Delivered through duct work

I neglected to post about our recent birthing class experience. It definitely wasn't for lack of material.
People told us ahead of time that they had found the pre-birth class for first-time parents worthless, full of info they didn't ever use.
To my surprise, that wasn't our experience. For the reporter, lots of questions were answered over two days. Many were practical or logistical -- like "Where do we go at the hospital?" and "How much say do parents really have in what the doctor does?" -- but it's all useful. For the mother, much of her anxiety about labor and delivery was alleviated by learning more about it, asking questions and listening to our instructor.
Of course, it wasn't just a buttoned-up baby briefing. You can't go several hours with 14 strangers -- who have the same questions and concerns but different backgrounds -- and not walk away somewhat amused by the whole experience.
Some of us had not thought much about the actual process of labor -- that would be the guys. Others had. One woman said that when she goes into labor she would prefer to snuggle with "animals or loved ones." Yes, animals -- plural. (Nobody had the gall to tell her this is a hospital, not a kennel.)
Even for a "drive-thru" delivery class -- we could have taken a six-week course -- there was a lot of information to digest.
At times, there was too much information. One mom-to-be works on the hospital's NICU floor. She came to the class with knowledge of just about everything that can go wrong in birth -- and decided it was Show and Tell Day. We had to hear about each of those obscure and traumatic scenarios in medical acronym-laced outbursts. The instructor, to her credit and our appreciation, put those Tales of Delivery Horror in perspective, given that in most cases things go just fine.
What's a class without props? We had plenty. The instructor held up a pelvic skeleton as she talked about the baby's positioning, etc. Then, she dug out some duct work and shoved it into the pelvic skeleton to complete the rudimentary but effective visual of a birthing canal.
However, I'm sure someone left that class thinking the birthing canal looks just like the elbow joints attached to a furnace.
Another prop made me think of a question, but I did not ask the question in order to spare Anni the embarrassment of having to sit next to the guy who asked the "What's life mean?"-type of unanswerable question.
See, the instructor's uterus prop was a large sock-like, stitched tube. She discussed the actual reason behind the need to "push" the baby out, that the cervix basically needs to be forced open.
So my question was: In human reproduction, every body part has a role and usually carries out that role on its own -- except for the cervix. The cervix seems lazy. I wondered why, after thousands of years of evolution, the cervix has not learned to "push" itself when the time is right. Why isn't there a hormone that's triggered to carry out that task when there seems to be a hormone for every other step of child-rearing?
I left without an answer.
Maybe that's the kind of topic delved into during the six-week class.