teach me

I had my first pseudo-teacher-like interaction today.
The professor that I TA for told one of the students who had a question in the previous sessions that I had an answer for her.
I her and the whole class my answer.
(the prof knew this because I had brought it up after the last class.)

anyway. class proceeded.
then after class while I was putting away cast skulls of the predecessors of our human lineage,
the same woman approached me.
older, maybe 40, she's one of those who might actually put a bit more effort into the undergrad- required class.

the question was basically this:
orrorin tugenensis, which is a 6 million-year-old find, was thought to be bipedal.
however, the issue with the femur found was that the bone had the cortex (outer hard portion of the bone) resembling that of a gorilla.

my professor didn't exactly know what this meant. i did.
i explained to her that cortical differences vary, because where the gorilla doesn't need to support all its weight on two legs, it doesn't require any specialization in the femur bone,
therefore the cortex is symetrical all up and down the femur bone.
but what human evolution has done, is taken the femur and angled it inward so the majority of our weight and supported it at a point more directly below the pelvis. this allows for more balance.
but what it also does is put further stress on the femur that now isn't columnar like a gorilla's femur.
so over time, the femur in humans has built a thicker cortex in the proximal (upper) regions of the bone on the main part of the shaft to absorb shock.

"my" student takes this knowlegde and returns to me the story of how she went to europe for two and a half weeks. before and after her trip she got a cortical thickness test.
apparently results showed that her bone density increased after all the rigorous activity she'd received while on vacation.

i look at her and don't really know what to say.
i appreciate your interest, but what you've given me really has no correlation to what i've told you.
yes, bone density increases with use, just as the number of muscle fibers increase with use.
but what you are telling me is about an individual event, whereas what i'm giving you is an evolutionary example. a change that can't happen in one person's lifetime.

granted, this is pretty much a 101 class, and i was once that dumb about the science.
but what the hell am i supposed to do?!
you give me no correlation to work with so i just stare back at you.
i'm glad you have had a life experience, but please try to make it relevant to what i'm trying to inform you with. i'm not telling you how i got buff legs from wandering around europe for 2 and a half month.
what the hell would you say in response to that? "good"?
exactly...

thanks for thinking, but if you wanted a discussion (which is what i was looking for), try again.
(is this what teaching all college students would be like?!)