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CarbonRobot CarbonRobot
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Posts: 393
Rep: 8 0
2 months ago
I was wondering if anyone has studied appendixes that are removed due to appendicitis versus those that never get infected and aren't removed until maybe an autopsy? They say it's a vestigial organ that we don't need, but I wonder if those that keep theirs have a less devolved organ that has more function still and stays more active?
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wrote...
Educator
2 months ago
The fact that people classify it as a vestigial structure is someone of a theory. In 2007 a group of scientists announced that the appendix houses beneficial bacteria essential to the digestive system. According to this research, the appendix repopulates the gut with healthy bacteria in response to conditions such as dysentery and diarrhea.

For reasons not fully understood, the appendix can become infected and filled with pus - particularly in children, teenagers, and young adults - resulting in appendicitis. This is where its removal becomes necessary. However, just because we can live without it, doesn't mean it's not required.

So to go back to your question, if you were to take an autopsy of a corpse with an appendix still in tact, it would be no different than any other person's appendix. We can probably even argue that those who had their appendix removed likely didn't have healthy gut bacteria at one point in their lives. This can be due to antibiotic use (which I believe was the case for me), dietary choices, etc.
CarbonRobot Author
wrote...
2 months ago
"However, just because we can live without it, doesn't mean it's not required."

Isn't that the definition of required in biology?

7% of people have it removed. That seems like a high number compared to other organs that are much more vital that are rarely removed.
wrote...
Educator
2 months ago
Of those 7%, do you have stats on their longevity? Perhaps this something we should look at. I will do some research and get back to you
wrote...
Educator
2 months ago Edited: 2 months ago, bio_man
The closest thing I found was this article:

https://onlinelibrary.wiley.com/doi/full/10.1111/joa.13501

The cecal appendix had been considered as a useless vestige since Darwin's work, but recent research questioned this idea demonstrating that the cecal appendix appeared among the mammals at least 80 million years ago and has made multiple and independent appearances without any obvious correlation with diet, social life, ecology, or size of the cecum. However, functions and probable selective advantage conferred by this anatomical structure still remain enigmatic. We found, through analyses of data on 258 mammalian species, that cecal appendix presence is correlated with increased maximal observed longevity. This is the first demonstration of a correlation between cecal appendix presence and life history. Interestingly, the classical evolutionary theory of aging that predicts an increased longevity when the extrinsic mortality is reduced has been questioned several times, but recent comparative studies asserted its validity in the taxa, which experience age-dependent and density-dependent mortality, as in mammals. Thus, the cecal appendix may contribute to the increase in longevity through a reduction of extrinsic mortality. A lower risk of fatal infectious diarrhea is one of the most plausible hypotheses that could explain it. However, several hypotheses coexist about the possible functions of the cecal appendix, and our results provide new insights about this much-disputed question. In addition, we show that the cecal appendix arose at least 16 times and was lost only once during the evolutionary history of the considered mammals, an asymmetry that supports the existence of a positive selective of this structure.

However, there are obvious problems with the study, one being that it is not focused on humans alone, but mammals. I didn't realize that animals have appendixes too; shows what I know Grinning Face with Smiling Eyes It also doesn't compare those humans with an appendix and those humans without.
CarbonRobot Author
wrote...
2 months ago
The closest thing I found was this article: https://onlinelibrary.wiley.com/doi/full/10.1111/joa.13501
The cecal appendix had been considered as a useless vestige since Darwin's work, but recent research questioned this idea demonstrating that the cecal appendix appeared among the mammals at least 80 million years ago and has made multiple and independent appearances without any obvious correlation with diet, social life, ecology, or size of the cecum. However, functions and probable selective advantage conferred by this anatomical structure still remain enigmatic. We found, through analyses of data on 258 mammalian species, that cecal appendix presence is correlated with increased maximal observed longevity. This is the first demonstration of a correlation between cecal appendix presence and life history. Interestingly, the classical evolutionary theory of aging that predicts an increased longevity when the extrinsic mortality is reduced has been questioned several times, but recent comparative studies asserted its validity in the taxa, which experience age-dependent and density-dependent mortality, as in mammals. Thus, the cecal appendix may contribute to the increase in longevity through a reduction of extrinsic mortality. A lower risk of fatal infectious diarrhea is one of the most plausible hypotheses that could explain it. However, several hypotheses coexist about the possible functions of the cecal appendix, and our results provide new insights about this much-disputed question. In addition, we show that the cecal appendix arose at least 16 times and was lost only once during the evolutionary history of the considered mammals, an asymmetry that supports the existence of a positive selective of this structure.
However, there are obvious problems with the study, one being that it is not focused on humans alone, but mammals. I didn't realize that animals have appendixes too; shows what I know Grinning Face with Smiling Eyes It also doesn't compare those humans with an appendix and those humans without.

I have heard removing an appendix reduces the chance of getting Parkinson's by a factor of 6, so that is good anyway.
wrote...
Educator
2 months ago
Just an epidemiological analysis. It's no different that linking how many movies people watch per year to the kind of cheese they enjoy Grinning Face with Smiling Eyes Just because there's a correlation, doesn't mean anything.

Parkinson’s disease (PD) has long been considered a brain disease, but studies now point to the gastrointestinal (GI) tract as a potential starting point for PD. In particular, the human vermiform appendix has been implicated in PD. The appendix is a tissue rich in immune cells, serving as part of the gut-associated lymphoid tissue and as a storehouse for the gut microbiome. The functions of the appendix converge with recent evidence demonstrating that gut inflammation and shifts in the microbiome are linked to PD. Some epidemiological studies have linked removal of the appendix to lowered PD risk, though there is controversy among these associations. What is apparent is that there is an abundance of aggregated forms of α-synuclein in the appendix relevant to PD pathology. α-Synuclein pathology is thought to propagate from gut to brain via the vagus nerve, which innervates GI tract locations, including the appendix. Remarkably, α-synuclein aggregates in the appendix occur not only in PD patients, but are also present in healthy individuals. This has led to the proposal that in the appendix α-synuclein aggregates are not unique to PD. Moreover, the molecular events leading to PD and the mechanisms by which α-synuclein aggregates transfers from gut to brain may be identifiable in the human appendix. The influence of the appendix on GI inflammation, autoimmunity, microbiome storage, and the lymphatic system may be yet unexplored mechanisms by which the appendix contributes to PD. Overall, the appendix represents a promising tissue site to advance our understanding of PD pathobiology.

The overall conclusion was that the appendix is a promising area of research for understanding the development of Parkinson's disease based on this one idea of how alpha-synuclein aggregates, which are found in the appendix, are linked to Parkinson's disease.
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