Tracking ancient diseases using ... plaque Christina Warinner
have you ever wondered what is inside
your dental plaque
probably not but people like me do I’m
an archaeological 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 are actually extremely
interesting you can learn a lot about
ancient diet and
no disease but they are very rare so to
to to address this problem I put
together a team of international
researchers in Switzerland Denmark and
the UK 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
though may know it by the term tartar
it’s what the dentist cleans off of your
teeth every time that you go in for a
visit and in a typical dentistry visit
you may have about fifteen to thirty
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 my Kostka
piece they 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 system 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 the gut and so we
can also now virtually gain access to
this even more distant organ system that
from the skeleton alone
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 but 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 it started out as an idea
is now being implemented to turn 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 that
I have convinced you of the value of
dental calculus and as a final parting
thought on behalf of future
archaeologists I would like to ask you
to please think twice before you go home
and brush your teeth