1947: Radiocarbon dating - The book of science

Radiocarbon dating
Calibration
Dating Ötzi
Commentary

Radiocarbon dating

The half-life of carbon-14
is about 5,730 years.
All living things
gather carbon-14
in known proportion
to carbon-12; therefore,
Willard Libby proposed
that the proportion of carbons
left in archeological artifacts
can determine their ages.
He used this idea
to date wood from the tombs
of two Egyptian kings,
Zoser and Sneferu,
finding these to be older
than scholars had thought
by nearly two thousand years.

Calibration

The proportion of carbon-14
has varied over time
because of climate change,
glaciation, volcanic activity,
variations in earth’s magnetic field,
human activities, and other factors,
so it was necessary
to correlate the results of radiocarbon dating
with the dates of artifacts
that could be independently established.
Overlapping tree rings
can be independently dated
by counting the rings
so this became the calibration
standard for the first
eleven thousand years
before the present,
and this range was extended
using deep ocean sediment cores,
lake sediment varves, coral samples,
and speleothems.

Dating Ötzi

Ötzi the Iceman, Europe’s
oldest natural human mummy,
is known to have lived
about 3,300 BCE
according to radiocarbon dating.
He died of an arrow to his shoulder
and a blow to his head,
fell into a glacier,
was discovered when it melted.
Today his body is grotesquely
on view at South Tyrol Museum
of Archaeology.

Radiocarbon dating has established that the Haraldskær woman, found in a peat bog in Jutland, Denmark, died around 490 B.C. The Kennewick man, found on a bank of the Columbia River, died before 7,300 B.C. The Eve of Naharon, found in an underwater cave near Tulum, Mexico, died about 11,600 B.C. This is not the kind of immortality that I hope to achieve.