Lucy brought humankind even more problems. If she did not happen to have three small blood vessels in her rectum that kept her anus watertight (the haemorrhoidal veins), she would probably have changed her mind after her first few steps and gone back to walking on four legs. The act of defecation has never succeeded in adapting: we still have to bend our hips at 90 degrees to do it. The fact that this now requires much greater pressure leads to typical human problems like haemorrhoids, prolapses and constipation.
