قارن الطرق

	Amino Acid Racemization	Frequency Seriation
المجال	علم الآثار	علم الآثار
العائلة	Regression model	Process / pipeline
سنة النشأة	1997	1962
صاحب الطريقة	Reviewed for archaeology by Beverly Johnson and Gifford Miller	Leslie Spier; James A. Ford (developed from W. M. F. Petrie's sequence dating)
النوع	Chemical kinetic dating clock based on the racemization of amino acids in biogenic materials	Relative-chronology ordering of assemblages by type proportions
المصدر التأسيسي	Johnson, B. J., & Miller, G. H. (1997). Archaeological Applications of Amino Acid Racemization. Archaeometry, 39(2), 265-287.	Lyman, R. L., & O'Brien, M. J. (2006). Measuring Time with Artifacts: A History of Methods in American Archaeology. University of Nebraska Press. ISBN: 9780803280526
الأسماء البديلة	AAR Dating, Amino Acid Geochronology, Amino Acid Epimerization, D/L Ratio Dating	Frequency Seriation Dating, Battleship-Curve Seriation, Proportional Seriation
ذات صلة	3	3
الملخص	Amino acid racemization (AAR) dating estimates the age of biogenic materials such as mollusc shell, ostrich eggshell, bone, and teeth from the slow chemical conversion of amino acids from one mirror-image form to the other after an organism dies. Living tissue builds proteins almost entirely from left-handed (L) amino acids, but after death these gradually interconvert toward an equilibrium mixture of left- and right-handed (D) forms, so the measured ratio of D to L rises predictably with time. Because the reaction is a temperature-dependent chemical process rather than a radioactive decay, AAR is fundamentally a kinetic clock that must be calibrated against an independently dated reference and corrected for the sample's thermal history. Reviewed for archaeology by Johnson and Miller and covered as a standard chronometric tool in Renfrew and Bahn's textbook, it offers a rapid, inexpensive way to date or correlate deposits across the Quaternary, well beyond the radiocarbon range.	Frequency seriation is a relative-dating technique that orders archaeological assemblages in time by the changing proportions of the artifact types they contain. Its premise is that any cultural type is introduced, gradually becomes popular, peaks, and then declines, so that the relative frequency of a type traces a single rise-and-fall curve through time. By rearranging the rows of a type-by-assemblage abundance table until every type's frequency forms one continuous unimodal sequence, the analyst recovers an ordering interpreted as chronological. Drawn as horizontal bars, these curves take the lens or 'battleship' shape that gives the method its popular name. Frequency seriation grew out of W. M. F. Petrie's sequence dating and was formalized for proportional data by mid-twentieth-century Americanists such as James A. Ford, becoming a backbone of culture-historical chronology before absolute dating was widely available.