Anatomy Is Now My Life :)

I realize it has been a while since I last posted.  Life has been crazy.  Two and a half weeks ago I started anatomy and I have been going no stop ever since.  I have been reading and diagramming up a storm.  Here are a few of my charts summing up arterial, venous and nervous connections in the thorax.  At this point I have these charts pretty well memorized, and I have been creating similar diagrams for the abdomen.

Thorax Arterial Flow

Thorax Venous Flow

Thorax Nerves

Anatomy lecture consists of a combination of learning anatomical structures along with an explanation of the developmental processes involved in creating those structures.  We also have lab time where we dissect the cadavers so that we can visualize the structures.  It is extremely interesting and there are tons of things about it that I would love to write about, I just have no time. :P

On a random side not, I did finish the angel project that I was working on over winter break, I just never got around to posting it.

Back to reading. :)

Squirrel Resurrection

Three years ago my family discovered a dead squirrel in our basement.  It was unclear how the squirrel got in, or exactly how the squirrel died, but it was in good condition when we found it.  So I convinced my dad to help me bury the squirrel so  that I could get a complete squirrel skeleton.  We wrapped the body of the squirrel in the black mesh that you put down under gardens to prevent weed growth so that the little bones would not get lost.  Next we dug a small hole out behind the shed and put the make shift mesh bag in.  After covering the body with dirt, we covered the burial with a large paving stone.

Today I dug up that squirrel!

Can you feel the anticipation??

Although the squirrel was probably fully skeletonized two years ago, I had completely forgotten about it, and usually when I am home for winter break the ground it frozen so it would be very difficult to recover the squirrel.  This winter has been surprisingly mild, so I was actually able to dig up the squirrel and sit outside for several hours sorting the skeletal remains out of the mass of dirt that has accumulated in the mesh. 

Big reveal!!! ;)

Ooooo, teeny tiny squirrel bones

After sorting out the bones from the dirt clods and roots, I was left with a nearly complete squirrel skeleton.  I was even able to collect most of the phalanges and a good number of carpals and tarsals.  I will need to look for a squirrel reference book, since I am not familiar with how many carpals and tarsals a squirrel should have.  Also, I learned that squirrels only have four toes on their front paws, though they do have five on their hind paws.  I was wondering why I only recovered four sets of metacarpals even after extensive searching so it was exciting to discover that I had actually collected them all.

Fingers and toes!!!

Ribs and verts

Box-o-squirrel

One interesting thing about this particular squirrel is that it was not fully grown.  I can determine this by looking at the epiphyseal fusion.  Epiphyses are the ends of the bones and form separately from the diaphysis or shaft of the element.  The epiphyses form via secondary ossification centers that are disconnected from the shaft.  As an individual grows, the shaft undergoes longitudinal growth (increase in length) reducing the space between the shaft and ends.  Eventually the portions meet along the metaphysis or growth plate and fusion occurs.  When the diaphysis and epiphysis initially come together a line can be seem at the point of union.  Over time this line is obliterated and it is impossible to see where the portions joined.  In this case, the distal femur (top of knee joint), proximal tibia (bottom of knee) and proximal humerus (at shoulder) are all unfused.  Furthermore, the fusion lines are still visible on the distal radius and ulna (wrist). 

After a little more cleaning, and research into squirrel skeletal development I will hopefully have a better idea of what happened to this little guy.  :)

Christmas Mold Fail

In order to understand the following e-mail, you should probably be aware that I am a pack rat and I have a high tolerance for clutter.  My housemate, X*, does not.  X* is one of the most organized and and ridiculously intense cleaners I have ever met.  My second housemate, Y*, is tidy as well, though not quite as intense as X*.  Anyway, yesterday I received this e-mail from my housemate.  I realize that my intense, fridge cleaning housemate has a point, and justifiably it would not be fun to be the one cleaning out the fridge, but this e-mail was hilarious.  I had to stop reading several times because I was laughing so hard. 

*names have been changed to letters to protect the identities of the two offending housemates ;)

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Last night I took advantage of both of you leaving for the holidays and performed the fridge's yearly cleaning, and I have to say that you two are disgusting and I cannot believe I share a fridge with either of you.  Y*, the food you told me I could eat if it looked like it would go bad before you returned had all already gone bad.  Those were Thanksgiving leftovers!  Z*, I understand why you would not want to finish those prepackaged hard boiled eggs after trying a couple, but why would you leave the still open package in your drawer and how long ago was that?!  These are just a couple of examples of the many repugnant odors and colorful molds I discovered last night.  Also, last year I kept items with long shelf lives, e.g. anything vinegar based, even if they were a few months past their expiration date, but this year, rather than wonder if any of these items were still good one year and a few months past their expiration date, I just threw them out because they obviously are not being eaten.  This includes the salad dressing, which has been in the fridge since before Z* moved in, that X* wanted to keep incase he ever started eating salad, and a jar of pickles in the back of Z's* shelf that expired in June which she must have brought with her when she moved in because all my pickled food, which I bought this year, isn't dated to expire until 2014.  Both of your shelves are nearly empty now because you both had more spoiled food then edible food on them.  So like I said, you two are disgusting, my nose is scarred, and I want my own fridge.  Merry Christmas.

X*

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Since I do not have any pictures of the fridge cleaning incident, I decided instead to share another interesting micro organism story.  Can you identify the shape of the bacterial colonies in this picture?  Here's a hint, the cut off words say "kiss plate."

Yes, all those little white blobs are bacteria that came from my lips and the tip of my nose.  A little creepy.  The bacteria are growing in a gel medium that was placed in an incubator for several days so that the colonies could flourish.  This experiment was for a biology 101 lab looking at micro organisms and antibiotics.  It is frightening to think about all the micro organisms surrounding us everyday, but luckily most are harmless pass us by completely unnoticed.

Hopefully X* won't be too mad by the time we all get back from our holiday traveling.  I will have to get him a nice gift, something without any multi-colored mold.

You've got a Lizard in your Ear

The mammalian skull offers a unique opportunity to discuss evolutionary adaptation and and the difference between homologous and analogous features.  When examining the fossil record, the separation of modern "mammals" is demarcated by a change in joint connecting the mandible to the skull.  Prior to this point the connection was formed by two separate bones, the quadrate and the articular.  In birds and lizards and other non-mammalian genera these bone are separate from the body of the mandible and the cranium.  In mammals, the mandible articulates directly with the temporal bone of the cranium, without any intermediary bones.

Meow?

So, are the quadrate and articticular bones present in mammalian skulls?  In fact these bones are conserved, but they serve a different function in the mammalian skull.  Homologous features are the same physical structure between different taxa.  While the features are morphologically the same, they may preform different functions in different organisms.  On the other hand, analogous features have the same functional uses, but arise from different anatomical structures.  In mammals, the incus and the maleus bones of the ear are homologous to the quadrate and articular, respectively.  Although the bones are the same anatomical structure, in mammals, the bones preform a major role in hearing rather than jaw movement.  Instead, the articulation between the temporal and the mandible is analogous to the quadrate/ articular connection in non-mammals, since it has taken on the functional job of connecting the mandible to the cranium.

Transitional fossils have been found showing organisms with a jaw articulation between the temporal and mandible as well as the quadrate and articular.  The change in the jaw articulation is likely due to several different factors.  First of all, reduction in size of the articular and quadrate made them more sensitive to vibrations and improved the hearing capabilities of these organisms.  Organisms with better hearing were better able to avoid predators and reproduce.  Thus, the continued reduction of the ear bones was adaptively advantageous.  Alternatively, the reduction of the jaw joint limited the size of the jaw and the bite strength of the organism.  In this case, a larger joint was more advantageous because it allowed the organism to consume larger prey and also subdue the prey more efficiently.  Thus, decoupling these two functions, allowed mammals to benefit from both increased hearing and jaw size.

Be Aware, It's a Bear!!!

If life ever gets you down, just remember, you have a tiny little lizard jaw joint working in your ear. :)

Darwin Day Submission

Man is descended from a hairy, tailed quadruped, probably arboreal in its habits.
~Charles Darwin

After much prodding, I transformed my human evolution design into a piece that I could submit for the Darwin Day T-shirt competition.  Here is the final design I decided to submit.

As you can see, the design is centered around my original human evolutionary tree concept, but I added the text and the outlines of extant primates.  The three additional taxa of primates include Pan (lower left), Gorilla (lower right), and Pongo (upper left), since these genera are mostly closely related to Homo out of the primates living today.  I decided to remove the arm with the apple because I didn't think a disembodied arm would work well on a t-shirt, without an edge to line up with.  

 

Instead I added a finch perched on the girl's outstretched hand.  If you are familiar with Darwin you will recognize the finch as a one of the species of Darwin's finches that had developed a large wide beak in order to specialize on tougher food sources that finches with long narrow beaks could not easily consume.  Finches with narrow beaks specialized in feeding on different resources, allowing the different morphs to exploit different niches rather than directly competing for the same limited resources.  Over time, initial variation in beak dimensions was enhanced, since different shapes provided different advantages allowing some birds to access resources that the others could not.  Thus they didn't starve and were able to reproduce and pass their genes onto the next generation.  Anyway, I digress, basically the finch is an homage to Darwin as well a representation of a possible mechanism of change.

 

I wasn't sure if I should draw the lettering or use a font.  Also, I realized that since Darwin Day isn't until February the actual year would be 2012 (oops) so I fixed that in my final design.  Here are the original design layouts with the girl, the text, the arm and the bird.

 

Originally, I had just thought I would use my design with the girl and text on a red background, but the t-shirt had to be white so that limited the background color.  Since I didn't want to just put the girl in a square of color I tried to add color to surround the outline in by containing it in the shapes of the other primates.  I didn't like the first design because I didn't think the ape was distinct enough, so I removed that image and changed to the large ape on the right of the girl.  I then added the small ape on the left bottom and finally re-added the one at the top left.  I was trying to use the apes to make the girl stand out more so I had a difficult time laying them out to minimize the area of the girl bordered by white while simultaneously positioning them to look like they looked like they belonged in the image.  Amusingly, all of the background primates are based on pictures of chimps, but by manipulating the size and design of the images they definitely look like different apes.  Finally, I changed the color to orange to fit with the Tennessee theme.

 

I mostly like the way the design came out.  The lettering is a little strange because it crosses the orange and white backgrounds, but I tried multiple different text layouts and I couldn't find any that I like better.  I really like the addition of the extant primates because it adds context to the evolutionary tree depicted in the girl.  It would be cool to include similar evolutionary lineages in the other primates, but unfortunately I am not very familiar with the evolutionary records of other primates and I know for chimpanzees few fossils have been recovered.

 

The judging of the designs doesn't happen until January, so I guess there won't be any updates till then.  Hope you like the design, and think it would make a neat t-shirt. :)

On the Correlation of Condyles (or lack there of)

Classes officially ended for the semester yesterday.

Fragmentary Human Remains: Isolated Mandiular Condyle

For one of my final projects I measured multiple dimensions of the mandible in hopes of finding something in the underlying boney structure and correspondence of the TMJ that might help me understand the disproportionately high number of females suffering from TMJ disorder in comparison to their male contemporaries.  Arguably my measurements only roughly captured the shape of the condyle and the sample I looked at was quite small with an N of 21 males and 10 females, but my limited results didn't show any consistent differentiation in the condyle based on sex.

Unpatterned variation in the dimensions of the human mandibular condyle surprised me a little.   Not only does there not appear to be differentiation between the dimensions of the condyle between males and females, the distribution is all over the place and there is almost no correlation between the lengths and widths of the condyles.  Condyles can by short and wide, short and narrow, long and wide or long and narrow.  This is not what I was expecting.

A War for Hearts and Minds?

Human evolution fascinates me.  The lack of acceptance of evolutionary theory in regards to human development astounds and horrifies me.

I designed this piece to express what I thought was a clear view on evolution.  Basically, the image depicts the evolutionary lineage leading to Homo sapiens, starting with Au. afarensis at the bottom.  Au. boisei is the skull that is placed off to the left and represents an off shoot of the hominin lineage that branches away from the human lineage on a different evolutionary trajectory, eventually becoming extinct.  The skulls that continue up the torso are Homo erectus, followed by archaic Homo sapiens, then Homo sapiens neanderthalensis.  In this depiction, Neanderthals are considered to be a subspecies of Homo sapiens, rather than a separate species, which is still a hotly debated topic amongst paleoanthropologists.

Originally, many were convinced that Neanderthals and humans were biologically distinct species that did not interbreed due to the lack of admixture in mitochondrial DNA sequences of modern humans.  But more recent studies comparing nuclear DNA mixture, suggest the possibility that admixture may have indeed been occurring as modern humans and neanderthals appear to have genetic overlap.

The hand in the upper left corner of the picture is holding an apple, which the girl is reaching for.  In my original interpretation the girl represents modern humans, and evolutionary lineage of hominins is indelibly imprinted fundamental structure of her existence and physical morphology.  The hand represents an unknown omnipotent deity, extending the "fruit of knowledge," although the gesture can be seen as a taunt since there is no way for the girl to actually reach the information.

After finishing the design I quickly, and a bit glibly or maybe snarkily wrote up this description of the piece:

"even with all the evidence supporting an evolutionary path of human origins, the search for supernatural explanations continues with answers danging, forever, just out of reach (2011/Sept. 12)"


It has been several months since I finished the piece and since then I have had found myself re-evaluating my initial description of the work and even the very thought process behind it.  While I still agree with my original plan for the girl depicting human evolution, the relationship between the girl and the hand has bothered me.  Rather than depicting a negative view of God, the hand could instead be culture as a whole including a human drive to understand existence in terms of a divine presence, or even another human passing cultural knowledge on to the next generation.  While some cultural learning may be incorrect or illogical, the adaptation of culture is uniquely human.  


Since most of my training is in biology I sometimes forget the importance of recognizing the importance of culture as an adaptation for humans.  It is easy to criticize what we don't fully understand.  Rather than invoking the imagery of a war between evolution and religion, this piece can simultaneously represent the dual forces of cultural knowledge and biological adaptation that contribute to the modern understanding of the species Homo sapiens sapiens.  If I were asked to describe the piece today I think I would choose this description instead:


"anthropology: a multi-faceted approach to understanding and connecting hearts, minds and morphological origins (2011/Nov. 28)"

Giraffefish and Other Nonsense

I love this painting.  It was made by one of my best friends, and it has inspired several debates about the nature of the universe and the existence of unknown or impossible creatures (such as a giraffe fish).  During one of these debates I found myself arguing the position that even though there is no tangible proof that giraffe fish exist, the possibility of their existence should not be ruled out on that basis alone.  My friend on the other hand, argued that since there is no proof of the existence of giraffe fish, it is foolish to even consider the possibility of the existence of such a creature.  While I was focused on the immensity of the ocean and the likelihood that there are numerous undiscovered species potentially living on our planet, my friend was debating the larger social question of the existence of God.  

Yes, in this case the fictitious character of the giraffe fish plays God.  

I suppose this issue brings up and interesting difference between atheism and agnosticism.  My friend is an atheist, or at least when we were discussing this topic several years ago she was. (I think she may have joined my agnostic/ indecisive worldview at this point, but that is an entirely different discussion.)  She had made up her mind that God did not exist and chastised me for being gullible/ naive enough to entertain the possibility of any form of supernatural deity.  In response I would argue that her strong belief in atheism is equally problematic since the main evidence she uses to argue against the existence of the divine is the failure of religion to prove its existence.

I consider myself agnostic.  I honestly have no idea whether or not there are supernatural forces existing in the world.  Sometimes I find this problematic.  While I have no evidence that there is any type of deity influencing the universe, I have equally little evidence to prove that one does not exist.  In this case, atheists and religious groups alike are basing their views on a belief system, or faith, as neither can provide evidence to substantiate their claims.  One key phrase that I have heard repeatedly in my studies or biology and anthropology is the adage "absence of evidence is not evidence of absence."  This phrase basically sums up my reasons for being agnostic.  The lack of evidence from either side prevents an adequate basis for drawing an informed conclusion on the topic.  While the fundamental inconsistencies in accepted modern religions lead me to reject any specific doctrine, I realize that humans created religions and humans are fallible.  Yet, it is possible that a deity beyond human comprehension exists.  Until I can gather further evidence on god's existence or lack there of, I have chosen to accept the unknowability or the universe and remain my indecisive self.

Today I was thinking about whether it would be possible for a giraffe fish to evolve through the process of natural selection.  I realize "fish" is probably and inappropriate term to use, as I expect that the proposed organism would be a mammal, but technically all tetrapods are evolutionary descendants of fish.  More on that another time.

Anyway, upon considering the potential advantages and disadvantages of giraffe features in an aquatic environment the prospects aren't great.  First of all, the elongated thin neck of a giraffe would not be streamlined or effective in an aquatic environment, especially given a more massive torso.  Secondly, the general consensus in the scientific field is that marine mammals evolved from a wolf-like ancestor that returned to an aquatic environment.  Thus, an aquatic giraffe would probably represent a parallel evolutionary trajectory of an herbivorous quadruped that returned to the water and adapted to the conditions by developing fins (ect.). While parallelism are common in mammalian evolutionary history, my friend had a point when she noted that an aquatic giraffe-like creature would probably have difficulty remaining unnoticed by humans since it would need to breath oxygen, and would need to be fairly large to maintain mammalian metabolic functions in an aquatic environment.  

That being said, I challenge anyone to completely disprove the possibility of the existence of a giraffe fish.