Most discussion involving evolution of humans has been centered on australopithecines. In the 1970s it was noted that australophithecines have small incisors compared with molars which made it believed that this could show the diet of ancient humans. incisor size might give us some clues to diet and tooth use for the early australopithecines, and we have good, consistent weight estimates from independent studies Chimpanzees and orangutans fall above the line, whereas gibbons and gorillas fall close to the line, with relatively smaller incisors. Relative incisor sizes for the three “gracile” australopithecines are remarkably similar, and they fall very close to the regression line, much like the gorilla. These results are similar to those and suggest that these hominids used their incisors in ingestion to a similar degree, although they all probably used these teeth less than either the chimpanzee or orangutan. One of the hallmarks of the australopithecines has always been their large, relatively flat molars. There are certainly differences in the amount of relief between slender and robust australopithecines. Food is a complicated structure. For example, tough foods, those that are difficult to fracture, are generally sheared between the leading edges of sharp crests. Basically, more folivorous species have the highest shearing quotients, followed by those that prefer brittle, soft fruits; finally, hard-object feeders have the lowest shearing quotients. As for the early hominids, A. africanus had more occlusal relief than did Paranthropus robustus, suggesting a dietary difference between these species. Next, is enamel thickness. The most frequently cited
