eli5 How was a whole organ’s usefulness unknown for such a long time(appendix)?

Question

eli5 How was a whole organ’s usefulness unknown for such a long time(appendix)?

In: 190

Answer 1

Interesting most animals the appendix is used for breaking down cellulose. In humans it doesn’t do this.

The assumption was that the breakdown of cellulose was the only function, and that humans, with the more varied diet, no longer needed it. So it became defunct. And since evolution rarely removes something, it just hung around.

It turns out it does more than that. But we were both blindsighted by our observations of its purpose in other animals, and not yet knowledgeable about gut bacteria and their role and importance.

We learned. Because that what science does — it changes over time as more data becomes available.

Edit: cellulose, not chlorophyll. 🤦🏼‍♂️

Edit 2: gut bacteria. With guy (and girl) bacteria.