Previous studies have shown that the gender difference in the tooth size of apes is very obvious, and its evolutionary trend is gradually increasing with the passage of time. These studies are based on the measured data of more than 700 great ape teeth discovered before 1990s. These 700-odd teeth include not only the specimens with accurate strata such as Liucheng Great Ape Cave, Daxin, Wuming, Bama and Jianshi, but also more than 65,438,000 specimens with unknown strata and age in Guangdong, Guangxi and western Hubei.
Since then, 12 fossil sites and hundreds of teeth of great apes have been discovered, most of which are supported by the results of biological chronology or absolute chronology. In view of the supplement of new materials and the new understanding of their age distribution, the researchers divided all the 14 sites in China into three groups in chronological order, and re-measured and statistically analyzed the premolars and molars of 12 18 (table 1) of apes.
Silverman tested the length, width and area of 558 teeth of 5704. Area C of Liucheng Great Ape Cave shows that the sex difference of premolar and molar size of Buchner Great Ape is not as obvious as previously thought. Although the test results can not deny the existence of gender differences, at least statistically, gender differences can be ignored, that is, samples of every tooth in every place can be regarded as simple samples.
The results of variance analysis and Tukey's sHSD test of three measured values in different groups show that the inequality of the average values between all two groups in the basic five groups is meaningful, and then it shows that the increase of the average values of premolars and molars in the first three groups in chronological order (Figure 2) represents a meaningful evolution trend from small to large.