Introduction
Neil Shubin’s book, Your Inner Fish, covers biological aspects that define life among various animals and species (Shubin, 2008). It uses the bodies of other animals to define human anatomy. For instance, it tells that the nerves in the human head can be easily illustrated by explaining the state of affairs in sharks. Besides, there is the most straightforward road map in explaining brain activities through the use of reptiles. The first chapter, Finding Your Inner Fish , talks about how ancient fish bones can be used to describe the concepts surrounding the human biological system (Shubin, 2008). It goes ahead to mention that the human body is taught from bizarre of species ranging from the fossils of fish and worms. This paper will cover two traits, including the human’s inner shark and the teeth and bones relying on the fish anatomy.
Human’s Inner Shark
Humans are assumed to be modified sharks. The arches and cranial nerves hold the secret of heads. Fish and shark have the same attributes. They comprise of the gill slits in the throat region that look and operate the same way as the swellings in the cranial nerves and other vital structures in the human head. Additionally, fish embryos comprise indentations and bulges from the spaces between gills where the water flows. In human’s such indentations are sealed over. In fishes, there are times when the gill slits fail to close (Shubin, 2008). They remain open as cysts. The bronchial cysts, a benign fluid that is filled with the cyst, forms and open pouch in the neck. The pouch is created by the failure of the arch to close. Similarly, newborn babies have a gill arch cartilage.
Delegate your assignment to our experts and they will do the rest.
The heads in every animal from fish to humans have four arches that develop from birth. The critical aspect is the process that occurs inside the arches of each species. A comparison between the human head and head of the shark will illustrate the role of the arches.
Fig . The human embryo and shark embryo. (Source: Shubin & Alberch, 1986).
The figure above shows the human embryo and shark embryo. The gill region of a developing shark and a developing human appear the same in the early stages of development. In the figure, the first arch in human and shark contains the same state of affairs, for instance, there are the jaws. However, the significant difference is that the human's first arch form some parts of the ear bones. Such an occurrence does not happen in sharks. The similarity in the function of the first arch in humans and shark is that both contain cranial nerve, which supplies the jaws of sharks and humans (Shubin & Alberch, 1986). In the sharks, the second-gill arch change and allow the development of the bar of cartilage and muscle.
In humans, the bar of cartilage develops into three of the middle ear bones. It as well forms other structures at the base of the throat and head. The hyoid is among the structures developed to aid in swallowing. Other parts developed from the second arch in the human body aid in different areas. For example, they facilitate taking a gulp and listening to sounds, including music. In sharks, the second arch rod breaks up to create two bones. These bones support the jaws. The lower bone can be compared to human hyoid. This bone also retracts and extends when it tries to bite. Conversely, the upper jaw of the second arch in sharks forms the lever system of bones that rotate to make. This part compares to the stapes (middle ear bones) in humans (Shubin & Alberch, 1986). The upper and lower bones in sharks are comparable to those that humans use to swallow and hear.
The thirds and fourth arches comprise of many structures in both sharks and humans. The parts that are used by sharks to support the gills are, in humans, used to talk and swallow. The cranial nerves and muscles move the gills in shark and fish. The human head may look complicated, but it is built from, an elegant and straightforward process (Shubin & Alberch, 1986). This notion is common to every skull of animals on earth, whether it belongs to salamander, fish, or shark.
Teeth and Bones
Teeth is a specialized organ because of its hardness. Teeth must be harder than the bits of food that they chew. Hence, teeth can be said to be hard as rocks, and the reason for such an assumption is because they contain a crystal molecule on their sides. The molecule is hydroxyapatite (Coates, Jeffery & Ruta, 2002). It forms a cellular structure that makes teeth resistant to compression and bending. Teeth are as well hard because of the outer layer (enamel) is more abundant in hydroxyapatite than any other body structure. Enamel, as well, gives teeth the white sheen. The inner layers of teeth, such as dentine and pulp, are as well filled with hydroxyapatite. There are lots of animals with hard tissues that are comparable to the bones and teeth in humans.
Creatures with hard tissues include fish, clams, and lobsters. It is important to note that these animals might have tissues with different contents as compared to those in humans. For instance, they do not have hydroxyapatite. Lobsters use materials such as chitin, calcium, and carbonate to make their tissues hard (Coates et al., 2002). Unlike humans, these animals as well have exoskeleton covering the body. A particular human brand of hardness with bones and teeth in the body forms part of what makes people healthy. Individuals eat breath, move, and metabolize minerals in the body to make the bones and teeth hard. Such features are also standard in fish. Some of the fossils were found to contain similar qualities. For instance, conodonts, which are the teeth of an ancient jawless fish, include spikes of projections (Riddle, Johnson, Laufer & Tabin, 1993). These organs have been discovered in every continent, especially in areas where there is a vast number of rocks.
In the past, scientists were not sure what conodonts were, as some assumed they were minerals, vegetables, and animals. Conodonts are teeth that get preserved easily. They as well comprise of soft parts, including skin, guts, and muscle that often decay without fossilizing. Conodont teeth were the ancient fossils found. It took over 150 years to find the body of the fish. However, various aspects were noted as remarkable in the body of the jawless fish (Riddle et al., 1993). Just like humans, they were soft bodies with hard teeth and bones. However, unlike humans, hard bones and teeth were used by these animals to eat other fish. The fish-eat-fish scenario began whereby the big fish ate small fish.
Conclusion
The relation between the morphological aspects in different aspects is crucial in understanding the way different species operate. It also aids in the expression of different parts of the human body. For example, the state of affairs in sharks is useful to explain the nerves in the human head. Humans have various aspects that can be related to those in fish and shark. For example, both shark and human body contain four arches in their heads that develop as they grow. The first arch in human and shark includes the same state of affairs; for instance, there are the jaws. The other organ is conodonts, that is in the body of jawless fish. The organ is a tooth, and it is hard as the human bones and teeth.
References
Coates, M. I., Jeffery, J. E., & Ruta, M. (2002). Fins to limbs: what the fossils say 1. Evolution & development , 4 (5), 390-401.
Riddle, R. D., Johnson, R. L., Laufer, E., & Tabin, C. (1993). Sonic hedgehog mediates the polarizing activity of the ZPA. Cell , 75 (7), 1401-1416.
Shubin, N. (2008). Your inner fish: a journey into the 3.5-billion-year history of the human body . Vintage.
Shubin, N. H., & Alberch, P. (1986). A morphogenetic approach to the origin and basic organization of the tetrapod limb. In Evolutionary biology (pp. 319-387). Springer, Boston, MA.
