The relevance of ancient dna to contemporary disease

Abstract

Disease prevalence and human health has been significantly impacted through time by cultural, environmental, and dietary changes. While we now know that the human microbiome significantly contributes to modern ‘Western’ diseases, including obesity, diabetes, and arthritis, we have yet to understand how historic events and factors influenced the formation of the modern human microbiome. Calcified dental plaque (calculus) provides a unique and powerful opportunity to examine ancient human oral microbiomes and investigate how these bacterial communities, and their associations to disease, have changed through time. We have used ancient DNA sequencing of ancient dental calculus to identify significant changes in the oral microbiome associated with major cultural and dietary revolutions, such as the onset of farming (Neolithic Revolution) and the Industrial Revolution, identifying how large shifts in the oral microbiome have impacted modern disease prevalence and severity. The modern human mouth appears to be in a chronic ‘diseased state’, not previously observed in human history. The incidence of several oral pathogens such as Streptococcus mutans , the causative agent of dental carries, has significantly increased through time. Together, ancient DNA studies from a variety of time periods and geographic locations around the world indicate that major dietary and cultural changes, such as the addition of carbohydrates or processed foods to our diets, have drastically altered our microbiomes and therefore directly impacted our health.