Soybean oil content in charred seeds?
The claim for earliest use of a synchrotron to look at charred archaeological pulse seeds, however, goes to our colleagues in China, in collaboration with Prof. Gary Carwford, Shandong archaeobotanist Xuexiang Chen. They argue that soybean underwent selection for increased oil content in prehistory during domestication-- undoubtedly true-- and that this can be tracked archaeological through a change in the number and size of pores visible on the inside of charred soybeans viewed through the synchrotron and High-Resolution Computed Tomography. I remain unconvinced on this last point, and although the paper reports on examination of modern soybeans and, other oily crop seeds, and experimentally charred seeds none of these are illustrated or really described so as to support this interpretation. The authors infer that more small pore is a product of more oil whereas large pores represent burned out protein, but is this true. The differences look to me more like artefacts of carbonization processes, and not a good proxy for the internal anatomy of the original uncharred soybeans. As the few illustrated example suggest larger and irregular pore are present in seeds with more distorted external surface anatomy (e.g. c), whereas small pores are more evident in better preserved examples (e.g. f).