Pointless Organ No More: Appendix Biological Function Discovered
The human appendix has a notorious reputation for its tendency to become inflamed and burst, often resulting in surgical removal. But thanks to this new study, appendix can finally be appreciated.
An international team of researchers, led by Heather F. Smith, Ph.D., Associate Professor, Midwestern University Arizona College of Osteopathic Medicine, found out that appendix actually is not a vestigial organ.
Charles Darwin first theorized that appendix is a shrunken organ from an evolutionary ancestor and it was used to digest leaves.
According to Science Alert, the researchers traced the appearance, disappearance, and reemergence of the appendix in several mammal lineages over the past 11 million years. Their analysis suggested that throughout mammalian evolution, it has only been lost a maximum of 12 times and it almost always never disappears once it existed in a lineage. This implies that the appendix has its strategic and adaptive purpose and has a value that plays a great role in the evolution.
"This statistically strong evidence that the appearance of the appendix is significantly more probable than its loss suggests a selective value for this structure," the team reports.
"Thus, we can confidently reject the hypothesis that the appendix is a vestigial structure with little adaptive value or function among mammals."
Delving deep into the mystery of the appendix, the researchers analyzed the ecological factors and social behaviors of the species with appendix. They found out that they had higher average concentrations of lymphoid (immune) tissue in the cecum, Business Insider reported.
Previous studies revealed that lymphatic tissue can also foster the growth of beneficial gut bacteria.
They concluded therefore that appendix has a paramount role in the immune system of humans and it specifically serves as a reservoir for beneficial gut bacteria. The study marks the first time that the relationship between the immune system and appendix has been proven by statistical analysis.