Page 128 - 1970S

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of a hunting people, called Solutreans,
in Europe. "Guesses as to when they
arrived vary widely. Peake and Fleure
think it was about 12,000 years ago,
while Zeuner puts them back to 67,000
years before our time. Radiocarbon
dates indicate only 18,000 years."
(Kenneth Macgowan and Joseph Hes–
ter, Early Man in the New W orld, New
York: Natural H istory Library Edition,
1962, p. 102.)
Why such confusion? The reason is
clear.
Archaeologists had no way to accu–
rately count actual years. Consequently,
no way initially existed to check the
dates radiocarbon gave in the pre–
historic period. Dr. Libby and h is asso–
ciates were faced with this problem
when they first devised the radiocarbon
me thod. They had expected a historical
check, through the use of historically
known dates, all the way to the l imits
of the method. But they were in for a
shock.
Dr. Libby, writing in the January,
1956 issue of tbe American Scientist
recouoted briefly the history of radio–
carbon dating: "The first shock Dr.
Aroold and I had was that our advisors
informed us that history extended back
only 5000 years.
"We had thought initially that we
would be able to get samples all along
the curve back to 30,000 years, put the
points in, and then our work would be
finished.
"You read in books aod find state–
ments that such and such a society or
arcbaeological site is 20,000 years old.
"We learned rather abruptly that
these numbers, these ancient ages, are
not known; in fact, it is at about the
time of the first dynasty of Egypt that
the last historical date of aoy real cer–
tainty has been established. So we had,
in the initial stages, the opportunity
to check against knowns, principally
Egyptian artifacts, and in the second
stage we had to go into the great
wilderness of prehistory to see whether
there were elements of interna! con–
sistency which would lead one to
believe that the method was sound"
(Willard F. Libby, "Radiocarbon Dat-
The PLAIN TRUTII March, 1970
HOW CARBON-14 CRACKS
THE RIDDLE OF AGE
The carbon- 14 doting method is
bosed on an ingeniously simple
process.
Cosmic roys bombord the upper
otmosphere with tremendous en–
ergy. These roys produce greot
numbers of ropidly moving neutrons
which collide with nitrogen atoms
in the otmosphere. The bulk of
these otoms are chemicolly trons–
muted into corbon-14. Chemicolly,
a positive proton in the nucleus of
the nitrogen otom is knocked out
ond reploced by on unchorged
neutron.
The corbon-14 then diffuses
throughout the otmosphere. lt
mokes up o tiny froction of oll the
corbon dioxide ovoiloble to plonts
for photosynthesis. When the plonts
use carbon dioxide during photo–
synthesis, they automotically obsorb
this carbon-14. Plants are eaten by
animals and humans. These also
acquire corbon-14 in their tissues.
All living things become equally
"tagged" with carbon-14.
But at death, an organism no longer
takes in corbon-14. Meonwhile the
amount possessed by this organism
at death begins to decay. Every
5730 yeors one half of the carbon-
14 will decoy back into nitrogen-14.
In the next 5730 years, half of the
remaining corbon-14 will decoy.
Now, only one fourth of the original
omount is left.
This process continues until the
corbon-14 remaining connot be
meosured by current laboratory
equipment. The practico! range for
most laboratories is the measure–
ment of 35,000 radiocarbon
(carbon-14) years; isotopic enrich–
ment can stretch the measurement
to 70,000 rodiocarbon yeors.
The reason for the limits is the
ing," American Scientist, VoL 44, No.
1, January 1956, p. 107).
What About "Historical" Dates
Egyptian history begins around 5,000
years ago, according to the most liberal
estimates. Sorne historians believe that
Egyptian history does not extepd that
far into the past. The idea that the vari-
infinitesimally smoll number of
carbon-14 otoms to ordinory corbon
atoms. There is only one radioactive
corbon-14 otom to every trillion
otoms of ordinory corbon. The
obundance of corbon-14 otoms in
modern wood is this tiny percent–
age: 0.000000000107%.
lf carbon-14 yeors equol calendar
yeors, it would moke every organ–
ism a living dock thot reveals
elopsed time since deoth . Any
organic material - flesh, bone,
peat, dung, charcoal, nuts, bees–
wax - thus would reveal its actual
age.
All one would hove to do is measure
the faint pulses of this disintegrating
corbon-14. Once the amount of
radiocorbon left ot any point was
determined, it could be meosured
oga inst a calibrated scole bosed
on the corbon- 14 content of
modern corbon.
l f the ratio of carbon-14 to ordinory
corbon found in, soy, wood today
is the sorne as for wood whi ch lived
thousonds of yeors ogo, then the
doting method is simple. The pres–
ent becomes o "key to the post."
Corbon-14 yeors equal calendar
yeors. But if for sorne reoson the
ratio of carbon- 14 to ordinary
carbon wos different in the post,
then there would be no woy to
determine the calendar oge of the
specimen. For example, if a sample
meosured ot 20,000 radiocarbon
years, had only 'Al of the present
strength of corbon-14, it would
be only 5000 yeors old!
lncreasing evidence indicotes that
there are grave problems in the
crucial corbon-14 to ordinary car–
bon ratio in the prehistoric post.
However, for ot leost the lost three
thousond yeors, the method is
remorkobly accurote.
ous Egyptian dynasties existed one after
another in time has been c¡uestioned not
only by scholars in antiquity, but even
today.
This factor alone would have a great
bearing on the radiocarbon method of
dating. Without KNOWN historical
dates to gauge an object to be dated,
one could not know for certain that the