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