Bipedalism and parturition: an evolutionary imperative for cesarean delivery?

Human biologic evolution involves a compromise between the physical adaptations for bipedalism with effects on birthing success and the much later increases in encephalization of our species. Much of what comes to define life history parameters like gestation length, and brain and birth weight in our species is best understood from this evolutionary perspective. Human populations have been dealing with the obstetric dilemma for many hundreds of thousands of years and modern biomedicine, using techniques like cesarean sections, has alleviated, but not eliminated, birthing as a "scar" of human evolution. If women begin to demand access to universal cesarean delivery, what will the outcome be for the future of human evolution? We can only speculate on the social, biologic, and demographic costs of this transition.