When I was young in the 1970's, I wanted to a be doctor, so I took the entrance exam to go to Medical School. One of the questions asked us was to rearrange the letters PNEIS into the name of an important human body part which is most useful when erect. Those who answered "spine" are doctors today. The rest of us are sending jokes via email.

Yes, with out a spine the other part is of no use in humans.

But the pass/fail was not determined just on that question alone.

Without the other part, there would be no humans. miles

I thought it started with a rib. But I am not sure.

it didn't continue with a rib though