You Use Your Appendix For What?

When I was a preschooler (I can’t remember my exact age), a first cousin died from a ruptured appendix. I barely remember her, but I still vividly recall every detail of the night she died.

All my life, I’ve had the impression the appendix was a useless organ. It simply existed in our digestive tracts, and if it got inflamed, it was (had to be) taken out, with no apparent adverse consequences. So who needs it?

This is why I was surprised to find “Your Appendix is Not, in Fact, Useless. This Anatomy Professor Explains” by Selena Simmons-Duffin on the National Public Radio website ( The hero of this story is Heather Smith, a professor of anatomy at Midwestern University and editor-in-chief of a journal called The Anatomical Record. Dr. Smith became intrigued about this pinky-sized organ as a 12-year-old when her case of appendicitis and resulting emergency surgery marred a family ski trip.

So what has this course of study taught her? First, the appendix has actually evolved independently multiple times throughout mammalian evolution. This would suggest it has some sort of beneficial role.

So what is this beneficial role? Big buildup for the big letdown — we still don’t know for sure. But there appear to be two related functions.

— The appendix has a high concentration of immune tissue, and that helps our immune system fight any bad things in the gut.

— It could serve as a safe house. During times of gastrointestinal distress (think diarrhea) when all of your good bacteria is unavoidably getting flushed out of the system, the appendix can serve (as a blind tube with a very narrow diameter) as a refuge where good bacteria can hide out until it’s safe to repopulate the gut again.  

The broader lesson is the importance of looking into small anatomical details. Do we know everything about our bodies? It’s a mistake to think yes. There’s actually a lot more variation and microanatomical adaptations that haven’t been fully explored. It’s easy to be charmed into studying exotic animals, but there’s still a lot to be learned about ourselves.

To read more about the humble, unappreciated appendix, check out the full article at the link above.

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