Studying ancient human oral microbiomes could yield insights into the evolutionary history of noncommunicable diseases

Abstract

Noncommunicable diseases (NCDs) have played a critical role in shaping human evolution and societies. Despite the exceptional impact of NCDs economically and socially, little is known about the prevalence or impact of these diseases in the past as most do not leave distinguishing features on the human skeleton and are not directly associated with unique pathogens. The inability to identify NCDs in antiquity precludes researchers from investigating how changes in diet, lifestyle, and environments modulate NCD risks in specific populations and from linking evolutionary processes to modern health patterns and disparities. In this review, we highlight how recent advances in ancient DNA (aDNA) sequencing and analytical methodologies may now make it possible to reconstruct NCD-related oral microbiome traits in past populations, thereby providing the first proxies for ancient NCD risk. First, we review the direct and indirect associations between modern oral microbiomes and NCDs, specifically cardiovascular disease, diabetes mellitus, rheumatoid arthritis, and Alzheimer's disease. We then discuss how oral microbiome features associated with NCDs in modern populations may be used to identify previously unstudied sources of morbidity and mortality differences in ancient groups. Finally, we conclude with an outline of the challenges and limitations of employing this approach, as well as how they might be circumvented. While significant experimental work is needed to verify that ancient oral microbiome markers are indeed associated with quantifiable health and survivorship outcomes, this new approach is a promising path forward for evolutionary health research.

A Journey into the Evolution of Human Host-Oral Microbiome Relationship through Ancient Dental Calculus: A Scoping Review

“…Calculus samples before and after the introduction of tobacco showed highly similar species profiles [34]. The most abundant bacterial taxa detected in many historical calculus samples included several commensal bacterial species commonly found in the human oral cavity, such as Streptococcus sanguinis, Streptococcus cristatus, and Lautropia mirabilis [7,37].…”

“…In healthy adults, the majority of species belong to the bacterial phyla Firmicutes, Proteobacteria, Actinobacteria, Bacteroidetes and Fusobacteria [33]. Since environmental and lifestyle factors influence oral health and disease, ancient dental calculus provides an opportunity to understand the relationship between microbial patterns and oral health and disease in key transition periods in our history [34]. In order to answer the research question "what scientific findings on oral health and diseases can be found from human oral microbiome data collected on ancient dental calculus samples?…”

Neuroinflammation in Alzheimer’s Disease: A Potential Role of Nose-Picking in Pathogen Entry via the Olfactory System?

“…In addition to periodontal pathogens, the altered composition of the oral microbiota has also been reported in participants with AD in several studies. For instance, a higher abundance of Moraxella, Leptotrichia, Sphaerochaeta, Lactobacillales, Streptococcaceae, Firmicutes/Bacteroidetes, and a significant reduction of Rothia and Fusobacterium was observed in the oral microbiota of AD participants [165][166][167]. Interestingly, similar to P. gingivalis, other Gram-negative bacteria-Moraxella, Leptotrichia, and Sphaerochaetafound in the oral cavity were linked to Aβ plaque formation through the production of LPS in the brains of AD patients [166,168].…”

Ancient human dental calculus metadata collection and sampling strategies: Recommendations for best practices

“…For example, accurate age estimation techniques may provide key information into how the oral microbiome changes during lifespans in archeological populations (Gancz & Weyrich, 2023). However, such analyses become infeasible if information regarding the age estimation techniques is not specified (Bailey & Vidoli, 2023;Clark et al, 2020;Milner & Boldsen, 2012).…”

“…In addition to these microscopic and biomolecular investigations, dental calculus has been utilized by bioarchaeological researchers as a marker of frailty and disease (DeWitte & Bekvalac, 2010;Yaussy & DeWitte, 2019). Recently, researchers have even attempted to combine these macroscale analyses with metagenomic approaches to provide more detailed insights into the health of ancient populations (Gancz et al, 2023;Gancz & Weyrich, 2023).…”