Replies

Dating

Immediately above the sediment of the distinct grave cut in SU7, a charcoal sample returned an accelerator mass spectrometry (AMS) radiocarbon (14C) age of 31,133 to 30,437 calibrated radiocarbon years before present (cal. BP) with a 95.4% probability (D-AMS38332), providing a stratigraphic minimum date for the inhumation of TB1 (Supplementary Table 2). In addition, a charcoal sample within the burial feature, collected from the pelvic girdle, returned an estimate of 31,110 to 30,437 cal. BP (D-AMS38337). Charcoal recovered from SU9, the stratum underlying the burial feature, provides a stratigraphic maximum date, with an estimate of 31,519 to 31,054 cal. BP (D-AMS38338). The SU9 sample was situated immediately underneath the burial cut, although within a completely distinct stratum that clearly underlies both the burial feature and the equally distinct sediments of SU8. Thus, associated radiocarbon dating of the charcoal samples indicates an age estimate for the TB1 burial feature of between 31,519 and 30,437 cal. BP, with a mean of 30,978 cal. BP. Bayesian chronology suggests that the boundary between SU7, which caps the burial, and the burial feature itself, is 30,853 ± 770 cal. BP; and the boundary between the burial and the underlying SU8 is 31,135 ± 864 cal. BP (Extended Data Fig. 10 and Supplementary Table 3). Furthermore, radiocarbon dating from overlying stratigraphic units confirms subsequent human occupation at the site transitioning the Last Glacial Maximum and the Holocene towards the surface (Supplementary Table 2), with the depth measurement of each sample showing strong and significant correlation with the mean calibrated age (r = 0.990, r 2 = 0.981, F = 253.942, p = 0.001). The positive age–depth relationship of these samples (completely lacking inversion) supports an argument for minimal deposit reworking and diminishes the possibility of introduced charcoals entering lower units, including burial-fill sediments.

In addition to radiocarbon dating of the charcoal, a combined uranium-series and electron spin resonance dating technique was undertaken on a sample of TB1’s left mandibular molar (M3) and this analysis returned an age estimate of 25.4 ± 4.3 thousand years old (1σ), which is within the error of the 14C burial-context age. Both the uranium-series analysis in isolation and radiocarbon dating of the skeletal remains were unsuccessful owing to insufficient amounts of uranium and collagen in the sample, respectively. Incorporating the electron spin resonance age into the Bayesian model gives a modelled date of 31,201 to 30,714 years ago (2σ or 95.4% probability) for the burial (Extended Data Fig. 10). In summary, we infer a secure Late Pleistocene age of between 31,000 and 30,000 years for TB1, making this, to our knowledge, the oldest intentional primary burial of a modern human currently known from Island Southeast Asia.

https://www.nature.com/articles/s41586-022-05160-8