Saturday, February 18, 2012

The "Net-Plus" Hypothesis


Building off my last post, I began thinking more about vestigial organs. The appendix in particular is worthy of further understanding because for something without much purpose, it somehow m
anages to affect humans rather frequently.

Appendicitis is no longer a rarity, but a norm. As a society, we accept the commonplace nature of this emergency procedure, and we tend not to think much about it. Interestingly, as curious as we are as a society, we fail to really ask the deeper questions. Personally, I've been around friends and siblings who have had appendicitis, and in every case, the process is standard: complaint of pain, emergency visit to the hospital, doctor diagnoses patient with appendicitis, surgical removal of appendix, patient recovery and discharge from hospital. Nowhere along the way, is there really much questioning of what exactly causes the appendix, could it have been prevented, is there any other option? What is the appendix really for?

Basically, our society has just become complacent with the appendicitis occurrence and we tend not to think anything of it more than just a standard medical procedure.

As I did more exploring, I came across this interesting NY times article that discusses the views of Dr. Rebecca Fisher, a physical anthropologist. This article caught my attention because Dr. Fisher asks many of the same questions that I have asked myself and I think she really sheds new perspect
ive on the situation.

To begin with, she asks one of the most fundamental questions in my opinion: If approximately 250-000-300,000 (NY times, Jan 2010) appendectomies are performed a year in the US alone, then why is it that this one organ is failing in so many healthy individuals? More interestingly, Dr. Fisher makes a great point in that we never hear about appendix transplants; it is either appendix or absolutely no appendix...which really opens up a whole range of puzzling questions.

Dr. Fisher continues to elaborate on the proposed functions and theories of the appendix such as the immunity assistance with vital gut bacteria. She then evaluates the appendix from an evolutionary perspective. Looking at phylogenetic records, it is highly likely that humans and chimpanzees descended from a common ancestor that did have an appendix. However, upon detailed assessment of other species in the primate family shows an inconsistent pattern of appendix presence.

Nevertheless, Dr. Fisher posits that such a disposable and problem-inducing organ really should be classified as maladaptive and it does not make sense how it could have continued to evolve. However, this theory contradicts Darwin's traditional views.

Other possible explanations presented by the article is that maybe there is a dual nature of the appendix based upon specific life stages. It could be that the appendix was a necessary organ in children to help them resist certain childhood diseases. The problems attributed could be something that developed later on in life. On the other hand, some researchers believe that our modern-day society makes us more vulnerable to appendicitis due to changes in our lifestyle (sanitation, food, etc).


After considering these facts and theories, Dr. Fisher concludes by presenting the "net-plus" hypothesis in which appendicitis, or essentially appendix usefulness, should be viewed as a trade-off situation. In which, the benefit of potentially avoiding certain diseases results in overall net benefits that outweigh painful symptoms that can be alleviated by surgical procedure.

I was very impressed by Dr. Fisher's theory and I think provides a more encompassing explanation for the paradoxical nature of this mysterious organ. It begs the question, that granted the appendix has remained in our human lineage thus far, will the changes in our lifestyles such as better hygiene dramatically change the evolutionary trend of the appendix in the future?

Sources:
Zimmer, Carl. The Riddle of the Appendix. The New York Times. August 2005.
http://www.nytimes.com/2005/08/09/science/09case.html

2 comments:

  1. What if appendices really have become detrimental to human health? It's just that with such great advancement in healthcare practices and the lack of selection for appendices that won't kill us that malfunctioning appendices have become the norm rather than a rarity?

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  2. I agree. I think this topic and the purpose of the appendix is really a topic that should be reopened for discussion within the scientific and medical community. I think the changing norm is a major signal that maybe there is more to the story than we as evolutionists know.

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