Final answer:
The skull has evolved significantly from chimpanzees to Homo sapiens, with humans developing a significantly larger brain capacity, a reduction in face, jaw, and tooth size, and the advent of skulls with rounded shapes and steep foreheads. These changes, which occurred alongside the development of culture and technology, corresponded with periods of rapid climate change, contributing to the survival and dominance of human species.
Step-by-step explanation:
The changes in the skull from chimpanzees to Homo sapiens reflect crucial adaptations in the hominid lineage. Originally, a common ancestor gave rise to the distinct lines of humans and chimpanzees, with chimpanzees retaining a skull with a smaller brain capacity, approximately 350 cubic centimeters (cc), similar to the early fossil ape Sahelanthropus tchadensis. In contrast, Homo sapiens developed a much larger brain size, averaging around 1,400 cc, accompanied by smaller faces, jaws, and front teeth.
For instance, Homo habilis, a species that lived around 2.5 million years ago, had a brain size of about 800 cc, and Homo rudolfensis, which lived during the same period, also had a larger brain than chimpanzees. These changes corresponded with new adaptive behaviors such as tool-making. More recently, around 200,000 years ago, Homo sapiens with similar physical characteristics to modern humans emerged, featuring rounded skulls, steep foreheads, and smaller teeth. The brain size increased even more rapidly between about 800,000 and 100,000 years ago, which included the development of culture and technology, paralleling the biological evolution of the brain.
During this period of rapid climate change, a larger, more complex brain provided a significant advantage. For example, Australopithecus afarensis had a skull that resembled that of modern humans but was smaller with a sloped forehead, larger teeth, and a prominent jaw. Over time, the modern human skull shape evolved to support a high level of cognitive function and sophisticated social interactions. This evolution enabled our ancestors to survive in varying environments and become the dominant land animals.