Chapters 8-11

Chapter 8 Making Scents:
Frankly, I am glad that I was out of the focus on fetuses because they were rather confusing to say the least. This chapter was quite short, but it was concise and taught me something new. Knowing basic biology, I knew that molecules in the air reached a lining filled with nerves in the back of our nose to send a signal to our brains. What I didn't know was that the process of smelling used a lock and key mechanism on a molecular level between molecules and the nerves. Thus, I learned that our smells are an accumulation of hundreds and thousands of different molecules being signaled to synthesize a combination of smells. Hence, reading about Axel and Buck's discoveries about the immense amounts of genes dedicated to detecting different odors was no surprise. The topic on nasal structures and internal and external nostrils was a nice touch to connect us with the ability of smelling with other creatures. In summary, Shubin reveals that many primitive species had few genes dedicated to smelling that were neither prioritized on air or water. However, these genes split into water and air types and then duplicated into many similar variations that detect different smells. Then finally, some creatures shut down some of these genes as a result of different adaptations in which dolphins sacrificed smell for breathing through the blowhole and humans sacrificed acute scent for a priority in sight.

Chapter 9 Vision:
The analogies in this chapter were helpful in understanding opsins. Shubin starts off with the structure of the eye and how it is a combination of many different parts. Than, he states how the retina has light-receiving cells that transfer light to our brains as images. In these cells are opsins, which send the images to our brain, are like ink jet printers in which there are three different opsins in our light-receiving cells to make a color picture. Like how genes for scent duplicated in species, we humans have a duplicated gene for another opsin so that we could have the three opsins need to more fully perceive color. Shubin then connects us with our ancestors by pointing out the existence of opsins in bacteria, and how the perception of color was probably created in response to the development of different colors in food sources. In addition, Arendt's discoveries pointed out that similar aspects of the different eyes in invertebrae and vertebrae were found in a primitive worm; suggesting a branch into the two different eyes. On a genetic level, Hoge's discoveries showed that many creatures, such as the mice and fly, share a very similar gene that is dedicated to the creation of an eye in the area it is active. This further supported our connection with primitive species. This chapter was very similar to chapter 8.

Chapter 10 Ears:
Like the previous chapters, Shubin starts off with the structure of the ear, the external ear which funnels the sound, the middle ear that rattles with the eardrum and three little bones, and the inner ear which perceives sound by use of sensory cells and fluids. As mentioned in previous chapters, the bones in our middle ear weren't created out of thin air, but rather, they were adapted from different bones seen in the jaws of ancient creatures. Shubin refers to how the stapes came from the second arch and the malleus and incus came from the first arch. Then he states how as reptiles became more adapt to land, these jaw bones became smaller and smaller until they became small bones ideal for catching vibrations in air. I then learned that the small fluids in our inner ear shift as we shift and bends bristles in our ear to send a signal to our brain on our position (which is made even more sensitive due to the presence of small rocks with the fluid). I then learned that these fluids are linked with the control with the eye in a way that when the fluids shift, the eye shifts to adapt to the velocity or change. It was interesting to know that fish use a similar system to our inner ear with fluids and bristles to detect the motion and direction of a current. I was disappointed to learn that there was lacking evidence to suggest which system came first. Luckily, I learned that we are still connected to older creatures for the development of a coiled inner ear for hearing and three tubes for the perception of three dimensional acceleration. In addition, the discovery that the box jellyfish has a gene that seems like a primitive combination between Pax 6 and Pax 2 shows that eyes and ears share a similarity in disease and history.

Chapter 11: The Meaning of it All
This was a great conclusion and addressed many of the ideas and perceptions that were rumbling chaotically through my head and cleared them into an effective thought. He points out that our DNA, genes, and structures all show that we are modifications of our "parents". Like his "bozos" we are modified from our ancestors and pass the trait down in which the descendants are further modified until you get "cousins" and generations that have many differences. In context with other creatures, our similar traits with theirs' show a lineage and evidence of modification. The diagram displaying all the chapters topics ( multicellularity, hands and feet, etc...) show how we are modifications adding layers of modifications as years pass. In relation, because we are all modifications on a similar base, there is a limit to the amount of modifications that species can create to adapt. Thus, we humans aren't perfect and are still prone to disease and illness. In relation to illness, many of them derive from our ancestry that result in our exposure to them as humans. For example, our adaptation to hold fat to resist scarcity result in problems such as in the heart. In all, this was a great conclusion that summed up our unbreakable connection with our ancestors.