The consequences of narrow pelves are dire and obvious. Baby stuck in pelvis is fatal for both. Alternatives also are bad. Small, preterm or low birth weight children are vulnerable. Narrow pelvis is so bad that pretty bad alternatives are evolved against it. Think of the importance of pelvis. Pelvis, like skull, consists of several bones, but these are fused into one rigid ring. Consider that pelvis carries the weight of man: the weight of backbone is cantilevered sidewards through sacroiliac joints to hip joints and thence to legs. Yet the pelvis of a woman literally disintegrates during pregnancy: sacroiliac joints (and pubic joint) undergo subluxation and move apart a long distance. Then they cannot support the weight! Women suffer intense and chronic back paint during pregnancy and often cannot walk. Now, why are pelves narrow? Narrow pelves are supposed to have evolved as man rose to walk, as adaptations to walk. Precisely how is a narrow pelvis better adapted to walk? Women with narrower than average hips and pelves suffer the complications described above. But what is the trouble with wide hipped women - women who have naturally wide girth not due to fat but wider than average pelvis bones before they get pregnant? Does wide pelvis´ unsuitability for walking get expressed in some forms of illnesses that are specifically complications of being big boned? How does natural selection eliminate wider hipped mothers so that the narrow hipped women continue to get born despite often dying in childbirth?