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23-Jan-2020 10:50

The amino acids combine with each other like the links of a chain to form a long protein chain.

Proteins contain from 50 to several hundred amino acids.

At a widely publicized news conference in August of 1972, Dr.

Jeffrey Bada of Scripps Institute of Oceanography announced the "discovery" of a new dating method based on the rate of racemization of amino acids in fossil material.

used to estimate the age of a specimen in paleobiology, molecular paleontology, archaeology, forensic science, taphonomy, sedimentary geology and other fields.

This technique relates changes in amino acid molecules to the time elapsed since they were formed. All amino acids except glycine (the simplest one) are optically active, having a stereocenter at their α-C atom.

Each amino acid has two chemical groups, an amino group and a carboxyl group, which can form chemical bonds with other amino acids.

The amino group of one amino acid can combine with the carboxyl group of a second amino acid to form a "peptide" bond, and its carboxyl group can combine with the amino group of a third amino acid, and the chain can thus be extended indefinitely.

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Thus, because of the rate problem, this dating technique must rely on other dating techniques to standardize its findings.

AMINO ACID SURVIVAL IN PHANEROZOIC FOSSILS Since amino acids have widely varying degrees of stability, after the death of an organism the less stable amino acid components will decompose more rapidly than those which are more stable, producing an amino acid signature that is increasingly distributed toward the more stable components as time progresses (Hare and Abelson 1967, Lee et al. Because of the range of variation among individual members of the same species (Hare and Abelson 1965, Hare and Mitterer 1967, King and Hare 1972, Jope 1980), amino acids may be expected to provide at best only a broad indication of fossil age.

Uncertainty as to the extent to which modern organisms represent in detail the characteristics of their ancient counterparts introduces additional lack of precision in a fossil age based on amino acid ratios.

He was quoted as saying that he had discovered the basis of the method in 1968, and that it was so obvious and simple he was amazed it hadn't been discovered earlier.

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As a matter of fact, the basis of this method had been discovered earlier and had been reported in a series of papers published by Hare, Mitterer and Abelson in 1967, 1968, and 1969.

To validate our age calculation algorithm, we used a wide series of radiometric datings (ESR and C), along with thermoluminescence and AAR dating on invertebrate (ostracode) samples.



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