Sunday, February 27, 2011
Making the Most of It: Science and Extrapolation
Intermaxillary Bones in Various Mammals – Notes
Looking at the selection of skulls we examined, the first thought, from an anthropic standpoint, would be that the skulls of other the other animals seem like elaborations and expansions of the human skull. Our jaws, compared to the distended shapes of those of, say, porpoises or dugongs, appear small, compact, and relatively simple, and our teeth seem similarly diminutive and similarly uncomplicated.
The explanation for human jaw proportions (from the Discovery Channel; make what you will of that) is that the invention of fire and therefore of cooking made the chewing of food easier. The necessity of biting through and masticating raw meat gone, jaws could shrink without unpleasant evolutionary consequences. The results of that not happening, I think, are visible in the skulls of the other primates we looked at. Both the gibbon and the gorilla had particularly large canine teeth, suggesting (assuming that, like humans, gorillas and gibbons are omnivorous) that the chewing of meat was the real issue at hand, the problem of how to deal with fibrous grass and foliage presumably requiring more radical adaptations.
Aside from size, I surmise that humans and the above-mentioned other primates eat in much the same way. The incisors and canine teeth tear or scissor off pieces of food, which are passed backwards to the molars to be ground down prior to swallowing. While not identical, teeth of these kinds in humans, gibbons, and gorillas are extremely similar; molars are all broad and roughly cylindrical, canines terminate in a point, and incisors narrow to an edge. Another similarity: the near-invisibility of the premaxilla as a distinct bone separate from the rest of the jaw. By contrast, the premaxilla, in the remainder of the animals, is generally quite distinct.
In grazing animals, such as the horse, and rodents, such as the capybara and the beaver, the premaxilla protrudes, like the bow of a ship, from the remainder of the jaw, which contains the molars. The reason for this, I think, is because there is a greater distinction between the roles the teeth play. In humans (and presumably other primates), teeth can perform each other's tasks somewhat interchangeably: incisors aren't wholly unsuited to chewing; molars just do a better job. Molars, depending on the food, can cleave off pieces as well. Contrast this with how a grazing animal would eat: the incisors clip off pieces of plant matter, which is passed backwards for prolonged chewing. In that case, a long row of molars, set far back from the mouth's front (possibly allowing for biting and chewing with the same movement), is more efficient at processing large amounts of grass than humans' compact jaw layout could ever be. A similar sharp distinction in function seems apparent in rodents, whose large incisors appear to play the predominant role in eating, shaving or tearing off small, manageable chunks of food. The molars are greatly reduced, possibly to (as in hamsters) allow the cheeks to serve as storage space, possibly because the individual pieces of food being dealt with aren't particularly substantial. Human mouths here occupy a “jack of all trades” role, with teeth and jaw portions not only shrunken but less differentiated.
Friday, February 25, 2011
Premax Lab
Premaxillae as a Unifying Characteristic
In his research on premaxillae, Johann Wolfgang von Goethe sought to establish an archetype for all animals (Goethe 111-112). The premaxilla, his chosen bone to focus on, is an interesting choice as it has many morphologies depending on the feeding habits and other needs of the mammal. For example, a reasonably basic version of the skull is shown in beavers, whose primaxillae are similar to many other groups in the class Mammalia.
Here one can see the basic structure of the beaver, whose premaxilla is located next to the nasal. The premaxilla is relatively small in comparison to surrounding structures like the prominent zygomatic arch.
In other mammals, evolution has driven unusual premaxilla morphologies. For example, grazing animals like horses have a significantly longer premaxilla. This is probably due their diet, which consists of grasses. In order to graze safely, long premaxilla, maxilla and nasal bones are required to push the eye back. Having a backset eye ensures that the horse will be able to see over the grass and watch for predators effectively while grazing. This supports Goethe’s assessment that an animals diet affects what type of premaxilla it has (Goethe 112). While Goethe was correct in this instance, there are also non-dietary reasons for changes in premaxilla shape.
A more extreme version of premaxilla elongation is seen in water mammals like porpoises and dolphins. In the specimen viewed in class, the premaxilla was clearly visible stretching from the front of the skull back to the top of the head. This extreme stretching of the premaxilla helps to allow the dolphins and porpoises to push back their nose holes. This morphology is necessary in underwater mammals because it allows a minimized surface area to be above the water when breathing. Breathing through the top of the head, as opposed to the front of the face, lets underwater mammals barely come above the surface, reducing risk of predation and exposure to air.
While Goethe’s work on the premaxilla wasn’t fully accepted by scientists of his time, we now know that premaxillae are one of the unifying charachteristics of animals. While they may vary in size and shape, the general structure remains an archetype as Goethe hoped.
Sources:
Goethe, Johann W. Scientific Studies. Trans. Douglas Miller. New York: Suhrkamp Publishers, 1988.
Thursday, February 24, 2011
Alexander von Humboldt: The Dark Knight of Science
Alexander von Humboldt was one of the most influential figures in science. He is most famous for his “Tableau” and trip to the Americas in which he compares and contrasts plant life at different altitudes and latitudes. This was revolutionary in the way that scientists understood plant life, since scientists assumed plants varies longitudinally more so than latitudinally. Humboldt was the one of the first to question this and test it fully, and his results were incredible. However, this is not the only revolution in science that Humboldt contributed to. Unfortunately, very few people today know about his full contributions. Stephen Jackson’s Introduction in the “Essay on the Geography of Plants” states that he also, “ . . . fostered development of the first international networks of meteorological observations, invented the isotherm, . . . advocated the volcanic origin of basalt, . . . pioneered the field of geomagnetism, . . . work[ed] in economic geography, . . . [and] work[ed] in atmospheric physics” (Jackson, 3). It is interesting that he isn’t as well known in these fields and it is important to discuss the reasons why this is the case.
The first point wroth discussing is that Alexander von Humboldt is what we would call today a “jack of all trades.” As an example, we can see how Jackson describes the first few days on Humboldt’s trip to the Americas. He writes, “It took them some weeks to prepare for systematic scientific work, between the continual barrage of new sights, smells, and sounds” (Jackson, 10). There was so much going on around him that he couldn’t initially focus on just one aspect. This mentality followed him to his death. He took tons of data back to Europe with him and spent the rest of his life writing books and volumes trying to get the data to the public. Humboldt was not like Darwin. Darwin spent a majority of time on his research on natural selection and that is what he is known for. Humboldt contributed so much to the scientific world that nowhere really knows where to classify him or what best o remember him by.
Another issue is that the work he had done that is best to remember him by was, soon after, “ . . . dispersed among subdisciplines within geology, zoology, climatology, oceanography, taxonomy, and other fields” (Jackson, 38). Each of these fields laid claim to some portion of Humboldt’s work, but none of it was every enough for him to be renowned by every scientist for all of the work that he accomplished. This specialization may not have taken place in the same manner that it did if it weren’t for Humboldt in the first place, so his work is much more important than the modern day people are led to believe. It is important to note that, “The past few decades have witnessed a convergence of several separate disciplines toward a new incarnation of Humboldt’s physique du monde” (Jackson, 40). Some fields that branched immediately after Humboldt’s studies are converging again in order to better understand the problems that every day society faces today, such as global warming, plate tectonics, and wildfires.
The Dark Knight is the most recent Batman movie, in which Batman becomes vilified by actions he didn’t commit; yet he still helps the city of Gotham and just doesn’t take credit for his actions. The scientific community certainly doesn’t vilify Humboldt, but if it weren’t for his studies, the specialization and consequent realization of the importance of unification of those branches of science may not have happened the way that it did, and Humboldt receives minimal credit for this. That makes him the Dark Knight of Science.
Bibliography:
Jackson, Stephen T. “Introduction: Humboldt, Ecology, and the Cosmos,” Essay on the Geography of Plants, ed. and intro. Stephen T. Jackson, trans. Sylvie Romanowski (Chicago: Chicago University Press, 2009), pp. 1-46.
Monday, February 21, 2011
Museum of Natural History Bone Lab
Museum of Natural History Bone Lab
This lab in the Natural History Museum was able to open the eyes making connections to the texts of Goethe that we have been reading and the physical bone structures under question. It was an experience which helped me better appreciate the things that Goethe accomplished in his studies of the intermaxillary bones also called the premaxillae. It was pretty unreal to see the structures in the skulls of the different species and then compare them to each other. The position of these bones and how they functioned for the specific species was a very interesting spectrum to see.
There were six different skulls of animals that I sketched in this lab, in addition to the human skull that I more completely sketched. The six animal skulls that I observed were a gorilla, a young chimpanzee, an older chimpanzee, a bison, a fox, and a harbor porpoise. These six animals I did not make complete sketches of the entire skull, just ones that better showed where the intermaxillary bones are located and what it looks like. I made sure to sketch the roof of the mouths of the animal and human skulls in order to compare the intermaxillary bones across the different species. There were some very interesting comparisons to be made.
The intermaxillary bones in humans are located on the roof of the mouth one on each side of the centerline of the mouth. They contain the incisors and are very hard to see in humans, if at all. The one skull that I looked at, I was able to barely make out the faint cracks that run along from the center of the mouth to a spot in between the last incisor and the canine. The sutures were very hard to spot because of how thin they were. In humans the intermaxillary bones must fuse earlier in life under a decent amount of pressure in order to be that thin.
I also studied the skulls of some animals that are closely related to humans, the chimpanzees and gorillas. In these species the intermaxillary bones are very easy to spot clearly running from the center of the mouth to a spot in between the canines and the last of the incisors. The line created by the intermaxillary bones and the bones of the rest of the mouth in the chimpanzees ran more perpendicular to the centerline of the mouth than they did in the gorilla. This makes sense because the snout of the gorilla is a little bit more elongated than that of the gorilla. I also looked at the skull of the both a younger and an older chimp to see the differences between them. The sutures created between the intermaxillary bones and the rest of the mouth are more readily seen in the younger chimpanzee. They are more jagged and appear like fissures in the bone. The sutures in the older chimpanzee look as if they have been put under a greater pressure and have been fused together. These lines are much smoother, as compared to the fissures of the younger chimpanzee.
Next I looked at the intermaxillary bones of a bison. These bones were very different then the premaxilla of the chimps and gorillas. The primates use their incisors to a great extent, so a lot of pressure is put on them when eating. In that way the intermaxillary bones are small, compact, and do not extend to far from the skull. This is different with bison though. They do not use their incisors too much because they are more of a grazing animal. Instead the bulk of the force is put on their molars. This seems to be the case at least, because the premaxilla of the bison is very long and protrudes out a great distance from the bulk of the skull, as shown in the sketch. It seems to be very fragile and not take a lot of force. They start at the roof of the mouth, like in the primates, and loop around very intricately, continuing up the front part of the face under the nostrils.
The fox skull that was looked at was almost a combination of the bison and primates in terms of premaxilla shape. The intermaxillary bones were angled a bit forward like the gorilla skull, and also headed up the front of the face like the bison. The interesting features of this skull were two little holes in the roof of the mouth. These are depicted in the sketch and their purpose is unknown.
The last skull that was looked at was that of the harbor porpoise. This skull looked like a mammal skull that had been pulled out long like taffy. This skull was unique because its intermaxillary bones are extremely long. They looked like two white strips on the top of the long snout. They were very thin and looked as if they were not used too much in terms of load bearing during eating.
It seems as if there are differences in the intermaxillary bones that correlate with differences in the types of food that the animal eats. Humans and animals like the primates have very stout intermaxillary bones that are held close to the skull. This would more than likely due to the use of the front incisors when biting into food to tear it. The canine skulls like the fox are similar to the primates except that their premaxillae are lengthened a little bit and not as stout, which might have to do with the fact that they use their canines more when eating. The bovine animals like cows and, in this experiment, bison have very long intricate intermaxillary bones since they do not use their incisors at all. They use their molars to grind up all the plant matter that they eat.
Comparing Spectra of Tungsten and Energy- Saving Light Bulbs
Comparing Spectra of Tungsten and Energy- Saving Light Bulbs
Purpose
Compare the spectrum of an energy-saving light bulb with that of a tungsten-filament light bulb by meanings of wavelength measurements and observational techniques.
Equipment and Materials
Shoe Box
Lamp
Tungsten-filament light bulb
Mercury vapor; energy saving light bulb
300 and/or 1000 diffraction grating
Scissors
Modeling Clay
Dark thread
Sewing pin
Drawing pin
Electrical tape
Protractor
Flashlight
Procedure
1. A fairly dark location was obtained for the conduction of the experiment. This was a room without windows (hallway and bathroom).
2. The light box was then prepared. This was done by cutting off one end of a shoe box and cutting a 1mm wide slit 5 cm long on the other side. This box was then taped to a table and covered with a light, non-synthetic towel to minimize light pollution.
3. The protractor was placed approximately 55 cm directly in front of the shoe- box; with its zero degree point of the protractor aligned with the slit of the box. A drawing pin was inserting through its apex, with its sharp point exposed.
4. The diffraction plating was placed parallel to the flat edge of the protractor and was secured upright with modeling clay. The diffraction plate was centrally aligned with the slit of the shoe- box and the tip of the drawing pin.
5. Black thread was attached to the drawing pin and a piece of modeling clay, which held a sewing pin. This served as the sighting mechanism.
6. A lamp with an energy-saving bulb was then inserted into the shoe -box and was turned on. Once observations and recordings were taken, the tungsten-filament bulb was inserted to compare qualitatively the differences between the two bulb-type’s spectra.
Data
1000 Gradient
Observation Table
| 1000 Gradient | | |
Order | Sin(Degrees) | Degrees | Wavelength |
Blue Spectral Line | | | 445 nm |
1 | 0.446 | 26.5 | |
1 | 0.446 | 26.5 | |
2 | 0.876 | 61.2 | |
2 | 0.906 | 64.9 | |
3 | | | |
4 | | | |
5 | | | |
| | | |
Green Spectral Line | | | |
1 | 0.581 | 35.5 | |
1 | 0.566 | 34.5 | |
2 | | | |
3 | | | |
4 | | | |
5 | | | |
| | | |
Red Spectral Line | | | |
1 | 0.67 | 42.1 | |
1 | 0.64 | 39.8 | |
2 | | | |
3 | | | |
4 | | | |
5 | | | |
Observation Table
| 300 Gradient | | | |
Order | Sin(Degrees) | Degrees | Wavelength | Wavelength with Zeros
|
Blue Spectral Line | | | 533.13 nm | 465 nm |
1 | 0.131 | 7.5 | | |
2 | 0.272 | 15.8 | | |
3 | | No Blue | | |
4 | | No Blue | | |
5 | 0.766 | 50 | | |
| | | | |
Green Spectral Line | | 533.47 nm | 589 nm | |
1 | 0.158 | 9.1 | | |
2 | 0.335 | 19.6 | | |
3 | 0.483 | 28.9 | | |
4 | | No Green | | |
5 | 0.804 | 53.6 | | |
| | | | |
Red Spectral Line | | | 692 nm | 692 nm |
1 | 0.206 | 11.9 | | |
2 | 0.376 | 22.1 | | |
3 | 0.52 | 31.3 | | |
4 | 0.728 | 46.7 | | |
5 | 0.909 | 65.3 | | |
Discussion/ Conclusions
Observations and data were taken after the equipment was set up. The first set of data was taken with the 1000 gradient. With the 1000 gradient, the blue spectra line produced two orders (26.5 and 64.9 degrees; 26.5 and 61.5). The green spectral line was only seen with one order (35.5; 34.50 degrees) and the red spectral line was only seen with one order (42.1; 39.8 degrees). The measurements for the 1000 gradient was taken twice; once from each side of the spectra (once from the right, once from the left). It was predicted that the degree measurement for a specific order from a specific color line would be the same from both the right and left side orders. As the data represents, the degree measurements from the left and right sides are very similar, with the largest difference being 3.7 degrees (blue spectral line, second order). This is most likely because the second order was blurry and not distinct.
The second set of data was taken with the 300 gradient. The 300 gradient produced more distinct, clear and bright color orders. The blue spectral line produced five orders, although the third and fourth orders were not distinct enough for measurements. The green spectral line also produced five orders, while the fourth order was not distinct enough to take measurements. The red spectral produced five vivid orders of color lines.
After the data was taken, the sin of the degrees measured were calculated. As implied by the graphs, with the 300 gradient, the sin (degrees) increased as the order number increased. This was true for all of the spectral lines that contained more than one order. In general, the slopes increased from blue, to green, to red; although the slope differences between the blue and green data was minute. This increase correlates to the increases in standard wavelengths from blue, to green, to red.
The second part of this experiment was performed with a tungsten- filament light bulb as compared to the energy-saving bulb that was used previously. With the tungsten-filament light bulb the orders were much different in appearance than the energy-saving light bulb. The tungsten-filament light bulb produced two full orders of diffraction and one partial order up to blue. These orders were very blurry and fuzzy. They were very non-distinct and had a grayish haze over the colors. The colors in the energy-saving light bulb were significantly more distinct and there were more orders observable.
Measurement uncertainties arose for the higher orders. This was due to the degradation of order clarity within the spectrum as the higher orders were reached. These measurements could be improved upon by using a diffraction gradient of a larger size. This would allow the higher orders to be clearer at less tangential viewing angles. Copious amounts of data and measurements would further the validity of this experiment.
Our calculated wavelengths with the 300 gradient deviated approximately 30-60 nm from the accepted wavelength values. This is most likely due to the light bulb or the specific condition that surrounded the experiment. Additionally, the 300 gradient diffraction plate had a slight diagonal crack, which may have slightly altered the results.