WEBVTT

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Between 2008 and 2012,

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archeologists excavated the rubble
of an ancient hospital in England.

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In the process, they uncovered
a number of skeletons.

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One in particular belonged 
to a wealthy male

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who lived in the 11th or 12th century

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and died of leprosy between 
the ages of 18 and 25.

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How do we know all this?

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Simply by examining some old,
soil-caked bones?

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Even centuries after death,

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skeletons carry unique features
that tell us about their identities.

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And using modern tools and techniques,
we can read those features as clues.

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This is a branch of science known as
biological anthropology.

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It allows researchers to piece together 
details about ancient individuals

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and identify historical events
that affected whole populations.

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When researchers uncover a skeleton,

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some of the first clues they gather,
like age and gender,

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lie in its morphology,

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which is the structure, appearance,
and size of a skeleton.

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Bones, like the clavicle, 
stop growing at age 25,

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so a skeleton with a clavicle
that hasn't fully formed

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must be younger than that.

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Similarly, the plates in the cranium
can continue fusing up to age 40,

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and sometimes beyond.

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By combining these with some 
microscopic skeletal clues,

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physical anthropologists can estimate
an approximate age of death.

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Meanwhile, pelvic bones reveal gender.

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Biologically, female pelvises are wider,
allowing women to give birth,

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where as males are narrower.

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Bones also betray the signs 
of ancient disease.

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Disorders like anemia leave their traces
on the bones.

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And the condition of teeth 
can reveal clues

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to factors like diet and malnutrition,

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which sometimes correlate with wealth
or poverty.

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A protein called collagen can give us
even more profound details.

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The air we breathe,

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water we drink,

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and food we eat

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leaves permanent traces 
in our bones and teeth

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in the form of chemical compounds.

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These compounds contain measurable
quantities called isotopes.

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Stable isotopes in bone collagen
and tooth enamel varies among mammals

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dependent on where they lived
and what they ate.

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So by analyzing these isotopes,

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we can draw direct inferences regarding 
the diet and location of historic people.

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Not only that, but during life,

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bones undergo a constant cycle
of remodeling.

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So if someone moves from one place
to another,

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bones synthesized after that move

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will also reflect the new isotopic 
signatures of the surrounding environment.

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That means that skeletons can be used
like migratory maps.

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For instance, between 1-650 AD,

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the great city of Teotihuacan in Mexico
bustled with thousands of people.

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Researchers examined the isotope ratios
in skeletons' tooth enamel,

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which held details of their diets
when they were young.

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They found evidence for significant
migration into the city.

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A majority of the individuals
were born elsewhere.

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With further geological 
and skeletal analysis,

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they may be able to map where
those people came from.

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That work in Teotihuacan is also
an example of how bio-anthropologists

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study skeletons in cemeteries 
and mass graves,

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then analyze their similarities 
and differences.

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From that information, they can learn
about cultural beliefs,

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social norms,

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wars,

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and what caused their deaths.

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Today, we use these tools to answer
big questions about how forces,

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like migration and disease,

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shape the modern world.

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DNA analysis is even possible in some
relatively well-preserved ancient remains.

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That's helping us understand how diseases
like tuberculosis

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have evolved over the centuries

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so we can build better treatments
for people today.

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Ancient skeletons can tell us a
surprisingly great deal about the past.

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So if your remains are someday 
buried intact,

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what might archeologists 
of the distant future learn from them?