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Noncommunicable diseases (NCDs) made up seven of the top ten causes of death in 2019, and account for 44% of all global deaths. Often thought of as modern diseases, we have little insight into what extent they were prevalent in ancestral human populations. In fact, the vast majority of NCD’s leave no distinctive traces on the skeleton. Here, Abigail Ganz, examines how microbial DNA could revolutionize our understanding of ancient human health. 

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Please tell us a little about yourself and your field of research   

The question of how researchers can use ancient human oral microbiomes to provide insights into human health and disease patterns is one that I have been pursuing for the last four years. Most recently, as an anthropology graduate student at the Pennsylvania State University (PSU), I use ancient human skeletons and the microbial communities that once lived within a person – their microbiome – to understand how human behaviors, health patterns, and environments have changed over the last 3,000 years.  

What inspired you to perform this review?  

The oral microbiome plays a critical role in human health, yet the application of cutting-edge ancient DNA (aDNA) approaches to the reconstructions of past human microbiomes is a relatively new and rapidly expanding discipline. Moreover, ancient human microbiome research has untapped potential to inform scientists about ancient human health and disease patterns, and how those relate to the present.   

 How will this review inform future research in the field? 

In this Review, my research team outlines the theoretical mechanisms that explore how diseases experienced by past individuals might be caused by, or linked to, the oral microbiome. Additionally, we outline the steps that researchers need to take to create a viable approach to studying these processes in the past. If we can discover the origins of chronic diseases using biomolecular research, we may be able to better predict future health outcomes and design improved prevention and treatment therapies. 

Why is it important to better understand frailty and non-communicable diseases?  

Non-communicable diseases are long lasting chronic diseases resulting from a combination of genetic, physiological, environmental, and behavioural factors. 

Typically caused by unhealthy behaviours, NCDs are the leading cause of death worldwide and present a huge threat to health and development. Some common NCD’s include: 

• Alzheimer’s 
• Heart attack 
• Stroke 
• Diabetes 
• Coronary artery disease 

What surprised me most when I first began to study biological anthropology was just how little we know about past human health and disease. While archaeologists can identify some diseases in the archaeological record, this is really limited to conditions that physically impact the skeleton, which are typically infectious diseases (e.g., leprosy, syphilis, tuberculosis). Even if an ancient individual had one of these diseases, the chances that an archaeologist would be able to identify it is low since the individual would have had to survive that condition long enough for skeletal manifestations to emerge. If an individual was very sick and died very quickly, their skeleton could appear completely healthy.  What’s more, by better understanding NCDs in ancient humans we’ll gain critical insights into how evolutionary and environmental factors have resulted in current manifestations of these conditions. 

Moreover, we know very little about these diseases in the past, as these conditions do not generally have specific microbial agents or skeletal lesions, so it is nearly impossible to diagnose them in ancient individuals. Being able to study them, even if indirectly, using microbial communities in past populations would be a major breakthrough.   

How could this approach improve our understanding of ancient human health? 

The potential benefits of pursuing this novel approach are numerous and include the ability to: 

• Better understand why certain individuals were more or less vulnerable to disease and death in the past.  
• Potentially quantify noncommunicable disease risk in ancient populations in a novel way. 
• Determine how the modern human microbiome came to be over time, especially in the context of modern diseases.  

How could this information reduce health gaps? 

All human groups have unique population histories, relationships with their environments, and practices or behaviors that can impact their health in significant ways. Ancient oral microbiomes have the capacity to not only identify and characterize past health and disease patterns in different groups, but to provide insights into the specific mechanisms that caused these trends.  

Why did you choose to focus on cardiovascular disease, diabetes, Alzheimer’s disease, and rheumatoid arthritis?  

In our review, we chose to focus on these conditions for two key reasons. These conditions have the richest oral microbiome literature and impact large segments of modern society. 

How could this information help inform treatments for the above morbidities?  

That is an excellent question! The ultimate goal of my research, and that of the rest of my lab, is to understand past health to improve the health of modern people. One of the ways that my research group seeks to achieve this is by developing oral microbiome transplants in conjunction with the University of Adelaide. If certain oral microbiomes or oral microbes are indeed associated with poor health then we need to know how to construct oral microbiomes to improve health and prevent disease. 

Additionally, this research could uncover whether the relationship between the oral microbiome and health is the same today as it was in the past. Due to drastically different environments, drugs, and diets, people living in modern societies have different oral microbiomes than people living hundreds or thousands of years ago. Understanding whether those microbiomes resulted in more or less morbidity and mortality risks would be immensely valuable when considering future treatments. 

What are the next steps for you and your research?  

I am currently in the process of testing and establishing whether the oral microbiome can be used as a tool for uncovering ancient frailty and non-communicable diseases. In collaboration with colleagues and curators, I am working on individuals from Medieval and Post-Medieval Britain that have very detailed skeletal health data and oral microbiome data. Our current results are promising, and we are looking forward to the publication of our first set of research findings within the next twelve months. 

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Read the full Review today on F1000Research or explore our Genomics and Genetics Gateway to discover a plethora of cutting-edge open research.