Temperature and humidity histories of microenvironments are being produced at ever increasing rates as technologies advance and technologists accumulate data.Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This technique relates changes in amino acid molecules to the time elapsed since they were formed. All amino acids except glycine possess an asymmetric carbon atom, which means that the amino acid can have two different configurations, "D" or "L". Amino acid dating is a dating technique used to estimate the age of a specimen in paleobiology, archaeology, forensic science, and other fields.When an organism dies, control over the configuration of the amino acids ceases, and the ratio of D/L moves slowly toward equilibrium, a process called racemization.
Amino acid dating is a dating technique used to estimate the age of a specimen in paleobiology, molecular paleontology, archaeology, forensic science, taphonomy, sedimentary geology and other fields.The rate itself of hydrolysis "depends on the strength of the individual peptide bonds, which in turn is determined by the characteristics of the amino acids on either side of the bond, the presence of water and the temperature."All of these are confounding factors, which, if not known exactly over extended periods of time, would play havoc with any sort of age determinations.Even the process of preparing a specimen for racemic dating can affect the D/L ratio.Due to the strong dependency of racemization rates on temperature, water concentration, and alkalinity, uncertainties regarding conditions of preservation can leave amino-acid-based age relationships among even similar fossils open to question.At the present time there is insufficient knowledge concerning the effective average racemization rate in a fossil as a function of time to justify dependence on D/L ratios for a quantitative determination of age.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.Again, those like Goodfriend and Hare (1995) have pointed out the "difficulties in estimating the amount of asparagine in proteins and reminded researchers of the dangers of extrapolating from the behaviour of pure Asn in solution at high temperature, to the behaviour of Asn in proteins associated with biominerals at ambient temperature . The rate of racemization can not be standardized by itself because it is too changeable.The possibilities for using these characteristics as a means for determining fossil age are frustrated by variations of the amino acid pattern among individual living organisms of the same species, and by the critical dependency of the racemization probability for an amino acid molecule on temperature, water concentration in the environment, alkalinity of the environment, association with other molecules (free state or a component of a macromolecule), size of the macromolecule of which it may be a component, specific location in the structure of a macromolecule, catalytic effect of clay surfaces with which it may be associated, presence of aldehydes and metal ions, concentration of buffer compounds in the environment, and ionic strength of the environment.In spite of these complications, fossils of similar characteristics, and which have experienced similar conditions of preservation, can be placed in a relative age sequence on the basis of D/L ratios.Also, D/L concentration thresholds appear to occur as sudden decreases in the rate of racemization.These effects restrict amino acid chronologies to materials with known environmental histories and/or relative intercomparisons with other dating methods.Thus, measuring the ratio of D/L of a sample can allow calculations of how long ago the specimen died.The rate at which racemization proceeds depends upon the type of amino acid, average temperature, humidity, acidity, p H, and characteristics of the enclosing matrix.This page is based on a Wikipedia article written by contributors (read/edit).