Wednesday, February 22, 2012

Look Mom...No Hands!

So this article has been floating around the internet lately.

Basically scientist have found the oldest fossil of what is now thought to be the oldest animal life ever.

The article also states that that this fossil that depicts the earliest ancestor of all animals lived 100 million years before predicted.

....and this fits into the blog because this great-great-as-far-as-you-can-go-back grandfather of human kind possesses no appendages.

What was the first appendage? That will be my next post.

Link to the article can be found here.


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?

Zimmer, Carl. The Riddle of the Appendix. The New York Times. August 2005.

Sunday, February 5, 2012

Are vestigial organs really useless?

Humans are equipped with a handful of vestigial, or “useless” organs including the appendix and coccyx (tailbone). According to scientific principle, over generations, natural selection selects for traits that contribute to fitness and in theory with time, vestigial organs would disappear among future humans. However, research suggests that these vestiges may not actually be entirely useless. While we tend to overlook these organs, it is worthy to understand the evolutionary progression of these vestigial parts. Insight into the evolutionary history of vestigial organs may help us understand the importance of these assumed-to-be vestiges and what the future human may be.

The coccyx although does not truly exhibit a function, is an important organ based on its mere structural placement. The coccyx serves as the attachment point between muscles and the pelvis, which allows for locomotion.

A more common vestige, the appendix, originally served to facilitate the digestion of grass many generations ago. However, now research suggests that the appendix is an indirect storage space for certain microbes involved in digestion.

Less known to common knowledge, the pinky toe is also classified as a vestigial organ. However, it has been stipulated that this toe actually assists in maintaining balance and can also alleviate some of the pressure and strain exerted on the foot as whole when running.

Alternatively, there are still some vestigial organs that remain “useless” by definition and serve no real purpose in the modern day human. Wisdom teeth, back ear muscles, and the male nipple are body parts that have not been shown to affect an individual’s fitness, ability to survive and reproduce. It has been postulated, that with enough passage of time, these 3 vestiges may eventually disappear leading to the evolution of a modified human.

So essentially, the underlying message is that the concept vestigial organs as being useless to function is actually false because it is not applicable to all vestiges. Personally, I think this warrants further investigation and discussion within the scientific community to re-evaluate the classification of which organs should be grouped into this category.