evidence that the population ate a diverse
diet that included plants as well as meat.
Hearing about the work, Warinner
wondered if looking at specimens from a
medieval German cemetery might yield
similar insights. But when she checked for
food remains under the microscope, masses
of perfectly preserved bacteria blocked her
from doing so. “They were literally in your
way, obscuring your view,” she recalls. The
samples were teeming with microbial and
human genes, preserved and protected by
a hard mineral matrix.
Warinner had discovered a way to see the
tiny organisms in the archaeological record,
and with them, a means to study diet. “I real-
ized this was a really rich source of bacterial
DNA no one had thought of before,” Warinner
says. “It’s a time capsule that gives us access
to information about an individual’s life that
is very hard to get from other places.”
The dental calculus research dovetailed
with rising interest in the microbiome,
rocketing Warinner to a coveted position
at Max Planck. (In 2019, Harvard hired her
as an anthropology professor, and she now
splits her time between Cambridge, Massa-
chusetts, and Jena, overseeing labs on two
continents.) Her TED talks have racked
up more than 2 million views. “I never ex-
pected to have an entire career based on
something people spend lots of time and
money trying to get rid of,” she quips.
That grimy dental buildup, Warinner has
learned, preserves more than just DNA.
In 2014, she published a study in which
she and her colleagues looked at the teeth
of Norse Greenlanders, seeking insight
into why Vikings abandoned their settle-
ments there after just a few hundred years.
She found milk proteins suspended in the
plaque of the area’s earliest settlers—and
almost none in that of people buried five
centuries later. “We had a marker to trace
dairy consumption,” Warinner says.
This discovery led Warinner to turn to
one of the biggest puzzles in recent humanfor dairy is made possible by a mastery of bacteria
3,000 years or more in the making. By scraping gunk
off the teeth of steppe dwellers who died thousands
of years ago, she’s been able to prove that milk has
held a prominent place in the Mongolian diet for
millennia. Understanding the differences between
traditional microbiomes like theirs and those prev-
alent in the industrialized world could help explain
the illnesses that accompany modern lifestyles—
and perhaps be the beginning of a different, more
beneficial approach to diet and health.Nowadays, Warinner does
her detective work at
the Max Planck Institute
for the Science of Hu-
man History’s ancient
DNA lab, situated on the
second floor of a high-rise
bioscience facility over-
looking the historic center of the medieval town
of Jena, Germany. To prevent any errant DNA
from contaminating its samples, entering the lab
involves a half-hour protocol, including disinfec-
tion of foreign objects, and putting on head-to-toe
Tyvek jumpsuits, surgical face masks, and eye
shields. Inside, postdocs and technicians wielding
drills and picks harvest fragments of dental plaque
from the teeth of people who died long ago. It’s here
that many of Warinner’s Mongolian specimens get
cataloged, analyzed, and archived.
Her path to the lab began in 2010, when she was a
postdoctoral researcher in Switzerland. Warinner
was looking for ways to find evidence of infectious
disease on centuries-old skeletons. She started with
dental caries, or cavities—spots where bacteria
had burrowed into the tooth enamel. To get a good
look, she spent a lot of time clearing away plaque:
mineral deposits scientists call “ calculus,” and that,
in the absence of modern dentistry, accumulate on
teeth in an unsightly brown mass.
Around the same time, Amanda Henry, now a
researcher at the University of Leiden in the Nether-
lands, put calculus scraped from Neanderthal teeth
under the microscope and spotted starch grains
trapped in the mineral layers. The results providedPOPSCI.COM
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