Scientific American has a nice article on how the anatomy of the human body has evolved, and how many of the designs that worked well for human ancestors are now maladies in human beings.
Routing of nerves and fluid pathways in the human body resembles the tangle of wiring and pipes in an aging house, a heritage from fish and amphibian ancestors.
Nerves that are inherited from fish and travel from the brain to the diaphragm can become irritated and trigger hiccups, a closing of the entryway to the windpipe, an action that itself is a hand-me-down from amphibians that breathe with both lungs and gills.
Complete article at http://www.scientificamerican.com/article.cfm?id=this-old-body