Potential sources of error include the addition of 'old' or reservoir carbon to the bone gelatin before death in the diet, or after deposition via unremoved humics or diagenetic processes in carbonate sedimentary environments, especially for small specimens.

Dietary influences were not apparent. Two individuals of known death date give calibrated ages that include their death dates. In addition, 14C dates on bone gelatin from two herbivorous birds (equilibrium carbon consumers) are not significantly different from those on rat bones from comparable levels. Humic contamination is unlikely, most being removed by gelatinization, but must still be considered fro earlier 'collagen' dates. Environmental carbonates were removed by an acid pre-wash, eliminating carbonate contamination. Measured ages were not related to whole-sample mass.

Longer-term diagenetic changes do not appear to have a significant effect. Samples of moa eggshell (species unknown) and bird bone from close proximity in sediment enclosed by two undisturbed volcanic tephras give indistinguishable ages.... These materials were prepared using different treatments. Finally, a rat dentary excavated from beneith the Taupo Tephra gives an age of 1,775±93 yr BP. In addition to the radiocarbon age being consistent with that of the covering tephra, the bone's position beneath the undisturbed layer provides independent evidence that Pacific rats were established in the North Island before the Taupo eruption (Holdaway 1996:226).

There is no simple explanation for the variable radiocarbon dates from Hohle Fels and Geienklösterle. The noisy signals result from a combination of factors including variable sample preparation, variable levels of atmospheric carbon, taphonomic mixing and excavation error. Given the lack of reproducibility within and between radiocarbon laboratories, I prefer to emphasize the stratigraphic context of the finds, and to use the highly variable radiometric dates as rough indicators of age8. Although there is no generally accepted calibration for radiocarbon dates over 30 kyr bp, preliminary calibrations suggest that dates of 32 kyr bp correspond to roughly 36 kyr bp in calendar years. If the early dates are correct, the Venus would be even older. The fact that the Venus is overlain by five Aurignacian horizons, containing a dozen stratigraphically intact anthropogenic features with a total thickness of 1 m, suggests that the figurine is of an age corresponding to the start of the Aurignacian, around 40,000 calendar years ago.