A study led by researchers at NYU Grossman School of Medicine identified shared molecular patterns in human milk that link maternal nutrition, mammary gland biology, and infant growth.

Why do large dogs tend to live shorter lives than their smaller counterparts? According to a new study of nearly 900 dogs, the answer may be written into their epigenome. The findings reveal that larger and male dogs undergo accelerated molecular aging, with pronounced DNA methylation (DNAm) on the X chromosome and at transposable elements (TEs). Aging is a universal process, but its pace and biological mechanisms substantially differ between individuals and species. Domestic dogs offer a particularly useful model for understanding the biology of aging because their lifespans vary dramatically with body size. For example, smaller breeds can live nearly twice as long as larger breeds. Moreover, companion dogs also live in human environments, consume commercial diets, and receive routine medical care, making them a relevant translational model for studying how genetic background and environmental exposures shape aging. However, how intrinsic factors such as size and biological sex influence variation in dog aging and lifespan remains unclear. Previous research has demonstrated that DNAm is a useful indicator of biological aging, with “epigenetic clocks” offering a way to understand the factors that accelerate or decelerate biological aging.

Blaise Mariner and colleagues generated 1,640 methylomes from a cohort of 894 dogs in the Dog Aging Project. They combined these molecular data with detailed genetic and demographic data. Mariner et al. found that molecular aging occurs most rapidly early in a dog’s life. What’s more, larger and male dogs – both of which have shorter lifespans than their respective counterparts – age more quickly at the molecular level. The authors identified different epigenetic patterns underlying these effects. According to the findings, sex-related changes were concentrated on the X chromosome, while body-size-related changes were especially prominent in TEs, stretches of DNA that can influence genome stability and gene regulation.

A person’s microbiome may help determine whether they develop a fever after receiving a vaccination, according to a new study. The findings suggest that the microbiome and potentially diet could one day be targeted to reduce vaccine-related inflammation without compromising the immune protection vaccines provide. Vaccines are a crucial tool for ensuring public health, but people vary widely in their immune responses and side effects. Fever and flu-like symptoms are among the most common adverse reactions to vaccines, particularly mRNA- and lipid nanoparticle-based vaccines. These reactions can discourage future vaccination and contribute to vaccine hesitancy and mistrust. However, not all those who receive a vaccination develop a fever and those who do tend to get a fever across repeated doses, suggesting the importance of individual risk factors for fever. The reasons for this variation are not well understood.

In this study, Kelsey Huus and colleagues speculated that the gut microbiome, which is known to influence immune activity, may play a role in driving these reactions. To test this hypothesis, Huus et al. profiled the fecal microbiomes, body temperature, and blood-based immune markers of 171 healthy adults before and after receiving the mRNA vaccination for SARS-CoV-2. The findings showed that certain gut bacteria, especially Lachnospiraceae, produce flagellin, which can activate inflammatory immune pathways and intensify vaccine-related reactions. Those who had greater pre-vaccination intestinal inflammation or higher levels of flagellin expression in the gut tended to develop vaccine-induced fever. What’s more, the authors found that industrialized diets may promote this inflammatory activity. Vegetarian diets tended to correlate with microbiome features that contributed to less fever, while lower consumption of whole plant foods and diets characterized by greater fat or processed-food intake were associated with the inflammatory, fever-associated microbiome. Dietary manipulation altered both microbiome compositions and their associated vaccine responses. Importantly, Huus et al. show that flagellin, inflammation, and diet do not affect antibody responses to vaccines, suggesting that the microbiome-driven inflammation increased vaccine side effects without necessarily affecting immunity. “Diet, microbial ecology, and the metabolic state are not immutable, and people might one day prepare for vaccination as deliberately as the vaccine itself is formulated,” writes Bali Pulendran in a related Perspective.

In this Policy Article, Alp Sungu and colleagues report on a large-scale randomized controlled trial evaluating the impacts of classroom phone restrictions on student outcomes in India. The findings show that restricting phone use can support learning, particularly among lower-performing students. Amidst growing concerns about smartphones’ effects on learning, mental health, and peer relationships, phone bans are being increasingly adopted in schools worldwide. However, large-scale experimental evidence supporting whether these bans improve learning or social outcomes is lacking. To address this gap, Sungu et al. performed a randomized controlled trial involving 16,683 students across 10 higher education institutions in Odisha, India – a state where smartphone ownership and use among youth aged 15 to 29 exceeds 70%. The authors measured academic performance, attitudes toward phone restrictions, well-being, motivation, digital use, and online harassment.

The findings show that banning smartphones in class improved academic performance, particularly among lower-performing students and first-year undergraduates. Effects were minimal among higher-performing, postgraduate, and STEM students. Removing phones also reduced disparities in GPA, suggesting that restrictions may help close gaps in learning outcomes. Importantly, attendance rates did not change, indicating that the improvement was likely driven by greater attention and more productive classroom dynamics, rather than students simply attending class more often. Students who experienced classroom phone bans became more supportive of the restrictions and more likely to view them as beneficial, while showing less preference for unrestricted phone use. Classroom observations also found less disruptive behavior and fewer off-topic conversations, along with greater teacher engagement. According to Sungu et al., these findings suggest that students may become more receptive to phone restrictions after experiencing a more focused, phone-free classroom environment.