Amino acid racemization dating method

Even the process of preparing a specimen for racemic dating can affect the D/L ratio.

For example, consider that neither the structure nor the proportion of the amino acids used for dating coral, ostrich eggshell, or snail shells is known. Using"Amino acid dating cannot obtain the age of the material purely from the data itself.

Conventional plus accelerator mass spectrometry (AMS) radiocarbon dating (Taylor et al.

1983) was carried out on the Sunnyvale skeleton and results of between 3,600 and 4,850 years BP were obtained.

These two forms are called "enantiomers", "chirals", or "stereoisomers", which basically means that they have the same molecular and structural formula but cannot be superimposed on each other no matter how they are oriented in space.

Such extrapolations have been fairly recently (1999) called into question by experiments showing that models based on high temperature kinetics fail to predict racemization kinetics at physiologic temperatures (i.e., 37 C). We argue that the D: L ratio of Asx reflects the proportion of non-helical to helical collagen "The local buffering effects of bone and shell matrixes are supposed to limit this effect, but it is still something to consider as potentially significant when acting over the course of tens of thousands to millions of years.replacement of the asparagine residue with aspartic acid resulted in a 34-fold decrease in the rate of succinimide (Asu) formation.

That is because the porosity of bones makes them more "open" to surrounding environmental influences and leaching.

They did note that there appeared to be a direct relationship between the extent of racemization and the level of preservation of collagen in the bones.

Those samples with the most racemization had the lowest amino acid content and this poor preservation of protein would contribute to anomalous AAR recalculated the AAR dates of the other Paleo-Indian samples.

In this light, it is interesting to consider what happened in 1974 when some of the major proponents of amino acid dating (Bada et al) decided to analyze the Paleo-Indian skeletal material from Del Mar, California.

Their estimated age of 48,000 years before present (BP) "stunned" the archaeological community who generally believed these bones to be less than 10,000 years old.