scholarly journals Non-Concordance of Radiocarbon and Amino Acid Racemization Deduced Age Estimates on Human Bone

Radiocarbon ◽  
1983 ◽  
Vol 25 (2) ◽  
pp. 647-654 ◽  
Author(s):  
R E Taylor
Keyword(s):  
Amino Acid ◽  
Aspartic Acid ◽  
Human Bone ◽  
Amino Acid Racemization ◽  
Aspartic Acid Racemization ◽  
Order Of Magnitude ◽  
Direct Counting ◽  
Organic Fractions ◽  
Skeletal Samples ◽  
Age Estimates

Radiocarbon determinations, employing both decay and direct counting, were obtained on various organic fractions of four human skeletal samples previously assigned ages ranging from 28,000 to 70,000 years on the basis of their D/L aspartic acid racemization values. In all four cases, the 14C values require an order of magnitude reduction in age.

Amino Acid Geochemistry of Fossil Bones from the Rancho La Brea Asphalt Deposit, California

1982 ◽  
Vol 18 (2) ◽  
pp. 174-183 ◽  
Author(s):  
Mark A. S. McMenamin ◽  
David J. Blunt ◽  
Keith A. Kvenvolden ◽  
Scott E. Miller ◽  
Leslie F. Marcus ◽  
...  
Keyword(s):  
Amino Acids ◽  
Los Angeles ◽  
Aspartic Acid ◽  
Equivalent Age ◽  
Aspartic Acid Racemization ◽  
Wide Range ◽  
Fossil Bones ◽  
Minimum Age ◽  
Rancho La Brea ◽  
Age Estimates

AbstractLow aspartic acid d:l ratios and modern collagenlike concentration values indicate that amino acids in bones from the Rancho La Brea asphalt deposit, Los Angeles, California are better preserved than amino acids in bones of equivalent age that have not been preserved in asphalt. Amino acids were recovered from 10 Rancho La Brea bone samples which range in age from less than 200 to greater than 36,000 yr. The calibrated rates of aspartic acid racemization range from 2.1 to 5.0 × 10−6yr−1. Although this wide range of rate constants decreases the level of confidence for age estimates, use of the larger rate constant of 5.0 × 10−6yr−1provides minimum age estimates which fit the known stratigraphic and chronologic records of the Rancho La Brea deposits.

scholarly journals Direct Bone Dating in a Small CO2 Counter

Radiocarbon ◽  
1983 ◽  
Vol 25 (2) ◽  
pp. 655-659 ◽  
Author(s):  
Rainer Berger
Keyword(s):  
Aspartic Acid ◽  
Lower Cost ◽  
Human Bone ◽  
Counting System ◽  
Complete Filling ◽  
Aspartic Acid Racemization ◽  
Bone Fragments ◽  
La Jolla

A small 200ml capacity CO2 proportional counting system has been developed which uses only 100mg of carbon for complete filling. Thus, with respect to the small quantities needed, it compares favorably to dedicated accelerators at significantly lower cost. The performance of this equipment is demonstrated using a variety of samples including some human bone fragments from La Jolla which had been estimated to be 28,000 years old by aspartic acid racemization analysis.

Age and growth estimates of bowhead whales (Balaena mysticetus) via aspartic acid racemization

1999 ◽  
Vol 77 (4) ◽  
pp. 571-580 ◽  
Author(s):  
John C George ◽  
Jeffrey Bada ◽  
Judith Zeh ◽  
Laura Scott ◽  
Stephen E Brown ◽  
...  
Keyword(s):  
Aspartic Acid ◽  
Standard Error ◽  
Sexual Maturity ◽  
Delta Method ◽  
Age And Growth ◽  
Eye Lens ◽  
Bowhead Whales ◽  
Aspartic Acid Racemization ◽  
Coefficients Of Variation ◽  
Age Estimates

A total of 48 eye globes were collected and analyzed to estimate ages of bowhead whales using the aspartic acid racemization technique. In this technique, age is estimated based on intrinsic changes in the D and L enantiomeric isomeric forms of aspartic acid in the eye lens nucleus. Age estimates were successful for 42 animals. Racemization rate (kAsp) for aspartic acid was based on data from earlier studies of humans and fin whales; the estimate used was 1.18 10-3/year. The D/L ratio at birth ((D/L)0) was estimated using animals less than or equal to 2 years of age (n = 8), since variability in the D/L measurements is large enough that differences among ages in this range are unmeasurable. The (D/L)0 estimate was 0.0285. Variance of the age estimates was obtained using the delta method. Based on these data, growth appears faster for females than males, and age at sexual maturity (age at length 12-13 m for males and 13-13.5 m for females) occurs at around 25 years of age. Growth slows markedly for both sexes at roughly 40-50 years of age. Four individuals (all males) exceed 100 years of age. Standard error increased with estimated age, but the age estimates had lower coefficients of variation for older animals. Recoveries of traditional whale-hunting tools from five recently harvested whales also suggest life-spans in excess of 100 years of age in some cases.

The Racemization Rate Constant for Protein-Bound Aspartic Acid in Woodrat Middens

1974 ◽  
Vol 4 (3) ◽  
pp. 340-345 ◽  
Author(s):  
Michael G. Petit
Keyword(s):  
Amino Acid ◽  
Aspartic Acid ◽  
Rate Constant ◽  
Isomeric Ratio ◽  
Acid Mixture ◽  
Acid Oxidase ◽  
Amino Acid Oxidase ◽  
Amino Acid Racemization ◽  
Crotalus Viridis ◽  
Protein Environment

The racemization rate constant for aspartic acid has been determined from the D/L isomeric ratio in four strata of radiocarbon dated woodrat midden in Arizona. Two different methods of stereospecifically deaminating L-aspartic acid prior to the assay are compared. It is found that pure L-amino acid oxidase pretreatment of the DL aspartic acid mixture requires one less step than treatment with crude, dialyzed venom (Crotalus viridis) but that the two methods give the same results. Application of the theory of amino acid racemization dating is discussed in the context of the steric properties ofthe protein environment in which the racemization actually occurs.

scholarly journals Use of AMS 14C Analysis in the Study of Problems in Aspartic Acid Racemization-Deduced Age Estimates on Bone

Radiocarbon ◽  
1986 ◽  
Vol 28 (2A) ◽  
pp. 539-546 ◽  
Author(s):  
Paul Ennis ◽  
E A Noltmann ◽  
P E Hare ◽  
P J Slota ◽  
L A Payen ◽  
...  
Keyword(s):  
Amino Acids ◽  
Aspartic Acid ◽  
Chemical State ◽  
Fossil Bone ◽  
Aspartic Acid Racemization ◽  
Age Estimates

Major discordances between AMS 14C- and aspartic acid racemization (AAR)-deduced age estimates on bone samples have led to an examination of factors other than time and temperature that can fundamentally influence the degree of racemization observed in fossil bone. Our studies support previous suggestions that for many bone samples the chemical state of amino acids must be routinely considered if AAR-deduced age estimates are to be used to make meaningful chronologic inferences.

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