Thursday, March 26, 2015

Residues and Residues

It has become increasingly common in archaeology to test the working edges of excavated artifacts for the presence of blood or protein residue. In some cases we can determine the species of animal was impaled or cut by the tool. Several years ago I posted about the Mahaffy Cache, a cache of Clovis tools discovered by a landscaping project in near-by Boulder. Analysis of blood residue from some of the tools showed they had been used on Pleistocene camels and horses. I recently saw a paper presented at the Colorado Council of Professional Archaeologists annual meeting, where projectile points excavated from a high-altitude site in western Colorado proved to have protein residue from bighorn sheep.

Good archaeologists don't wash or handle excavated tools anymore.

I recently came across this article about a research program at Cambridge University to identify another sort of residue on projectile points - poison residue. The use of poison arrows for example is well known from history and ethnology, but it doesn't appear that anyone has systematically looked for it on artifacts. Dr. Valentina Borgia of Cambridge is working with forensic chemists to come up with techniques to identify poison residue on artifacts. The ancient Chinese crossbow bolts pictured above are involved with her testing program.


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