Originally Posted by zahratustra
If you don't nitpick on a detail or two but study nature in its variety, you will discover that along with some amazing stuff it also contain a lot of examples of, judging by human standards, shoddiness.
Bipedal vertebrates usually carry much of the spine roughly horizontally, and balance it with a tail. Equally, a string of cotton reels with spongy cushions between is a good cantilever bridge type design for flexible quadrupedal running. But it's a lousy thing to stand on its end and withstand the compression strains of vertical bipedalism. Compression strains are best absorbed by pillars. If you want the pillars to be flexible, you put joints in them. In biology, we have examples called 'legs'.
The urethra — the tube via which urine exits the body — is a soft tube. And it runs through the prostate, an organ prone to infection and subsequent swelling.