LONDON — You can learn a lot from a tooth.
Molars taken from skeletons unearthed by work on a new London
railway line are revealing secrets of the medieval Black Death —
and of its victims.
This week, Don Walker, an osteologist with the Museum of London,
outlined the biography of one man whose ancient bones were found by
construction workers under London's Charterhouse Square: He was
breast-fed as a baby, moved to London from another part of England,
had bad tooth decay in childhood, grew up to work as a laborer, and
died in early adulthood from the bubonic plague that ravaged Europe
in the 14th century.
The poor man's life was nasty, brutish and short, but his afterlife
is long and illuminating.
"It's fantastic we can look in such detail at an individual who
died 600 years ago," Walker said. "It's incredible, really."
The 25 skeletons were uncovered last year during work on Crossrail,
a new rail line that's boring 13 miles (21 kilometers) of tunnels
under the heart of the city. Archaeologists immediately suspected
the bones came from a cemetery for plague victims. The location,
outside the walls of the medieval city, chimes with historical
accounts. The square, once home to a monastery, is one of the few
spots in the city to stay undisturbed for centuries.
To test their theory, scientists took one tooth from each of 12
skeletons, then extracted DNA from the teeth. They announced Sunday
that tests had found the presence of the plague bacterium, Yersinia
pestis, in several of the teeth, meaning the individuals had been
exposed to — and likely died from — the Black Death.
The findings didn't stop there. Archaeologists, historians,
microbiologists and physicists worked together to apply techniques
from several scientific disciplines to the discovery.
Radiocarbon dating and analysis of pottery shards helped determine
when the burials took place. Forensic geophysics — more commonly
used in murder and war-crimes investigations — helped locate more
graves under the square. Studying oxygen and strontium isotopes in
the bones revealed details of diet and health.
These were, by and large, poor people. Many of the skeletons showed
signs of malnutrition consistent with the "Great Famine" that
struck Europe 30 years before the Black Death. Many had back
injuries suggesting lives of hard labor. One man became a
vegetarian late in life, indicating he may have entered an order of
monks.
Archaeologists were surprised to discover that the skeletons lay in
layers and appeared to come from three different periods: the
original Black Death epidemic in 1348-1350, and later outbreaks in
1361 and the early 15th century.
"It suggests that the burial ground was used again and again for
the burial of plague victims," said Jay Carver, Crossrail's lead
archaeologist.
The Black Death is thought to have killed at least 75 million
people, including more than half of Britain's population, yet the
burials suggest a surprisingly high degree of social order — at
first. As the plague ravaged continental Europe — borne westward by
fleas on rats — city fathers leased land for an emergency burial
ground. The burials were simple but orderly, the bodies wrapped in
shrouds and laid out in neat rows, sealed with a layer of clay.
The later skeletons, however, show more signs of upper-body
injuries, consistent with a period of lawlessness and social
breakdown.
Archaeologists are planning a new dig this summer to learn how many
bodies lie under the square. Carver says the number appears to be
in the "low thousands."
And the teeth may not have yielded all their secrets. Experts in
ancient DNA at McMaster University in Canada are working to
sequence the plague genome found in the teeth, in order to learn
more about a disease that still infects several thousand people a
year around the world. Most patients recover if treated early with
antibiotics.
Scientists want to know if the 14th-century disease is the same as
the modern version, or whether the disease has evolved. Study of
DNA from the teeth of skeletons discovered in the 1980s at another
London plague cemetery suggested the bug was largely unchanged, but
the scientific jury is still out.
Brendan Wren, a professor of molecular biology at the London School
of Hygiene and Tropical Medicine, said the new information could
help scientists "understand how the plague bacillus — and other
nasty bugs — become so virulent to humans."
"It is useful information that could warn and avert potential
epidemics and pandemics," he said.
In this Wednesday, March 26, 2014 photo, Don Walker, a human
osteologist with the Museum of London, holds the scull of one of
the skeletons found by construction workers under central
London's
In this Wednesday, March 26, 2014 photo, members of the media film
one of the skeletons found by construction workers under central
London's Charterhouse Square. Twenty-five skeletons were
uncovered
In this Wednesday, March 26, 2014 photo, one of the skeletons found
by construction workers under central London's Charterhouse Square
is pictured. Twenty-five skeletons were uncovered last
year
