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These are important for amino acid dating because racemization occurs much faster in warm, wet conditions compared to cold, dry conditions.Temperate to cold region studies are much more common than tropical studies, and the steady cold of the ocean floor or the dry interior of bones and shells have contributed most to the accumulation of racemization dating data.Generally, they are not assumed to have a great impact in the natural environment, though tephrochronological data may shed new light on this variable.The enclosing matrix is probably the most difficult variable in amino acid dating.In this article we shall discuss the principles behind amino acid dating (also known as racemization dating); we shall discuss how it ought to work, and why it often doesn't.An object is said to have chirality if it is not possible to make it into a mirror-image of itself by turning it round.(For it would be strange and anti-scientific to conjecture that the rate of racemization of the shells in the Arctic mud is constant whenever we can check it, but variable when we can't.) Just this was established by Kaufman et. (2008) in their paper Dating late Quaternary planktonic foraminifer Neogloboquadrina pachyderma from the Arctic Ocean by using amino acid racemization, Paleoceanography, 23(3).
With a few important exceptions, living organisms keep all their amino acids in the "L" configuration.
So it would seem that if we want to know how long it was since an organism died, all we have to do is see how racemic its amino acids are. The process of racemization would have to go at a constant rate, and we'd have to know what it was. As a result, it isn't possible to say that racemization happens at such-and-such a rate. Suppose we examine a particular material (let us say tests of the foraminiferan Neogloboquadrina pachyderma) in a particular environment (let us say in mud in Arctic waters) and by comparing it with a dating method we know we can rely on, we establish that under these conditions racemization does happen at a reasonably steady rate.
In that case we could use the foraminiferans to date sediment in places where we aren't able to use radiometric dating.
They both have exactly the same chemical formula, but one is left-handed, and the other is right-handed. When we make chiral molecules using ordinary chemical processes, we usually produce equal quantities of both enantiomers. However, biological processes produce molecules with a distinct chirality: all the amino acids are "left-handed" (with the exception of glycine, which is not chiral) and all the sugars are "right-handed".
So when an organism dies, its amino acids are left-handed.