Using the Diamond Light Source, researchers have documented the rate of evolution of seed-coat thinning, a primary marker of crop domestication, from archaeological remains. They reported evidence for seed-coat thinning between 2000 BC and 1200 BC in the legume horsegram (Macrotyloma uniflorum), a bean commonly eaten in southern India.
According to the researchers, conventional methods used to study the seed coat necessitate breaking and destroying archaeological specimens. “Being able to look at the seed coat thickness without breaking the sample is possible by other methods, but you can only look at a spot on the seed,” explained co-author Charlene Murphy. “The beamline at Diamond has allowed us to look at the entire seed, and has shown considerable variation within individual specimen’s seed coat thickness.”
Christoph Rau, Principal Beamline Scientist on I13, where the work was carried out, said, “The beamline … has enabled the team to produce 3-D images of the seeds with incredible micrometer scale resolution, without damaging their precious samples.”