Final answer:
The dental arcade of modern humans is parabolic, while that of an ape is U-shaped, reflecting evolutionary changes in jaw structure, diet, and brain size.
Step-by-step explanation:
The dental arcade of modern humans is parabolic while that of an ape is U-shaped.
Over the past millions of years, humans have evolved to have distinctive dental features compared to apes. The chimpanzee jaw, for example, protrudes more significantly than that of humans, indicative of the U-shaped dental arcade seen in many non-human primates. On the other hand, human jaws have become less pronounced due to smaller faces and frontal teeth, and our dental arcade has assumed a more parabolic shape. This change accompanies the increased brain size and changes in diet, where humans have shifted towards a diet consisting of cooked foods which require less chewing force than the raw foods eaten by apes.
Comparing early hominids to modern humans, we see that species like Australopithecus afarensis had larger teeth and a more prominent jaw, while modern Homo sapiens exhibit small front teeth, larger, more complex brains, and a reduction in bone mass in the skull and face.
Morphological differences in the dental arcade have also been noted between gracile and robust forms of australopithecines, where gracile species had less flared cheeks and smaller teeth and jaws compared to robust australopithecines, which had features suited for chewing tough plant materials.
In summary, the modern human dental arcade is more refined and less robust than that of apes and early hominids, reflecting changes in diet, facial structure, and brain size.