Archaeology: new technique using chemical analyses

Posted December 9th, 2007 by Andrea Vianello

Here at Intute we are trying to promote awareness of archaeological sciences, recently also with a series of podcasts. Scientific techniques are providing many new tools to archaeologists, and scientists are trying to reach archaeologists also through the Web. Our heading Archaeological Sciences is crossing the boundaries of many disciplines, and we are sure this is just the tip of the iceberg. Sometimes new research really surprises us, and we want to spread the word even before we can find websites on the subject suitable for our catalogue. Our Newsround service can be useful to access and search news from many websites, but sometimes the amount of information can be really overwhelming.

A new paper published in Analytical Chemistry (DOI: 10.1021/ac070993k) and entitled Identification of Ritual Blood in African Artifacts Using TOF-SIMS and Synchrotron Radiation Microspectroscopies reports that sculptors from the African kingdom of Mali used blood to form the patina characteristic of their works of art.

Dogon art

Image above: Dogon anthropomorphic wooden figurines by “herr_hartmann“, published in Flickr with Creative Commons licence.

 

The researchers describe the new technique in this way:

A new three-steps protocol (set of analyses) has been developed. The first step consists in demonstrating the presence of proteins and localizing them in the sample’s cross sections using time-of-flight secondary ion mass spectrometry (TOF-SIMS) and synchrotron-based infrared microspectrometry (μFT-IR). Then, TOF-SIMS is used to investigate heme, which is a blood marker. If heme is missing, which could mean that it is too degraded to be detected, X-ray microfluorescence (μXRF) and X-ray absorption near-edge microspectroscopy (μXANES) are used to prove the presence of iron in the protein area and to get a fingerprint of its chemical environment.

The researchers have analysed eight objects from the Dogon and Bamana cultures of Mali, all thought to be “ritual” or “sacred” (boliw) artefacts. Among the artefacts are anthropomorphic and zoomorphic wooden statuettes. The use of blood in the manufacture of art objects in Africa and elsewhere had been reported by ethnographic research (e.g. among the Dogon of Africa; Ifugao Bu-lul of the Philippines; the Kenyah-Kayan of Borneo, etc.; the African Art Museum and Tribalarts websites may be useful), but this is the first time that it can be proven with scientific analyses. This research empowers archaeologists of one more technique, and it reminds us of the powerful symbolic value of certain artefacts among some cultures. In Africa, the link between art, symbolism and blood goes back at least to 75,000 years ago: the oldest objects discovered so far are the ochre plaques from Blombos Cave (red ochre probably symbolised blood). And as I mentioned earlier, such link spread across the entire world, from Africa to Asia, Europe and America.

Video above: Dogon Blacksmith published by “bradcwatson” on YouTube.