| Abstract: |
To study the effect of ultrafiltration on the radiocarbon ages of relatively poorly preserved bones in Japan, we analyzed the <sup>14</sup>C dates of high-molecular-weight (HMW) gelatin samples and compared them with those of other extracted organic fractions, unfiltered gelatin samples extracted from NaOH-treated or NaOH-untreated collagen, and XAD-purified hydrolysates of animal fossil bones (~4600 BP
gelatin yield of 2-4%) from the Awazu underwater archaeological site, Shiga, Japan. NaOH-treated, unfiltered gelatins and XAD-purified hydrolysates showed statistically similar <sup>14</sup>C ages to those of HMW gelatins. The <sup>14</sup>C ages of the HMW gelatins were the oldest and similar to those of wood collected from the same layer as the bones, and the NaOH-treated, unfiltered gelatins gave <sup>14</sup>C ages within the acceptable margins of error
therefore, ultrafiltration was effective for accurate <sup>14</sup>C dating, while NaOH-treated gelatin without ultrafiltration was also sufficient to obtain accurate <sup>14</sup>C dates on the animal bones. The <sup>14</sup>C ages of human skeletons (~750 BP
gelatin yield of 2-11%) from 5 individuals excavated from an archaeological site in Yuigahama, Kamakura, Japan, showed statistically the same <sup>14</sup>C ages as NaOH-treated, unfiltered gelatins and HMW gelatins within the margins of error, although HMW gelatins were likely to give slightly older ages than unfiltered gelatin with a yield of less than ~3%. These results indicate that unfiltered gelatins extracted from fossil bones of gelatin yield more than ~3% can produce accurate <sup>14</sup>C ages without the need for ultrafiltration. Ten bone fragments from 3 humans showed the same <sup>14</sup>C ages for each individual, suggesting that any bone part from an individual can be used to obtain a representative age. The <sup>14</sup>C ages of tooth dentins of 2 individuals were 35 and 70 yr older than their bone ages. Death dates obtained from these age gaps agreed with those determined by morphology.
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