way You Lie

 

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JOURNAL

Personal Relationships

DOI

10.1111/pere.12448 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Individuals' favorite songs' lyrics reflect their attachment style