Your Appendix Might Be Important After All

Posted: Jan 12 2017, 9:00am CST | by , Updated: Jan 12 2017, 9:29am CST, in News | Latest Science News

Your Appendix Might Be Important After All
Photo Credit: Getty Images

You probably learned a lot about human evolution while you were in school, and one of the things you learned (either in class or because of classmates) is that the appendix, like the tailbone and the wisdom teeth, isn't actually essential to our health anymore.

While our wisdom teeth really do just cause us pain, a new study shows that your appendix might actually serve an important biological function that we shouldn't be so quick to give up.

Researchers from Midwestern University traced the usage of the appendix in several mammal lineages over the last 11 million years, looking at how many times it was taken away and brought back. They found out that the organ has evolved at least 29 times and as many as 41 times throughout mammalian evolution. It has only been lost, at most, 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 made comebacks, that means it has to be good for something, even though conventional wisdom says that it is simply a remnant of another organ that we don't need.

The reason it still exists is because it is too "evolutionarily expensive" to eliminate it altogether. This means it would take too much to get rid of it, and since it doesn't harm us, the body hasn't really taken to eliminating it.

So why might you want to keep it?

A 2012 study shows that people without an appendix were 4x more likely to have Clostridium difficile colitis - a bacterial infection that causes diarrhea, fever, nausea, and abdominal pain.

The team at Midwestern gathered their data from 533 mammal species over the last 11.244 million years. They traced how the appendix evolved through years of evolution and found that once the organ appeared, it was almost never lost, according to Science Alert.

"[T]he appendix has evolved independently in several mammal lineages, over 30 separate times, and almost never disappears from a lineage once it has appeared," the team explains in a press statement. "This suggests that the appendix likely serves an adaptive purpose."

Researchers then considered ecological factors - such as behavior, diet, habitat, and climate - in order to find out what the "adaptive purpose" could be. What they found was that species who had an appendix had higher concentrations of lymphoid (immune) tissue in the cecum, a small pouch connected to the small and large intestines. The thought is that it regulates gut bacteria.

"While these links between the appendix and cecal factors have been suggested before, this is the first time they have been statistically validated," the team concludes in their paper. "The association between appendix presence and lymphoid tissue provides support for the immune hypothesis of appendix evolution."

While the study isn't conclusive, it is something that we need to look into to see if removing the appendix could harm our immune system.

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The Author

<a href="/latest_stories/all/all/46" rel="author">Noel Diem</a>
Noel passion is to write about geek culture.




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