Nice to hear from you. I'd like to reply at once but I am at office so this instant, I can only ask one question that is worth considering:
There must be something behind why anal canal have to be separated from reproductive organs and urinational organ. It is true both for men and women. I have once wondered why urinational organ can share the same ducts in men and get so near with vagina (or almost same location with vagina) in women, but it's not the case for anus.
Have to research more about this.
Lyon