Goddess on a cave bottom

I don’t have much value to add to the “figurative art” angle to the Hohle Fels Venus figurine. It seems very interesting that there is a concentration of carved iconic figures in the Swabian Aurignacian. That has two elements – first, the concentration itself; second, the focus on carved ivory. Other regional Upper Paleolithic variants have their own concentrations of unique artifacts, sometimes tools (like the Solutrean leaf point) other times found objects (like the fossil shells in the Belgian and German Magdalenian. And we know that other times and places in the Upper Paleolithic have carved objects, so here we have the combination of both, in a very early Upper Paleolithic culture.

I do think it’s worth discussing the date of the figurine a little more closely. Conard’s paper includes a nice short discussion of the difficulties of establishing an accurate chronology – a bunch of dates are available spanning much of the sequence, and there is substantial mixing of older and younger dates across the sequence.

There is no simple explanation for the variable radiocarbon dates from Hohle Fels and Geienklsterle. 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 30kyrbp, preliminary calibrations suggest that dates of 32kyrbp correspond to roughly 36kyrbp 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 1m, suggests that the figurine is of an age corresponding to the start of the Aurignacian, around 40,000 calendar years ago.

The paper also includes a very nice picture showing the stratigraphy profile of the site in terms of artifact positions, color-coded by level. The Venus does lie beneath a well-stratified Aurignacian, with a depth of in this area of more than a half meter, although I am also impressed by the overlying meter of “Gravettian-Aurignacian transition.” Conard’s text is slightly more definitive than the figure, since two of the five “overlying” Aurignacian layers are not represented directly above the artifact, and one appears mostly to underlie it.

The research report is accompanied by a perspective piece by Paul Mellars. He frames the importance of the site by referring to its early date:

Fragments of the figure were excavated from archaeological deposits in the Hohle Fels cave in south Germany, dated by a range of more than 30 radiocarbon measurements to at least 35,000 years in age (in terms of the newly 'calibrated' radiocarbon timescale) (Mellars 2009:176).

This is a tricky statement to parse. Conard provides eight radiocarbon dates for objects in the lowest Aurignacian level (Vb) at Hohle Fels, only two of these are older than 35,000 radiocarbon years. Mellars refers to calibrated dates, not radiocarbon dates. On that basis, the statement is likely correct but a little misleading in comparison with later, Gravettian-associated figurines, whose dates are reported in uncalibrated years.

For those not familiar with the arcana of radiocarbon dating, the atmospheric proportion of carbon-14 varied during the last 40,000 years, so that there was actually more or less of it at some times than others. For the oldest radiocarbon dates, up above 25,000 BP, the age reported in half-lifes is systematically younger than the real age of an object in calendar years (given in “years ago” or some such). Over the span above 30,000 years ago, the difference is up to 5000 years or more – so that a radiocarbon date of 30,000 BP might correspond to a calendar date older than 35,000 years ago.

This creates the potential for much confusion when describing dates. In this case, what does it mean to see that a Venus figurine from the Aurignacian is “more than 35,000 years old” when other figurines from the Gravettian date to “25,000 BP”? There’s a 5000-year gap between those two timescales – one that amounts to a sixth of the total age of an artifact. And when we read that an object is “more than 35,000 years old” and remember that Neandertals lived up to “29,000 BP” it is very easy to forget that these dates may well be synchronous. So we have to continually remind ourselves to use comparable timescales when talking about objects in the Upper Paleolithic.

I’ve discussed the problems with radiocarbon calibration at some length, in association with some earlier work by Mellars. Sometimes I find that reading and learning more about a subject actually clarifies matters a bit. In the case of radiocarbon chronology, it seems that the more I learn, the more confused things really are.

Given the error associated with calibration and atmospheric variation, it is no surprise (as Conard reports in the paper) that the radiocarbon dates in a site over around 30,000 BP should be somewhat mixed and confused. The problem is not so much that ten objects from the same moment will have different proportions of carbon-14, it is that ten objects from different times may have the same proportion. So it is especially important to understand the stratigraphy of a site completely. This appears to be a good, conservative example, and it will be interesting to see what happens if the excavation progresses further into the deeper underlying Mousterian.

But meanwhile there are other sites, excavated in a range of circumstances, in which the stratigraphy was not so carefully documented, or may have been more mixed. I suspect we’ll be hearing more confusion before we get a lot more clarification.

References:

Mellars P. 2009. Origins of the female image. Nature 459:176-177. doi:10.1038/459176a

Conard NJ. 2009. A female figurine from the basal Aurignacian of Hohle Fels Cave in southwestern Germany. Nature 459:248-252. doi:10.1038/nature07995