SCIENCE NEWS - Some body parts like APPENDIX seem pointless but in fact have purpose

Throughout history, scientists, too, have wondered about structures that don’t seem to do anything useful. The appendix is a popular example. This little, worm-like pouch is about four inches long and less than half an inch wide.The organ grows near where the long intestine meets the short intestine. The intestines are essential for digestion, but the appendix appears to just sit there.
“It’s a dead-end sack,” says William Parker, an immunologist at Duke University in Durham, N.C. “It doesn’t go anywhere.”Parker didn’t start out intending to study the appendix. His specialty is the immune system — a collection of organs, cells and molecules that our bodies use to stay healthy. But his research led him to the appendix anyway.
Parker knew that the human body is full of tiny organisms called bacteria, which can overwhelm the immune system, cause infections and make a person sick. He also knew that some bacteria are good for human health. Among other benefits, these “good” bacteria help people digest food and fight off “bad” bacteria that cause disease.The immune system doesn’t just benefit from good bacteria, though. In the 1990s, Parker and colleagues began to figure out that the immune system also helps good bacteria flourish. These bacteria appear in thin layers called biofilms, which grow on the side of the gut near and inside the appendix. These biofilms, the researchers learned, provide a barrier that keep out bad bacteria. “Once we figured that out, it should have been obvious to us what the appendix did,” says Parker, whose team also found that the appendix has a particularly robust biofilm. “It’s in the perfect spot to harbor bacteria — out of the flow and with a thin, narrow opening. And there’s a large amount of immune tissue associated with it.”
After stumbling on a possible link between the immune system and the appendix, though, the scientists still had some clues to compile before being sure of the organ’s purpose.

Hangout for good bacteria

In 2007, Parker’s team put together all the evidence they had gathered and came up with a conclusion: The appendix serves as a “safe house,” Parker says, a storage bin for good bacteria. If bad bacteria attack, good bacteria emerge from the appendix and come to the rescue.
Having a safe space for good bacteria should be especially useful in parts of the world that are poor and undeveloped — places where people are starving, medicine is hard to come by, clean water is scarce and diarrhea can kill. In those places, Parker says, the appendix probably helps keep people alive, especially young children.
In fact, people in the developing world rarely get infected appendixes, like Smith’s. Most cases of appendicitis, in fact, occur in the United States and other developed countries, where water is purified, hospitals are sterilized and medical care is easier to get.

Those trends suggest that the appendix evolved in our ancestors to maintain health in a bacteria-filled world. Today, places such as the United States might be too sterile for the appendix. When the organ has nothing do, the immune system can turn on itself, sending people to the emergency room, Parker says. Other problems, such as allergies and immune diseases, might have similar roots.

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