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TED2012

Christina Warinner: Tracking ancient diseases using ... plaque

February 27, 2012

Imagine what we could learn about diseases by studying the history of human disease, from ancient hominids to the present. But how? TED Fellow Christina Warinner is an achaeological geneticist, and she's found a spectacular new tool -- the microbial DNA in fossilized dental plaque.

Christina Warinner - Archaeological geneticist
Christina Warinner is a researcher at the University of Zurich, where she studies how humans have co-evolved with environments, diets and disease. Full bio

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Double-click the English subtitles below to play the video.
Have you ever wondered
00:15
what is inside your dental plaque?
00:17
Probably not, but people like me do.
00:20
I'm an archeological geneticist
00:22
at the Center for Evolutionary Medicine
00:24
at the University of Zurich,
00:26
and I study the origins and evolution of human health and disease
00:28
by conducting genetic research
00:31
on the skeletal and mummified remains of ancient humans.
00:33
And through this work, I hope to better understand
00:36
the evolutionary vulnerabilities of our bodies,
00:39
so that we can improve
00:41
and better manage our health in the future.
00:44
There are different ways to approach evolutionary medicine,
00:46
and one way is to extract human DNA
00:49
from ancient bones.
00:51
And from these extracts,
00:53
we can reconstruct the human genome at different points in time
00:55
and look for changes that might be related to adaptations,
00:58
risk factors and inherited diseases.
01:01
But this is only one half of the story.
01:04
The most important health challenges today
01:07
are not caused by simple mutations in our genome,
01:10
but rather result from a complex and dynamic interplay
01:13
between genetic variation,
01:16
diet, microbes and parasites
01:18
and our immune response.
01:20
All of these diseases
01:22
have a strong evolutionary component
01:24
that directly relates to the fact
01:26
that we live today in a very different environment
01:28
than the ones in which our bodies evolved.
01:30
And in order to understand these diseases,
01:33
we need to move past studies of the human genome alone
01:35
and towards a more holistic approach
01:38
to human health in the past.
01:40
But there are a lot of challenges for this.
01:42
And first of all, what do we even study?
01:44
Skeletons are ubiquitous; they're found all over the place.
01:47
But of course, all of the soft tissue has decomposed,
01:50
and the skeleton itself
01:53
has limited health information.
01:55
Mummies are a great source of information,
01:57
except that they're really geographically limited
01:59
and limited in time as well.
02:02
Coprolites are fossilized human feces,
02:04
and they're actually extremely interesting.
02:07
You can learn a lot about ancient diet and intestinal disease,
02:09
but they are very rare.
02:12
(Laughter)
02:14
So to address this problem,
02:17
I put together a team of international researchers
02:19
in Switzerland, Denmark and the U.K.
02:21
to study a very poorly studied, little known material
02:23
that's found on people everywhere.
02:29
It's a type of fossilized dental plaque
02:31
that is called officially dental calculus.
02:34
Many of you may know it by the term tartar.
02:37
It's what the dentist cleans off your teeth
02:39
every time that you go in for a visit.
02:41
And in a typical dentistry visit,
02:43
you may have about 15 to 30 milligrams removed.
02:45
But in ancient times before tooth brushing,
02:48
up to 600 milligrams might have built up on the teeth
02:51
over a lifetime.
02:54
And what's really important about dental calculus
02:56
is that it fossilizes just like the rest of the skeleton,
02:59
it's abundant in quantity before the present day
03:02
and it's ubiquitous worldwide.
03:05
We find it in every population around the world at all time periods
03:07
going back tens of thousands of years.
03:10
And we even find it in neanderthals and animals.
03:12
And so previous studies
03:15
had only focused on microscopy.
03:17
They'd looked at dental calculus under a microscope,
03:19
and what they had found was things like pollen
03:21
and plant starches,
03:24
and they'd found muscle cells from animal meats
03:26
and bacteria.
03:28
And so what my team of researchers, what we wanted to do,
03:30
is say, can we apply
03:33
genetic and proteomic technology
03:35
to go after DNA and proteins,
03:37
and from this can we get better taxonomic resolution
03:39
to really understand what's going on?
03:42
And what we found
03:44
is that we can find many commensal and pathogenic bacteria
03:46
that inhabited the nasal passages and mouth.
03:48
We also have found immune proteins
03:51
related to infection and inflammation
03:54
and proteins and DNA related to diet.
03:57
But what was surprising to us, and also quite exciting,
04:00
is we also found bacteria
04:03
that normally inhabit upper respiratory systems.
04:05
So it gives us virtual access to the lungs,
04:07
which is where many important diseases reside.
04:10
And we also found bacteria
04:13
that normally inhabit the gut.
04:15
And so we can also now virtually gain access
04:17
to this even more distant organ system
04:20
that, from the skeleton alone,
04:22
has long decomposed.
04:24
And so by applying ancient DNA sequencing
04:26
and protein mass spectrometry technologies
04:28
to ancient dental calculus,
04:30
we can generate immense quantities of data
04:32
that then we can use to begin to reconstruct a detailed picture
04:35
of the dynamic interplay
04:38
between diet, infection and immunity
04:40
thousands of years ago.
04:42
So what started out as an idea,
04:44
is now being implemented
04:46
to churn out millions of sequences
04:48
that we can use to investigate
04:50
the long-term evolutionary history of human health and disease,
04:52
right down to the genetic code of individual pathogens.
04:55
And from this information
04:58
we can learn about how pathogens evolve
05:00
and also why they continue to make us sick.
05:02
And I hope I have convinced you
05:05
of the value of dental calculus.
05:07
And as a final parting thought,
05:09
on behalf of future archeologists,
05:11
I would like to ask you to please think twice
05:14
before you go home and brush your teeth.
05:17
(Applause)
05:19
Thank you.
05:21
(Applause)
05:23

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Christina Warinner - Archaeological geneticist
Christina Warinner is a researcher at the University of Zurich, where she studies how humans have co-evolved with environments, diets and disease.

Why you should listen

Tna analyzes DNA from the bones and teeth of ancient people to study human evolution in response to changes in infectious disease, diet and the environment over the last 10,000 years. Using samples from ancient skeletons and mummies, she investigates how and why lactase persistence, alcohol intolerance and HIv-resistance have evolved in different populations around the world. As an archaeogeneticist, she’s particularly interested in bridging the gap between archaeology, anthropology and the biomedical sciences.

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