Publishing in PLOS ONE, the team reports that the Hirota people, who lived on the southern Japanese island of Tanegashima around the 3rd century to 7th century CE, also partook in the practice. Moreover, the study found no significant differences in cranial modification between sexes, indicating that both males and females practiced intentional cranial modification.

Cranial modification is a form of body alteration where the head of a person is pressed or bound, usually at an early age, to permanently deform the skull. The practice predates written history, and researchers theorize that it was performed to signify group affiliation or demonstrate social status.

“One location in Japan that has long been associated with cranial deformation is the Hirota site on the Japanese island of Tanegashima, in Kagoshima Prefecture. This is a large-scale burial site of the Hirota people who lived there during the end of the Yayoi Period, around the 3rd century CE, to the Kofun Period, between the 5th and 7th century CE.” explains Noriko Seguchi of Kyushu University’s Faculty of Social and Cultural Studies who led the study. “This site was excavated from 1957 to 1959 and again from 2005 to 2006. From the initial excavation, we found remains with cranial deformations characterized by a short head and a flattened back of the skull, specifically the occipital bone and posterior parts of the parietal bones.”

However, while the site provided an ideal opportunity to study the phenomenon, it had remained unclear whether these cranial modifications had been intentional, or were simply the unintended result of other habits.

To conduct the study, the research group employed a hybrid approach, utilizing 2D images to analyze the shape of the skulls’ outline, as well as 3D scans of their surface. The group also compared crania data from other archeological sites in Japan, such as the Doigahama Yayoi people in Western Yamaguchi, and the Kyushu Island Jomon people, who were the hunter-gatherer predecessors to the Yayoi people. Along with visually assessing skull morphology, the team gathered all this data and statically analyzed the contours and shapes between the skulls.

“Our results revealed distinct cranial morphology and significant statistical variability between the Hirota individuals with the Kyushu Island Jomon and Doigahama Yayoi samples,” continues Seguchi. “The presence of a flattened back of the skull characterized by changes in the occipital bone, along with depressions in parts of the skull that connects the bones together, specifically the sagittal and lambdoidal sutures, strongly suggested intentional cranial modification.”

The motivations behind this practice remain unclear, but the researchers hypothesize that the Hirota people deformed their crania to preserve group identity and potentially facilitate long-distance trade of shellfish, as supported by archaeological evidence found at the site.

“Our findings significantly contribute to our understanding of the practice of intentional cranial modification in ancient societies,” concludes Seguchi. “We hope that further investigations in the region will offer additional insights into the social and cultural significance of this practice in East Asia and the world.”

The study exemplifies how variable the impacts of even the same tropical cyclone have been, driven differences in by demographic, economic, and social factors. Total excess deaths were particularly high in counties the largest proportion of minorities. Until now, there had been a critical knowledge gap about estimating post-cyclone excess deaths with a consistent methodology from a large-scale study covering the entire United States across multiple decades.

The researchers found that the single largest number of excess deaths was in Orleans Parish, LA, after Hurricane Katrina in 2005, with 719 excess deaths. followed by Harris County, TX, after Hurricane Rita in 2005 (309 excess deaths), Broward County, FL, after Hurricane Matthew in 2016 (185 excess deaths), and Nassau County, NY, after Hurricane Sandy in 2012 (178 excess deaths). Full results of the top-20 most impacted counties and associated year and hurricane can be found in the Table below.

The most estimated excess deaths in a single year were during 2005, with 2,163 estimated post-tropical cyclone excess deaths, with 1,491 from Hurricane Katrina in 2005. Where probabilities of excess deaths were high, 83 percent of post-hurricane-force and 70 percent of post-gale-to-violent-storm-force excess deaths occurred more recently (2004 — 2019); and 94 percent were in more socially vulnerable counties.

“In our study, excess death counts after tropical cyclones were higher more recently and for the most socially vulnerable,” said Robbie M. Parks, PhD, assistant professor of Environmental Health Sciences at Columbia Public Health, and first author. “This was likely in part due to lack of access to adequate short-term transportation, as well as inequitable access to financial resources, education, employment opportunities and timely warnings on tropical cyclone proximity, all of which are results of long-term institutional neglect.”

Knowledge of short-term excess deaths — i.e., the difference between the observed number of deaths in the immediate aftermath post-tropical cyclone and the number of deaths had a cyclone not occurred — is essential for understanding the public health burden of climate-related disasters and a key recommended measure for post-disaster mortality assessment, note the authors.

Following a tropical cyclone, deaths can result from several major causes, including deaths from injuries, infectious and parasitic diseases, cardiovascular diseases, neuropsychiatric conditions, and respiratory diseases. In earlier research published In JAMAand Nature Communications, Parks and colleagues detailed the kinds of causes and risks for death which increased after tropical cyclones.

Using death registration data across four decades and an ensemble of 16 Bayesian statistical models, the researchers estimated the number of excess deaths after tropical cyclones in all impacted areas in the United States including estimates by county, year, tropical cyclone name, and strength of tropical cyclone. Estimated excess deaths in the study were also compared to data from official sources and EM-DAT, the international disaster database.

“Trends of heightened activity and increased intensity of tropical cyclones in recent years indicate that tropical cyclone exposure is and will remain a public health concern,” noted Marianthi-Anna Kioumourtzoglou, ScD, associate professor of Environmental Health Sciences at Columbia Mailman, and senior author. ‘Future research may be able to study associations by smaller areal units — ZIP Codes, for example — as appropriate exposure and outcome data become available. “It is also essential to prepare for tropical cyclones by accounting for the social determinants of risk and vulnerability of exposed communities, since the most socially vulnerable bear the greatest burden of excess mortality.”

“Our work highlights how deaths are impacted by tropical cyclones, an understudied exposure in relation to public health, and one which will remain an important threat as the climate changes,” observed Parks. As a public health priority, future research should focus on understanding the biological and structural drivers of cyclone-related mortality, how to minimize the number of excess deaths related to tropical cyclones, and the impacts on the scale from years to decades.”

Co-authors are Vasilis Kontis, Ralf Toumi, and Majid Ezzati, Imperial College London; G. Brooke Anderson, Colorado State University; Jane W. Baldwin, University of California, Irvine, and Columbia Lamont-Doherty Earth Observatory; Goodarz Danaei and Francesca Dominici, T. H. Chan School of Public Health, Harvard.

The authors would be happy to work with data visualization teams to produce interactive articles.

Funding was provided by NIH grants K99 ES033742, R00 ES033742, R00 ES022631, R01 S030616, R01 ES028805, R01 ES028033, R01 MD012769, R01 AG066793, R01 ES029950, 5 R01 AG060232, RF1 AG071024, R21 ES028472, P30 ES009089, and P42 ES010349, and the Climate Change Solutions Fund.

The group, led by Associate Professor Jason Lee from the Human Potential Translational Research Programme at the Yong Loo Lin School of Medicine, National University of Singapore (NUS Medicine), identified and reviewed relevant research papers using keyword searches on databases such as PubMed and Google Scholar. These papers studied the associations and effects of medications on thermoregulation. The review findings were presented in a topical manner, focusing on medication classes used to treat commonly diagnosed chronic conditions (e.g., diabetes, cardiovascular disease, neurodegenerative disease, and cancer). The findings were published in Pharmacological Reviews, titled Effects of Medications on Heat Loss Capacity in Chronic Disease Patients:

Health Implications Amidst Global Warming

The findings show that medications used to treat common chronic conditions, like blood thinners, blood pressure drugs, Parkinson’s disease/Alzheimer’s medications, and some chemotherapy drugs, can make it harder for the human body to handle hot weather by reducing its ability to sweat or increase blood flow to the skin.

Lead author and second-year PhD candidate from the Human Potential Translational Research Programme Mr Jericho Wee said, “Rising global temperatures caused by climate change pose a significant health concern for clinical patients reliant on long-term medications and healthcare. Increasingly, we will continue to see more elderly patients, many who have multiple health conditions and are taking different types of medication concurrently to manage their chronic diseases, compounding the risk of heat-related illness and dehydration. Understanding how each medication impacts thermoregulation, in the face of warmer environments, is the crucial first step to predicting the possible health outcomes when multiple medications are taken concurrently.” While previous reviews have highlighted the impacts of medications on heat, the scope of those reviews did not present the evidence in the context of the chronic diseases and ageing. The team’s narrative review presents the evidence in the context of high ambient temperatures and their impact on chronic disease sufferers who are on long-term and life-long medication.

Senior author Assoc Prof Jason Lee said, “This review emphasises the importance of studying the mechanisms of altered thermoregulation in individuals with diabetes and other cardiometabolic conditions to prevent heat-induced conditions. This is most relevant in Singapore and many other countries, where we have rapidly ageing populations and rising ambient temperatures. Pharmacological and thermal physiologists should focus transdisciplinary efforts on this area of research to refine and enhance safe medication prescription guidelines to preserve the health of people who need these medications, even in hot weather.”

Assoc Prof Melvin Leow, the review’s co-author and Senior Consultant Endocrinologist at Tan Tock Seng Hospital said, “Physicians are often unaware of the potential harms certain drugs may cause by compromising the body’s thermoregulatory control mechanisms. This is an especially important area to delve into as those with chronic diseases and older adults are susceptible to adverse health outcomes in the heat, due to their reduced thermoregulatory capacity. It is timely and prudent that scientists and doctors collaborate even closer in this important field that cuts across a wide range of medical disciplines.”

The study was supported by the National Research Foundation, Prime Minister’s Office, Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) Programme.

The findings, in brief:

Cancer

Patients on certain cancer medications have reported symptoms of hot flushes, such as inappropriate sweat responses and an increase in core temperature which affects quality of life. Exercise and improved fitness levels have been shown to reduce the frequency of hot flushes and improve thermoregulatory responses in other chronic conditions such as diabetes, and it remains a crucial component in maintaining the nervous and cardiovascular functions of cancer patients. However, bodily impairments and limitations caused by chemotherapy and medications may limit their ability to exercise, which perpetuates a cycle of loss in exercise capacity that is crucial to their recovery.

Cardiovascular disease

Patients who have cardiovascular diseases, such as coronary heart disease, stroke and heart failure, are more vulnerable to high heat exposure because their hearts will be working harder to deliver blood to the skin and working muscles to maintain core temperature at an optimal level whilst maintaining work output. Anti-platelet medications, such as aspirin and clopidogrel, are usually taken to prevent blood clots from forming in the blood vessels, that could lead to stroke or heart disease. Yet, these anti-platelet medications may increase core temperature, whether at rest or during exercise. These medications also reduce skin blood flow and suppress sweat responses, which means thermoregulatory responses would be less sensitive to accumulated heat, and delay in cooling itself down, which could lead to heat stroke.

Used for multiple cardiovascular conditions, such as ischemic heart disease, high blood pressure, and heart failure, beta-blockers can reduce skin blood flow during heat stress by reducing blood pressure and facilitating additional constriction of skin blood vessels. However, the findings of the effects of beta-blockers on sweat responses remain mixed, with some studies showing no changes in sweating, while others demonstrate reduced sweating. As such, greater research efforts are needed to understand how different types of beta-blockers may impact sweating.

Some studies have highlighted that the type of beta-blocker is an additional consideration. For example, non-selective beta-blockers like propranolol, widely prescribed at the population level, can result in greater impairments in thermoregulation than selective-beta-blockers that only target cardiac or peripheral tissues. Hence, non-selective beta-blockers could predispose patients to greater heat strain and heat-related illness.

Diabetes

Insulin, which is typically used to reduce high blood sugar, or hyperglycaemia, in patients with Type 1 diabetes, has been shown to impair the ability of the body to regulate heat properly. It also increases metabolic heat production at rest and during exercise, which can be fatal to the body when the accumulated heat cannot be dissipated quickly. For patients with Type 2 diabetes who consumed metformin to manage their condition, nearly 30% of patients experience diarrhoea and nausea when they are first prescribed the medication. If the fluid loss cannot be sufficiently replaced, patients, especially the elderly, are at a higher risk of dehydration, which may result in greater cardiovascular strain during exertional heat stress.

Neurocognitive diseases

Due to an internal imbalance in dopamine and acetylcholine levels, patients with neuropsychiatric diseases such as Parkinson’s and Alzheimer’s disease experience thermoregulatory dysfunction when their body is unable to control its temperature. However, the medications to manage these neurological conditions have been known to alter the brain’s control of thermoregulation and thermoregulatory responses, such as sweating and cutaneous vasodilation, which could result in both hyperthermia and hypothermia. Anticholinergics and cholinesterase inhibitors are prescribed to improve motor and cognitive symptoms in the brain for Parkinson’s Disease patients. However, these agents also alter the dopamine and acetylcholine levels, likely inducing changes in the central thermoregulatory drive that affects the central processing and integration of thermal information and numbs the instinctive responses to heat stress, while driving up the body’s core temperature. This could lead to an increased risk of developing heat-related illnesses.

Dopamine replacement agents and dopamine agonists are usually prescribed to those with Parkinson’s disease to increase dopamine levels to help in movement and coordination. While highly effective, these agents have been observed to significantly influence thermoregulation and impair sweat responses which are crucial for heat dissipation. It is important that the dosage of these agents is appropriately adjusted to minimise the onset of severe after-effects.