Written by Girish Khera on

The human appendix, a slimy sac that hangs between the small and large intestine, has always been known as an evolutionary artifact that serves no purpose, but can potentially become a lethal case of inflammation. CDC reports 320,000 people are hospitalized each year and upto 400 Americans die due to appendicitis.

However, recent research studies have suggested that it is a lot more than a just a useless remnant sitting in the abdomen.

Researchers from Midwestern University traced the appearance, disappearance, and reemergence of the appendix in several mammal lineages over the past 11 million years, to figure out how many times it was cut and brought back due to evolutionary pressures.

They found that the organ has evolved at least 29 times - possibly as many as 41 times - throughout mammalian evolution, and has only been lost a maximum of 12 times.

Had the appendix been a vestigial organ, what could be the reason for its multiple comebacks in humans and other mammals across millions of years?

The usual location of appendix is in the lower right side of the abdomen but, in rare cases, it may also be located on the left side (situs inversus).

As indicated by the above numbers, appearance of the appendix is significantly more probable than its loss. Thus, the hypothesis that the appendix has a little adaptive value or function among mammals, can likely be rejected.

The reason it still exists is because it’s too ‘evolutionary expensive’ to lose.

Simply put, for the human species to gradually lose the appendix through thousands of years of evolution, it needs to be causing trouble to everyone, and to be of little use otherwise. But that’s not the case. In fact, it is likely not just dormant in the body.

Some surprising functions of vermiform appendix might be: