Christina Warinner: Tracking ancient diseases using ... plaque

45,003 views ・ 2012-04-20

TED


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00:15
Have you ever wondered
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what is inside your dental plaque?
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Probably not, but people like me do.
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I'm an archeological geneticist
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at the Center for Evolutionary Medicine
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at the University of Zurich,
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and I study the origins and evolution of human health and disease
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by conducting genetic research
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on the skeletal and mummified remains of ancient humans.
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And through this work, I hope to better understand
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the evolutionary vulnerabilities of our bodies,
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so that we can improve
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and better manage our health in the future.
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There are different ways to approach evolutionary medicine,
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and one way is to extract human DNA
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from ancient bones.
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And from these extracts,
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we can reconstruct the human genome at different points in time
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and look for changes that might be related to adaptations,
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risk factors and inherited diseases.
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But this is only one half of the story.
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The most important health challenges today
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are not caused by simple mutations in our genome,
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but rather result from a complex and dynamic interplay
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between genetic variation,
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diet, microbes and parasites
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and our immune response.
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All of these diseases
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have a strong evolutionary component
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that directly relates to the fact
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that we live today in a very different environment
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than the ones in which our bodies evolved.
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And in order to understand these diseases,
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we need to move past studies of the human genome alone
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and towards a more holistic approach
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to human health in the past.
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But there are a lot of challenges for this.
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And first of all, what do we even study?
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Skeletons are ubiquitous; they're found all over the place.
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But of course, all of the soft tissue has decomposed,
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and the skeleton itself
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has limited health information.
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Mummies are a great source of information,
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except that they're really geographically limited
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and limited in time as well.
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Coprolites are fossilized human feces,
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and they're actually extremely interesting.
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You can learn a lot about ancient diet and intestinal disease,
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but they are very rare.
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(Laughter)
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So to address this problem,
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I put together a team of international researchers
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in Switzerland, Denmark and the U.K.
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to study a very poorly studied, little known material
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that's found on people everywhere.
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It's a type of fossilized dental plaque
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that is called officially dental calculus.
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Many of you may know it by the term tartar.
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It's what the dentist cleans off your teeth
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every time that you go in for a visit.
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And in a typical dentistry visit,
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you may have about 15 to 30 milligrams removed.
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But in ancient times before tooth brushing,
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up to 600 milligrams might have built up on the teeth
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over a lifetime.
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And what's really important about dental calculus
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is that it fossilizes just like the rest of the skeleton,
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it's abundant in quantity before the present day
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and it's ubiquitous worldwide.
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We find it in every population around the world at all time periods
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going back tens of thousands of years.
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And we even find it in neanderthals and animals.
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And so previous studies
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had only focused on microscopy.
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They'd looked at dental calculus under a microscope,
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and what they had found was things like pollen
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and plant starches,
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and they'd found muscle cells from animal meats
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and bacteria.
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And so what my team of researchers, what we wanted to do,
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is say, can we apply
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genetic and proteomic technology
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to go after DNA and proteins,
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and from this can we get better taxonomic resolution
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to really understand what's going on?
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And what we found
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is that we can find many commensal and pathogenic bacteria
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that inhabited the nasal passages and mouth.
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We also have found immune proteins
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related to infection and inflammation
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and proteins and DNA related to diet.
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But what was surprising to us, and also quite exciting,
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is we also found bacteria
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that normally inhabit upper respiratory systems.
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So it gives us virtual access to the lungs,
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which is where many important diseases reside.
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And we also found bacteria
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that normally inhabit the gut.
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And so we can also now virtually gain access
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to this even more distant organ system
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that, from the skeleton alone,
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has long decomposed.
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And so by applying ancient DNA sequencing
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and protein mass spectrometry technologies
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to ancient dental calculus,
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we can generate immense quantities of data
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that then we can use to begin to reconstruct a detailed picture
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of the dynamic interplay
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between diet, infection and immunity
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thousands of years ago.
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So what started out as an idea,
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is now being implemented
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to churn out millions of sequences
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that we can use to investigate
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the long-term evolutionary history of human health and disease,
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right down to the genetic code of individual pathogens.
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And from this information
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we can learn about how pathogens evolve
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and also why they continue to make us sick.
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And I hope I have convinced you
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of the value of dental calculus.
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And as a final parting thought,
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on behalf of future archeologists,
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I would like to ask you to please think twice
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before you go home and brush your teeth.
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(Applause)
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Thank you.
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05:23
(Applause)
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