Abstract: The skeletal specimens of the ankylosing spondylitis used in this study were from the Neolithic period sites of Xiawanggang in Henan province and Banpo in Shaanxi province, as well as the burial sifts of Han Dynasty of Shouzhou city and Beiwei Dynasty of Daton city in Shanxi province. These pathological specimens are preserved in local museum or Archaeological Teams, separately.
The method used to observe pathological pattern, that is to say, the diagnosis of the ankylosing spodylitis mainly based on the presence of the annulus fibrosus calcification, the sacroiliac fusion or erosion. In addition, the presence of the cervical vertebrae fusion should serve as an criteria for the diagnosis of the ankylosing spondylitis. At the same time, the zygoapophyseal joint fusion, even when limited to two vertebrae, appears indicative of the ankylosing spondylitis. The results of the observation in this study are as follows.
The nine individuals with the ankylosing spondylitis are identified among observed 322 individuals of three populations from the Neolithic period to the historic period (see Table 1). From table 1, it is found that the frequency of the ankylosing spondylitis in ancient Chinese varied in individual populations from 2.3% to 3.4%, and the significant time-related frequency is not present. The mean frequency of the individual is calculated as 2.8%, which is similar to that of the ancient population in America (2.7%).
In five cases of the sacroiliac fusion, one case appears the complete fusion of the sacroiliac joint and the suture of sacroiliac joint is closed and lost completely. Other four cases also show the sacroiliac fusion, but the sutures of the sacroiliac joint are closed incompletely. From the back sides, the sutures of all of the saccoiliac joints are closed and lost completely.
In four cases of the spine fusion, one case is afflicted with the fusion of the cervical and post-cervical zygoapophyseals (IC-IVC), one case is afflicted with the ankylosing of thoracic vertebral joint fusion (III T-VI T), other two cases are afflicted with the lumbar fusion characterized by the ossified outer fibers appears a smooth and undulating surface of bone connecting the vertebrate, but it shows no typical "bamboo spine".
In view of these cases as mentioned above, it is reasonable to conclude that Chinese people have afflicted with the ankylosing spondylitis since the Neolithic period. From comparative results of the mean frequency in individual populations, it can be seen that the frequency is not statistically different from that noted among ancient populations in China or America, or between both. The comparison of sex ratios, however, in the individuals with sacroiliac fusion reveals marked difference between ancient Chinese and American, the frequency of sacroiliac fusion of male is higher than that of the female for American. On the contrary, the frequency of sacroiliac joint of female is higher than that of the male for Chinese.
The author expresses his thanks for helpful advice and encouragment of Professor Bruce M. Rothschild of the Arthritis Center of Northeast Ohio. The author also wishes to thank Dr. Bruce Latimer, Director of Department of Cleveland Museum of Natural History, Professor J.Desmond Clark, Director of Laboratory for Human Evolutionary Studies, University of California, Berkeley for their kind permission to compare the skeletal pathological materials in their care, and Dr.D.R.Gary, Dr. Dennis Etler and Mr. Peng Langlin for their useful cooperations.

Key words: Ankylosing spondylitis; Ancient Chinese