Midwestern University researchers have found an interesting fact about the human appendix. Apparently, there's more to it than what is commonly believed.

It is a widespread notion that the appendix is one of the "vestigial" parts of the human body along with the wisdom teeth and tailbone. Science Alert reported that Midwestern University researchers have been able to trace the appearance, disappearance and reappearance of the appendix.

The internal organ has been in and out of mammals' bodies over the past 11 million years. The scientists learned that it may have evolved a minimum of 29 times or a maximum of 41 times throughout the mammalian evolution. It was also noted that the appendix has only been lost by mammals about 12 times.

The study was published in the journal "Elsevier." The scientists explained that the appendix's disappearance and reappearance through the years debunks the notion that it is a useless organ with little value or function among mammals.

The most popular hypothesis regarding the use of the appendix is that it is a "haven for good intestinal bacteria." The presence of the organ in mammals' bodies may be the one thing that helps fight infections.

According to Quartz, animals with an appendix have a higher concentration of lymphoid tissue in the cecum, which is part of the digestive tract. This tissue, as said by Heather Smith, an anatomist and lead author of the paper, is filled with cells that create an immune reaction when the body is under stress.

The new study also supported the fact that the appendix is a container of emergency bacteria. This is used when the gut is wiped clean, especially when humans take antibiotics or get food poisoning.

Smith added that the appendix is filled with "good gut bacteria" that has the ability to repopulate the gut. She clarified that humans can still function without an appendix but it does provide the body with a degree of immunity and beneficial bacteria.