The findings were published in two papers in the same issue of Nature and challenge decades of assumptions about the thymus. The results indicate that the organ remains important throughout adulthood and could eventually help guide disease prevention strategies and cancer treatment decisions.

“The thymus has been overlooked for decades and may be a missing piece in explaining why people age differently, and why cancer treatments fail in some patients,” said Hugo Aerts, PhD, corresponding author on the papers and director of the Artificial Intelligence in Medicine (AIM) Program at Mass General Brigham. “Our findings suggest thymic health deserves much more attention and may open new avenues for understanding how to protect the immune system as we age.”

What the Thymus Does

Located in the chest, the thymus helps train T cells, a type of immune cell that helps defend the body against infections and disease. Because the organ gradually shrinks after puberty and produces fewer new T cells over time, many scientists assumed it played only a limited role in adult health.

As a result, the thymus has received relatively little attention in large population studies. Earlier research connected T cell diversity to aging and declining immune function, but those studies were typically small and focused on blood samples.

The new research took a much broader approach. Investigators analyzed data from more than 25,000 adults participating in a national lung cancer screening trial, along with more than 2,500 people enrolled in the Framingham Heart Study, a long-running study that tracks the health of generally healthy adults.

AI Reveals Links to Longevity and Disease Risk

Using artificial intelligence (AI) to evaluate routine CT scans, the researchers measured the size, structure, and composition of the thymus. From those measurements, they created a “thymic health” score.

People with higher thymic health scores experienced significantly better outcomes. Compared with individuals who had poorer thymic health, they had about a 50% lower risk of death from any cause, a 63% lower risk of death from cardiovascular disease, and a 36% lower risk of developing lung cancer. These relationships remained strong even after accounting for age and other health factors.

The researchers believe that declines in thymic health may reduce T cell diversity, making it harder for the immune system to recognize and respond to new threats such as cancer and other diseases.

Their analysis also identified several factors associated with poorer thymic health, including chronic inflammation, smoking, and higher body weight. These findings suggest that lifestyle factors and ongoing inflammation may affect the immune system’s ability to remain resilient over time.

Thymus Health and Cancer Immunotherapy

In a separate study, the team examined CT scans and clinical outcomes from more than 1,200 cancer patients treated with immunotherapy.

The results showed that patients with healthier thymuses tended to respond better to treatment. They faced about a 37% lower risk of cancer progression and a 44% lower risk of death, even after researchers adjusted for differences in patients, tumors, and treatment approaches.

According to the researchers, these findings highlight a potentially important but previously underrecognized role for the thymus in determining how effectively modern cancer immunotherapies work.

More Research Needed

The scientists emphasize that additional studies will be needed to confirm the results. They also note that the imaging technique used to measure thymic health is not yet ready for routine use in clinical practice.

Although lifestyle factors were associated with thymic health, the studies did not investigate whether changing those factors can directly improve thymus function.

The research team is continuing to explore other influences on thymic health. One ongoing study is examining whether unintended radiation exposure to the thymus during lung cancer treatment could affect patient outcomes.

“Improving our understanding and monitoring of thymic health could eventually help physicians better assess disease risk and guide treatment decisions,” said Aerts.

In addition to Aerts, study co-authors of the overall adult health paper include Simon Bernatz, Vasco Prudente, Suraj Pai, Asbjørn Kjær, Yumeng Cao, Jiachen Chen, Asya Lyass, PhD, Borek Foldyna, Leonard Nürnberg, Christopher Abbosh, Charles Swanton, Mariam Jamal-Hanjani, MD, PhD, Michael T. Lu, Joanne M. Murabito, Kathryn L. Lunetta, and Nicolai J Birkbak.

Aerts’ co-authors of the immunotherapy outcomes paper include Simon Bernatz, Vasco Prudente, Suraj Pai, Asbjørn Kjær, Alessandro Di Federico, Andrew Rowan, Selvaraju Veeriah, Lars Dyrskjøt, Leonard Nürnberg, Joao V. Alessi, Patrick A. Ott, Elad Sharon, Allan Hackshaw, Nicholas McGranahan, Christopher Abbosh, Raymond H. Mak, Danielle Bitterman, Mark Awad, Biagio Ricciuti, Charles Swanton, Mariam Jamal-Hanjani, and Nicolai J Birkbak, PhD.

This research received funding support from the National Institutes of Health, European Research Council, Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), Lundbeck Foundation, Novo Nordisk Foundation, and Savvaerksejer Jeppe Juhl og Hustru Ovita Juhl Research Stipend.

In 2015, Sweden drew international attention when researchers reported that its Conservation Performance Payment (CPP) program, the oldest initiative of its kind, had helped boost populations of the endangered wolverine.

More than a decade later, however, that early success appears increasingly difficult to maintain. The program was designed to benefit both wolverines and the Indigenous Sámi reindeer herders who share the landscape with them. New findings suggest that the arrangement is under growing strain.

Researchers from the University of York and the Swedish Agricultural University found that documented wolverine numbers have dropped sharply in parts of northern Sweden where the species was once strongest. At the same time, government payments have remained unchanged for two decades, and many local communities say they no longer trust the system.

The findings, published in Conservation Letters, suggest that governments risk undermining conservation gains when they fail to address the long-term financial and social costs that wildlife recovery can place on local residents.

A Revolutionary Approach to Predator Conservation

Dr. Hanna Pettersson of the University of York’s Leverhulme Centre for Anthropocene Biodiversity explained how the program differed from traditional compensation systems.

“Implemented in 1996, the scheme was at the time revolutionary. Instead of paying reindeer herders for damages caused by predators, the government paid communities for coexisting with them, whether or not damage actually occurs.

“The idea is to tie an income to the presence of the predator, providing an incentive to find ways to live alongside them, thus decreasing conflicts and improving social justice.

“Initial findings showed encouraging results of the scheme, namely a marked increase of the wolverine population, but after studying 30 years of data from the scheme, we have shown that this success has not been sustained.”

To investigate the program’s long-term impact, Dr. Pettersson accompanied wildlife rangers working in the Arctic. The researchers also combined ecological monitoring records with interviews conducted in Norrbotten, Sweden’s northernmost county.

Their results point to growing challenges within the program and raise broader concerns for conservation efforts elsewhere.

Wolverine Numbers Decline in Northern Sweden

The study found that wolverines are spreading into southern parts of Sweden while declining in regions that historically supported the largest populations.

In the early 2000s, Norrbotten accounted for roughly two-thirds of all documented wolverine reproductions in Sweden. Today, that figure has fallen to less than one-third, and the county regularly fails to meet minimum conservation targets.

Researchers say stagnant funding has become a major issue.

Dr. Pettersson said: “The payments to the reindeer herders from the scheme have remained frozen at 200,000 SEK per predator reproduction since 2002, but due to rising costs and meat prices, the real value of the payment has approximately halved over the last two decades.

“While the Sámi Parliament calculates the legal payout should be at least 480,000 SEK to comply with the law, the government offered only a 25,000 SEK increase in 2024.”

Climate Change and Tracking Challenges

The research also identified climate change as an additional obstacle. Shifting snow conditions across the Arctic have made wolverine tracks harder to detect and document.

As a result, official counts may not fully reflect the true number of animals. Researchers noted that many apparent wolverine sightings were rejected because they did not satisfy strict documentation requirements.

According to Dr. Pettersson, these challenges illustrate the need for governments to adapt conservation programs as conditions change.

“If a government fails to adapt payments to rising costs of coexistence, the burden is shifted onto local, often marginalized, communities, who in this case are already straining under the cumulative impacts of mining, forestry, and climate change.

“It is a warning sign for other global conservation efforts. Governments must plan ahead and adapt interventions to changing conditions and local needs.”

A team from XPANCEO, working with scientists from the National University of Singapore and the University of Chemistry and Technology, Prague, has reported a major advance in that effort. Their study focuses on a layered crystal called molybdenum oxychloride (MoOCl₂), which displays a collection of unusual optical properties that could help dramatically shrink future optical devices.

Published in Nano Letters, the research presents the first experimental mapping of the crystal’s optical behavior. The findings show that MoOCl₂ exhibits the strongest light-bending effect ever measured in a natural material, potentially opening a path toward much smaller and more capable optical technologies.

A Crystal That Acts Like Metal and Glass

Researchers describe MoOCl₂ as a kind of optical “chameleon.” Its behavior changes depending on how the crystal is oriented.

When positioned one way, it reflects light much like a metal. Rotate it by 90 degrees, and it becomes transparent like glass. This unusual characteristic stems from its extreme optical anisotropy, meaning its properties vary dramatically depending on direction.

The crystal also has an in-plane birefringence value of approximately 2.2, allowing it to split and bend light with exceptional efficiency. For XPANCEO, this could make it possible to perform the sophisticated light control needed for AR displays using materials that are thousands of times thinner than a human hair.

Rare Light-Slowing Effect Found in Visible Light

The researchers also identified a rare epsilon-near-zero point at 512 nm (green light).

At this point, part of the material’s optical response falls almost to zero. As a result, light effectively slows down while the electric field inside the crystal becomes stronger. This combination can significantly enhance interactions between light and matter.

For integrated photonic chips, this effect could be especially valuable. Stronger light-matter interactions may enable faster data processing while using much less power.

Why Scientists Are Interested in MoOCl₂

Physicists have been studying MoOCl₂ for several years because of its unusual electronic structure.

The material is classified as a “bad metal” and contains one-dimensional chains of molybdenum atoms. These chains allow electrons to move more easily in one direction than another. As a result, the crystal behaves like a metal along one axis and like a dielectric material along the perpendicular axis, creating its exceptionally strong anisotropy.

Previous studies published in Science and Nature Communications had already observed tightly confined light waves called hyperbolic plasmon polaritons traveling through the crystal. Those experiments showed that MoOCl₂ could guide light in highly directional and unexpected ways.

However, an important piece of the puzzle was still missing. Scientists could observe the optical effects, but they had not directly measured the material’s full optical constants. Without those measurements, designing practical devices based on the crystal remained much more difficult.

Mapping the Crystal’s Optical Properties

The new work provides those missing measurements.

The researchers found that near 512 nanometers in the green region of the visible spectrum, one component of the crystal’s optical response approaches zero. In practical terms, this can intensify the electric field inside the material and slow light down, squeezing electromagnetic energy into a very small volume and boosting light-matter interactions.

This phenomenon is known as a visible-light epsilon-near-zero (ENZ) point. While many materials exhibit ENZ behavior only in the deep ultraviolet or mid-infrared regions, MoOCl₂ reaches this state within the visible spectrum. That is particularly important because many existing technologies, including lasers, microscopes, cameras, and sensing systems, already operate in this range.

“Observing a phenomenon is the first step, but engineering requires precise numbers,” said Dr. Valentyn Volkov, founder and CTO of XPANCEO and corresponding author of the study. “By rigorously measuring the complete dielectric tensor of MoOCl₂, our work provides the experimental foundation needed to understand why this material behaves the way it does and to design around it with greater confidence. That makes it a valuable scientific result for the field, with possible relevance across compact polarization optics, nonlinear devices, and, in the longer term, highly miniaturized integrated systems including smart contact lenses.”

Shrinking Future Optical Hardware

The detailed optical map also highlights the material’s potential for further miniaturization of optical technologies.

Because of its strong structural anisotropy, MoOCl₂ functions as a natural hyperbolic medium. In simple terms, this allows light to travel through the crystal in highly directional nanoscale paths without diffracting (or scattering), a key requirement for building smaller optical circuits.

Its ability to operate in the visible spectrum further strengthens its appeal for integrated photonic chips, where light must be routed, filtered, and concentrated within extremely small spaces.

The researchers point to several possible applications. These include ultrathin broadband polarizers that control the direction of light in compact optical systems, as well as sub-diffractional waveguides capable of guiding light through spaces smaller than those allowed by conventional optics.

The findings also suggest opportunities in nonlinear nanophotonics, where intense light-matter interactions can be used to create new colors of light or process optical signals more efficiently.