What this paper shows is that an ancestral allele believed to have been lost during wheat domestication, was actually present in 19th century wheat cultivars. What this means is that (a) the derived allele may not be fixed (100% frequency) but may co-exist with the ancestral one, and (b) if it is indeed fixed, then this fixation did not occur in Neolithic times, but over the last century and a half or so.
Journal of Archaeological Science doi:10.1016/j.jas.2010.04.003
Re-evaluating the history of the wheat domestication gene NAM-B1 using historical plant material
Linnéa Asplund et al.
The development of agriculture is closely associated with the domestication of wheat, one of the earliest crop species. During domestication key genes underlying traits important to Neolithic agriculture were targeted by selection. One gene believed to be such a domestication gene is NAM-B1, affecting both nutritional quality and yield but with opposite effects. A null mutation, first arisen in emmer wheat, decreases the nutritional quality but delays maturity and increases grain size; previously the ancestral allele was believed lost during the domestication of durum and bread wheat by indirect selection for larger grain. By genotyping 63 historical seed samples originating from the 1862 International Exhibition in London, we found that the ancestral allele was present in two spelt wheat and two bread wheat cultivars widely cultivated at the time. This suggests that fixation of the mutated allele of NAM-B1 in bread wheat, if at all, occurred during modern crop improvement rather than during domestication. We also discuss the value of using archaeological and historical plant material to further the understanding of the development of agriculture.