Question

In some cases, our bipedal adaptations have changed areas of our bodies so much that it is difficult (if not impossible) for these areas to perform other functions.  For example, our pelvis provides the areas of muscle attachment that we need, but its unusual shape makes human childbirth more difficult. The foot is another area that reflects the impact of bipedal specialization. What foot traits and corresponding functions seen in other primates has been lost in our feet, why would we have lost helpful features such as this?

Answer 1

The mechanical requirements for locomotion, childbirth and thermoregulation often conflicted among hominids during evolution.

The advent of the human modern birth canal, the shape and it's alignment for fetal rotation during birth, allows human species to deal obstetrically with increases in encephalization while maintaining a narrow body to meet thermoregulatory demands and enhance locomotor performance. The width and depth of the pelvis affects ability to regulate body temperature, and thereby influencing heat loss through the body's surface.

Bipedalism slows speed that attributed to the human anatomy. The average human speed was slower than that of other apes, it makes a dangerous trait for survival because hominins became vulnerable to carnivores.