Blood from Stones

Certain ceremonial objects from the Dogon and other cultures of West Africa are known for their dark patina. There is plenty of ethnological evidence that the thick coating on these wood sculptures, which are often in human or animal shapes, contains blood from animals sacrificed as part of the ceremonies. But the presence of blood had not been proved through chemical analysis.

Now, don’t get too excited yet … I’ve seen this a half dozen times before. The indicators of blood are everywhere in the environment. It is almost impossible to chemically test an artifact and not find evidence of blood on it (if you use the right test). So, let’s see what this new find, just reported in the New York Times, may turn out to be….

Vincent Mazel and Pascale Richardin of the Center for Research and Restoration of the Museums of France and colleagues have done just that, finding blood on seven of eight Dogon and Bambara objects from Mali, all dating from the late 19th or early 20th centuries, except for one that is at least 500 years older. Their findings are published in the journal Analytical Chemistry.

The researchers used several precision analytical techniques, including time-of-flight secondary ion mass spectrometry.

Nope, I’m not buying it. Ions are everywhere….

the researchers first demonstrated that they contained proteins.

Proteins. They’re everywhere….

Then they showed that some samples contained heme, the iron-containing molecule that is bound to hemoglobin. In a few samples, heme was not present, although iron was.

Have you been to Africa? Especially this region? If so, you are probably still washing the lateritic dust out of your stuff.

So the researchers used X-ray scanning techniques to show that in all but one of these samples, the iron was associated with the proteins, indicating simply that the heme had degraded over time.

Or, that the “protein” (is it hemoglobin or is it not hemoglobin?) and the iron associated, as they would likely do anyway (metals are always stucking onto proteins).

OK, I admit, I have not read the original paper yet. I may never read it, as my pile of papers to read is at present growing faster than I can read and I’m workin’ hard on it. I look forward to critical analysis by colleagues. Most likely, this will be deconstructed on the Archeology list serve. I’ll let you know..

Comments

  1. #1 CS
    December 6, 2007

    “The researchers used several precision analytical techniques, including time-of-flight secondary ion mass spectrometry.”

    GL: Nope, I’m not buying it. Ions are everywhere….

    I don’t know if you were joking or don’t really know, but “time-of-flight secondary ion mass spectrometry” is not searching for ions any more than Magnetic Resonance Imaging (MRI) is looking for magnets in your body. Mass spectrometers take molecules and give them a charge (sometimes after breaking them into smaller pieces), turning them into ions, so that they may be accelerated under electric fields. How those ions behave under that electric force allows their masses to be determined. “Ions” refers to the testing technique, not the test subject.

  2. #2 Greg Laden
    December 6, 2007

    I was joking about the ions. But I do appreciate the description!

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