Carbon Dating Spectrometer
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Scientists now say their key tool for dating ancient artifacts
might be wrong by 10,000 years, which could push back the
timing of key events in history and improve our understanding
of climate change and ancient civilizations.
Their study could force to rethink the dates when events
occurred, especially the period when modern humans lived
alongside Neanderthals in Europe. It suggests that modern
humans might have lived in Europe far longer than thought
and that prehistoric paintings recently found in the Chauvet
cave, in southern France, might be 38,000 years old rather
than the estimated 33,000 years.
A research team made up of English and American scientists
found large variations in levels of the carbon-14 isotope,
which is used as the basis of carbon dating, preserved in a 19
inch stalagmite recovered from a submerged cave in the Blue
Holes of the Bahamas. These are limestone caverns that were
created when sea levels were nearly 330 feet lower than
they are today.
These findings suggested dramatic changes in the amount of
radioactive carbon in Earth’s atmosphere during the last Ice
Age, probably as a result of changes in the strength of the
planet’s magnetic field. The field shields Earth from the
cosmic rays that create carbon-14 in the atmosphere, and
this would have altered the levels of the isotope during the
past 45,000 years.
Dr. David Richards of the University of Bristol, who did the
study with colleagues in Arizona and Minnesota,
says, “Beyond about 20,000 years ago there are some
dramatic swings in radiocarbon concentration, which means
the age offset between the radiocarbon age and true
calendar age can be up to 8,000 years.” This means that
radiocarbon dating, which depends on the steady decay of
carbon-14, is less reliable if an artifact is older than 16,000
years.
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