DIET AND DISCREPANCY BETWEEN TOOTH AND JAW SIZE IN THE YIN-SHANG PERIOD OF CHINA

Tooth to denture base discrepancy (the discrepancy) is the difference between the dental arch length and the sum of crown diameters of teeth in the jaw, a concept which was originally developed in orthodontics, Since the cause-effect relationship between a soft diet and the discr epancy has been demonstrated, the size of the discrepancy should indic ate the amount of load on the masticatory system from chewing foods in jaws from archaeological periods, The dietary condition of 71 citizen s compared to that of 186 slaves from the Yin-Shang period of China wa s reconstructed through a study of the discrepancy. The prevalence of the discrepancy in the Yin-Shang period was around 15%, almost the sam e as it was during the later Jomon to Yayoi (3000-2000 BP) periods, wh en rice agriculture was introduced into Japan, and also the same as fo r present-day pastoralists around Lake Turkana, Kenya. Although the fr equency of the discrepancy was slightly higher in male citizens, there were no significant differences in the frequencies between male citiz ens and female citizens or slaves. The differences in diet may not hav e been fundamental since the Yin-Shang period would be at the very beg inning of the age in which differences of diet according social class began to appear, with implications for the load on the masticatory sys tem. At that time agriculture may not been sufficiently intensified in variety or quantity to have produced a differentiation of the diet be tween social classes. (C) 1997 Wiley-Liss, Inc.