Amino Acid Racemization as a Dating Method
Amino Acid Racemization as a Dating Method
David A. Plaisted
An article in the Dec 13, 1996 issue of Science, page 1842, discusses
dating based on the amino acid racemization technique. In proteins,
amino acids only come in the L (left?) form, but with time some
transform to the D (right) form. So, by examining how many have
shifted, one can estimate the age of the sample. Gould and Goodfriend
used this to date some snails. Now, my question is, what's the chance
that an amino acid will shift to the D form in say, one year. This
could easily be measured. I suppose it may depend on heat and
pressure, but this dependence can also be measured. Then one could
use this as an independent test on other dating schemes. I heard of a
case where ancient fossils were dated this way and turned out to be
tens of thousands of years old, rather than millions of years old. Of
course, since this technique may be calibrated in terms of Carbon 14
dating, which itself may be open to question, even those dates may be
wrong. Anyway, I'd be interested to know, if one extrapolates known
(laboratory measured) rates of racemization back in time, what kind of
a check does this give on Carbon 14 and other dating methods.
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