The results also show that variety itself matters. People who participate in different types of physical activity tend to have a lower risk of death regardless of how much total exercise they do. Still, the researchers emphasize that staying active overall remains important.

Why Exercise Variety Matters

Physical activity has long been linked to better physical and mental health, along with a reduced risk of death. However, it has been less clear whether certain types of exercise offer unique advantages, or whether mixing activities provides additional benefits beyond total volume.

To investigate this, researchers analyzed data from two major long-term studies: the Nurses’ Health Study (121,700 female participants) and the Health Professionals Follow-Up Study (51,529 male participants). These studies tracked participants for more than 30 years, with regular updates on lifestyle, health history, and exercise habits collected every 2 years through questionnaires.

Decades of Data on Movement and Lifestyle

Participants reported a wide range of physical activities over time. Since 1986, this included walking, jogging, running, cycling (including stationary machines), lap swimming, rowing or callisthenics, tennis and squash or racquetball.

Later surveys added more detail, covering weight training or resistance exercise; lower intensity exercise, such as yoga, stretching, and toning; vigorous tasks like lawn mowing; moderate outdoor work such as maintenance and gardening; and heavy outdoor work like digging and chopping.

Participants also reported how many flights of stairs they climbed daily, based on the estimate that each flight takes 8 seconds to ascend.

The analysis included 111,467 participants for total physical activity and 111,373 participants for activity variety. To measure activity levels, researchers used MET scores, calculated by multiplying the average time spent on each activity (in hours/week) by its MET value. METs indicate how much more energy an activity uses compared to resting.

Activity Levels, Habits, and Health Profiles

Across both groups, individuals could report up to 11 or 13 different activities depending on the study. Walking was the most common form of leisure exercise, while men were more likely than women to jog or run.

People who reported higher overall activity levels were generally healthier. They were less likely to smoke or have high blood pressure or high cholesterol. They also tended to have a lower body weight (lower BMI), eat healthier diets, drink alcohol, maintain stronger social connections, and take part in a wider range of activities.

Exercise and Risk of Death Over 30 Years

During more than three decades of follow-up, 38,847 participants died, including 9901 from cardiovascular disease, 10,719 from cancer, and 3,159 from respiratory disease.

Higher levels of physical activity, along with most individual types of exercise except swimming, were linked to a lower risk of death from any cause. However, the relationship was not linear. The benefits of total activity appeared to level off after about 20 weekly MET hours, suggesting there may be a point beyond which additional activity provides less added benefit.

Which Activities Were Linked to Lower Risk

Walking showed one of the strongest associations, with those who walked the most having a 17% lower risk of death compared with those who walked the least. Climbing stairs was linked to a 10% lower risk.

Other activities were also associated with reduced risk when comparing the least active to the most active participants. Tennis, squash, or racquetball were linked to a 15% lower risk. Rowing or callisthenics showed a 14% reduction. Weight training or resistance exercises and running were each linked to a 13% lower risk. Jogging was associated with an 11% reduction, while cycling showed a smaller 4% decrease.

The Added Benefit of Exercise Variety

Engaging in a wider range of activities was linked to even greater benefits. After accounting for total exercise levels, participants who performed the most diverse set of activities had a 19% lower risk of death from all causes.

They also showed a 13-41% lower risk of death from cardiovascular disease, cancer, respiratory disease, and other causes compared with those who engaged in fewer types of activity.

Study Limitations and What It Means

This research is observational, which means it cannot prove cause and effect. The researchers also point out several limitations. Physical activity was self-reported rather than directly measured, which may affect accuracy.

In addition, MET scores were calculated under the assumption that participants were fully engaged in each activity, and the lack of detailed information on intensity could have led to some misclassification of energy use. The study population was also mostly White, which may limit how widely the findings apply.

Even so, the researchers conclude: “Overall, these data support the notion that long term engagement in multiple types of physical activity may help extend the lifespan.”

Much of what we understand about dinosaurs comes from fossilized bones and teeth. These durable remains preserve well, but they offer only limited insight into how these animals actually lived.

Soft tissues, on the other hand, can reveal far more. These rare fossilized materials include muscles and ligaments, pigments or even skin (like scales or feathers). They provide important clues about appearance, movement, and behavior.

Another type of soft tissue sometimes preserved inside bones is blood vessels. My research team and I identified preserved blood vessels in a Tyrannosaurus rex fossil, and our findings were recently published in Scientific Reports.

A Discovery That Began With Physics

As an undergraduate physics student at the University of Regina, I joined a research group that used particle accelerators to study fossils. During that time, I used advanced 3D imaging techniques to examine a T. rex bone and noticed structures that appeared to be blood vessels.

Nearly six years later, I am now pursuing a PhD, continuing to apply physics-based methods to improve how fossils are analyzed.

The Largest T. Rex Ever Found

The preserved vessels came from an extraordinary specimen known as Scotty. Housed at the Royal Saskatchewan Museum in Canada, Scotty is the largest T. rex ever discovered and one of the most complete.

Evidence suggests Scotty lived a difficult life around 66 million years ago. Many of its bones show signs of injury, possibly from combat with another dinosaur or from disease. One rib stands out, showing a large fracture that had only partially healed.

When bones are damaged, the body increases blood vessel activity in the affected area to support healing. The structures we observed in Scotty’s rib appear to be part of that process, forming a dense network of mineralized vessels that we reconstructed using 3D models.

Advanced Imaging Reveals Hidden Structures

Studying the inside of fossil bones presents two major challenges. First, researchers need to look inside without damaging the specimen. Second, fossilized bones are extremely dense because minerals have replaced the original organic material over millions of years.

We initially considered using an computed topography (CT) scan, similar to those used in medicine. While this method is non-destructive, standard CT scanners cannot penetrate the dense structure of large fossils.

Instead, we turned to synchrotron light, a powerful form of high-intensity x-rays produced at specialized particle accelerator facilities. This technique allowed us to visualize tiny internal features such as blood vessels with remarkable clarity.

Synchrotron imaging also made it possible to analyze the chemical composition of the structures. The vessels had been preserved as iron-rich mineralized casts, which is a common fossilization process. Interestingly, they appeared in two distinct layers, reflecting a complex environmental history that contributed to their preservation.

What Blood Vessels Reveal About Dinosaur Life

The partially healed fracture in Scotty’s rib offers a rare opportunity to study how a T. rex recovered from injury. By examining the preserved blood vessels, researchers can gain insight into healing processes and survival strategies in large predatory dinosaurs.

This work may also provide a basis for comparison with other dinosaur species and with modern animals such as birds, which are closely related to dinosaurs.

The findings could guide future fossil discoveries as well. Bones that show signs of injury or disease may be more likely to preserve blood vessels or other soft tissues, helping scientists target promising specimens.

With the combination of physics, paleontology, and advanced imaging technologies, researchers are beginning to uncover details about dinosaur biology that were once thought impossible to study.

The study, published in Nature in 2023, compared genetic material from present day African populations with fossil evidence from early Homo sapiens populations. The result was a model of human evolution that replaces a clean family tree with something more like a network of deeply connected branches.

A More Complex Beginning in Africa

Scientists broadly agree that Homo sapiens originated in Africa. The harder question is how early human groups separated, moved, reconnected, and shaped one another across the continent.

Brenna Henn, professor of anthropology and the Genome Center at UC Davis and corresponding author of the study, said the uncertainty comes from gaps in both fossils and ancient DNA.

“This uncertainty is due to limited fossil and ancient genomic data, and to the fact that the fossil record does not always align with expectations from models built using modern DNA,” she said. “This new research changes the origin of species.”

The work was co led by Henn and Simon Gravel of McGill University. Their team tested several competing ideas about human evolution and migration in Africa, drawing from models proposed in paleoanthropology and genetics. The analysis included genome data from southern, eastern and western Africa.

The Nama Genomes Added a Key Clue

A major part of the study came from 44 newly sequenced genomes from modern Nama individuals in southern Africa. The Nama are an Indigenous population known for carrying unusually high levels of genetic diversity compared with many other living groups.

Researchers collected saliva samples from people in their villages between 2012 and 2015, while participants were going about daily life. Those samples helped the team examine whether human origins fit a single source model or something broader and more interconnected.

The best fitting model suggested that the earliest population split among early humans still detectable in living people happened roughly 120,000 to 135,000 years ago. Before that split, two or more weakly differentiated Homo populations had been exchanging genes for hundreds of thousands of years.

Even after the split, movement and mating continued between these early groups. The researchers describe this as a weakly structured stem, meaning the roots of modern humans were not one isolated population, but a loose set of connected populations with ongoing gene flow.

Not One Branch, But a Network

That network like model may explain human genetic diversity better than older models, according to the authors. Instead of needing to assume major contributions from an unknown archaic hominin population in Africa, the model shows how patterns in modern DNA could have emerged from structure within ancestral human populations themselves.

“We are presenting something that people had never even tested before,” Henn said of the research. “This moves anthropological science significantly forward.”

Co-author Tim Weaver, a UC Davis professor of anthropology who studies early human fossils, said the results shift how scientists should think about older explanations.

“Previous more complicated models proposed contributions from archaic hominins, but this model indicates otherwise,” he said.

Weaver contributed comparative fossil expertise to the study, helping connect genetic models with what early human remains looked like.

What This Means for Ancient Fossils

The model also has consequences for how scientists interpret the fossil record. According to the authors, only 1 to 4% of genetic differentiation among living human populations can be traced to variation between these ancestral stem populations.

Because the early branches continued mixing, they were probably similar in appearance. That means fossils with very different physical traits (such as Homo naledi) are unlikely to represent lineages that directly contributed to the evolution of Homo sapiens, the authors said.

In other words, the roots of humanity may have been geographically and genetically widespread, but not necessarily divided into sharply different human forms. The deeper picture is one of movement, contact, and repeated mixing across Africa.

Later Research Adds More Depth

Work published after the 2023 study has continued to show how important African genomic diversity is for understanding human origins. A 2024 Nature Ecology & Evolution study reported 9,000 years of genetic continuity in southernmost Africa, highlighting the region’s long and unusually deep human population history.

A later Nature study analyzed genomes from 28 ancient southern African individuals dated between 10,200 and 150 years before present. That work found that ancient southern Africans carried genetic variation outside the range seen in living people and identified Homo sapiens specific variants that may shed light on adaptation and evolution within Africa.

Together, these findings strengthen a bigger message: human origins were not a single spark in one place. They were shaped by many populations, deep African diversity, and long periods of connection across the continent.

Additional co-authors of the 2023 study include Aaron Ragsdale, University of Wisconsin, Madison; Elizabeth Atkinson, Baylor College of Medicine; and Eileen Hoal and Marlo Möller, Stellenbosch University, South Africa.

The research was led by neuroscientist Onder Albayram, Ph.D., an associate professor at MUSC and a member of the National Trauma Society Committee. His team focused on the biological processes involved in repairing blood vessels in the brain after injury.

Rising Popularity of Omega-3 Supplements

Interest in omega-3 fatty acids, the key components of fish oil, has been growing rapidly. According to Fortune Business Insights, these supplements are now appearing not only in capsules but also in drinks, dairy alternatives, and snack products.

That surge in popularity does not surprise Albayram. “Fish oil supplements are everywhere, and people take them for a range of reasons, often without a clear understanding of their long-term effects,” he said.

“But in terms of neuroscience, we still don’t know whether the brain has resilience or resistance to this supplement. That’s why ours is the first such study in the field.”

Albayram collaborated with Eda Karakaya, Ph.D., Adviye Ergul, M.D., Ph.D., and several other researchers at MUSC and partner institutions. Among them was Semir Beyaz, Ph.D., at the Cold Spring Harbor Laboratory Cancer Center in New York.

EPA Identified as a Potential Weak Point in Brain Recovery

The team discovered what they describe as a context-dependent metabolic vulnerability. In simple terms, this means that changes in how cells use energy may reduce the brain’s ability to recover under certain conditions. This vulnerability appears to be linked to the buildup of eicosapentaenoic acid, or EPA, one of the main omega-3 fatty acids found in fish oil.

In their experimental models, higher levels of EPA in the brain were associated with weaker repair after injury.

Albayram noted that not all omega-3s behave the same way. Docosahexaenoic acid, or DHA, is well known for its beneficial role in the brain and is a major part of neuronal membranes. EPA, however, follows a different pathway. It is less incorporated into brain structures, and its effects can vary depending on how long it is present and the surrounding biological conditions. Because of this, the long-term impact of omega-3 intake on brain recovery and blood vessel adaptation has remained unclear.

Experiments Link Diet, Brain Biology, and Recovery

To better understand these effects, the researchers used a series of models to connect diet, brain function, and healing. In mice, they examined how long-term fish oil use influenced the brain’s response to repeated mild head impacts. Their focus was on signals related to blood vessel stability and repair.

They also studied human brain microvascular endothelial cells, which form part of the barrier between the brain and the bloodstream. In these cells, EPA, but not DHA, was linked to reduced repair capacity, aligning with the findings from the animal models.

To extend the findings to real-world disease, the team analyzed postmortem brain tissue from individuals diagnosed with chronic traumatic encephalopathy (CTE) who had a history of repeated brain injury.

The researchers described the results as having “implications for precision nutrition, therapeutic strategies and the design of dietary interventions targeting brain injury and neurodegeneration.”

Key Findings From the Study

The study identified several major patterns, which are summarized below along with simplified explanations.

1. EPA-driven neurovascular instability triggers perivascular tauopathy and cognitive decline following TBI.

“In a sensitive brain state modeled in mice, long-term fish oil supplementation revealed a delayed vulnerability. The animals showed poorer neurological and spatial learning performance over time, together with clear evidence of vascular-associated tau accumulation in the cortex, linking impaired recovery to neurovascular dysfunction and perivascular tau pathology,” Albayram said.

2. EPA reprograms cortical transcriptional responses and suppresses angiogenic signaling following traumatic brain injury.

“In the injured cortex, the team observed a coordinated shift in gene programs that normally support vascular stability and repair,” Albayram said. “The pattern included reduced expression of genes tied to extracellular matrix organization and endothelial integrity, alongside broader changes consistent with altered lipid handling after injury.”

3. EPA utilization under permissive metabolic conditions impairs angiogenesis and endothelial integrity, recapitulating post-traumatic brain injury cerebrovascular dysfunction.

Albayram said that in human brain microvascular endothelial cells, EPA did not act as a universal toxin. “Instead, when cells were placed in conditions that encouraged fatty acid engagement, EPA was associated with weaker angiogenic network formation and reduced endothelial barrier integrity, matching key features of the neurovascular repair deficit seen in vivo.”

4. CTE brain reveals neurovascular and fatty acid metabolic reprogramming consistent with EPA-linked vulnerability.

“In postmortem cortex from neuropathologically confirmed CTE cases with a history of repetitive brain injury, the researchers found evidence of disrupted fatty acid balance and broad transcriptional changes affecting vascular and metabolic pathways,” Albayram said. “This human arm was used to provide translational context, asking whether chronic disease tissue shows convergent signatures of altered lipid handling and reduced vascular stability.”

What the Findings Mean for Fish Oil Use

Albayram stressed that the study should not be interpreted as a blanket warning against fish oil. “I am not saying fish oil is good or bad in some universal way,” he said. “What our data highlight is that biology is context-dependent. We need to understand how these supplements behave in the body over time, rather than assuming the same effect applies to everyone.”

The researchers hope their work encourages a more careful look at omega-3 supplementation, both in clinical settings and among the general public. Their experiments focused on a specific scenario, repeated mild brain injury, and used CTE tissue to provide supporting observations rather than direct proof of cause and effect.

“As with any study, there are important boundaries,” Albayram said. “In the human CTE tissue, we can observe patterns, but we cannot prove what drove them. We also cannot capture every variable that shapes omega-3 handling in real life, including overall diet, health status and lifestyle.”

Next Steps in Understanding Omega-3 Effects

The team plans to continue investigating how EPA moves through the body, including how it is absorbed, transported, and distributed. They are especially interested in the mechanisms that control fatty acid movement.

“This paper is a starting point,” Albayram said, “but it is an important one. It opens a new conversation about precision nutrition in neuroscience, and it gives the field a framework to ask better, more testable questions.”

Researchers led by the University of Alaska Fairbanks examined the stomach contents of northern pike collected by the U.S. Fish and Wildlife Service in the Deshka River during the summers of 2021 and 2022. They compared those findings with samples taken from pike in the same river about ten years earlier.

Their analysis showed that pike across all age groups increased their fish consumption as temperatures rose. The change was especially striking among younger fish, with year-old pike consuming 63 percent more fish than before.

The findings were published in the journal Biological Invasions.

“We expect there will be significant warming in the future, and the amount of fish that pike consume is going to increase with it,” said Benjamin Rich, who led the study while pursuing his graduate degree at the UAF College of Fisheries and Ocean Sciences.

Rising Temperatures in Air and Water

The study area has already experienced a steady warming trend. Average summer air temperatures have climbed by about 3 degrees Fahrenheit since 1919, including an increase of 0.8 degrees over the past decade. Water temperatures in the Deshka River, which flows into the Susitna River, have also remained above historical averages in recent years, Rich said.

Looking ahead, scientists expect this warming to continue throughout the 21st century. Models suggest that northern pike could increase their food intake by another 6%-12% by the year 2100.

Warmer Water Boosts Predator Appetite

The growing appetite of pike in the Deshka River reflects patterns seen in other freshwater systems. As water temperatures rise, predator metabolism speeds up, increasing their energy demands and pushing them to feed more aggressively.

This shift is particularly troubling in Southcentral Alaska, where northern pike were introduced illegally and now share habitat with Chinook and coho salmon populations that are already in decline.

Interestingly, the number of Chinook and coho salmon found in pike stomachs dropped over the past decade. Researchers suggest this likely reflects the shrinking salmon populations in the river rather than reduced predation.

Salmon Face Multiple Pressures

Salmon are already under strain from warming conditions, said UAF fisheries professor Peter Westley. More aggressive predation adds another layer of pressure in an already challenging environment.

“We know that invasive species and climate are individually associated with freshwater fish extinctions,” said Westley, a co-author of the study. “Those impacts may be working together into the future.”

Complex Ecosystem Changes

Erik Schoen, a researcher at UAF’s International Arctic Research Center, emphasized the importance of understanding these interconnected effects. Salmon are a key species, but they are only one part of a broader ecosystem influenced by rising temperatures.

“There’s been a lot of work done about how changes in temperature affect salmon directly. That’s really important, but salmon aren’t alone in these rivers,” said Schoen, who also contributed to the paper. “It’s also important to understand how these changes are affecting salmon indirectly through their predators, prey and pathogens.”

Other contributors to the research included Adam Sepulveda and Jeffrey Falke of the U.S. Geological Survey and Daniel Rinella of the U.S. Fish and Wildlife Service.

One bacterium in particular, Morganella morganii, has been linked in several studies to major depressive disorder. Until recently, though, it was unclear whether this microbe contributes to depression, whether depression changes the microbiome, or whether another factor explains the connection.

Researchers at Harvard Medical School have now identified a biological mechanism that strengthens the case that M. morganii can affect brain health. Their findings offer a clearer explanation of how this bacterium may influence depression.

Published in the Journal of the American Chemical Society, the study points to an inflammation-triggering molecule and suggests a possible new target for diagnosing or treating certain cases of depression. It also provides a framework for studying how other gut microbes may shape human health and behavior.

“There is a story out there linking the gut microbiome with depression, and this study takes it one step further, toward a real understanding of the molecular mechanisms behind the link,” said senior author Jon Clardy, the Christopher T. Walsh, PhD Professor of Biological Chemistry and Molecular Pharmacology in the Blavatnik Institute at HMS.

How an Environmental Chemical Triggers Inflammation

The researchers discovered that an environmental contaminant called diethanolamine, or DEA, can sometimes replace a sugar alcohol in a molecule produced by M. morganii in the gut.

This altered molecule behaves very differently from the normal version. Instead of remaining harmless, it activates the immune system, prompting the release of inflammatory proteins known as cytokines, especially interleukin-6 (IL-6).

This chain of events provides a potential explanation that links M. morganii to depression. Chronic inflammation is known to play a role in many diseases and has also been associated with major depressive disorder.

Previous research supports this connection. Studies have linked IL-6 to depression and have also associated M. morganii with inflammatory conditions such as type 2 diabetes and inflammatory bowel disease (IBD).

More research will be needed to determine whether this altered molecule directly causes depression and to understand how many cases might be influenced by this process.

New Possibilities for Diagnosis and Treatment

DEA is commonly found in industrial, agricultural, and consumer products.

“We knew that micropollutants can be incorporated into fatty molecules in the body, but we didn’t know how this occurs or what happens next,” Clardy said. “DEA’s metabolism into an immune signal was completely unexpected.”

The researchers suggest that DEA could potentially be used as a biomarker to help identify certain cases of major depressive disorder.

Their findings also add weight to the idea that depression, or at least some forms of it, may involve the immune system. This raises the possibility that treatments targeting immune responses, such as immune-modulating drugs, could be effective for some patients.

More broadly, the study shows how a bacterial molecule can change human immune function by incorporating a contaminant. This insight may help scientists investigate how other gut bacteria influence immunity and different biological systems.

“Now that we know what we’re looking for, I think we can start surveying other bacteria to see whether they do similar chemistry and begin to find other examples of how metabolites can affect us,” said Clardy.

Collaborative Research Advances Microbiome Science

This breakthrough was made possible by combining expertise from two research groups. The Clardy Lab focuses on the chemistry of small molecules produced by bacteria, while the lab of Ramnik Xavier, the HMS Kurt J. Isselbacher Professor of Medicine at Massachusetts General Hospital, specializes in understanding how the microbiome affects health at a molecular level.

Together, these collaborations have advanced the understanding of how gut bacteria interact with the immune system and influence disease. Their recent work includes:

• Demonstrating how a single bacterium (A. muciniphila), the molecule it produces, the biological pathway it uses, and its effects on the body are connected (protecting against inflammation and increasing sensitivity to cancer immunotherapies).
• Showing that the gut bacterium R. gnavus produces an immune-activating sugar-molecule chain that may explain its link to Crohn’s disease and IBD.
• Discovering that a fatty molecule on the surface of the “strep throat” bacterium S. pyogenes can trigger the immune system to release inflammatory cytokines — helping explain severe immune complications, possible links to autoimmune diseases like lupus, and ways to improve cancer immunotherapies.

That fatty molecule belongs to a group called cardiolipins, which are known to stimulate cytokine release. In the new study, researchers found that when DEA is incorporated into the molecule produced by M. morganii, it begins to behave like a cardiolipin, triggering inflammation.

Authorship, Funding, Disclosures

Sunghee Bang and Yern-Hyerk Shin are co-first authors. Additional authors are Sung-Moo Park, Lei Deng, R. Thomas Williamson, and Daniel B. Graham.

Co-author Xavier is a core institute member of the Broad Institute of MIT and Harvard, where he also directs the Klarman Cell Observatory and the Immunology Program and co-directs the Infectious Disease and Microbiome Program.

This work was funded by the National Institutes of Health (grant R01AI172147) and The Leona M. and Harry B. Helmsley Charitable Trust (2023A004123). The authors also acknowledge the HMS Analytical Chemistry Core, HMS Bio-molecular NMR Facility (formerly East Quad NMR facility; NIH OD028526), and Institute of Chemistry and Cell Biology (ICCB)-Longwood Screening Facility.