Your appendix might serve an important biological function after all

One of the first things you learn about evolution in school is that the human body has a number of 'vestigial' parts - appendix, wisdom teeth, tailbone - that gradually fell out of use as we adapted to more advanced lifestyles than our primitive ancestors.

But while our wisdom teeth are definitely causing us more pain than good right now, the human appendix could be more than just a ticking time bomb sitting in your abdomen. A new study says it could actually serve an important biological function - and one that humans aren’t ready to give up.

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.

"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."

If the appendix has been making multiple comebacks in humans and other mammals across millions of years, what exactly is it good for?

Conventional wisdom states that the human appendix is the shrunken remnant of an organ that once played an important role in a remote ancestor of humans millions of years ago.

The reason it still exists - and occasionally has to be removed due to potentially fatal inflammation and rupturing - is that it’s too 'evolutionarily expensive' to get rid of altogether. There's little evolutionary pressure to lose such a significant part of the body.

In other words, the amount of effort it would take for the human species to gradually lose the appendix though thousands of years of evolution is just not worth it, because in the majority of people, it just sits there not hurting anyone.

But what if it's doing more than just sitting there?

For years now, researchers have been searching for a possible function of the human appendix, and the leading hypothesis is that it’s a haven for 'good' intestinal bacteria that help us keep certain infections at bay.

One of the best pieces of evidence we’ve had for this suggestion is a 2012 study, which found that individuals without an appendix were four times more likely to have a recurrence of Clostridium difficile colitis - a bacterial infection that causes diarrhoea, fever, nausea, and abdominal pain.

As Scientific American explains, recurrence in individuals with their appendix intact occurred in 11 percent of cases reported at the Winthrop-University Hospital in New York, while recurrence in individuals without their appendix occurred in 48 percent of cases.

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Last Edited by STAX on 10/09/2020 11:53 PM