Shelling it out

Very old pierced shells are back in the headlines, heralding a new paper by a group of archaeologists working in Morocco. As the paper’s still unavailable at PNAS, I can only really comment on what’s in the press reports, but the paper in question likely builds on two earlier reports that more pierced shells had been found at Grotte des Pigeons over the past couple of years.

I’ve discussed early pierced shell ornament earlier on this blog, so I won’t really reiterate the argument for why they matter. That these shells can be referred to as ornaments is based on the presence of intentional perforations, use wear along the edges of those holes, and some of the beads having been covered in ochre. Another report suggests that there is even evidence that at leats one shell was burned in order to change its color, which would be pretty cool in light of recent reports about heat-treating of silcrete dating to ca. 75,000BP in South Africa (Brown et al. 2009).

Similar items of roughly the same age are know from both South Africa (Henshilwood et al. 2004) and from North Africa and the Near East (Vanhaeren et al. 2006, Bouzouggar et al. 2007), so that’s not the main novelty here. Rather, the real news is that similar shell ornaments (all made on Nassarius gibbosolus shells) have been found in roughly contemporaneous deposits in four distinct sites in Morocco. This is a pretty big deal because it suggests that people at more than one point in space and time were using ornaments, which provides some much needed empirical support for the notion that these ornaments represent some kind of visual language shared by several groups of hunter-gatherers at that time. Obviously, if you’re hoping to make an argument about the social implications of ornaments at a specific moment in prehistory, you have to be able to demonstrate with some degree of certainty that these objects were found distributed pretty widely. Otherwise, you might be talking about an idiosyncratic behavior that might actually not have a social dimension at all, no matter what referents tell us about ornament use in ethnographically documented foragers. So, on that level, it seems that this paper establishes this. I can see people raising quibbles about the fact that we’re only talking about ca. 25 shells across four sites spanning a period of 15,000 years (these all apparently date to between 85-70,000 BP), but really, for these time periods, this is a pretty decent argument for contemporaneity in behavior within a relatively small area.

One especially interesting aspect of this study is that some of these sites seem to be located relatively far inland, far enough to imply that humans must have brought these shells there from quite far away. In the newsreport, F. d’Errico is quoted as saying

“Either people went to sea and collected them, or more likely marine shell beads helped create and maintain exchange networks between coastal and inland peoples. This shows well-structured human culture that attributed meaning to these things… Organised networks would also assist trading of other items, as well as genetic and cultural exchange – so these shells help reveal the connections between cognition and culture.”

This provides a testable hypothesis for the existence of such networks, namely that some ‘inland’ material would need to have made its way to the coastal sites. If this can be shown to have occurred, you also have the most solid evidence for the oldest trade networks in the archaeological record. Of course, what may have been traded need not have left archaeologically-visible traces (i.e., it could have been knowledge of resource distribution further inland, rituals, etc.). But if it did, this is an even bigger deal than has been suggested so far in the reports.


References:

Bouzouggar, A., N. Barton, M. Vanhaeren, F. d'Errico, S. Colcutt, T. Higham, E. Hodge,S. Parfitt, E. Rhodes, J.-L. Schwenninger, C. Stringer, E. Turner, S. Wardo, A. Moutmir, and A. Stambouli. 2007 82,000-year-old shell beads from North Africa and implications for the origins of modern human behavior. Proceedings of the National Academy of Sciences 104:9964-9969.

Brown, K. S., C.W. Marean, A.I. R. Herries, Z. Jacobs, C. Tribolo, D. Braun, D. L. Roberts, M. C. Meyer, and J. Bernatchezet. 2009 Fire As an Engineering Tool of Early Modern Humans. Science 325:859-862.

Henshilwood, C., F. d'Errico, M. Vanhaeren, K. van Niekerk, and Z. Jacobs. 2004.Middle Stone Age Shell Beads from South Africa. Science 304:404.

Vanhaeren, M., F. d'Errico, C. Stringer, S. L. James, J. A. Todd, and H. K. Mienis. 2006. Middle Paleolithic Shell Beads in Israel and Algeria. Science 312:1785 - 1788.