Assessment Questions 4.9

The reconfiguration of the human pelvis, necessary for bipedal locomotion, posed challenges by narrowing the pelvic outlet, making it difficult for a baby's body to pass through the birth canal. To address this, evolution fine-tuned the pelvic configuration, maximizing pelvic outlet size in females. Additionally, natural selection timed the birth of human babies at an earlier stage of fetal development, allowing the head, though large, to pass through the birth canal more easily.

The passage suggests that human babies are born at an early stage of physical development due to the reconfiguration of the human pelvis for bipedal locomotion. This reconfiguration, while advantageous for walking upright, resulted in a narrower pelvic outlet, making it difficult for babies with larger heads to pass through. As a solution, human babies are born at an earlier stage of development, which is advantageous for learning and social bonding.

The author characterizes human evolution as not a simple, progressive process with each species thriving in succession, giving way to the next until reaching modern humans. Instead, human evolution is described as far more complex, marked by geographically separated, multiple contemporary hominins.