On occasion, I point out interesting findings from archaeological chemistry and microscopic study of site formation processes. Last month, I pointed to the ability to distinguish animal and plant fat residues on ancient artifacts. Before that, there was the discovery of flax fibers from the Upper Paleolithic of Dzudzuana Cave, Georgia.
In July, a paper by Paul Goldberg and colleagues described the “micromorphology” of the sediments from Middle Stone Age levels of Sibudu Cave, South Africa. The excavations at Sibudu have been able to distinguish many distinct stratigraphic units with distinctive spatial locations and compositions. Micromorphology involves looking at these sediments in microscopic detail, picking out small grains of crushed bone, charcoal, plant fibers, phytoliths, and other materials.
Goldberg and his colleagues were able to make some very cool observations. For one thing, they have charred drips of broiled grease:
Two types of amorphous organic combustion remains were identified in samples from Sibudu: a type with a typically vesicular texture and a type with a cracked texture. The first type was found as isolated bodies, subrounded with a diameter of 10 m to 1 mm, and they exhibited no evidence of cell structure. Bubbles or vesicles give the bodies a highly porous nature, and they are often thin walled. The microstructure of these homogenous or finely heterogeneous isotropic particles and their droplet-shaped occurrence suggest that these bodies were originally fluid and that they underwent a degassing process but have since hardened. These bodies resemble char and are probably derived from the burning of flesh or animal fat (104-105).
Mmmmm…MSA barbecue. The other type of “amorphous organic combustion remains” are charred resins, from trees or seeds. Mmmm…MSA smokehouse.
Second, they have beds.
Because of its long fibrous nature, it seems that this material consists of herbaceous plants, possibly some type of sedge, reed, or grass. There is no evidence to suggest that this plant would have grown naturally in the rock shelter, and the presence of clay aggregates derived from the river valley found in association with the laminated plant fibers implies that the grass or reed was transported to the cave from the nearby Tongati River by the shelters inhabitants.
The compact and laminated structure of the organic fibers in this microfacies also suggests that, once brought to the cave, the grass or reed was subjected to compaction, most likely through trampling. Further evidence supporting the interpretation of trampling is seen in the stringers of charcoal, clay aggregates, and burnt bone that define horizontal and subhorizontal surfaces on top of and within the laminated organic fibrous material. Pieces of boulis and lithic fragments also define surfaces wi thin the microfacies. The fact that this grass or reed was transported to the cave by humans and that once there it was influenced by human trampling suggests that this microfacies represents a type of constructed bedding. If this is the case, then Sibudu contains the oldest evidence for constructed bedding, significantly older than that reported at the open-air site of Ohalo in Israel (Nadel et al. 2004).
The bedding material was in some instances burned, in some instances swept or trampled in such a way that the regular alignment of the phytoliths was jumbled and disrupted. They interpret this as efforts to “maintain” the site – in other words, housekeeping:
What seems a likely and reasonable scenario is that the original organic matter of this laminated layer of sedges, grass, or reeds was completely combusted, resulting in total ashing of the organic material. The calcitic ash in this microfacies was transformed through phosphatization, as evidenced by the presence of a few remnant pockets of phosphate in this microfacies. The fact that large crystals of gypsum often form directly below these phytolith layers provides suggestive evidence for the downward leaching of CO3- or P-rich solutions.
Just an aside – that is such interesting chemistry, like the organic materials and ash are melting down into the underlying deposits.
The association between microfacies 2 and 4 suggests that the sedges, grass, or reeds that were brought into the cave for bedding were usually burned and probably by humans when they no longer used the bedding. This observation explains the sequence seen in samples SS-6 and SS-5 of laminated nonburnt fibrous organic material grading into laminated burnt fibrous organic material with phytoliths (microfacies laminated type 2B); the sequence is finally capped by a layer of laminated phytoliths.
Why did they burn the stuff? The authors guess that they were trying to cut down on parasites:
Together, this evidence shows that not only were the occupants of Sibudu bringing grass or reeds into the cavelikely for the construction of beddingbut they were periodically burning them, possibly as a means to remove pests or insects that had colonized the beds. (Smoldering goat dung and organic matter can be observed in many parts of the Middle East, including Hayonim, where tick removal is one of the important objectives; P. Goldberg 1992, personal observation.)
The MSA at Sibudu dates to between 45,000 and 65,000 years ago, with the best evidence for bedding in the units that OSL puts around 50,000 years ago. The implications of the “site maintenance” and spatial characteristics of the site are mentioned in the paper’s conclusion:
Organization of living space, and particularly a deliberate use of space, has been suggested by Wadley (2001) and also Binford (1996) as an important trait of culturally modern behavior, reflecting a more complex social organization. While the evidence from the laminated units at Sibudu may reflect such organization, the lack of evidence for such spatial organization, such as is the case for the lower homogeneous layers at Sibudu, should not automatically suggest that occupation in these units was any less complex.
If spatial organization of living space is a “modern” behavioral feature, it is one shared by Neandertals (I noted that briefly in a 2006 post). But then, it’s shared by any number of invertebrates, also. I think the interpretation of this kind of behavior will have to wait until we have more sites investigated with comparable methods. As the introduction to the current paper points out, a lot of spatial information could be brought out of these micro-scale studies, if they were conducted routinely.
Goldberg P, Miller CE, Schiegl S, Ligouis B, Berna F, Conard NJ, Wadley L. 2009. Bedding, hearths, and site maintenance in the Middle Stone Age of Sibudu Cave, KwaZulu-Natal, South Africa. Archaeol Anthropol Sci 1:95-122. doi:10.1007/s12520-009-0008-1