What they are, which groups are affected, and pandemic and economic impacts Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link What are health inequalities? Last updated: 05/02/26, 10:08 Published: 08/01/26, 08:00 What they are, which groups are affected, and pandemic and economic impacts This is Article 1 in a series on health inequalities. Next article: Socioeconomic health equalities . Welcome to the first article in a series of articles about health inequalities. This first article will look more in detail at exactly what health inequalities are. Introduction Imagine that you lived in Blackpool, and that your friends or family lived in Kensington. Your life expectancy would be 76 years, while theirs would be 86 years, a full decade of difference! Or consider the fact that even though men have shorter life-spans compared to women, women spend longer living with ill health or major illnesses. These are some examples of health inequalities, which are health differences between different groups of people. They aren’t just random variations in health outcomes between different groups or people: instead, they’re systematic and avoidable. What groups are affected by health inequalities? Health inequalities can be seen across various populations. A person’s health can be impacted by socioeconomic factors, like income or wealth, and geographic factors, like where they live. Other characteristics affecting health include ethnicity or gender. These factors don’t act in isolation. For individuals who experience multiple levels of disadvantage, the effects of inequalities are worsened. For example, ethnic minority groups who live in deprived areas, or socioeconomically disadvantaged women, experience even worse health outcomes. This interconnectedness means that understanding health inequalities and addressing them requires a holistic approach. Health status and health inequalities Differences in health outcomes can manifest in different ways. One indicator is health status, which includes overall life expectancy and healthy life expectancy, which is the time people live in good health. In England, there’s an almost 10-year gap in life expectancy between the most and least deprived areas, shown by the example above, where the life expectancy is 76 years in Blackpool and 86 years in Kensington. Differences in healthy life expectancy between the most and least deprived areas are even more pronounced. Healthy life expectancy is more than 18 years lower for the most deprived areas compared to the least deprived areas, as shown in Figure 1 . Males living in the most deprived areas can expect to live 52.3 years in good health, while for males living in the least deprived areas, this number increases to 70.5 years. For females, it’s 51.9 years in the most deprived areas, compared to 70.7 years in the least deprived. The impact of the COVID-19 pandemic on health inequalities The COVID-19 pandemic has exacerbated health inequalities, with those living in the most deprived areas and people from ethnic minority backgrounds being the worst impacted. For example, as the pandemic strained healthcare services, more deprived areas had longer waiting lists, highlighting issues of unequal access and quality of care. In addition, death rates in the most deprived areas were higher compared to the least deprived areas: at a deprivation level of 1 (most deprived), deaths from COVID-19 were 566.2 per 100,000, with this number decreasing to 228.7 deaths per 100,000 at a deprivation level of 10 (least deprived), as seen in Figure 2 . The economic impact of health inequalities Health inequalities can have economic impacts as a result of the added costs needed to address them. The persistence of health inequalities, particularly among the working-age population, is a challenge to economic growth, as increasing levels of ill health can lead to economic inactivity. For example, data from before COVID-19 suggests that health inequalities cost the UK £31bn to £33bn per year in lost productivity, £20bn to £32bn per year in lost tax revenue and higher benefits payments and £4.8bn of the NHS budget. This is equivalent to almost a fifth of the NHS budget. As the pandemic exacerbated inequalities, these numbers have only increased: for example, the long-term impacts of COVID-19 have varied between demographics. Given that at least 2.5 million working-age adults are unable to work due to long-term sickness, as per the Office for National Statistics estimates, this is a significant economic challenge for the country, as well as a health issue. Conclusion Health inequalities have been shown to affect different groups disproportionately, with deprivation, ethnicity, socioeconomic status and other social factors having compounding effects, resulting in poorer health and shorter healthy lives. The COVID-19 pandemic further exacerbated these inequalities, with the most marginalised communities being the most affected. Failure to address these differences has resulted in not only human costs but also billions in lost productivity and increased burdens on health services. Socioeconomic status is one specific factor that influences health outcomes: as mentioned above, people in the most deprived areas face a gap of approximately ten years in life expectancy compared to the least deprived, seen when comparing life expectancy in Blackpool and Kensington. The next article in this series will look more in detail at socioeconomic inequalities, so watch out for that! Written by Naoshin Haque Related article: Global Health Injustices (series) Project Gallery

The finches are a classic example of adaptive radiation, which is the rapid diversification of an organism into many different species with different ecological roles. Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Beak diversity in Darwin's finches Last updated: 24/09/26, 20:33 Published: 10/09/26, 08:00 The finches are a classic example of adaptive radiation, which is the rapid diversification of an organism into many different species with different ecological roles. Darwin’s finches are a family of birds from the Geospiza , Platyspiza , and Certhidea species on the Galápagos Islands, located in the Pacific Ocean. They are named after their contribution to Charles Darwin’s theories on evolution by natural selection. The finches are a classic example of adaptive radiation, which is the rapid diversification of an organism into many different species with different ecological roles. In this example, an ancestral bird on the Galápagos Islands evolved into about 18 species over 1-2 million years. Restricted gene flow with South America, climatic oscillations from the El Niño phenomenon, glacial cycles, and volcanic activity created the conditions for this rapid evolution. Different Galápagos islands vary in size, elevation, and food availability, so Darwin’s finches diversified by adapting to these different islands. This created a wide range of beak shapes and sizes, both within and between finch species. This article will describe Darwin’s finch beak diversity and the molecular basis behind it. How beak morphology varies in Darwin’s finches Darwin’s finches have diverse beak sizes and shapes, which match their diverse diets. Their beaks vary in length, depth, and curvature. Warbler finches have pointy beaks to spear insects, while tee finches have triangular beaks suitable for eating fruits and insects in tree canopies. Ground finches have blunt beaks suitable for crushing seeds, and birds with bigger beaks eat bigger seeds ( Figure 1 ). This partitioning of food between finches with different beaks is most prominent during the dry season, when there is more competition for food; in the wet season, there is more diet overlap between finches with different beaks. Beaks play the dual role of hands and mouth – foraging, feeding, communicating, nest building and more – so even small changes in beak morphology can have big impacts on finch lifestyles. Therefore, beak morphology is a hallmark of adaptive radiation in Darwin’s finches. Evolution of beak size within a species While Figure 1 highlights different beak sizes between species, the Galápagos' changing environment makes beak size evolve within a species too. A well-known example is the medium ground finch ( Geospiza fortis ) , which eats seeds and whose beak size varies depending on the size of available seeds. When there was a drought on the Galápagos Island of Daphne Major in 1977, small seeds did not survive, so G. fortis could only eat large seeds with hard shells. Finches survived if they had larger beaks that could crack open these larger, harder seeds. Since natural selection favoured larger beaks, the average beak size of the species increased in the late 1970s. However, the large ground finch ( Geospiza magnirostris ) colonised Daphne Major island in late 1982 and outcompeted the native G. fortis for large seeds. This meant G. fortis was left with smaller seeds, creating a selection pressure which reduced G. fortis beak size for the next 15 years. Figure 2 shows how opposing selection pressures have made the beak size of G. fortis vary over time. Molecular basis of beak morphology Evolution of beak size within and between species of Darwin’s finches has a complex molecular basis. Beak morphology has to be heritable (i.e. have a genetic basis) for natural selection to act on it: birds with beaks more suitable to their environment pass down genes for those beaks to their offspring. Beaks are made of bone and cartilage, so genes involved in the formation and development of bone and cartilage are suspected to control beak morphology. The ALX1, CALM1, GSC, RDH14, FGF10, and FOXC1 genes have different variants in Darwin’s finch species with blunt and sharp beaks, meaning nucleotide sequence differences in these genes are responsible for changes in beak shape. These variations are not necessarily in the coding sequence of those genes: often, the variations are in transcription factor genes, promoters, and other DNA sequences which regulate the expression of genes like ALX1 and CALM1 ( Figure 3 ). Therefore, beak morphology is heritable, but it involves a complex combination of developmental genes. Conclusion The size and shape of beaks in Darwin’s finches are diverse because of an adaptive radiation over 1-2 million years. Changes in interspecific competition and geography of the Galápagos Islands affected food availability over space and time. Finches with different beaks adapted to eating different types of food, as natural selection acted on various genes involved in beak development both directly and indirectly. Molecular and phenotypic studies of Darwin’s finches have revealed the complex interaction between developmental genes and the environment in controlling beak morphology. Nearly 200 years after Charles Darwin’s expedition to the Galápagos, his finches remain a classic example of natural selection and adaptive radiation. Written by Simran Patel Related articles: Galapagos tortoises / The diversity of bat faces REFERENCES De León LF, Podos J, Gardezi T, et al. Darwin’s finches and their diet niches: the sympatric coexistence of imperfect generalists. J Evol Biol 2014; 27: 1093–1104. Grant PR, Grant BR. Evolution of character displacement in Darwin’s finches. Science 2006; 313: 224–226. Foster DJ, Podos J, Hendry AP. A geometric morphometric appraisal of beak shape in Darwin’s finches. J Evol Biol 2008; 21: 263–275. Boag PT, Grant PR. Intense natural selection in a population of Darwin’s finches (Geospizinae) in the Galápagos. Science 1981; 214: 82–85. Grant PR, Grant BR. From microcosm to macrocosm: adaptive radiation of Darwin’s finches. Evol J Linn Soc 2024; 3: kzae006. Lamichhaney S, Berglund J, Almén MS, et al. Evolution of Darwin’s finches and their beaks revealed by genome sequencing. Nature 2015; 518: 371–375. Cheng Y, Miller MJ, Lei F. Molecular Innovations Shaping Beak Morphology in Birds. Annu Rev Anim Biosci 2025; 13: 99–111 Project Gallery

A rare disease that causes inflammation in the blood vessels Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Understanding and detecting Kawasaki disease on time Last updated: 24/02/25, 11:31 Published: 06/02/25, 08:00 A rare disease that causes inflammation in the blood vessels What is Kawasaki disease? Kawasaki disease is a rare type of vasculitis that damages blood vessels through inflammation and is prevalent in children under the age of five. Kawasaki disease is predominantly found in children of Asian races–mainly in Japan, Korea, Taiwan, and Asian races in the US–and is the leading cause of acquired heart disease in children in most developed countries. What causes Kawasaki disease? There is no known cause of Kawasaki disease, however, studies suggest a link between genetics and the disease, noting a high incidence between siblings and in children with a parental history of Kawasaki disease. Another study provided further evidence of genetic susceptibility, stating that variation in the expression of CASP3 and ITPKC—genes heavily involved in T cell function—leads to an overexpression of T cells.This can be attributed to the inflammatory symptoms of the disease. There are speculations that it may be caused by an airborne agent originating in Central Asia which moves across different geographical regions. This study suggests that through winds, the airborne agent is able to cause Kawasaki disease via infection of the respiratory tract–further investigation is needed regarding this hypothesis. Diagnosing Kawasaki disease Symptoms of Kawasaki disease, which are often accompanied by a fever, are classified into three phases: acute, subacute, and convalescent. The acute phase usually lasts between two to three weeks and symptoms include: Carditis Mucosal inflammation (cracked and dry lips, strawberry tongue, swollen lymph nodes) Polymorphous rash Coronary artery aneurysms The subacute phase also lasts up to three weeks and includes symptoms such as: - Perineal and periungual desquamation - Arthralgia - Myocardial disease The convalescent phase is when most clinical signs dissolve and usually lasts up to three months. It is important to note that while most symptoms clear up during this phase, cardiac issues may still persist in some patients. Misdiagnosing Kawasaki disease is very common as its symptoms are similar to that of many diseases like scarlet fever or toxic shock syndrome. With that being said, confirming its diagnosis is often a case of ruling out these diseases. In addition to identifying symptoms linked to other diseases, conducting laboratory tests such as CRP, CBC, and ESR can help confirm a diagnosis of Kawasaki disease. Additionally, echocardiograms and electrocardiograms can help assess coronary abnormalities as well as overall heart function. Treating Kawasaki disease Following diagnoses, patients are first administered an IVIG and a high dose of aspirin to reduce inflammation as well as eliminate pain, swelling and fever. Patients are then administered lower doses of aspirin which helps prevent blood clotting. Roughly 25% of untreated patients are at a higher risk of developing coronary artery aneurysms and lasting cardiovascular issues in general. This risk drops down to 5% when treated appropriately. IVIG is proven to be effective in treating approximately 85-90% of cases when administered within the first ten days of the illness which is why it is imperative that patients are treated early. X-rays are regularly conducted on patients as they can help visualise blood vessels and potential heart abnormalities that may suggest further complications. It can also observe the effectiveness of treatment over time. Post-recovery, an echocardiogram is recommended periodically to detect any coronary abnormalities that may have developed much later on. Summary Kawasaki disease is a rare disease that causes inflammation in the blood vessels. It normally develops in children under the age of five and is yet to have a known cause. It is often hard to diagnose as its symptoms are similar to that of other diseases, which is why it is important to identify its symptoms (polymorphous rash, mucosal inflammation, desquamation, etc) as well as conduct tests such as CBC, CRP, ESR, an electrocardiogram, etc to help rule out other diseases. It is essential that children with Kawasaki disease are diagnosed and treated early as this can help treat coronary artery aneurysm and prevent lasting coronary and cardiovascular abnormalities. Written by Sherine Latheef Related articles: Sideroblastic anaemia / Blood / Inflammation therapy REFERENCES Onouchi, Y., Ozaki, K., Buns, J.C., Shimizu, C., Hamada, H., Honda, T., Terai, M., Honda, A., Takeuchi, T., Shibuta, S., Suenaga, T., Suzuki, H., Higashi, K., Yasukawa, K., Suzuki, Y., Sasago, K., Kemmotsu, Y., Takatsuki, S., Saji, T. and Yoshikawa, T. (2010). Common variants in CASP3 confer susceptibility to Kawasaki disease. Human Molecular Genetics , 19(14), pp.2898–2906. doi: https://doi.org/10.1093/hmg/ddq176 . Agarwal, S. and Agrawal, D.K. (2017). Kawasaki Disease: Etiopathogenesis and Novel Treatment Strategies. Expert review of clinical immunology , [online] 13(3), pp.247–258. doi: https://doi.org/10.1080/1744666X.2017.1232165 . Wolff, A.E., Hansen, K.E. and Zakowski, L. (2007). Acute Kawasaki Disease: Not Just for Kids. Journal of General Internal Medicine , [online] 22(5), pp.681–684. doi: https://doi.org/10.1007/s11606-006-0100-5 . Oh, J.-H., Cho, S. and Choi, J.A. (2023). Clinical Signs of Kawasaki Disease from the Perspective of Epithelial-to-Mesenchymal Transition Recruiting Erythrocytes: A Literature Review. Reviews in Cardiovascular Medicine , 24(4), pp.109–109. doi: https://doi.org/10.31083/j.rcm2404109 . Team, H.J. (2018). Kawasaki Disease - Causes, Signs, Symptoms,Treatment . [online] Health Jade. Available at: https://healthjade.com/kawasaki-disease/ . Project Gallery

Research shows that insomnia does have a hereditary side Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Does insomnia run in families? Here's what genetics tells us Last updated: 10/07/25, 19:25 Published: 10/07/25, 19:11 Research shows that insomnia does have a hereditary side Have you ever noticed restless nights affecting more than one relative? Maybe your sister tosses and turns, or your brother wakes up before dawn, wide awake and anxious. It might feel like poor sleep is passed down from parents to kids, and science suggests that feeling isn’t just in your head. In one study, nearly 40% of people with insomnia had a close family member with it, compared to 29% of those without; making them 1.57 times more likely to share the struggle. So is that inherited, or just a string of bad luck? Here’s what science has to say. Your DNA can affect sleep Research shows that insomnia does have a hereditary side. If someone in your family, say a parent, sibling or even a grandparent, struggles night after night, you’re more likely to face similar problems. That doesn’t guarantee you’ll wake up at 3 a.m. every night, but it does raise your baseline risk: studies estimate that around one-third of insomnia liability is genetic. In practical terms, inheriting certain gene variants can make the brain’s sleep-promoting signals weaker or the wake-promoting signals stronger. Think of those genes as nudging you toward more restless nights rather than pushing you entirely into insomnia. So if genes only lay the groundwork, what else determines whether someone actually stays awake counting sheep? That’s where life’s daily stresses come into play. How genes shape your sleep Scientists have identified a handful of genes that guide our body’s natural clock. Our circadian rhythm influences how deeply and how long we sleep. For instance, variants in the PER3 or CLOCK genes can shift your internal timing. This makes it harder to feel sleepy at a conventional hour. Picture the circadian clock as an orchestra conductor: if the conductor’s timing fluctuates, the entire performance, your sleep cycle, can fall out of sync. Other inherited factors affect the brain’s “volume knobs” for alertness. Certain gene differences can heighten sensitivity to minor disturbances; like a creaky floorboard or an ambulance siren, so that you jitter awake even when there’s no real threat. Over time, those tiny awakenings add up, preventing you from reaching the deep, restorative stages of sleep. Yet, these genes don’t act in isolation. The brain remains remarkably adaptable through epigenetic changes; chemical tags that turn genes on or off. Experiences such as stress, illness, or a drastically changed schedule can strengthen or weaken those genetic susceptibilities. Sleep isn’t just genetic; here’s why Even if you inherit gene variants linked to insomnia, your environment and habits often decide the end result. High-pressure jobs, financial worries, or family conflicts can ignite sleep troubles in someone without a family history of insomnia. Conversely, someone with a strong genetic vulnerability might sleep soundly if life stays relatively stress-free and routines remain consistent. Everyday choices, like scrolling through social media until the last minute, drinking coffee late afternoon, or keeping wildly shifting bedtimes, further fuel the problem. For example, evening exposure to bright screens suppresses melatonin, the hormone that signals your brain it’s time to sleep. That means even if your “insomnia genes” are mild, you’re still creating obstacles to a good night’s rest. On the other hand, regular exercise (aim for at least 30 minutes most days), a balanced diet, and a calm, screen-free wind-down routine signal the brain that it’s safe to switch off. Over months, those good habits can overwrite the nudge from your genes, steering you towards deep, uninterrupted rest. Can you change your genetic destiny? Knowing that insomnia has a genetic component can feel validating. It clarifies that tossing and turning isn’t simply an unexplained routine. That awareness reduces shame and makes it easier to adopt practical solutions. If you suspect poor sleep runs in your family, watch for early warning signs: difficulty falling asleep, waking often, or waking too early. Catching these patterns early means you can experiment with sleep hygiene tweaks before the problem becomes chronic. Actionable steps include setting a consistent bedtime, dimming lights an hour before sleep, avoiding caffeine after mid-afternoon, and practising relaxation techniques, such as deep breathing or progressive muscle relaxation. If these changes don’t help, cognitive behavioural therapy for insomnia (CBT-I) targets both the thoughts and behaviours that perpetuate sleeplessness, effectively retraining the brain’s response to the bedroom. Those inherited sleep tendencies might suggest insomnia is written in your DNA; but by keeping a consistent bedtime, cutting down on late-night screens and being kind to yourself, you can rewrite that genetic script and finally enjoy the deep rest you’ve earned. Written by Rand Alanazi Related articles: Does anxiety run in families? / Link between sleep and memory loss / The chronotypes REFERENCES Beaulieu-Bonneau S, LeBlanc M, Mérette C, Dauvilliers Y, Morin CM. Family History of Insomnia in a Population-Based Sample. Sleep. 2007 Dec;30(12):1739–45. Pacheco D. Is Insomnia Genetic? [Internet]. Sleep Foundation. 2021. Available from: https://www.sleepfoundation.org/insomnia/is-insomnia-genetic PER3 [Internet]. Wikipedia. 2023. Available from: https://en.wikipedia.org/wiki/PER3 Dashti HS, Jones SE, Wood AR, Lane JM, van Hees VT, Wang H, et al. Genome-wide association study identifies genetic loci for self-reported habitual sleep duration supported by accelerometer-derived estimates. Nature Communications [Internet]. 2019 Mar 7;10(1):1–12. Available from: https://www.nature.com/articles/s41467-019-08917-4 Halperin D. Environmental noise and sleep disturbances: A threat to health? Sleep Science [Internet]. 2014 Dec;7(4):209–12. Available from: https://www.sciencedirect.com/science/article/pii/S1984006314000601 www.ushealthconnect.com H. Unraveling the Impact of Environmental Factors on Sleep Quality and Parkinson Disease [Internet]. Practicalneurology.com . 2025. Available from: https://practicalneurology.com/diseases-diagnoses/movement-disorders/unraveling-the-impact-of-environmental-factors-on-sleep-quality-and-parkinson-disease/32197/ Levenson JC, Kay DB, Buysse DJ. The Pathophysiology of Insomnia. Chest [Internet]. 2015 Apr;147(4):1179–92. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC4388122/ Spielman AJ, Caruso LS, Glovinsky PB. A Behavioral Perspective on Insomnia Treatment. Psychiatric Clinics of North America [Internet]. 1987 Dec 1;10(4):541–53. Available from: https://www.sciencedirect.com/science/article/pii/S0193953X1830532X the I. amBX [Internet]. amBX. 2020 [cited 2025 Jun 6]. Available from: https://www.ambx.com/news/what-is-the-natural-circadian-rhythm Hassell K, Reiter RJ, Robertson NJ. MELATONIN AND ITS ROLE IN NEURODEVELOPMENT DURING THE PERINATAL PERIOD: A REVIEW. Fetal and Maternal Medicine Review. 2013 May 1;24(2):76–107. Wang J, Liu J, Xie H, Gao X. Effects of Work Stress and Period3 Gene Polymorphism and Their Interaction on Sleep Quality of Non-Manual Workers in Xinjiang, China: A Cross-Sectional Study. International Journal of Environmental Research and Public Health. 2022 Jun 3;19(11):6843–3. Project Gallery

Nanogels are tiny, water swollen polymer networks and encapsulate therapeutic agents Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Nanogels: the future of smart drug delivery Last updated: 17/07/25, 11:54 Published: 17/07/25, 08:00 Nanogels are tiny, water swollen polymer networks and encapsulate therapeutic agents Nanomedicine is a rapidly advancing field, with nanogels emerging as promising innovations for drug delivery applications. Nanogels are soft nanoscale hydrogels that are transforming how we deliver drugs and treat diseases. Whilst hydrogels themselves have long been used in biomedical applications such as tissue engineering and wound healing, their relatively larger sizes (above 100 micrometres) limits their ability to interact with cells and cross biological barriers. Nanogels, however, are thousands of times smaller, and offer unique advantages as a result. What are nanogels? Nanogels are tiny, water swollen polymer networks and are made up of crosslinked polymer chains to form a 3D matrix. Nanogels can encapsulate therapeutic agents inside their porous core shell structure. This swelling allowing nanogels to carry payloads, such as drugs, proteins, nucleic acids and these cargo materials are protected from degradation in the body whilst enabling controlled and targeted delivery. Due to their small sizes, nanogels can penetrate tissues and even enter cells, which overcomes the limitations faced with hydrogels. The surface of nanogels can also be engineered for specificity, to allow for precise targeting of drugs to receptors on diseased cells or inflamed tissues. Advantages over other nanocarriers Compared to liposomes and polymeric micelles, nanogels have a larger inner surface, which means they can carry more payload. The higher loading capacity improves the therapeutic efficiency whilst reducing the risks of side effects cause by off-target drug release. Nanogels also undergo the enhanced permeability and retention (EPR) effect - a phenomenon where the nanoparticles naturally accumulate in tumour or inflamed tissues due to leaky blood vessel, and as a result this improves drug delivery to targeted disease sites. Stimuli responsive ‘smart’ nanogels A key feature of nanogels is their stimuli responsiveness, or ability to act as ‘smart’ materials. The nanogels can be designed to respond to environmental triggers such as changes in pH, temperature, light, redox conditions, pressure and more. This responsiveness enables controlled release of drugs exactly when and where they are needed12. For example, thermoresponsive nanogels can change their structure at body temperature or when exposed to localised heating, making them ideal for applications like wound healing and cancer therapy. This controlled release prevents premature drug leakage, reduces systemic toxicity and overall improves the precision of the treatment. The future of nanogels in medicine Nanogels have huge potential as customisable drug delivery systems to target specific disease systems. They are biocompatible, stable, and have high drug loading capacities and are stimuli responsive; these properties combined make them a powerful tool in applications such as targeted drug delivery and gene therapy. As nanomedicine research progresses, nanogels are set to revolutionise healthcare with smarter, safer and more targeted therapies. Written by Saanchi Agarwal Related articles: Nanomedicine / Nanoparticles and diabetes treatment / Nanoparticles and health / Nanocarriers / Silicon hydrogel REFERENCES L. Blagojevic and N. Kamaly, Nanogels: A chemically versatile drug delivery platform, Nano Today, 2025, 61, 102645. F. Carton, M. Rizzi, E. Canciani, G. Sieve, D. Di Francesco, S. Casarella, L. Di Nunno and F. Boccafoschi, Use of Hydrogels in Regenerative Medicine: Focus on Mechanical Properties, Int. J. Mol. Sci. , 2024, 25 , 11426. N. Rabiee, S. Hajebi, M. Bagherzadeh, S. Ahmadi, M. Rabiee, H. Roghani-Mamaqani, M. Tahriri, L. Tayebi and M. R. Hamblin, Stimulus-Responsive Polymeric Nanogels as Smart Drug Delivery Systems, Acta Biomater. , 2019, 92 , 1–18. N. Rabiee, S. Hajebi, M. Bagherzadeh, S. Ahmadi, M. Rabiee, H. Roghani-Mamaqani, M. Tahriri, L. Tayebi and M. R. Hamblin, Stimulus-Responsive Polymeric Nanogels as Smart Drug Delivery Systems, Acta Biomater. , 2019, 92 , 1–18. A. Vashist, G. P. Alvarez, V. A. Camargo, A. D. Raymond, A. Y. Arias, N. Kolishetti, A. Vashist, P. Manickam, S. Aggarwal and M. Nair, Recent advances in nanogels for drug delivery and biomedical applications, Biomater. Sci. , 2024, 12 , 6006–6018. K. S. Soni, S. S. Desale and T. K. Bronich, Nanogels: an overview of properties, biomedical applications and obstacles to clinical translation, J. Control. Release Off. J. Control. Release Soc. , 2016, 240 , 109–126. A. Bordat, T. Boissenot, J. Nicolas and N. Tsapis, Thermoresponsive polymer nanocarriers for biomedical applications, Adv. Drug Deliv. Rev. , 2019, 138 , 167–192. K. S. Soni, S. S. Desale and T. K. Bronich, Nanogels: an overview of properties, biomedical applications and obstacles to clinical translation, J. Control. Release Off. J. Control. Release Soc. , 2016, 240 , 109–126. T. Alejo, L. Uson, G. Landa, M. Prieto, C. Yus Argón, S. Garcia-Salinas, R. de Miguel, A. Rodríguez-Largo, S. Irusta, V. Sebastian, G. Mendoza and M. Arruebo, Nanogels with High Loading of Anesthetic Nanocrystals for Extended Duration of Sciatic Nerve Block, ACS Appl. Mater. Interfaces , 2021, 13 , 17220–17235. S. V. Vinogradov, Nanogels in The Race for Drug Delivery, Nanomed. , 2010, 5 , 165–168. Project Gallery

The most famous pericyclic reaction is the Diels–Alder cycloaddition Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Diels–Alder Reaction Last updated: 02/04/26, 18:27 Published: 02/04/26, 08:00 The most famous pericyclic reaction is the Diels–Alder cycloaddition Introduction How does a chemical reaction proceed? This is one of the most important questions in chemistry and still drives research today. Traditionally, reactions have been classed as either ionic or radical processes. But there is a third class: a pericyclic reaction. The pericyclics, named because of their concerted curly arrow mechanisms, are a class of reaction governed by orbital symmetry. Often triggered by heat or light, they are some of the ‘greenest’ reactions, frequently achieving 100% atom economy. Perhaps the most famous pericyclic reaction is the Diels–Alder cycloaddition. Awarded a Nobel Prize in 1950, this reaction has been used extensively in both industry and academia. This article will explore how the Diels–Alder reaction works, supported by examples of its use in total natural product syntheses. Diels-Alder reaction: orbital considerations The Diels–Alder reaction proceeds thermally, with a diene and a dienophile interacting with the correct orbital phases. To explain this, let’s consider the reaction of butadiene (diene) with ethene (dienophile) to form cyclohexene. In butadiene, there are four valence p orbitals, each of which can interact in phase (same colours touching) or out of phase (different colours overlapping), leading to the generation of four molecular orbitals. For ethene, two molecular orbitals are generated, as there are only two valence p orbitals. For all chemical reactions to proceed, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the reactants must overlap in phase. Considering the phases of the diene HOMO and the dienophile LUMO shows they can interact favourably. The curly arrows move cyclically to generate cyclohexene. Stereochemistry In terms of stereochemistry, the Diels–Alder reaction follows two rules which govern its reactivity. Firstly, the diene starting material must be s‑cis, meaning the double bonds must be cis to one another for the orbital overlap to be successful. Secondly, the Diels–Alder reaction always maintains any stereochemical information of the starting material. For example, reacting butadiene with dimethyl maleate always gives a cis product. Both isomers of the product will form, as this reaction is not stereoselective. Applications of the Diels–Alder Reaction The Diels–Alder reaction has a rich and diverse history in the synthesis of total natural products. In 1952, Woodward et al. were the first to incorporate a Diels–Alder reaction into a total synthesis of cholesterol. Woodward also used a Diels–Alder reaction in his famous synthesis of reserpine, a medicinal product used to treat high blood pressure. Another interesting example of the Diels–Alder reaction in a complex synthesis was Danishefsky’s synthesis of myrocin C, an antibiotic with anti‑tumour properties. The ingenuity of this synthesis is that the intermediary fragment was specifically designed to undergo an intramolecular Diels–Alder reaction. Conclusion In conclusion, the Diels–Alder reaction is a titan of synthetic chemistry. As the chemical industry continues to adopt more sustainable chemistry, the Diels–Alder reaction is still as relevant as it was almost 100 years ago. While this article has centred on the Diels–Alder reaction, the pericyclic reactions are far more extensive. There are further cycloadditions as well as electrocyclisations, sigmatropic rearrangements and group transfer reactions. These transformations show the elegance of synthetic chemistry and re‑emphasise the importance of symmetry in all chemical disciplines. Written by Antony Lee Related article: Symmetry in chemistry Project Gallery

The neural pathways behind movement Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Mastering motion- reflex, rhythmic and complex movements Last updated: 12/03/25, 11:49 Published: 03/04/25, 08:00 The neural pathways behind movement Introduction Movement is arguably the most fundamental aspect of human behaviour and is one of the most obvious features distinguishing plants and animals. The ability to physically respond to stimuli has enhanced our chances of survival an immeasurable amount. As such, our body’s ability to move has evolved and refined itself over many millennia, even developing new ways to move that protect us in many ways. For example, involuntary reflexes have reduced the computational demand on our brain to move parts of our body away from hot or painful objects, making the process almost instantaneous. Meanwhile, central pattern generators (CPGs) in our spinal cord have also reduced cognitive load by carrying out subconscious movement. This has allowed the motor cortex and cerebellum to focus on planning, coordinating, and refining purposeful movements in response to sensory feedback. While movement can be separated into even more categories, understanding the neural pathways of these three types can be beneficial to uncover core concepts of human neurophysiology, and even pave the way for treating movement disabilities. With that said, let’s take a deep dive into the circuitry and principles of reflex, rhythmic, and voluntary movement. Reflex movements Reflex movements are rapid, involuntary responses to stimuli that are commonly used to help us avoid danger or harm. An example includes touching a hot object and immediately jerking our hand away from it. The goal of this form of movement is to be as quick as possible in order to avoid injury. As such the neural pathway, known as a reflex arc, is simple and can take as few as three neurons. Firstly, sensory receptors detect a stimulus, such as heat, and send a signal up towards the central nervous system (CNS) through sensory neurons. Instead of going up to the brain for processing and movement planning, the sensory neuron connects with a relay neuron in the spinal cord, and then to motor neurons. This reduces the time taken to respond as it bypasses the brain’s processing circuitry. Motor neurons then carry a signal to relevant muscles to contract and move the body away from danger. Because the signal from the sensory receptors bypasses the brain, this movement is subconscious, meaning it happens without consciously deciding to move. This makes the movement rapid and stereotyped – the motion is predictable as there is minimal planning; just a need to move anywhere away from the stimulus. Central Pattern Generators (CPGs) CPGs are networks of neurons in the spinal cord that, when activated, produce rhythmic pattern-like movement such as walking or running. This type of movement is also subconscious as it does not require active focus to perform. However, unlike reflex movements, CPG output does not require sensory activation or feedback. Instead CPGs are activated by descending pathways from the medulla – a region of the brainstem that is responsible for performing involuntary movement. CPGs typically control movements that are necessary for survival such as breathing and heartbeats. The lack of need to consciously focus on these movements allows us to instead direct our attention to more complex situations, such as responding to stimuli or achieving a specific goal. This is where voluntary movements are required. Voluntary movements Any movement performed via conscious decision-making requires activity from a range of areas in the brain. To respond to our environment, we firstly need information on what is around us. This is largely handled by the frontal lobe which perceives our external environment through sensory input and attention. Human fMRI studies have highlighted increased activity in the frontal lobe as we switch our attention, thus perceiving different parts of our external environment. This information of our environment is sent to the motor cortex which plans our next movement. Complex multi-limb movements may require additional processing from premotor and association areas. Once the movement has been planned, it then has to pass through the cerebellum, which refines specific parts of the movement, such as precise finger motion. After refinement, the movement signal is then sent to relevant muscles via motor neurons to carry out the intended movement. An example of a complex movement is reaching out and grabbing an object. This seemingly simple task requires coordinated movement of the hand, arm, shoulder, and torso to ensure we move our arm the right amount – not too far so that we go past the object, and not too near so that we do not reach it. This also requires great precision to grab the object with appropriate force, to gain a firm grip while ensuring we do not break the object. A lot of planning goes into rudimentary movements, and yet sometimes we can still get things wrong. For instance, suppose we couldn’t see the object too well so we end up going too far and missing it. This will be picked up by our sensory organs, giving our brain feedback on what we ended up doing. By comparing the actual movement with our intended movement, we can create an error signal of how far we missed and in what direction. This drives learning – by using our previous errors, we can refine our future movements to eventually achieve our intended goal. In this example, we may learn that we keep extending our arm too far, and so with repetitive trials we eventually move the right amount in order to grab the object, as we intended. The cerebellum is largely seen as responsible for motor learning, however the deep underlying mechanism is still being researched. When the same complex movement is performed again and again, it can be trained to become subconscious movements activated by spinal CPGs, gradually requiring less coordination from the motor cortex to perform. This is how common movements such as walking, go from being a strenuous task as a toddler to a simple ability requiring minimal focus as an adult. Conclusion Overall, we can see a general trend of movements requiring more parts of the CNS as they become more complex. Precise, unfamiliar movements requiring multiple limbs are the most complex, thus recruiting decision-making and motor coordination areas in order to perform. By repeating an action again and again, we can train ourselves to perform it with less and less input from higher brain regions, until it eventually becomes a subconscious coordinated act that can be performed on demand. Written by Ramim Rahman Related articles: Dopamine in the movement pathway / Mobility disorders REFERENCES Dickinson, P.S. (2006) ‘Neuromodulation of central pattern generators in invertebrates and vertebrates’, Current Opinion in Neurobiology , 16(6), pp. 604–614. doi:10.1016/j.conb.2006.10.007. Latash, M.L. (2020) Physics of biological action and perception . London, United Kingdom: Academic Press. Brent Cornell (no date) BioNinja . Available at: https://old ib.bioninja.com.au/options/option-a-neurobiology-and/a4-innate-and-learned-behav/reflex-arcs.html (Accessed: 11 February 2025). Berni, D.J. (2023) The motor system , Introduction to Biological Psychology . Available at: https://openpress.sussex.ac.uk/introductiontobiologicalpsychology/chapter/the-motor-system/ (Accessed: 11 February 2025). Rossi, A.F. et al. (2008) ‘The prefrontal cortex and the executive control of attention’, Experimental Brain Research , 192(3), pp. 489–497. doi:10.1007/s00221-008-1642 z. Project Gallery

How colonialism, interventionism and health are interwoven Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link How colonialism and geopolitics shape health injustices: a deep, critical reflection Last updated: 02/04/26, 18:29 Published: 16/10/25, 08:00 How colonialism, interventionism and health are interwoven This is the final article (article no. 7) in a series about global health injustices. Previous article: Addressing the health landscape in Bangladesh's Rohingya community Introduction Welcome to the reflective article of the Global Health Injustices Series. Before I begin, I want to thank Jana Antar again for her contributions to the Lebanon and Syria article, and Dr Nasif Mahmood for his contributions to the Rohingya people in Bangladesh article. Writing and researching about these different countries was an incredible experience. Although I initially planned for this series to go beyond ten articles, focusing on the most enduring and neglected injustices was vital, particularly as the world is becoming more dynamic with geopolitical power shifts. With this in mind, I want to emphasise that each vulnerable population faces unique challenges, but they have challenges shared with others that are not mentioned in this series. I wanted to address these injustices because they are urgent and demonstrate how interconnected global struggles truly are. Through writing this last article, I deepened my understanding of how colonialism, interventionism, and health are interwoven. How the past impacts present reality (colonialism) The injustices we see in news headlines, social media, or the ones we directly experience should not be understood as isolated examples ( Table 1 ). Instead, they stem from European colonialism and later foreign interventionism, shaping how regional governments were created. The ongoing Gaza genocide and expanding illegal settlements pushing out Palestinians in the West Bank are due to Israel’s brutal military occupation and apartheid for 70+ years, and its acts, including the Nakba. Sudan had external rulers (notably Egypt and the British Empire) contributing to its civil wars through political destabilisation, among other factors. This similarly happened in Yemen, though it is also important to note that foreign intervention from the United States (US) and Saudi Arabian governments contributed to the country's existing crises. Lebanon and Syria were divided up and governed by Britain and France after the Ottoman Empire collapsed shortly after World War 1, a significant event leading to political destabilisation and ongoing catastrophes, which also happened to Palestine. In Kashmir, the people’s plight erupted through the British Empire partitioning the Indian subcontinent into multiple nations in 1947 (India, West Pakistan becoming Pakistan and East Pakistan becoming Bangladesh), with Kashmir being a disputed territory between Pakistan and India. As for the Rohingya population and Bangladesh, civil wars during the 20th century and ensuing persecution by the government of Myanmar have contributed to their crises. Therefore, it is clear that all of these events I summarised showcase how their root causes lead to the substantial effects of the current daily injustices. Moreover, what connects these substantial injustices and many others worldwide traces back to the consequences of European colonialism; these powers dispossessed indigenous peoples of their lands and resources through violence, subsequently broken treaties, or legal frameworks that did not identify Indigenous land tenure systems. While they did disrupt indigenous governments, some recent injustices prevail because post-colonial elites embraced or exacerbated these exploitative systems. This severed deep cultural, spiritual, and economic ties that indigenous communities had with their land. For example, Canada’s colonial legacy, notably its Indian Residential Schools, involved forcibly removing children from their families, leading to negative outcomes for the Indigenous communities. Moreover, it is vital to acknowledge the impact of settler colonialism on Indigenous communities globally across South America, Africa, Asia and the Aboriginal people of Australia and New Zealand. If we do not critically think and learn about these past events, how will we improve our present reality and build a future for everyone? Table 1: Summary of the historical and modern perpetrators of injustices affecting the countries/communities explored in the Global Health Injustices Series Country/ community explored in the Global Health Injustices Series Main perpetrator(s) of their injustices Palestine Israel + foreign military aid from the US, UK + other countries Sudan RSF + other local political factions with foreign military aid from the UAE + other countries Yemen Houthis + other local political factions + foreign Interventionism from Saudi Arabia + US + foreign military aid Lebanon Local political factions + US, UK + other countries Syria Local political factions + US, UK + other countries Kashmir Indian + Pakistani militaries + foreign military aid Rohinyga Government of Myanmar + foreign military aid Bangladesh UK via the partition of Subcontinental India (1947), contributing to later injustices Current major health problems Health is essential in global injustices because it is a mirror and a driver of the disparities among various populations. Accessing quality healthcare is usually affected by factors, such as race and ethnicity, which accentuate deep-rooted inequalities. For example, communities with lower incomes encounter challenges, ranging from a lack of healthcare infrastructure to environmental hazards, leading to worse health outcomes. Therefore, tackling them is essential for achieving justice, as improved health outcomes can empower marginalised groups. Aside from warfare being a major determinant of health and injustice, I want to highlight migration as a significant co-occurring determinant. Although research is expanding, the bidirectional relationship between migration and health remains inadequately incorporated into practice and laws. Migration is a complicated and heterogeneous multiphase process ( Figure 1 ). Meanwhile, collecting migration data remains difficult due to polarised political views, unwillingness to finance research on discriminatory laws, varying migration definitions, and limited comparable global data. Unfortunately, political rhetoric and media depictions form incorrect assumptions, stereotypes, and negative views of migrants and refugees, leading to a weakened understanding of the severity and positive aspects of migration. Also, this manifests into hatred and scapegoating of migrants and refugees through their “perceived” impact on countries like employment and healthcare. In reality, accessing employment and healthcare is very difficult for them, leading to negative health outcomes. Thinking more broadly, health behaviours are not solely individual choices, but are deeply rooted in and affected by social, cultural, and political environments. For example, when looking at politics and health through a framework ( Figure 2 ), it is clear how politics is influential through labour markets and welfare states, leading to socioeconomic, income and wealth inequalities and poor health. One systematic review found that a generous welfare state is typically associated with positive population health outcomes, with the Nordic model as an example. This suggests that political leaders are vital in affecting agendas, encouraging intersectoral partnerships, and showing political will to promote health equity. Another review supported the benefits of a generous welfare state through maternal and child health outcomes. Therefore, health and politics are intertwined, as addressed in previous articles through specific contexts. Now I will discuss it more broadly. Current major geopolitical problems Geopolitical dynamics are crucial to shaping the lives of vulnerable populations by influencing their access to security, resources, and fundamental human rights; this is impacted by governments, policies, geographies, and the relationships and interests between countries. In countries or regions plagued by continuous conflict or authoritarian governments, these communities often find themselves at greater risk of challenges like displacement, violence, and systemic discrimination. Moreover, the complicated relationship between global and local power systems results in specific communities being neglected, as more powerful geopolitical interests repeatedly overshadow their needs. To truly support these communities, it is vital to consider how foreign interventionism from countries like the US and the UK impacts the Palestinians, Sudanese, Lebanese, Syrian, Yemeni, Kashmiri, and the Rohingya populations. Foreign interventionism, which typically occurs through militarism, is characterised as the international and social relations of training for and executing organised political violence; this is a pervasive feature of geopolitics, rising into civilian domains by shaping countries and regions. Then, humanitarianism is typically seen as an unbiased moral discourse centred on universal humanity and aid. Yet, it is historically linked to militarism, particularly in Western countries and has deepened in recent decades. Humanitarian standards, like International Humanitarian Law (IHL), are supposed to limit wars’ consequences, but IHL may implicitly tolerate particular levels of ‘collateral damage’ as allowable. IHL is embedded in a hierarchy that determines who can be saved and who cannot, possibly causing inequalities and unstable power relations tied to imperial dynamics. Hence, I see Western humanitarianism as deeply entangled with militarism because of how it can serve to justify and expand political violence across diverse countries and regions, as seen in modern news headlines. More importantly, this dynamic drives a vicious cycle of violence, where armed conflicts cause vulnerability by destroying infrastructure, destabilising nations and other negative consequences, like climate change and rising extremism, leading to civil wars and genocide. Moving forward To truly move forward, adopting a multifaceted approach (e.g. decolonising global health) to addressing all the injustices and health disparities is vital; this can work, but I think that should involve giving all the most vulnerable communities their autonomy, liberation and fundamental human rights. There is the notion of peace plans coming from Western governments like the US, yet that cannot start without putting those directly experiencing war, genocide, displacement, ethnic cleansing and other atrocities as the central voice in those conversations. Moreover, we should highlight those most accountable for making amends. For example, they should allow a right to return and a payment of extensive reparations to the displaced Palestinians, Sudanese, Lebanese, Syrian, Yemeni, Kashmiri, and the Rohingya populations to their homelands, among numerous others. The big question is whether these suggestions will become tangible realities. Although reparations and the right to return may seem distant from contemporary political realities, they are moral imperatives for real justice to occur. Continuously raising awareness and rallying support for affected communities so they can tackle their needs and challenges is important. There is also advocacy, which is vital in showcasing the issues they encounter, which can pave the way for significant policy changes. Moreover, the participation of local and international non-governmental organisations (NGOs), like Amnesty International, is crucial for enforcing ongoing solutions, as they better grasp the vulnerable communities’ needs. When these efforts are done collaboratively, fostering a more supportive environment for those needing it most is vital. Unfortunately, NGOs cannot replace genuine international political will because their impact will always be limited without structural change. Importantly, recognising how interconnected everyone is as a global community is crucial. Engaging in different cultures and experiences should foster empathy and build a collective strength to face challenges, notably climate change and warfare driven by the weapons industry. Uniting and sharing knowledge can encourage real change and all countries actually following international law, which requires powerful countries to be held responsible in ways that have been avoided so far; this should involve acknowledging that the vulnerable communities have a right to resist and defend themselves against their oppressors. Conclusion The global health injustices seen today have historical roots in European colonialism, which has stripped indigenous global communities of their homelands and disrupted their cultural connections. Furthermore, they are influenced by many factors. Moreover, health behaviours are influenced by the broader social, cultural, and political landscapes. Geopolitical dynamics impact vulnerable populations by undermining their security, access to resources, and fundamental human rights; foreign interventionism via militarism makes them worse. Humanitarianism with militarism can reinforce cycles of violence by legitimising unequal power dynamics despite its good intentions. To effectively tackle the global health injustices, uplifting vulnerable communities by prioritising their human rights is vital. The perpetrators should pay reparations and grant the right of return to the most impacted. As individuals, we must raise awareness and push for policy changes. Local and international organisations are pivotal in understanding and addressing community needs. With everything said, I enjoyed writing this series because it showed me how connected all these injustices are and how we can act, listen and reflect together. Ultimately, we must focus on all the countries and communities highlighted in this series, as well as others currently facing injustices like the Uyghurs in China and Afghanistan. We must open our eyes, hearts, souls, and minds to nurture global connections and share knowledge for impactful change. Written by Sam Jarada Related articles: How does physical health affect mental health? / Beyond medicine: health through different stances / Addressing Health Inequalities REFERENCES Banat BYI, Entrena-Durán F, Dayyeh J. Palestinian Refugee Youth: Reproduction of Collective Memory of the Nakba. Asian Social Science. 2018 Nov 29;14(12):147.2. Amiad Haran Diman, Miodownik D. Bloody Pasts and Current Politics: The Political Legacies of Violent Resettlement. Comparative Political Studies. 2023 Aug 13;57(9). Abubakar M, Yahaya TB. Secession and border disputes in Africa: The case of Sudan and South Sudan border. African Journal of Political Science and International Relations. 2021 Oct 31;15(4):131–8. Tamer Abd Elkreem, Jaspars S. Sudan’s catastrophe: the role of changing dynamics of food and power in the Gezira agricultural scheme. Disasters [Internet]. 2024 Oct 30 [cited 2025 Sep 18];49(1). Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC11603519/ eClinicalMedicine. Under the shade of world events: a never-ending crisis in Yemen. EClinicalMedicine [Internet]. 2023 Oct 1 [cited 2025 Sep 18];64:102302–2. Available from: https://www.thelancet.com/journals/eclinm/article/PIIS2589-5370(23)00479-0/fulltext Bordón J, Eyad Alrefai. Saudi Arabia’s Foreign aid: the Singularity of Yemen as a Case Study. Third World Quarterly. 2023 Jul 14;45:1–18. Osman O. Western Domination, Destructive Governance, and the Perpetual Development Crisis in the Arab Region. World review of political economy. 2024 Apr 15;15(1). Huber D, Woertz E. Resilience, conflict and areas of limited statehood in Iraq, Lebanon and Syria. Democratization. 2021 Jun 25;28(7):1–19. Gupta H. 1947 Partition of India and its lessons. Journal of Family Medicine and Primary Care [Internet]. 2024 Jul 26 [cited 2025 Sep 18];13(8):3471–2. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC11368293/ Jong K de, van, Ford N, Kamalini Lokuge, Fromm S, Galen R van, et al. Conflict in the Indian Kashmir Valley II: psychosocial impact. Conflict and Health [Internet]. 2008 Oct 14 [cited 2025 Sep 18];2(1). Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC257762/ Project Gallery

Knowing which species menstruate lets us pick suitable animal models Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Do other animals get periods? Last updated: 29/03/26, 16:48 Published: 26/06/25, 08:00 Knowing which species menstruate lets us pick suitable animal models Periods, formally called menstruation, happen to female mammals every menstrual cycle when an egg cell is not fertilised. Levels of the progesterone hormone decrease, causing the lining of the uterus to self-destruct and shed. This lining is called the endometrium and is flushed out of the body with blood during menstruation. Some primates, bats, the spiny mouse, and elephant shrews get periods ( Figure 1 ). Since these groups are distantly related, menstruation likely evolved multiple times independently. Knowing which species menstruate lets us pick animal models which best reflect the human female reproductive system. Why do we get periods? Despite being painful and inconvenient, menstruation must have some benefit; otherwise, natural selection would not favour it on multiple separate occasions. Hypotheses put forward to explain menstruation include clearing the uterus of pathogens and saving energy compared to maintaining an endometrium all the time. A 2012 paper argues that neither of these hypotheses are true and that menstruation is an unfortunate byproduct of the way pregnancy occurs in certain animals. A more recent article expands on this idea; menstruation was not selected for in isolation, rather it evolved as one small part of a complex reproductive system. In non-menstruating animals, an embryo induces morphological and biological changes in the uterus, so those changes do not happen if they are not pregnant. The uterus of a menstruating animal undergoes regular changes even without an embryo, and one of those changes is shedding the endometrium. However, there is no consensus on the benefits of menstruation. Non-human primates Old World monkeys, apes, and humans menstruate conspicuously. This could be because their endometria have spiral arteries, which dilate and weaken in response to hormones. Eventually, the weakened arteries break and release blood, which carries dead and detached endometrial tissue out of the body. While chimpanzee menstruation is visible to the naked eye, menstrual blood in orangutans and gorillas is detected with a chemical urine strip. Gorillas bleed for 3 days, while orangutans bleed for 1-4 days. Humans have the most obvious, and possibly the most prolonged, menstruation out of the Old World primates. (Aren’t we unlucky?). On the other hand, the very few New World monkey species which menstruate need a microscope to detect it. Pedro Mayor and colleagues sampled the endometria of various New World monkeys and viewed those samples under a microscope. They found that monkeys from the Aotus nancymaae and Sapajus macrocephalus species had weakened endometria with dilated blood vessels and blood clots ( Figure 2 ). Combined with other context clues from those endometrium samples, they concluded that those monkeys must be menstruating. Bats Microscopy also identified menstruation in some bat species. In a 2011 study, uterus sections from Carollia perspicillata bats showed the endometrium getting thinner over a few days with associated bleeding. Some sections had endometrial debris in the lumen of the uterus – but unlike in Old World primates and humans, this debris was reabsorbed by the body rather than released. Menstruating Molossus ater bats had blood and endometrial cells in their cervix under a microscope, while one individual was visibly bleeding in its vagina. In contrast, a colony of female Rousettus leschenaulti bats all had visible vaginal bleeding on the same day. On that day, two-thirds of their endometria were shed, and they had low progesterone levels – meaning those bats were menstruating. Bat menstruation differs from primates in at least two ways. Firstly, menstruation happens simultaneously with ovary development in Carollia perspicillata and before ovary development in primates. Secondly, some bat species only menstruate after an interrupted mating attempt – which scientists call coitus , and the public would call “pulling out”. Perhaps menstruation gives these bats a second chance at successful mating in that breeding season. Conclusion We rarely see other animals on their period because if the species does menstruate, they do not bleed as much as humans do. Evidence of menstruation in New World monkeys and bats usually came from microscopy, where the endometrium was seen to detach, and blood was seen in the uterine lumen. These monkeys and bats could be used as rudimentary animal models to study what happens in humans during a period. Written by Simran Patel Related article: Monkey see, monkey clone REFERENCES Catalini L, Fedder J. Characteristics of the endometrium in menstruating species: lessons learned from the animal kingdom. Biology of Reproduction [Internet]. 2020 May 26 [cited 2025 Jan 8];102(6):1160–9. Available from: https://doi.org/10.1093/biolre/ioaa029 Mayor P, Pereira W, Nacher V, Navarro M, Monteiro FOB, El Bizri HR, et al. Menstrual cycle in four New World primates: Poeppig’s woolly monkey (Lagothrix poeppigii), red uakari (Cacajao calvus), large-headed capuchin (Sapajus macrocephalus) and nocturnal monkey (Aotus nancymaae). Theriogenology [Internet]. 2019 Jan 1 [cited 2025 Jan 7];123:11–21. Available from: https://www.sciencedirect.com/science/article/pii/S0093691X18302796 Rasweiler IV JJ, Badwaik NK, Mechineni KV. Ovulation, Fertilization, and Early Embryonic Development in the Menstruating Fruit Bat, Carollia perspicillata. The Anatomical Record [Internet]. 2011 [cited 2025 Jan 8];294(3):506–19. Available from: https://onlinelibrary.wiley.com/doi/abs/10.1002/ar.21304 Graham C. Reproductive Biology of the Great Apes: Comparative and Biomedical Perspectives. Elsevier; 2012. 456 p. Rasweiler IV JJ. Spontaneous decidual reactions and menstruation in the black mastiff bat, Molossus ater. American Journal of Anatomy [Internet]. 1991 [cited 2025 Jan 8];191(1):1–22. Available from: https://onlinelibrary.wiley.com/doi/abs/10.1002/aja.1001910102 Martin RD. The evolution of human reproduction: A primatological perspective. American Journal of Physical Anthropology [Internet]. 2007 [cited 2025 Jan 8];134(S45):59–84. Available from: https://onlinelibrary.wiley.com/doi/abs/10.1002/ajpa.20734 Emera D, Romero R, Wagner G. The evolution of menstruation: A new model for genetic assimilation. BioEssays [Internet]. 2012 [cited 2025 Jan 8];34(1):26–35. Available from: https://onlinelibrary.wiley.com/doi/abs/10.1002/bies.201100099 Etxeberria, A. and Rodriguez-Muguruza, A. (2025) Reframing the significance of menstruation: evolutionary insights from an organismal-relational perspective. HPLS , 48(1), 2. Zhang X, Zhu C, Lin H, Yang Q, Ou Q, Li Y, et al. Wild Fulvous Fruit Bats (Rousettus leschenaulti) Exhibit Human-Like Menstrual Cycle1. Biology of Reproduction [Internet]. 2007 Aug 1 [cited 2025 Jan 8];77(2):358–64. Available from: https://doi.org/10.1095/biolreprod.106.058958 Project Gallery

Various people are needed to make a successful David Attenborough nature documentary Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Behind the scenes of a David Attenborough nature film Last updated: 25/05/26, 19:40 Published: 25/05/26, 19:29 Various people are needed to make a successful David Attenborough nature documentary Sir David Attenborough celebrated his 100th birthday on 8th May 2026 to much fanfare. He is the visionary and narrator of iconic BBC nature documentaries like the Planet Earth series (the first released in 2006, the sequel released in 2016, and the most recent instalment released in 2023, see Figure 1 ). Sir Attenborough’s landmark docuseries Life on Earth , released in 1979, showed the public natural beauty in a way no producer had done before. However, there are dozens of people around Sir Attenborough away from the spotlight, who carry out excruciating work to make his nature documentaries so engaging. In honour of the centenarian, the BBC released an interview with Sir Attenborough and the crew behind Life on Earth . This article explains what I learned from watching that interview, and how nature documentary filming has changed over the course of Sir Attenborough’s long, illustrious career. People behind the scenes Various people are needed to make a successful David Attenborough nature documentary. Before filming begins, there are producers responsible for planning travel, accommodation, meetings with local wildlife experts, and other logistics. Lawyers help secure filming permissions in each country, and health & safety experts help write risk assessments. Then there is the camera crew, managed by a film director. To precisely operate the heavy cameras, the crew need physical strength, dexterity, and concentration. After the camera crew returns from filming, the producers pick the best scenes and video editors stitch them together. In addition, a live orchestra is recorded playing bespoke music scores for each documentary, the audio from which is passed on to sound mixers. Depending on what needs to be filmed and where, other specialists may also be needed. For example, a camera was attached to a professional paraglider for filming a fast-flying golden eagle in the Planet Earth II documentary. As Sir Attenborough has got older, his role has shifted from presenting and directing on-site to script-writing and narrating from home, but the dedication and expertise of his team have stayed the same. Challenges of filming Everyone in a nature documentary crew faces many challenges throughout the filming process, but it is all worth it when the final documentary is released. Ensuring the wildlife are not disturbed by filming is crucial, so that they behave naturally and do not attack the crew. Behind-the-scenes footage from the Planet Earth III documentary shows the camera crew staying still, keeping a respectful distance, even putting on camouflage to discreetly film wildlife. Another challenge is the physical toll of filming in extreme habitats. In the Life on Earth interview celebrating his 100th birthday, Sir Attenborough said he did not know he was allergic to donkey fur until he had to ride one for the docuseries, and it flared up his skin exactly when he needed to be on camera. While filming Planet Earth III, the crew in Madagascar got sick from eating local food, and a producer in the Himalayas got mountain sickness from the low oxygen conditions. These health issues are made worse by the lack of medical care in some of the remote regions being filmed in. The mental challenges of wildlife filming are not to be underestimated – a cinematographer on Planet Earth II describes how difficult it was to watch an animal die because trying to save its life would risk the crew’s safety. It is also challenging to be away from loved ones for weeks, especially during holidays or important family events. Cinematographers need to be incredibly patient when filming wildlife. It could take weeks for the animals to feel comfortable enough in the presence of humans to behave naturally, or for unpredictable natural phenomena to occur, or to find a rare animal in the vast empty wilderness. Despite the patience and sacrifices, it may be that the crew does not get the footage they want in the time they have. If the country being filmed in is politically unstable, both the video footage and the crew could be at risk. In the Life on Earth interview, one of the producers recalls Saddam Hussein’s troops seizing the crew’s hotel in Iraq. Sir Attenborough describes in the same interview how the most famous moment of the documentary, where he gets close and personal with gorillas, was almost captured by armed soldiers in Rwanda. Issues with filming permits could also threaten a shoot’s success, such as if a rebel group controlling the filming area does not acknowledge permits issued by the official government. Since the filming equipment is expensive and possibly irreplaceable, it must be carefully protected. Extreme weather events and wildlife, even animals that are not being filmed, risk damaging the equipment. With all these challenges, everyone involved in a wildlife documentary needs to be resilient. How technology has evolved Nature documentaries have changed a massive amount since Life on Earth was filmed in the mid-1970s, during the advent of colour television, whereas now we can watch wildlife in 4K ultra-high definition, showing how cameras have evolved rapidly in the last 50 years. Cameras have also gotten smaller, like drones or remote camera traps, meaning parts of nature which people cannot reach can still be filmed ( Figure 2 ). Camera traps also help with discreet filming, as mentioned earlier, allowing us to get closer to wildlife than ever before. Assistant producers on Life on Earth explained in the Sir David Attenborough centenarian interview that they arranged logistics on physical paper since there were no e-mails, so it could take weeks to hear back from international colleagues. The producers also said the documentary was filmed when commercial aeroplanes were a new concept, so they could plan to film on opposite ends of the world faster than ever before. The COVID-19 pandemic helped the innovation of remote technology, making filming even faster than flying to the filming site. Local camera operators can now send footage to the UK for editing, or robot cameras can be controlled halfway across the world. Thus, while Life on Earth was the first documentary of its kind, new technology since its release has made nature documentaries more engaging. Conclusion Filming a David Attenborough nature documentary requires patience and tenacity from a wide range of skilled people, in the face of health-, safety-, and weather-related challenges. Using state-of-the-art camera equipment, the documentaries we have access to today have captured wildlife in a level of detail Sir Attenborough could not have dreamed of when he filmed Life on Earth in the 1970s. The next time you relax to the sound of Sir Attenborough’s voice, think of the years of blood, sweat, and tears it took to produce such a marvellous celebration of nature. Written by Simran Patel Project Gallery