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  • Have you ever wondered

  • what is inside your dental plaque?

  • Probably not, but people like me do.

  • I'm an archeological geneticist

  • at the Center for Evolutionary Medicine

  • at the University of Zurich,

  • and I study the origins and evolution of human health and disease

  • by conducting genetic research

  • on the skeletal and mummified remains of ancient humans.

  • And through this work, I hope to better understand

  • the evolutionary vulnerabilities of our bodies,

  • so that we can improve

  • and better manage our health in the future.

  • There are different ways to approach evolutionary medicine,

  • and one way is to extract human DNA

  • from ancient bones.

  • And from these extracts,

  • we can reconstruct the human genome at different points in time

  • and look for changes that might be related to adaptations,

  • risk factors and inherited diseases.

  • But this is only one half of the story.

  • The most important health challenges today

  • are not caused by simple mutations in our genome,

  • but rather result from a complex and dynamic interplay

  • between genetic variation,

  • diet, microbes and parasites

  • and our immune response.

  • All of these diseases

  • have a strong evolutionary component

  • that directly relates to the fact

  • that we live today in a very different environment

  • than the ones in which our bodies evolved.

  • And in order to understand these diseases,

  • we need to move past studies of the human genome alone

  • and towards a more holistic approach

  • to human health in the past.

  • But there are a lot of challenges for this.

  • And first of all, what do we even study?

  • Skeletons are ubiquitous; they're found all over the place.

  • But of course, all of the soft tissue has decomposed,

  • and the skeleton itself

  • has limited health information.

  • Mummies are a great source of information,

  • except that they're really geographically limited

  • and limited in time as well.

  • Coprolites are fossilized human feces,

  • and they're actually extremely interesting.

  • You can learn a lot about ancient diet and intestinal disease,

  • but they are very rare.

  • (Laughter)

  • So to address this problem,

  • I put together a team of international researchers

  • in Switzerland, Denmark and the U.K.

  • to study a very poorly studied, little known material

  • that's found on people everywhere.

  • It's a type of fossilized dental plaque

  • that is called officially dental calculus.

  • Many of you may know it by the term tartar.

  • It's what the dentist cleans off your teeth

  • every time that you go in for a visit.

  • And in a typical dentistry visit,

  • you may have about 15 to 30 milligrams removed.

  • But in ancient times before tooth brushing,

  • up to 600 milligrams might have built up on the teeth

  • over a lifetime.

  • And what's really important about dental calculus

  • is that it fossilizes just like the rest of the skeleton,

  • it's abundant in quantity before the present day

  • and it's ubiquitous worldwide.

  • We find it in every population around the world at all time periods

  • going back tens of thousands of years.

  • And we even find it in neanderthals and animals.

  • And so previous studies

  • had only focused on microscopy.

  • They'd looked at dental calculus under a microscope,

  • and what they had found was things like pollen

  • and plant starches,

  • and they'd found muscle cells from animal meats

  • and bacteria.

  • And so what my team of researchers, what we wanted to do,

  • is say, can we apply

  • genetic and proteomic technology

  • to go after DNA and proteins,

  • and from this can we get better taxonomic resolution

  • to really understand what's going on?

  • And what we found

  • is that we can find many commensal and pathogenic bacteria

  • that inhabited the nasal passages and mouth.

  • We also have found immune proteins

  • related to infection and inflammation

  • and proteins and DNA related to diet.

  • But what was surprising to us, and also quite exciting,

  • is we also found bacteria

  • that normally inhabit upper respiratory systems.

  • So it gives us virtual access to the lungs,

  • which is where many important diseases reside.

  • And we also found bacteria

  • that normally inhabit the gut.

  • And so we can also now virtually gain access

  • to this even more distant organ system

  • that, from the skeleton alone,

  • has long decomposed.

  • And so by applying ancient DNA sequencing

  • and protein mass spectrometry technologies

  • to ancient dental calculus,

  • we can generate immense quantities of data

  • that then we can use to begin to reconstruct a detailed picture

  • of the dynamic interplay

  • between diet, infection and immunity

  • thousands of years ago.

  • So what started out as an idea,

  • is now being implemented

  • to churn out millions of sequences

  • that we can use to investigate

  • the long-term evolutionary history of human health and disease,

  • right down to the genetic code of individual pathogens.

  • And from this information

  • we can learn about how pathogens evolve

  • and also why they continue to make us sick.

  • And I hope I have convinced you

  • of the value of dental calculus.

  • And as a final parting thought,

  • on behalf of future archeologists,

  • I would like to ask you to please think twice

  • before you go home and brush your teeth.

  • (Applause)

  • Thank you.

  • (Applause)

Have you ever wondered

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