Reconstructing Our Ancient Microbial Self

The advent of high throughput metagenomic sequencing has revealed a startling fact - that our bodies are not merely ourselves. Microorganisms comprise 90% of our cells, contain 99% of our genes, and perform vital functions in digestion, immunity, and homeostasis. And while we have made great strides in revealing the diversity, variation, and evolution of the human genome, we know surprisingly little about the microbial portion of ourselves, our microbiome. Recently it has been discovered that dental calculus (calcified dental plaque) entraps a rich biomolecular record of the oral microbiome that preserves for thousands of years. Metagenomic and metaproteomic analyses of ancient dental calculus have revealed a wide range of commensal and pathogenic bacterial taxa, bacteriophages, human and dietary biomolecules, and an abundance of DNA “dark matter” from unknown and uncharacterized organisms. Recovering ancient organisms from this metagenomic soup is a difficult task, but advances in sequencing technologies and bioinformatics tools are making this goal increasingly feasible. This talk discusses the successful applications, methodological challenges, and future possibilities of using dental calculus to reconstruct our ancient microbial self.