Sex and Gender Identity Are Linked to Human Brain Activity, Feinstein Institutes Research

The findings were recently published in Science Advances

Dr. Elvisha Dhamala, professor in the Institute of Behavioral Sciences at the Feinstein Institutes for Medical Research, led the study. (Photo: Business Wire)


July 12, 2024


MANHASSET, N.Y.--(BUSINESS WIRE)--Discussion about gender identity has become a mainstream topic, with questions surrounding how the brain is wired and how behavior is influenced by someone’s sex or gender. New research from The Feinstein Institutes for Medical Research published today in Science Advances shows neurobiological underpinnings of sex and gender in children to better understand how sex (assigned at birth) and gender (identity and expression) influence the brain, and ultimately a person’s health.

“Dr. Dhamala’s findings are a step towards understanding the brain’s inner connections and impact on one’s overall health.”Post this

Led by Elvisha Dhamala, PhD, assistant professor in the Institute of Behavioral Sciences at the Feinstein Institutes, and in collaboration with Dani Bassett, PhD, professor at the University of Pennsylvania, Thomas Yeo, PhD, associate professor at the National University of Singapore, and Avram Holmes, PhD, associate professor of psychiatry at Rutgers University, the study analyzed data from nearly 4,800 children from the Adolescent Brain Cognitive Development (ABCD) Study – the largest long-term study of brain development and child health in the United States. The study finds that sex and gender have unique and overlapping associations with brain functional connections. Specifically, sex is primarily linked to connectivity within motor, visual, control and limbic networks, while gender-related networks are more widely distributed throughout the brain. These sex and gender differences in brain connectivity might contribute to differences in brain-related illnesses.

“Sex and gender have traditionally been conflated in research when they should have been studied separately,” said Dr. Dhamala. “This research sheds light on the complex and nuanced ways in which biological and environmental factors influence brain organization and shows the need to consider a person’s sex and gender to fully understand health and disease across the human lifespan.”

Over the last 20 years, scientists have studied how sex and neurobiology interact with behavior. Many of these studies have had differing results and have been hard to reproduce, suggesting there might be misunderstandings or biases in this research area. The focus on assigned sex, without consideration for gender, in the past, may have further limited the research.

Using machine learning to predict sex and gender based on brain connectivity, Dr. Dhamala determined that the two are linked to different parts of the brain. This underscores that sex and gender are distinct from one another. Previous research in the biomedical sciences has primarily focused on sex, but these findings highlight the importance of accounting for gender as well.

Prior studies have found that people assigned female at birth are more likely to experience mood and anxiety disorders while people assigned male at birth are more likely to be diagnosed with substance use or attention deficit disorders. The present study shows that while sex is linked to specific brain networks, gender’s influence spreads more widely across the brain. Many of the brain networks shown to be related to sex and gender in this study are implicated in brain disorders. These findings that sex and gender have unique effects on brain connectivity might explain sex and gender differences in brain-related illnesses.

“Understanding how sex and gender affect the brain can help develop better therapies to treat mental health and other conditions,” said Anil K. Malhotra, MD, co-director of the Institute of Behavioral Science at the Feinstein Institutes. “Dr. Dhamala’s findings are a step towards understanding the brain’s inner connections and impact on one’s overall health.”

About the Feinstein Institutes

The Feinstein Institutes for Medical Research is the home of the research institutes of Northwell Health, the largest health care provider and private employer in New York State. Encompassing 50 research labs, 3,000 clinical research studies and 5,000 researchers and staff, the Feinstein Institutes raises the standard of medical innovation through its five institutes of behavioral science, bioelectronic medicine, cancer, health system science, and molecular medicine. We make breakthroughs in genetics, oncology, brain research, mental health, autoimmunity, and are the global scientific leader in bioelectronic medicine – a new field of science that has the potential to revolutionize medicine. For more information about how we produce knowledge to cure disease, visit http://feinstein.northwell.edu and follow us on LinkedIn.

you are here: science media centre > roundups for journalists > expert reaction to study looking at sex, gender, and brain network patterns using brain imaging in children

JULY 12, 2024

expert reaction to study looking at sex, gender, and brain network patterns using brain imaging in children

A study published in Science Advances looks at the association of brain network patterns with children’s birth sex and self/parent-reported gender.

 

Dr Anne-Lise Goddings, Clinical Academic Consultant in Paediatrics and Adolescent Health at London North West University Healthcare NHS Trust; and Honorary Senior Clinical Lecturer at Imperial College London with a research background in adolescent cognitive neuroscience and neuroimaging, said:

“This study reports relatively weak brain functional connectivity associations with parent-reported ‘gender’ over and above sex assigned at birth.  It’s crucial when interpreting this study to contextualise that this ‘gender’ measure focuses mainly on how much parents report their children engaged in stereotypical ‘gendered’ play.  Parents answered questions including about how much their child plays with “girl-type dolls such as ‘Barbie’”, “boy-type dolls such as ‘GI-Joe’”, “how much they play sports with girls (but not boys)” and “with boys (but not girls)”, and how much they “imitate male and female TV and movie characters”.

“This measure of gender doesn’t capture the broader concept of gender identity which incorporates an individual’s own feelings and perceptions of their identity.

“In the absence of clear hypotheses or accounting for confounders, the findings of the study are of limited impact and should be interpreted with caution.  Later Adolescent Brain Cognitive Development project (ABCD) study waves and other cohort studies may help to improve understanding of this complex topic.”

 

Prof Derek Hill, Professor of Digital Health, and of Medical Imaging Science, UCL, said:

“This paper seeks to use a special type of brain scan to better understand the brain biology behind sex and gender in children.  This type of MRI brain scan is often used in research studies, and can be analysed with sophisticated algorithms to produce maps of functional connectivity: how different parts of the brain are connected together.

“The paper uses a type of artificial intelligence called machine learning to build a computer model that can predict a child’s sex at birth or self-reported and parent reported gender from their brain scan.  In this way they can determine which type of functional connectivity are associated with sex and gender.

“To test and train this model, they used brain scans from nearly 5000 children aged 9-10 years, for whom the sex assigned at birth and their self-reported and parent-reported gender identity was known.

“This is a relatively large imaging study, using carefully collected data from nearly 5000 children, and state-of-the art brain image analysis.  However, the results must be viewed with caution because:

• artificial intelligence algorithms are very data hungry, and the number of children in some of the sex / gender categories in this dataset is small, meaning reliability of the model may be limited.
• the authors use a method called “cross validation” to train and test their Artificial Intelligence model on this single dataset, which often gives an exaggerated impression of how well the model works.  Very often, Artificial Intelligence models trained and tested in this way suffer from “over-fitting”, which means they appear to perform better on the training data than when applied to other people in a real-world setting.  A more rigorous approach, which is now required by medical device regulators for any algorithm that might be used for diagnosis or management of patients, is to use a truly independent dataset for testing and training.  Without demonstrating that this model performs equally well on an independent dataset, the confidence in the conclusions must be considered low.
• the children looked at are all very similar age – with imaging collected when they are aged 9 or 10 and the gender and self report gender being recorded a year later.  It isn’t at all clear whether the results presented here would translate to children of other ages.”

 

 

‘Functional brain networks are associated with both sex and gender in children’ by Elvisha Dhamala et al. was published in Science Advances at 19:00 UK time on Friday 12 July 2024.

DOI: 10.1126/sciadv.adn4202

 

 

Declared interests

Dr Anne-Lise Goddings: “I don’t think I have any declarations to note, but for full openness, below is my current and previous funding:

Current funding bodies:

MRC

NHS.

Previous funding bodies:

NIHR

MRC

Academy of medical sciences.

I haven’t had any industry funding of my own research, scientific meetings, advisory roles or employment.  I’m not aware of any industry funding to my current or previous department.”

Prof Derek Hill: “No conflicts of interest relevant to this study, but currently CEO of Panoramic Digital Health, and previously co-founder of IXICO.”

 

Q&A: What past environmental success can teach us about solving the climate crisis

In a new book, Professor Susan Solomon uses previous environmental successes as a source of hope and guidance for mitigating climate change.

Paige Colley | EAPS
Publication Date:July 12, 2024

"Students today have grown up in a very contentious and difficult era in which they feel like nothing ever gets done. But stuff does get done, even now," says Professor Susan Solomon. "Looking at how we did things so far really helps you to see how we can do things in the future."
Credits:Photo of Susan Solomon by Justin Knight.

Susan Solomon, MIT professor of Earth, atmospheric, and planetary sciences (EAPS) and of chemistry, played a critical role in understanding how a class of chemicals known as chlorofluorocarbons were creating a hole in the ozone layer. Her research was foundational to the creation of the Montreal Protocol, an international agreement established in the 1980s that phased out products releasing chlorofluorocarbons. Since then, scientists have documented signs that the ozone hole is recovering thanks to these measures.

Having witnessed this historical process first-hand, Solomon, the Lee and Geraldine Martin Professor of Environmental Studies, is aware of how people can come together to make successful environmental policy happen. Using her story, as well as other examples of success — including combating smog, getting rid of DDT, and more — Solomon draws parallels from then to now as the climate crisis comes into focus in her new book, “Solvable: How we Healed the Earth and How we can do it Again.”

Solomon took a moment to talk about why she picked the stories in her book, the students who inspired her, and why we need hope and optimism now more than ever.

Q: You have first-hand experience seeing how we’ve altered the Earth, as well as the process of creating international environmental policy. What prompted you to write a book about your experiences?

A: Lots of things, but one of the main ones is the things that I see in teaching. I have taught a class called Science, Politics and Environmental Policy for many years here at MIT. Because my emphasis is always on how we’ve actually fixed problems, students come away from that class feeling hopeful, like they really want to stay engaged with the problem.

It strikes me that students today have grown up in a very contentious and difficult era in which they feel like nothing ever gets done. But stuff does get done, even now. Looking at how we did things so far really helps you to see how we can do things in the future.

Q: In the book, you use five different stories as examples of successful environmental policy, and then end talking about how we can apply these lessons to climate change. Why did you pick these five stories?

A: I picked some of them because I’m closer to those problems in my own professional experience, like ozone depletion and smog. I did other issues partly because I wanted to show that even in the 21st century, we’ve actually got some stuff done — that’s the story of the Kigali Amendment to the Montreal Protocol, which is a binding international agreement on some greenhouse gases.

Another chapter is on DDT. One of the reasons I included that is because it had an enormous effect on the birth of the environmental movement in the United States. Plus, that story allows you to see how important the environmental groups can be.

Lead in gasoline and paint is the other one. I find it a very moving story because the idea that we were poisoning millions of children and not even realizing it is so very, very sad. But it’s so uplifting that we did figure out the problem, and it happened partly because of the civil rights movement, that made us aware that the problem was striking minority communities much more than non-minority communities.

Q: What surprised you the most during your research for the book?

A: One of the things that that I didn’t realize and should have, was the outsized role played by one single senator, Ed Muskie of Maine. He made pollution control his big issue and devoted incredible energy to it. He clearly had the passion and wanted to do it for many years, but until other factors helped him, he couldn’t. That's where I began to understand the role of public opinion and the way in which policy is only possible when public opinion demands change.

Another thing about Muskie was the way in which his engagement with these issues demanded that science be strong. When I read what he put into congressional testimony I realized how highly he valued the science. Science alone is never enough, but it’s always necessary. Over the years, science got a lot stronger, and we developed ways of evaluating what the scientific wisdom across many different studies and many different views actually is. That’s what scientific assessment is all about, and it’s crucial to environmental progress.

Q: Throughout the book you argue that for environmental action to succeed, three things must be met which you call the three Ps: a threat much be personal, perceptible, and practical. Where did this idea come from?

A: My observations. You have to perceive the threat: In the case of the ozone hole, you could perceive it because those false-color images of the ozone loss were so easy to understand, and it was personal because few things are scarier than cancer, and a reduced ozone layer leads to too much sun, increasing skin cancers. Science plays a role in communicating what can be readily understood by the public, and that’s important to them perceiving it as a serious problem.

Nowadays, we certainly perceive the reality of climate change. We also see that it’s personal. People are dying because of heat waves in much larger numbers than they used to; there are horrible problems in the Boston area, for example, with flooding and sea level rise. People perceive the reality of the problem and they feel personally threatened.

The third P is practical: People have to believe that there are practical solutions. It’s interesting to watch how the battle for hearts and minds has shifted. There was a time when the skeptics would just attack the whole idea that the climate was changing. Eventually, they decided ‘we better accept that because people perceive it, so let’s tell them that it’s not caused by human activity.’ But it’s clear enough now that human activity does play a role. So they’ve moved on to attacking that third P, that somehow it’s not practical to have any kind of solutions. This is progress! So what about that third P?

What I tried to do in the book is to point out some of the ways in which the problem has also become eminently practical to deal with in the last 10 years, and will continue to move in that direction. We’re right on the cusp of success, and we just have to keep going. People should not give in to eco despair; that’s the worst thing you could do, because then nothing will happen. If we continue to move at the rate we have, we will certainly get to where we need to be.

Q: That ties in very nicely with my next question. The book is very optimistic; what gives you hope?

A: I’m optimistic because I’ve seen so many examples of where we have succeeded, and because I see so many signs of movement right now that are going to push us in the same direction.

If we had kept conducting business as usual as we had been in the year 2000, we’d be looking at 4 degrees of future warming. Right now, I think we're looking at 3 degrees. I think we can get to 2 degrees. We have to really work on it, and we have to get going seriously in the next decade, but globally right now over 30 percent of our energy is from renewables. That's fantastic! Let’s just keep going.

Q: Throughout the book, you show that environmental problems won’t be solved by individual actions alone, but requires policy and technology driving. What individual actions can people take to help push for those bigger changes?

A: A big one is choose to eat more sustainably; choose alternative transportation methods like public transportation or reducing the amount of trips that you make. Older people usually have retirement investments, you can shift them over to a social choice funds and away from index funds that end up funding companies that you might not be interested in. You can use your money to put pressure: Amazon has been under a huge amount of pressure to cut down on their plastic packaging, mainly coming from consumers. They’ve just announced they’re not going to use those plastic pillows anymore. I think you can see lots of ways in which people really do matter, and we can matter more.

Q: What do you hope people take away from the book?

A: Hope for their future and resolve to do the best they can getting engaged with it.

The lexical divide: propositive modes and non-agentic attitudes define the progressive left in Chile

• María P. Raveau, 
• Juan P. Couyoumdjian, 
• Claudio Fuentes-Bravo, 
• Carlos Rodriguez-Sickert & 
• Cristian Candia 

Humanities and Social Sciences Communications volume 11, Article number: 908 (2024) Cite this article

• • Article
  • Open access
  • Published: 12 July 2024

  details

Abstract

Internal factors-such as psychological traits or individual attitudes-relate to and explain political cleavages. Yet, little is known about how locus of control, agency, and modal attitudes impact political ideology. Utilizing textual analysis within the context of the Chilean 2015 constituent process, we go beyond traditional survey methods to explore community clusters in “Values” and “Rights” networks built upon the deliberation of 106,000 people. Our findings reveal distinct attitudinal patterns across political orientations: the progressive left generally exhibits a more propositive and non-agentic attitude, the traditional left adopts an evaluative stance towards values, and the right-wing community leans towards a factual attitude but shifts to an evaluative stance when discussing rights. These results underscore the role of psychological constructs in shaping political ideologies and introduce textual analysis as a robust tool for psychological and political inquiry. The study offers a comprehensive understanding of the complexities of political behavior and provides a new lens through which to examine the psychology of political ideology.

Introduction

In an era characterized by political polarization and social unrest, the rise of the New Left offers a compelling lens through which to explore the psychological traits that shape political affiliations. The grassroots movements led by Bernie Sanders in the United States and “Podemos” in Spain serve as illustrative examples, each attracting individuals with distinct psychological profiles. In the United States, Bernie Sanders’ campaigns have galvanized individuals with a strong sense of agency, who believe that their actions can effectuate societal change (Bandura 2006; Smyth 2018). This aligns with the broader understanding that a sense of agency, often associated with an internal locus of control, can significantly influence political engagement (Smyth 2018).

"Podemos” has similarly attracted individuals with a strong sense of agency in Spain. This is consistent with the broader academic consensus that enduring psychological differences, such as openness to new experiences, significantly influence political participation and ideological affiliation (Mondak 2010; Sibley et al. 2012).

In Chile, the “Frente Amplio” has led massive social protests, advocating for constitutional reform and greater social equality. This movement has garnered attention for attracting individuals with a collective sense of agency and a focus on social justice. This is particularly relevant as we aim to compare our findings about this group with traditional left and right political affiliations in Chile (González et al. 2008; Torcal and Mainwaring 2003).

A pressing question emerges from this setting: How do individual psychological traits like sense of agency differentiate among affiliations with the New Left, traditional left, and traditional right political parties in Chile?

To delve deeper into this complex interplay of psychological constructs and political ideology, we turn to innovative methodologies that go beyond traditional survey-based approaches, which often struggle with inherent biases, such as socially desirable responding (an exceedingly positive self-description), acquiescent responding (tendency to agree with statements regardless of their contents), and extreme responding (tendency to use the extreme choices on a rating scale). All of these tendencies may vary between individuals because of differences in personality, turning themselves into confounding variables (Paulhus et al. 2007).Footnote1

In recent years, text analysis has emerged as a promising avenue for psychological inquiry. Particularly, the “psychological language analysis” approach posits that our language serves as a mirror reflecting our psychological states (Boyd and Schwartz 2021). This foundational premise has led scholars to validate the efficacy of language in deducing psychological states across various domains, including neuropsychology and political behavior (Kacewicz et al. 2014; Vine et al. 2020).

However, the prevailing “words as attention” paradigm in text analysis may limit our understanding of the nuanced relationship between language and psychology (Boyd and Schwartz 2021). Responding to a growing call for a more expansive approach, we aim to go beyond mere description to explore the underlying motivations behind linguistic patterns. Guided by the principle that “our words echo our thoughts” (Pennebaker et al. 2014), we shift our focus from content to linguistic structures.

This shift is particularly relevant in the current digital age, where the rise of social movements and the proliferation of communication platforms have revolutionized how political agency is perceived and exercised. In this new landscape, political agency has evolved to adopt a more multiplex view, considering the specific contexts and power dynamics inherent in communication processes (Kavada 2016). This shift is further influenced by a systems worldview, which moderates the relationship between agency and civic engagement (Moore et al. 2016; Rosen and Salling 1971).

Our research is set against the backdrop of the Chilean 2015 constituent process boosted by digital technologies, a largely uncharted territory in this field (Raveau et al. 2022a, b, 2023). We analyze community clusters in co-ocurrence networks of “Values” and “Rights” based on the data gathered in the participatory phase of this process. Using these clusters we seek to uncover the linguistic fingerprints that are indicative of specific political orientations. Notably, we find that these community clusters exhibit a high level of agreement in their decisions, emphasizing the role of texts that come from a group discussion, as valid markers for individual political ideology.

In summary, this paper aims to weave together these diverse threads—ranging from the psychology of modal attitude of control and agency to the digital transformation of political engagement and the emerging methodologies in text analysis. We aim to understand how individual psychology shapes political ideology. Through our multi-faceted approach, we aspire to contribute to the evolving discourse on the psychology of political behavior

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The lexical divide: propositive modes and non-agentic attitudes define the progressive left in Chile | Humanities and Social Sciences Communications (nature.com)

ANALYSIS
Climate change could return us to the pre-antibiotic era

We are in a race with ever-evolving bacteria — and we are losing. Climate change is making the battle much harder

By HOWARD DEAN
PUBLISHED JULY 12, 2024

SALON

A gloved hand holding a blood agar plate with bacteria colonies grown, and a thermometer reading 39 degree Celsius. (Photo illustration by Salon/Getty Images)

The extreme heat that recently blanketed the United States is a clear sign of climate change. But rising temperatures are fueling more than just hotter summers. Climate change is contributing to the spread of drug-resistant infections. And alarmingly, the medicines we use to fight those pathogens are losing their effectiveness.

Antimicrobial resistance, or AMR, occurs when bacteria, viruses, and other pathogens evolve to resist the effects of medications, making common infections harder to treat and increasing the risk of disease spread, severe illness, and death. Recent figures link AMR to nearly 5 million deaths annually — far more than the combined death toll of AIDS and malaria. By 2050, more people will die of drug-resistant infections than currently die of cancer.

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Climate change is accelerating the spread of these superbugs, providing favorable conditions for pathogens to grow and spread. Warmer temperatures can increase the reproduction rates of bacteria and viruses, extend the range of habitats suitable for pathogens, and even heighten the chances of gene transfer among bacteria, leading to more robust strains of drug-resistant microbes. Floods, hurricanes, and other climate-induced natural disasters can disrupt sanitation systems and clean water supplies. And as populations move to escape extreme weather, they often end up in over-crowded, unsanitary conditions, which become hotbeds for disease.

Warmer temperatures can increase the reproduction rates of bacteria and viruses, extend the range of habitats suitable for pathogens, and even heighten the chances of gene transfer among bacteria.

AMR disproportionately affects developing countries, but even in the United States, drug-resistant germs sicken nearly 3 million people and kill more than 35,000 annually. Warmer weather has led to the reemergence of diseases long absent from the United States — like dengue and West Nile virus. In my home state of Vermont, tick-borne illnesses like Lyme disease are rising as earlier springs and longer falls increase tick survival rates.

Higher temperatures also correlate strongly with greater antibiotic resistance. One study of more than 1.6 million bacterial strains collected from 41 states found that common pathogens, like E. coli, became more resistant to treatment as temperatures increased.

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The pressure cooker of climate change is moving us closer to the pre-antibiotic era. Patients I once treated as a family physician could have very different outcomes without the backstop of antibiotics. Ordinary infections could become life-threatening, and routine, minor surgeries could become high-risk procedures.

Investment in research and innovation is crucial to stay ahead of evolving pathogens. But our current efforts to develop new antibiotics are not keeping pace. There are fewer than 100 antibacterial therapies now in the pipeline, according to the World Health Organization. Just 32 of the new antibiotic candidates target priority pathogens, with only six active against high- and medium-priority pathogens.

By contrast, there are over 6,500 active clinical trials for cancer treatments.

We are in a race with ever-evolving bacteria — and we are losing. The main hurdle is financial. It costs nearly $1 billion to shepherd a new antibiotic through clinical trials.

But successfully developing an antibiotic is often financially ruinous. Most new antibiotics target small patient populations with specific drug-resistant infections, and the new medicines to treat those infections are rightly used sparingly, only as a last resort — since the more you use antibiotics, the more likely bacteria will eventually become resistant. A new antibiotic can be desperately needed, yet suffer low sales that fail to recoup extensive R&D costs. It is no wonder that just five pharmaceutical companies are currently working on new antibiotics, and many biotech firms that have developed such medicines in the past decade have gone belly up.

Combating climate change requires new technologies and new economic models. The same is true of AMR. We must rethink how we incentivize antibiotic research. Subsidies, tax credits, or direct funding for early-stage R&D can provide relief to companies developing new antibiotics. Other countries, like the United Kingdom, have experimented with subscription models, where drugmakers receive a flat fee for bringing a successful new antibiotic to market. Faster FDA approval pathways can help reduce the time and cost of clinical trials.

Ultimately, the fight against antimicrobial resistance requires a multifaceted approach, integrating scientific innovation, policy reform, and global collaboration. By addressing both climate change and AMR with the urgency and resources they demand, we can protect public health and secure a safer, healthier future for all.
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Howard Dean is the former chair of the Democratic National Committee and former governor of Vermont.

How ants acts for the common good of the colony

Researchers observe reverse social contagion at work.


BY TOM HAWKING
POSTED ON JUL 12, 2024 

An ant colony itself is sometimes referred to as an organism. Credit: Bob Peterson


The emergent complexity of ant societies is one of the most fascinating phenomena in the natural world: how do these tiny creatures form such intricate social networks? These networks are so nuanced that the colony itself is sometimes referred to as an organism—or “superorganism”—in its own right, with individual ants as its component parts.


A paper published this month in the journal PNAS Nexus examines how the behavior of ants is affected by social contagion. Social contagion is the process by which a certain behavior can spread throughout a group, resulting in what’s called a “mass behavior.”

Social contagion is common among all manner of social animals, from ants and fish to birds and humans. But while it can be beneficial when it leads to co-operation and collective action, the study points out that the mass behaviors it creates can also have “catastrophic outcomes such as mass panic and stampedes.” As such, the positive reinforcement of social contagion is generally counterbalanced in animal societies by what the authors call “reverse social contagion.”

Social contagion stems from an individual’s urge to imitate an activity that they see being carried out by their neighbors, while reverse social contagion arises when individuals are less likely to do something if they see their neighbors already doing that same thing. This prevents situations where entire groups all end up carrying out the same activity, regardless of that activity’s utility.

As the paper points out, negative outcomes of social contagion are strikingly rare amongst ants, suggesting that that reverse social contagion plays an important role in ant societies. To quantify how reverse social contagion regulates ant behavior, the researchers examined individual ant activity amongst 12 colonies of harvester ants. These colonies varied in size from several dozen ants to several hundred. The experiment set out to determine how the size of a colony influenced the activity level of its workers: if ant behavior depended only on positive social contagion, more ants would be expected to be active in a larger colony, as they would have more opportunities to observe a given behavior in their fellow ants.

Fig. 1. Illustration of the concepts of social contagion (top) and reverse social contagion (bottom). (top) An inactive ant interacts with an ant engaged in a foraging task: through social contagion (for example, caused by active recruitment), it also begins foraging. (bottom) Two ants engaged in foraging interact: through reverse social contagion (for example, caused by steric exclusion), one of them ceases their activity to become inactive. Image credit: Isabella Muratore.

The study found that just because the colony was larger, did not mean that more ants were exhibiting the same behavior. Because different groups engaged in a variety of behaviors, observations suggest that reverse social contagion was also at play.

This also forms a stark contrast to human societies, where the level of individuals’ activity tends to increase more quickly as a society’s population grows. The announcement accompanying the paper uses the general example of food gathering to illustrate the difference: if an ant sees multiple fellow workers gathering food, it saves its own energy for another task that might be more beneficial to the colony. If a human sees their neighbors all gathering food, however, they worry there might be none left for them—a worry that tends to become more pressing as population increases.

Fig. 7. a) Illustration of an urban settlement composed of individuals who act for their own benefits: each person transforms their cost of movement (measured in some form of currency depending on their means of transport, 𝐶 / 𝑁⁠ ) into their own social interactions (proxied by the average connectivity, ⟨ 𝑘 ⟩ = 2 𝐸 / 𝑁⁠). b) Illustration of a social colony of insects acting as a superorganism: each insect adjusts its energy expenditure, 𝐵 / 𝑁⁠, in response to its average connectivity so that it will increase its expenditure in response to reductions in connectivity. Image credit: Anna Sawulska.

As Simon Garnier, the lead author on the paper and an Associate Professor of Biological Sciences at the New Jersey Institute of Technology, explains in the announcement, “Human behavior is often driven by personal gain, [but] ants … tend to prioritize the needs of the colony over their own. This has huge implications for understanding the differences between the organization of human and social insect societies.” That, of course, is a bit of a generalization, as there are plenty of human societies that value the collective over individual interests, but that may be a question of sociology and culture, rather than behavioral science.

Regardless, the authors draw a fascinating conclusion: the oft-heard metaphors about ant colonies being “superorganisms” are actually pretty accurate. “This work,” the paper concludes, “suggests that the appropriate atomic unit for an ant is its colony—and not itself as a single organism.”

Study finds health risks in switching ships from diesel to ammonia fuel

Ammonia could be a nearly carbon-free maritime fuel, but without new emissions regulations, its impact on air quality could significantly impact human health

Date: July 11, 2024

Source: Massachusetts Institute of Technology

Summary: 

Without additional regulation, burning ammonia in ship engines could cause serious impacts on air quality that could result in more than 600,000 additional premature deaths per year, according to new research.


FULL STORY

As container ships the size of city blocks cross the oceans to deliver cargo, their huge diesel engines emit large quantities of air pollutants that drive climate change and have human health impacts. It has been estimated that maritime shipping accounts for almost 3 percent of global carbon dioxide emissions and the industry's negative impacts on air quality cause about 100,000      premature deaths each year.

Decarbonizing shipping to reduce these detrimental effects is a goal of the International Maritime Organization, a U.N. agency that regulates maritime transport. One potential solution is switching the global fleet from fossil fuels to sustainable fuels such as ammonia, which could be nearly carbon-free when considering its production and use.

But in a new study, an interdisciplinary team of researchers from MIT and elsewhere caution that burning ammonia for maritime fuel could worsen air quality further and lead to devastating public health impacts, unless it is adopted alongside strengthened emissions regulations.

Ammonia combustion generates nitrous oxide (N2O), a greenhouse gas that is about 300 times more potent than carbon dioxide. It also emits nitrogen in the form of nitrogen oxides (NO and NO2, referred to as NOx), and unburnt ammonia may slip out, which eventually forms fine particulate matter in the atmosphere. These tiny particles can be inhaled deep into the lungs, causing health problems like heart attacks, strokes, and asthma.

The new study indicates that, under current legislation, switching the global fleet to ammonia fuel could cause up to about 600,000 additional premature deaths each year. However, with stronger regulations and cleaner engine technology, the switch could lead to about 66,000 fewer premature deaths than currently caused by maritime shipping emissions, with far less impact on global warming.

"Not all climate solutions are created equal. There is almost always some price to pay. We have to take a more holistic approach and consider all the costs and benefits of different climate solutions, rather than just their potential to decarbonize," says Anthony Wong, a postdoc in the MIT Center for Global Change Science and lead author of the study.

His co-authors include Noelle Selin, an MIT professor in the Institute for Data, Systems, and Society and the Department of Earth, Atmospheric and Planetary Sciences (EAPS); Sebastian Eastham, a former principal research scientist who is now a senior lecturer at Imperial College London; Christine Mounaïm-Rouselle, a professor at the University of Orléans in France; Yiqi Zhang, a researcher at the Hong Kong University of Science and Technology; and Florian Allroggen, a research scientist in the MIT Department of Aeronautics and Astronautics. The research appears this week in Environmental Research Letters.

Greener, cleaner ammonia

Traditionally, ammonia is made by stripping hydrogen from natural gas and then combining it with nitrogen at extremely high temperatures. This process is often associated with a large carbon footprint. The maritime shipping industry is betting on the development of "green ammonia," which is produced by using renewable energy to make hydrogen via electrolysis and to generate heat.

"In theory, if you are burning green ammonia in a ship engine, the carbon emissions are almost zero," Wong says.

But even the greenest ammonia generates nitrous oxide (N2O), nitrogen oxides (NOx) when combusted, and some of the ammonia may slip out, unburnt. This nitrous oxide would escape into the atmosphere, where the greenhouse gas would remain for more than 100 years. At the same time, the nitrogen emitted as NOx and ammonia would fall to Earth, damaging fragile ecosystems. As these emissions are digested by bacteria, additional N2O is produced.

NOx and ammonia also mix with gases in the air to form fine particulate matter. A primary contributor to air pollution, fine particulate matter kills an estimated 4 million people each year.

"Saying that ammonia is a 'clean' fuel is a bit of an overstretch. Just because it is carbon-free doesn't necessarily mean it is clean and good for public health," Wong says.

A multifaceted model

The researchers wanted to paint the whole picture, capturing the environmental and public health impacts of switching the global fleet to ammonia fuel. To do so, they designed scenarios to measure how pollutant impacts change under certain technology and policy assumptions.

From a technological point of view, they considered two ship engines. The first burns pure ammonia, which generates higher levels of unburnt ammonia but emits fewer nitrogen oxides. The second engine technology involves mixing ammonia with hydrogen to improve combustion and optimize the performance of a catalytic converter, which controls both nitrogen oxides and unburnt ammonia pollution.

They also considered three policy scenarios: current regulations, which only limit NOx emissions in some parts of the world; a scenario that adds ammonia emission limits over North America and Western Europe; and a scenario that adds global limits on ammonia and NOx emissions.

The researchers used a ship track model to calculate how pollutant emissions change under each scenario and then fed the results into an air quality model. The air quality model calculates the impact of ship emissions on particulate matter and ozone pollution. Finally, they estimated the effects on global public health.

One of the biggest challenges came from a lack of real-world data, since no ammonia-powered ships are yet sailing the seas. Instead, the researchers relied on experimental ammonia combustion data from collaborators to build their model.

"We had to come up with some clever ways to make that data useful and informative to both the technology and regulatory situations," he says.

A range of outcomes

In the end, they found that with no new regulations and ship engines that burn pure ammonia, switching the entire fleet would cause 681,000 additional premature deaths each year.

"While a scenario with no new regulations is not very realistic, it serves as a good warning of how dangerous ammonia emissions could be. And unlike NOx, ammonia emissions from shipping are currently unregulated," Wong says.

However, even without new regulations, using cleaner engine technology would cut the number of premature deaths down to about 80,000, which is about 20,000 fewer than are currently attributed to maritime shipping emissions. With stronger global regulations and cleaner engine technology, the number of people killed by air pollution from shipping could be reduced by about 66,000.

"The results of this study show the importance of developing policies alongside new technologies," Selin says. "There is a potential for ammonia in shipping to be beneficial for both climate and air quality, but that requires that regulations be designed to address the entire range of potential impacts, including both climate and air quality."


Ammonia's air quality impacts would not be felt uniformly across the globe, and addressing them fully would require coordinated strategies across very different contexts. Most premature deaths would occur in East Asia, since air quality regulations are less stringent in this region. Higher levels of existing air pollution cause the formation of more particulate matter from ammonia emissions. In addition, shipping volume over East Asia is far greater than elsewhere on Earth, compounding these negative effects.

In the future, the researchers want to continue refining their analysis. They hope to use these findings as a starting point to urge the marine industry to share engine data they can use to better evaluate air quality and climate impacts. They also hope to inform policymakers about the importance and urgency of updating shipping emission regulations.

This research was funded by the MIT Climate and Sustainability Consortium.

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Materials provided by Massachusetts Institute of Technology. Original written by Adam Zewe. Note: Content may be edited for style and length.

Journal Reference:Anthony Y H Wong, Noelle E Selin, Sebastian D Eastham, Christine Mounaïm-Rousselle, Yiqi Zhang, Florian Allroggen. Climate and air quality impact of using ammonia as an alternative shipping fuel. Environmental Research Letters, 2024; 19 (8): 084002 DOI: 10.1088/1748-9326/ad5d07