Your Inner Fish Essay
Your Inner Fish
1. Why should we care about evolution? Why is it important?
Evolution is the building blocks to biological science. If we did not care about evolution, we would not understand the concept of biology, or any type of science for that matter.
2. What does it mean to be human? Did your concept change after reading the book?
After reading the book, I began to understand why my body looks the way it looks. I realized that we are all the same inside—from fish to monkeys, and even some reptiles. We all started from the same thing. In my opinion, being human can be summed up into a simple definition—a unique individual. Although we all developed from a similar place, being different makes us human. Each one of us has our differences, we can do things that others can’t, and that’s what makes us one-of-a-kind. Internally, our bodily structures will be alike, but our personalities and physical features make us who we are.
3. In what way do scientific explanations differ from other ways of knowing? What makes evolutionary biology a science?
Scientific explanations begin with a hypothesis, ending with experiments that are performed to support the hypothesis made. This can then become a theory. Other ways of knowledge, on the other hand, don’t need to be tested to be true; we just know that they are true. Evolutionary biology is a science because we have theories relating to the concept of evolution.
4. What insights do we gain when we integrate molecular and fossil data?
Through the combination of molecular and fossil data, we gain a better understanding to the concept of evolution and change.
5. Can we look to examples in the natural world to inform our conceptions of what is “normal” or ethical human behavior?
I believe in that statement partially. We can look at some examples in the natural world to inform our conceptions of what is “normal” or ethical human behavior, but we can’t do it all the time. There will be times when humans will adopt other behaviors
and not have it be found in the natural world.
Chapter 1 – Finding Your Inner Fish
1. Explain why the author and his colleagues chose to focus on 375 million year old rocks in their search for fossils. Be sure to include the types of rocks and their location during their paleontology work in 2004. The author and his colleagues chose to focus on 375 million year old rocks in their search for fossils because they believed that those amphibians which were far different from fish were identified within the 365 million year old rocks. They researched sedimentary rocks because it displayed itself as the most helpful type of rock to finding fossils. Shubin and his colleagues searched for fossils on Ellesmere Island in northern Canada in 2004 because of its human absence and abundance of trees surrounding the area.
2. Describe the fossil Tiktaalik. Why does this fossil confirm a major prediction of paleontology? The fossil Tiktaalik encompassed characteristics of amphibious animals and land mammals. Tiktaalik had fins and scales like a fish, a malleable neck, flat head, and a bone arrangement that acted as legs of land animals. This specific fossil confirms a major prediction of paleontology because it was found exactly when it should have been found, in the 375 million year old rock.
3. Explain why Neil Shubin thinks Tiktaalik says something about our own bodies? (in other words – why the Inner Fish title for the book?) Neil Shubin thinks that Tiktaalik says something about our own bodies because he believes that the structure of Tiktaalik is similar to the anatomy of a human body. As Shubin proves his point through different examples such as Tiktaalik’s fin bones are analogous to our arms, he states that the evolution of humans could be discovered through research on the evolution of Tiktaalik or a similar fossil. This is where the title of Inner Fish comes into play; the similarity between the fish and the human being.
Chapter 2 – Getting a Grip
1. Describe the “pattern” to the skeleton of the human arm that was discovered by Sir Richard Owen in the mid-1800s. Relate this pattern to his idea of exceptional similarities. The “pattern” that was discovered by Sir Richard Owen in the mid-1800s resembled the skeleton of a human arm. Owen found several mammals which exhibited the “one bone-two bone-lotsa blobs- digits pattern”. This pattern that Owen found basically indicated that the location of the bones in the arm were similar—the humerus, radius, ulna, few wrist bones, and lastly, the digits. He found that this pattern could also be found in the human legs.
2. How did Charles Darwin’s theory explain these similarities that were observed by Owen? Charles Darwin had a theory, essentially saying that the human body’s arm and a bat’s wing have the same bony attributes because they once shared a common ancestor. Darwin’s theory explains the observations that Sir Richard Owen made from the pattern he found.
3. What did further examination of Tiktaalik’s fins reveal about the creature and its’ lifestyle? The further examination of Tiktaalik’s fins revealed that it had wrists, similar to a human body. Tiktaalik’s wrists allowed it to maneuver its way to the base of shallow bodies of water.
Chapter 3 – Handy Genes
1. Many experiments were conducted during the 1950s and 1960s with chick embryos and they showed that two patches of tissue essentially controlled the development of the pattern of bones inside limbs. Describe at least one of these experiments and explain the significance of the findings. Hint: see p. 58 In the 1950s and 1960s, biologists Edgar Zwilling and John Saunders performed an experiment by cutting up the chick’s embryos and moving the tissues around to see what how it would affect the chick’s development pattern. Zwilling and Saunders discovered that two tiny pieces of tissue controlled the development of the chick’s bone pattern inside the limbs. Removing those specific pieces of tissue changed how its arms developed.
2. Describe the hedgehog gene using several animal examples. Be sure to explain its’ function and its’ region of activity in the body. The hedgehog gene was initially found in fruit flies. It was a gene that made each region of the body unique. Biologists examined other animals for the hedgehog gene. They found it in chickens and called it the Sonic hedgehog gene. The hedgehog gene is found in every creature with limbs. It is necessary to have this gene to form proper arms and wrists. Scientists have also found the hedgehog gene in mice and fish. They discovered that using the gene found in mice on a fish would create different shapes of skeletal rods.
Chapter 4 – Teeth Everywhere
1. Teeth make great fossils – why are they “as hard as rocks?”
Teeth make great fossils but are “as hard as rocks” because they contain a large amount of hydroxyapatite. The hydroxyapatite makes it harder to decay, allowing it to be the best part of the creature that can be preserved.
2. What are conodonts? What extant species contains them?
Conodonts are described as organisms that have spikes sticking out of them, but are known as the teeth of fish without jaws. Lampreys are a type of extant species that have conodonts.
3. Shubin writes that “we would never have scales, feathers, and breasts if we didn’t have teeth in the first place.” (p. 79)
Explain what he means by this statement. Shubin tells us that scales, feathers, breasts, and teeth all emerge from the same place—skin. Although they all come from the lower layers of skin, he believes that teeth were created first, while the scales, feathers, and breasts were all developed after discovering the making of teeth.
Chapter 5 – Getting Ahead
1. Why are the trigeminal and facial cranial nerves both complicated and strange in the human body?
The trigeminal and facial cranial nerves are both complicated and strange in the human body because just a single nerve of either carries information about sensation and action. These nerves go through the brain in cable like features, branching out into different parts of the head. The trigeminal and facial cranial nerves have a complicated and strange pathway in us. They have an odd structure.
2. List the structures that are formed from the four embryonic arches (gill arches) during human development. The first embryonic arch forms the upper and lower jaws, the malleus and incus, and all the vessels and muscles that provide support for them. The second embryonic arch forms the stapes, or the third small ear bone, a tiny throat bone, and many muscles that control your facial expressions. The third embryonic arch forms the bones, muscles, and nerves that help us to swallow. The fourth embryonic arch forms the larynx, along with the surrounding muscles and vessels.
3. T or F. Homeobox genes are conserved segments of DNA found within the DNA sequence of Hox genes. What are Hox genes and why are they so important?
True, Homeobox genes are conserved segments of DNA found within the DNA sequence of Hox genes. Hox genes tell our cells how to make the different structural regions of our head. These Hox genes are active in gill arches, allowing us to understand how to map our gill arches.
4. Amphioxus is a small invertebrate yet is an important specimen for study – why?
Be sure to include characteristics that you share with this critter! Amphioxus is a small invertebrate yet is an important specimen for study because it contains many like features to back-boned animals. Although it shares many features with the back-boned animals, it does not have a backbone; it only had a nerve cord running along its back. Along with the nerve cord, it has a rod, called the notochord. The notochord supports the body. Amphioxus’ notochord retains its notochord, while we break ours.
Chapter 6 – The Best Laid (Body) Plans
1. Early embryonic experiments in the 1800s led to the discovery of three germ layers. List their names and the organs that form from each. The three germ layers were called the ectoderm, endoderm, and mesoderm. The ectoderm is the most outer layer. It forms the outer part of the body, also known as the skin, as well as the nervous system, skin cells, brain cells, hair, tooth enamel, and nails. The endoderm is the inner most layer. It forms the inner structures of our body such as the digestive tract and glands, as well as our lungs. The mesoderm is the middle layer. It forms tissue within our guts and skin. They also create our skeleton and muscles.
2. Describe the blastocyst stage in embryonic development.
The blastocyst stage in embryonic development is when the egg begins to divide due to the sperm and egg fusing. These cells form a ball, which is known as the blastocyst. There is a thin wall encompassing the fluid in the center. The ball then attaches to the uterus, attempting to connect itself so that the bloodstream will form together.
3. What is meant by “ontogeny recapitulates phylogeny?”
The “ontogeny recapitulates phylogeny” refers to the development of an embryo exhibiting the recurrence of the evolutionary stage. Though this was confirmed as a false hypothesis, it showed that if you were to observe the development of an embryo, you would see more stages of development, the further you go back through a phylogenetic tree.
4. What type of gene is Noggin and what is its function in bodies? Is Noggin an activator or a suppressor?
Noggin is a HOX gene. It helps organs, as well as the body structure. Noggin and a gene called BMP-4 work together. Noggin is a suppressor.
5. Sea anemones have radial symmetry while humans have bilateral symmetry but they still have “similar” body plans – explain. Both sea anemones and humans have similar body plans because they are based on the same process. Although sea anemones have radial symmetry while humans have bilateral symmetry, they have many similar body plans such as the belly-to-back genes and head-to-anus axis, or oral-aboral axis of anemones.
Chapter 7 – Adventures in Bodybuilding
1. Refer to the timeline on p.121 in Your Inner Fish – what is most surprising to you about the timescale? Explain your choice. The most surprising thing I find about the timescale was the extremely long period of time in which there were no bodies on earth. This shocks me because it seems like forever until the bodies started to exist after life was found. It took approximately 3 billion years for bodies to come into existence.
2. What is the most common protein found in the human body?
Name it and describe it. Collagen is the most common protein found in the human body. The structure mirrors a rope. When collagen is held tightly, it is strong, but when it is released, it is fragile.
3. Explain how cells “stick” to one another; give at least one example. Cells “stick” to one another by biological glue. This biological glue helps the cells communicate with each other. It consists of molecules that allow the tissues and organs to have its own functions. The biological glue, or molecules, shows how strong the bone is.
4. How do cells (generally) communicate with one another?
Cells communicate by sending molecules back and forth to one another. One cell sends a molecule to the other, which links to the membrane of the cell. Because it sticks to the membrane, it discharges a chain reaction which travels to the cell nucleus. 5. What are choanoflagellates and why have they been studied by biologists? Choanoflagellates are single-celled microbes which are closely related to animals with bodies, placozoans, and sponges. They have been studied by biologists because it allowed them to compare apparatus’ to microbes much easier.
6. What are some of the reasons that “bodies” might have developed in the first place?
Include any environmental conditions that might have favored their evolution. One theory explaining why bodies might have developed in the first place is that the bodies emerged when microbes began “eating at each other” as well as avoiding being eaten. To have a body containing countless cells would let the creature grow hugely, and being big would allow them to avoid being eaten.
Chapter 8 – Making Scents
1. Briefly explain how we perceive a smell.
We gain our sense of smell by sucking in tiny molecules that are floating through the air. We suck these molecules into our nostrils while breathing. The molecules, also known as “odor molecules”, travel through our nose, where they are captured by mucous. The mucous contains nerve cells, which when are combined with the odor molecules, send signals to our brain,
letting us know that we smell something.
2. Jawless fish have a very few number of odor genes while mammals have a much larger number. Why does this make sense and how is it possible? Jawless fish have a very few number of odor genes while mammals have a much larger number because mammals are a particular type of organism that need to smell, therefore requiring a larger amount of odor genes. They are able to have a larger amount of odor genes because the “extra” genes are basically just duplicates of the same genes, just in a smaller amount in jawless fish.
Chapter 9 – Vision
1. Humans and Old World monkeys have similar vision – explain the similarity and reasons for it. Humans and Old World monkeys have similar vision because they share a similar construction in their optical systems. Humans and Old World monkeys see the same colors. We see the same colors because of the change in color of our plants. Nearly 55 million years ago, we discovered the colors we see today by observing the different plants in our world—from the dull colors of the figs to the bright colors of the fruits and berries.
2. What do eyeless and Pax 6 genes do and where can they be found?
Eyeless, or Pax 6 genes allow all animals to have eyes. Lacking an eyeless or Pax 6 gene, one would not have eyes. Biologist Walter Gehring discovered that adding this gene would generate an eye. Eyeless genes were found in flies, mice, and human. When they were found in mice, they were called Pax 6 genes.
Chapter 10 – Ears
1. List the three parts of the ear; what part of the ear is unique to mammals?
The three parts of the ear are the inner, middle, andouter ear. The pinna is unique to mammals because it is only found in mammals.
2. An early anatomist proposed the hypothesis that parts of the ears of mammals are the same thing as parts of the jaws of reptiles. Explain any fossil evidence that supports this idea. Karl Reichert was an early, German anatomist who proposed the hypothesis that parts of the ears of mammals are the same thing as parts of the jaws of reptiles. While observing “gill arches” in different mammals, he found that two ear bones in mammals were the same as the bones in the jaws of the reptiles.
Ernst Gaupp, also an early, German anatomist, had the same belief as Reichert. In the 1840s, fossils were discovered in Russia and South Africa. These fossil pieces were put together to become what was called a “mammal-like reptile”. In 1913, embryologists and paleontologists started to take part in Gaupp and Reichert’s beliefs. They began observing more fossils, and soon enough, agreed with Gaupp.
3. What is the function of the Pax 2 gene?
The Pax 2 gene is in the ear. It allows the inner ear to advance and flourish. This gene is necessary for the ear, as it helps the ear properly work.
Chapter 11 – The Meaning of It All
1. What is Shubin’s biological “law of everything” and why is it so important?
Shubin’s biological “law of everything” states “that every living thing on the planet had parents”. It is important because it is a law that no one can disagree on. It is so important, but at times, people do forget about it, taking it for granted. Shubin explains that everyone, from people to sharks, have parents. We all formed through some type of parental genetic information. Although we come from the same genetic information as our parents, we are the more modified version of them; we aren’t exactly like them. 2. What is the author trying to show with his “Bozo” example? Through the use of Shubin’s “Bozo” example, he was able to show us how important family trees are. He showed us that family trees allow us to go back in time to learn more about and make theories about our ancient family members. Constructing family trees would help us to categorize our family members based on their physical features, leading us to understand who came first.
3. This chapter includes many examples of disease that show how humans are products of a lengthy and convoluted evolutionary history. Choose three (3) of the problems listed below and briefly explain how ancient ancestors’ traits still “haunt” us: Obesity
Sleep apnea: In order to have the ability to talk, we must live with two problems—sleep apnea and choking. Sleep apnea occurs when you take a long pause in breathing while sleeping. This leads to an increased risk of high blood pressure and heart attack. If you have heart problems, sleep apnea can be very dangerous. Hemorrhoids: Hemorrhoids form as blood pools develop around your rectum. This occurs during long periods of time of sitting, for example. The veins grow bigger, swelling and causing pain. Obesity: Obesity is one of the leading causes of death in humans today. We have a body capable of being active, yet we sit around all day because we are too lazy to get up. Our bodies are meant to store food, but not too much. Obesity occurs when an individual has saved a disproportionate amount of food in his or her body.
Afterword (new findings re: Tiktaalik)
1. Tiktaalik was a fish that lacked an operculum – what does this tell us about the animal?
An operculum is a bone that allows water to move past the gills of a fish. Because Tiktaalik had lacked an operculum, it had a real neck. Tiktaalik had to constantly swim in order to breathe, similar to sharks.
2. Tiktaalik had a true neck – what did this allow the animal to do (advantages?)
Since Tiktaalik had a true neck, it gave it natural selection. Having a neck was useful in both land and water. It also allowed the animal to move around without having to reposition its entire body.