Why do we have an appendix?

Biological Insight

The appendix sits at the junction of the small and large intestine like a tiny dead-end alley off a major highway. For most of the 20th century, surgeons removed them casually - often preemptively, while they were in there for something else. Why not? It did nothing. Except it does do something. Your gut contains roughly 38 trillion bacteria - more bacterial cells than human cells in your entire body. These bacteria aren't passengers; they're essential partners in digestion, immune function, and even mood regulation. When you get severe diarrhea, food poisoning, or cholera, these bacterial communities get flushed out. The gut becomes a wasteland. And this is where the appendix earns its keep. That little dead-end alley? It's a bomb shelter. Protected from the main flow of the intestine, it maintains a reserve population of beneficial bacteria. After the catastrophe passes, these survivors emerge and recolonize the gut. The appendix is a backup drive for your microbiome. People without appendixes recover more slowly from gut infections and have higher rates of certain intestinal diseases. The organ we spent a century dismissing as useless was actually a resilience mechanism we didn't understand. The business parallel writes itself. Every organization has its 'appendixes' - departments, processes, or people that seem to serve no current purpose. The instinct is to cut them for efficiency. But some of those appendixes are maintaining capabilities, relationships, or knowledge that only reveal their value during a crisis. The question isn't 'what does this do today?' It's 'what does this do when everything goes wrong?'