New developments in the radiocarbon dating of mud wasp nests

12,000-Year-old Aboriginal rock art from the Kimberley region, Western Australia

“…As part of a larger multiyear rock art dating project (24,25), nest samples associated with 21 different motifs of the distinctive Gwion style are reported here. All samples were obtained with Traditional Owner consent and participation.…”

“…Detailed results are listed in table S1, and specific details of radiocarbon pretreatments are listed in table S2. Each age measurement is given a qualitative "Reliability Score" [described in detail elsewhere (25)] based on the carbon mass analyzed, the physical cleaning of the sample, and the chemical pretreatment applied. The reliability score is a relative measure that communicates the susceptibility of the age measurement to potential sources of contamination .…”

“…The calibrated ages of the 12 oldest wasp nests overlying art are mostly in the range from 4.5 to 12.1 ka [median calibrated years before the present (median cal BP)] with one nest (DR006_03) significantly older at 16.6 ka (median cal BP), with a reliability score of 5 out of 10 ( Fig. 2) (25). Five of the six nests underlying pigment were dated to between 13 and 15 ka (median cal BP).…”

“…Weathering of the initially large surface area of mud wasp nests gives results in a rapid reduction in nest volume until the nest is reduced to a stump ( Fig. 1) (25). Hence, the age distribution of all nests is likely to be broadly exponential, with most nests being young and the probability of nests being preserved diminishes as age increases.…”

“…However, when the available sample was small, the nest was critically examined to determine whether more of the nest could be included in the sample. The color, texture, and morphology of the nest were used to verify that it was all constructed at the same time (i.e., a single generation nest), with the practice progressively refined as hundreds of nests of all ages were studied (25). Given that new material can be added by wasps at the edge, or over an existing nest, only that part of the nest directly under the pigment or unequivocally part of the same construction episode was relied on.…”