 He observed that Watson's thesis did not depend on claims of new introductions of plants into any region, but of their "diffusion and normalization", i.e.of their becoming widely and generally used, even if they were known from Roman times.Calling Watson's "philological" approach "old fashioned", and given that Watson had worked "virtually without archaeology", Squatrini expressed surprise that recent research in archaeobotany had failed to "decisively undermine" Watson's thesis.