Most of our internal organs have pretty clear job descriptions, but there is one organ that doesn't seem to serve any purpose at all.

In fact, the only time we notice it is when it stops working, which can be fatal within days unless the organ is removed.

The "Vestigial" Organ

The organ we're talking about is the appendix. It's a small tube about three and a half inches long, attached to the beginning of our large intestine.

Some scientists think it might have served some purpose far back in our evolution, and that the modern appendix is "vestigial," or left over. Only humans and apes have appendixes, whereas the rest of the animal kingdom seems to do fine without them.

Bacteria Factory?

There are two main theories about the function of the appendix. Some experts think it serves as a factory for bacteria that help us digest the cellulose in some plants we eat.

However, most scientists believe that both the appendix and the tonsils are part of our immune system, manufacturing B-Lymphocytes, which are white blood cells that produce antibodies to fight infections in the body.

Living Without

Whatever the appendix really does, we know we can live without it. About 1 in 15 of us has to have a malfunctioning appendix removed, since appendicitis can be fatal.

That's a pretty high survival risk to face for an organ that doesn't do something good for us. If it didn't, natural selection probably would have done away with it by now. It's probably best that the appendix not be removed if nothing is wrong with it.