From ONE Health to ONE Paleopathology: Deep-Time Perspectives on Health in the Face of Climate and Environmental Change

Definition

This entry explores the emergence of ONE Paleopathology as a holistic, interdisciplinary approach to understanding health through deep time. The entry discusses key areas where paleopathological research provides crucial insights: animals as sentinels of environmental health, the evolution and transmission of infectious diseases, the impacts of urbanization and pollution on human health, and the effects of climate change on disease patterns. Special attention is given to case studies involving malaria, tuberculosis, and environmental toxicity, demonstrating how past human–environment interactions inform current health strategies. The entry also emphasizes the importance of indigenous and local knowledge (ILK) systems in understanding and managing health challenges, highlighting how traditional ecological knowledge complements scientific approaches. By bridging past and present, ONE Paleopathology offers valuable perspectives for addressing modern health challenges in the context of accelerating environmental change, while promoting more equitable and sustainable approaches to global health.

1. Introduction

In The Western Medical Tradition, Vol 1, the Wellcome Institute for the History of Medicine traces the origins of “modern medicine” to developments that began in classical Greek civilization and through to the ascendancy of humans as the focus of anatomical science and medicine in late Medieval and early Modern universities of western Europe [1]. Human and veterinary medicine became formalized and completely distinct in the 19th century; however, for the duration of human evolution, human, animal, and environmental health were never distinct [2]. Famous progenitors of modern medicine like Galen, whose ancient wisdom was preserved by scholars in the Arab world in works like the Kitab al Baytara, used vivisection and dissection of animals to discover basic principles of anatomy and physiology [3,4]. Western medical science revisited its roots with the concept of ONE Medicine [5].

ONE Medicine was a concept that humans and animals are interdependent on one another, sharing anatomical and physiological aspects, relying on one another for sustenance, and strongly connected through shared ecosystems—and diseases [6]. ONE Health extended the concept of ONE Medicine to integrate all aspects of environmental science to optimize the health of humans, animals, and ecosystems [7]. More recently, these concepts have been further extended to planetary health, which embeds the well-being of all life and ecosystems within the planetary system and incorporates socioeconomic and equitable sustainability principles into medicine and public health [8]. While understanding the interconnectedness of all life on Earth is increasingly gaining traction in Western medicine and public health, the importance of this interconnectedness has long been recognized in ancient and modern indigenous and local knowledge (ILK) systems from around the globe [9,10,11]. Western medicine is pivoting to embrace knowledge systems and insights that were historically obscured by colonial histories and attitudes.

Human and animal health were intertwined early in the history of paleopathology but, like human and veterinary medicine, they diverged in the 20th century [12,13]. More recently, there has been a growing movement to invigorate a more comprehensive paleopathology—one that incorporates human, animal, environmental, and planetary health into a deep-time perspective that could be instrumental in addressing contemporary health challenges in the face of climate change [13,14,15,16,17,18,19,20,21,22,23]. This is largely driven by the recognition that the Anthropocene is the principal driver of prokaryotic and eukaryotic evolution, that the interconnectedness of life and Earth’s systems will shape health for the foreseeable future, and that discussions of public health are the greatest opportunity for inspiring the drastic and rapid changes in behavior needed to survive beyond the next century.

ONE Paleopathology is a holistic, interdisciplinary approach to environmental health from a deep-time perspective. It incorporates archaeological, paleoenvironmental, and paleopathological evidence to bear on contemporary public health and policy concerns: animals as sentinels, emerging and reemerging infectious diseases, antibiotic-resistant pathogens, respiratory pathogens and air quality, syndemics, migration and disease spillover, nutritional insufficiency, environmental toxicology, environmental migration, and interpersonal violence (Figure 1). Among policy and planning communities, there is growing interest in historical phenomena such as the Little Ice Age and the Medieval Warm Period, which affected health, patterns of disease, population dynamics, and had long-term impacts on human society. The past is becoming an attractive place to seek insights from completed experiments of human history as uncertainty and even panic arise about how extreme weather events, rising global temperatures, ecosystem alterations, and socio-cultural phenomena will intersect to shape the future of our planet.

2. ONE Paleopathology Approaches to Key Health Topics

2.1. Animals as Sentinels

Animals can act as biological indicators or “sentinels” for environmental and health conditions that affect past populations [17,20,23]. This historical perspective is particularly relevant for modern surveillance and public health strategies related to pathogen spillover. Paleopathologists and epidemiologists have often focused on the risks of zoonoses for human populations, particularly in the past 50 years as more than 300 new infectious diseases have emerged [24]. However, transmission has gone both ways in the past [25,26,27,28].

For example, the risk of brucellosis in human populations increased significantly with the Neolithic domestication of sheep and goats [14,17]. Fournié and colleagues developed models examining brucellosis transmission in early domestic goat populations and found that during a defined breeding season, when male goats are introduced to females, increased close contact can facilitate the transmission of brucellosis, as bacteria spread through reproductive fluids, urine, and other bodily secretions [17]. Infected does then transmit brucellosis to their offspring during gestation, through placental tissues and fluids, or at birth, which can expose other goats in the herd during the birthing process. Pregnancy and lactation can be stressful, and immune compromise can also enhance the potential for spread. Synchronized breeding thus creates concentrated periods for the risk of spread.

Bendrey and colleagues focus on how understanding historical patterns could inform modern veterinary practice [14,15]. Their research suggests several management practices that could limit disease spread: vaccinating goats before breeding seasons can reduce the incidence of the disease within herds; herders and farmers can be encouraged to control animal movement and limit contact between herds during high-risk periods, implement stringent hygiene protocols around birthing, use isolation practices and monitor the health of newly introduced animals. Public health officials should concentrate surveillance efforts on breeding periods and work with local and indigenous people to further refine our understanding of transmission dynamics and the sociocultural aspects of human–animal interactions [18].

Managing spillover risk is crucial for both conservation and human health. Tuberculosis serves as a notable example of global disease transfer that creates a severe threat to health and well-being today. The evolutionary origins of the Mycobacterium tuberculosis complex (MTBC) are traced to Africa, where this human disease spilled over into domestic and wild mammal species, including cattle, goats, voles, and pinnipeds [29,30,31]. Domesticated animals then offered a reservoir for the pathogen and a means for its migration into new human communities. In the case of pinnipeds, a pre-1000 CE ancestral form of the bacterium leaped from humans to pinnipeds in Africa and was then carried to South America, where humans using seals for food and for materials to make tools likely acquired the disease [32]. Tuberculosis is also a threat to global conservation efforts as spillover from human communities increasingly threatens great apes in Africa [33] and monkeys in the Americas [34].

A closely related member of the same genus, Mycobacterium leprae, evolved as an obligate human pathogen sometime in the Holocene, with the most recent common ancestor of all modern strains evolving in the Bronze Age, between 2500 and 1000 BCE [35,36,37,38]. This ties in with skeletal evidence of the disease in the cemeteries of one of the largest inter-connected urban civilizations at that time [39]. Demographic changes at the end of the Roman Empire (250 CE) brought the disease to Europe [37], where it eventually spilled over into red squirrel populations (Sciurus vulgaris) in the British Isles [28]. Another demographic expansion during European-led chattel slavery and settler colonialism (1600 CE) brought M. leprae to the Americas [37], where it again spilled over into populations of nine-banded armadillos (Dasypus novemcinctus), which still serve as a reservoir of the disease today [40].

Studies of ancient human and animal remains can trace how diseases, such as brucellosis, tuberculosis, and leprosy, spread between species over millennia. This deep-time analysis informs our understanding of zoonotic disease origins and pathways, vital for modern disease prevention. Research to understand disease transmission dynamics and zoonotic spread in the MTBC is an important avenue for considering how biocultural and historical phenomena shape divergent evolutionary pathways of human pathogens. These two closely linked diseases have vast differences in their transmissibility and virulence, their potential for innate immunity to develop in humans, and the possibility that they will become resistant to antibiotic treatment, among other distinctions. Despite the importance of reconstructing evolution, molecular biology, and migrations of these pathogens, there are significant barriers to this research. For example, M. leprae is very difficult to study in vitro and in vivo. Paleopathology is a critical part of the understanding of the evolution of MTBC.

2.2. Climate Change, Zoonoses, and ILK

Climate change has historically influenced the spread of infectious diseases [41,42], exemplified by recent interest in the Little Ice Age’s impact on the Black Death, a medieval global pandemic caused by Yersinia pestis [43], for example. Paleopathology offers insights into how climate and environmental changes coincide with sociocultural and historical factors to reshape disease ecology and what risk factors might put human communities at risk from a resurgence of vector-borne diseases.

Archaeologists identify ecological changes associated with zoonoses by examining the interplay between environmental transformations and pathogen dynamics through a multidisciplinary lens that integrates archaeological records, ecological data, and epidemiological insights [20,21]. This approach often involves analyzing historical land use changes, such as deforestation and urbanization, which can facilitate zoonotic disease transmission by creating new ecological niches and increasing contact between wildlife and human populations [44,45]. For instance, anthropogenic alterations to ecosystems can disrupt the natural balance of species, leading to increased pathogen prevalence in wildlife and heightened spillover risk to humans [46]. The archaeological record serves as a long-term archive of human–environment interactions, allowing researchers to trace the origins and impacts of these ecological changes over time [47].

The expansion of agricultural practices and urban development has altered habitats, leading to increased interactions between humans and vector species, some of which thrive in disturbed environments. One pertinent case study illustrating these dynamics is Chagas disease, caused by the parasite Trypanosoma cruzi, which is primarily transmitted through triatomine bugs. Research has shown that land use changes, particularly in regions like Mexico, have significantly influenced the ecology and evolution of the vector and the reservoir hosts, thereby increasing the risk of Chagas disease [48,49]. This happened 9000 years ago along the coast of Chile and Peru, where Chagas was transmitted orally among fisher-gatherer Chinchorro people until they settled down and began keeping domesticated animals (and triatomines) in their homes [50]. This case exemplifies how archaeological and ecological perspectives converge to elucidate the historical and ongoing processes in the emergence and maintenance of zoonotic diseases.

Extreme weather events also play a role in environmental health, as evidenced by archaeological records that document the impact of the El Niño-Southern Oscillation (ENSO) on ancient societies [51,52,53,54,55]. ENSO events affect resource availability, particularly in coastal regions where communities rely on marine resources. Variations in sea surface temperatures associated with ENSO can lead to changes in fish populations, which are critical for the diets of coastal populations. Archaeological evidence from the Peruvian coast indicates that periods of El Niño were correlated with both increased fish availability and subsequent population growth, while La Niña events impacted agricultural practices, leading to food shortages and health challenges due to malnutrition [52,53,56,57].

Moreover, extreme rainfall and flooding during El Niño years have been associated with increased interpersonal and ritual violence in Andean archaeological sites [54,55,58,59]. These findings underscore the interconnectedness of climate variability, resource availability, and human health, highlighting the need for a comprehensive understanding of how ENSO and extreme weather events have shaped the health outcomes of past populations. This knowledge can inform current public health initiatives to mitigate the effects of climate change and extreme weather on vulnerable communities today.

Malaria is also a critical focus of ONE Paleopathology because this disease has been a major source of mortality and disability for millennia and the impacts of global warming are already becoming apparent [60,61,62,63]. Through skeletal and ancient DNA evidence, paleopathology provides a deep-time perspective on how malaria affected ancient pathogen, vector, and human communities during environmental shifts, such as the early Holocene warming [64,65,66,67,68,69,70,71,72,73,74,75]. This field also reveals ancient human adaptations and their impact on natural selection in response to changing environmental conditions due to agriculture and deforestation, offering a framework to understand present and future public health challenges under global warming [76,77,78]. Finally, paleopathology and human evolutionary biology demonstrate how human–animal interactions influence the potential for spillover events that are already compromising eradication efforts [79,80,81,82].

The parasites responsible for malaria, Plasmodium spp., spilled over into human communities from infected non-human primates. Over time, zoonotic spillover—where pathogens jump from animals to humans—facilitated the pathogen’s adaptation to human hosts. This spillover likely intensified with increased human contact with malaria-carrying mosquitoes in altered landscapes, such as those resulting from early agricultural practices, deforestation, and settled communities, which provided ideal conditions for mosquito breeding [76]. Social determinants of health also play a very influential role in the impact of malarial parasites. Social forces—socioeconomic inequality, structural violence, capitalism, and colonialism—create conditions where parasites are more easily transmitted, and malaria and associated sequelae create more significant health impacts as there is differential access to basic resources for treatment and prevention. Exemplary of this are the epidemiological patterns of malaria in the Roman Empire [83,84], Late Antique and Medieval Europe [85,86], and Medieval England [74,87].

ONE Paleopathology and planetary health perspectives indicate that climate change will increasingly facilitate malaria transmission by expanding the habitats and lengthening the reproductive cycles of mosquito vectors [60,88]. Projections suggest that, under worst-case climate scenarios, an additional 76 million people in sub-Saharan Africa alone could face malaria risk by 2080 [62]. Climate models also predict that malaria vectors may expand into areas across North America, Europe, and Asia, introducing malaria risks back into populations without immunity or public health infrastructure [89]. Additionally, extreme weather events, such as El Niño cycles, which promote ideal conditions for mosquito breeding, are expected to increase the frequency and intensity of malaria outbreaks [63,90].

Indigenous and local communities will be critical in mitigating these risks in cases where traditional knowledge of local ecosystems and effective disease prevention methods have been preserved. Indigenous practices in malaria-prone regions include prevention strategies [91], using medicinal plants [92,93], zootherapeutics, and ILK about human–animal interactions that facilitate the spread of disease [91,94,95]. Collaborative public health programs could integrate ILK to create early-warning systems based on environmental indicators and offer culturally appropriate solutions for malaria control while enhancing community resilience [96]. Traditional medicine is a less expensive, more easily accessible option for the treatment of malaria in many areas, and it is culturally accepted as safe and effective [97,98,99]. Local and indigenous knowledge systems about the nature of a disease, its transmission, treatment, and relationship to environmental and climatological factors have been and will be critical for the future of infectious disease eradication, including malaria [96,100,101,102,103,104,105,106,107].

Globally, indigenous people (5% of the global population) are conserving and protecting biodiversity on around 25% of the world’s land mass [108]. Overall, these lands protected by indigenous stewards are in better health than surrounding areas [109,110]; yet indigenous peoples’ customary rights to the land they protect are rarely respected or codified and, in some cases, traditional livelihoods are criminalized, and indigenous people are displaced or forced into meager subsistence [111]. A focus on ILK could shift power dynamics to exert authority in prediction scenarios for the global North. Scientists who want to participate in these alternative systems must not simply extract information for their own purposes but also work to ensure that indigenous peoples’ rights, roles, and contributions are recognized [111].

2.3. Ancient Syndemics, Urbanism, and Pollution

Paleopathology sheds light on how ancient urban lifestyles, sanitation issues, and environmental pollution have influenced human health over time, revealing patterns that are increasingly relevant today [112]. In urbanized ancient societies, densely populated areas often had inadequate waste disposal and poor sanitation, leading to infectious disease spread, sinusitis, and respiratory issues due to indoor and outdoor pollution [112,113,114,115]. Biocultural phenomena—racism, poverty, institutionalization, and capitalism—also affect susceptibility to respiratory disease from infections [116,117,118]. By analyzing skeletal remains from ancient cities, paleopathologists uncover signs of chronic infection, degenerative diseases, and exposure to harmful environmental conditions that mirror modern health challenges related to urbanization and pollution [119].

Tuberculosis (TB) has been present in ancient populations dating back thousands of years [27,120,121] and paleopathological studies of TB reveal how urbanization, sanitation issues, and environmental pollution have historically created ideal conditions for the spread of the disease, much like they do today [122,123]. As human societies transitioned from small, nomadic groups to densely populated urban centers, TB and other respiratory diseases became more prevalent due to close living quarters, poor ventilation, and inadequate waste management, all of which facilitated airborne transmission of the bacteria [26].

Skeletal remains with characteristic lesions in the spine, ribs, and other bones provide crucial evidence of TB in ancient populations [121]. For example, paleopathologists have identified spinal deformities known as symptoms of Pott’s disease, caused by TB infection, in skeletal remains from ancient Egyptian civilization, where the urban environment and dense population would have fostered the spread of TB [124]. Studies of Roman societies and medieval European populations also show a high prevalence of TB in crowded city environments with poor sanitation [120,125]. These findings suggest that the rise of urbanism was closely tied to increased rates of TB, as people in cities had greater exposure to one another in settings lacking proper hygiene and healthcare resources.

Environmental pollution also played a role in TB’s prevalence in ancient populations, as air pollution from indoor fires, industrial processes, and crowded living spaces increased vulnerability to respiratory diseases in general [114,115]. In ancient urban areas, especially in societies where coal and wood were used for heating and cooking, air quality would have been poor, weakening immune defenses and exacerbating respiratory issues, including sinusitis and TB [112,113]. This insight from paleopathology connects past and present by highlighting how urban conditions, environmental pollution, and inadequate sanitation contribute to the persistence and spread of TB. Understanding these historical patterns helps public health professionals address the ongoing challenges posed by TB, especially in areas with high population density and limited access to clean air and sanitary living conditions.

Another significant area of paleopathological research involves identifying heavy metal toxicity in ancient populations, revealing the impact of soil and water contamination, occupational hazards, and biocultural practices that can jeopardize environmental health. For example, lead poisoning has been documented in ancient Roman populations through isotopic analysis of bones and teeth, reflecting widespread exposure from lead pipes and other infrastructure [126,127,128]. Similarly, Andean societies have suffered from high levels of arsenic and mercury poisoning related to the use of cinnabar (a mercury-based pigment) in burial practices and silver mining activities [129,130,131,132]. This is a particularly important topic in the Brazilian Amazon today, for example [133].

By examining how ancient populations were affected by toxic substances and environmental pollution, researchers can identify long-term patterns of toxicity and resilience in human biology. Ancient skeletal analyses, especially for heavy metals—lead, arsenic, and mercury—show how environmental contamination has long affected human health. Understanding these historical exposures helps us better assess and mitigate the health impacts of modern pollution and toxic exposures from poor working conditions [134,135,136,137]. This type of study is critical to assess the history of cancer [138,139] and insights from these investigations could inform modern public health initiatives to manage similar exposures today, particularly in urban areas where industrial pollution and legacy contaminants like lead remain health hazards.

Paleopathology thus bridges past and present, offering a long-term view of environmental health impacts that informs current risk assessments and interventions. For example, Whitley and Boyer [140] examined a high prevalence of skeletal lesions from cancer in an ancestral Puebloan population that lived in the Taos Valley of north-central New Mexico from 1050–1320 CE. The study’s findings of high radon levels in ancient dwellings provide insights into how environmental factors, such as naturally occurring ionizing radiation, could have contributed to health issues like cancer in ancient populations. This research highlights the importance of understanding historical health conditions and their causes, which can inform current public health policies and cancer prevention strategies. By controlling for many modern confounding factors, the study offers a unique perspective on the long-term health impacts of radon exposure, which remains a significant concern today.

3. Conclusions and Prospects

Identifying articles that directly cite paleopathological literature to inform diagnostics or treatment in modern clinical practice is challenging, as most of the impacts of paleopathological research are indirect. However, there are examples of paleopathology contributing insights that directly assist contemporary clinicians with diagnosing diseases based on skeletal lesions. For example, leprosy can be difficult to diagnose in 30% of patients due to the difficulty of culturing M. leprae in vitro or in vivo [141,142,143,144,145,146]. Paleopathology demonstrates the progression of untreated disease that resembles the severe deformities that result from delayed diagnosis today, providing an avenue for diagnostics using radiology [147,148,149,150]. It is also the case that paleopathology has contributed directly useful insights that led to advancements in treatment for inflammatory bowel disease and neuropsychiatric disorders using oral microbiome transplantation therapy, for example [151,152,153].

Paleopathology is perhaps better appreciated for its potential to enhance our understanding of the historical, social, biocultural, and evolutionary aspects of health and disease, which can indirectly influence contemporary medicine and public health, particularly concerning infectious diseases (c.f., [18,78,154,155,156,157,158]). There are challenges that paleopathology as a discipline will have to overcome to improve its contributions to ONE Health. The first key issue will be bridging the time gap, translating historical and ancient data to have modern relevance. For example, molecular methods have detected Y. pestis genomes in skeletons from skeletons of people who lived across Bronze Age Eurasia (2800–5000 years ago) [159]. These findings demonstrate that the Black Death has affected human populations for millennia and that genetic changes occurred at roughly similar periods as changes to the pathogen’s virulence. Leveraging paleopathological and archaeogenetics research could lead researchers and public health officials to a better understanding of the persistence of plague in Madagascar, for example [160]. In turn, this knowledge could guide targeted interventions, from rodent control to vaccine development, that will mitigate the impact of this disease. New interdisciplinary frameworks and computational models are required to compare epidemiological and ecological scenarios over time if these data are to be useful for applications and predictions about modern pandemics.

In keeping with the example of studying ancient diseases, ONE Paleopathology, being a historical and observational science, also has methodological barriers due to the nature of our samples [161]. Human skeletons and mummified tissues often become altered by the preservation environment and taphonomic processes that cause issues for anthroposcopic and molecular detection of ancient diseases. Investments in advanced molecular techniques and refining methods for studying degraded and fragmentary remains using new biotechnical tools will be essential for understanding disease progression, reconstructing pathogen transmission dynamics and co-evolution with humans [162].

Interdisciplinarity will be an important part of the future of this endeavor. Paleopathology intersects with archaeology, environmental science, anthropology, epidemiology, molecular biology, public health, and other disciplines. Coordinating these diverse fields requires overcoming silos and aligning our goals, methodologies, and funding priorities. International, interdisciplinary research consortia and funding mechanisms are necessary to develop shared, centralized, open databases and platforms for analysis to integrate our perspectives and findings across fields. This will require deep, authentic collaboration with indigenous and local communities and scholars to develop research questions and designs that can effectively create partnerships to address global challenges.

Working to address these challenges is worth doing as there are public health policy issues that our discipline is well-situated to address in the coming decades. The study of deep-time health impacts through ONE Paleopathology provides invaluable insights for addressing modern health challenges, including infectious disease management, environmental toxicity, climate resilience, and social equity in healthcare. Historical sciences, such as paleopathology, reveal ways in which ancient humans adapted to environmental stressors, offering a vital perspective on human resilience and vulnerability that informs contemporary health responses. This deep-time approach emphasizes that health is not isolated but shaped by interconnected human, animal, and environmental factors, reflecting the ONE Health concept of population health rooted in ecological balance.

ONE Paleopathology highlights the complex interplay between humans, animals, and their environments, which has shaped health outcomes throughout history. From zoonotic diseases to toxic exposures, ancient human remains provide a record of how populations responded to shared threats, underscoring the importance of ecological connectivity for building resilience. As climate change accelerates and new health threats emerge, understanding this long history of human adaptation equips us with strategies for addressing future challenges.

Paleopathology’s contribution to ONE Health lies in its ability to explore the diversity of human responses across different societies and environments. This broad, comparative approach uncovers variations in health practices and adaptations, enabling a fuller understanding of possible responses to current global challenges. Through integrating ancient insights with modern public health goals, ONE Paleopathology enriches our capacity to envision and implement equitable, effective solutions for a sustainable future.

There is a planetary health emergency with threats from global warming, mass extinction, antibiotic resistance, and environmental degradation. Global human communities are also facing increasing polarization, disinformation, mistrust of science, post-truth media consolidation, and a rising specter of synthetic biology and artificial intelligence. The scientific community must collaborate to provide knowledge to policymakers, communicate nuanced perspectives and uncertainties, and support evidence-based decision-making necessary to build an equitable, sustainable future for our planet.