Obligate Midwifery

As humans, one characterisitc that defines us as a species is obligate miwifery.  Although there is not guarentee and neonate would surive with a midwife or not survive without one, the changes of survival by the neonate greatly increased if a midwife is present.  There are several factors which lead to a more complicated birth which resulted in the need for a midwife.  First, obligate bipedalism resulted in changes to the pelvis which narrowed the birth canal of the pelvis as well as lead to protrusion into the birth canal by the pelvic bones to form muscle attachments.  At the same time, the brain size of humans were getting larger.  The evolution of human was pushed by both these factors at the same time.  During birth, the neonate twists in the birth canal and exits so the it faces away from the mother, therefore the mother cannot pull the neonate out like in other primate species.