The variety of smells in the world can help us survive. When we smell an object, the brain reacts to the signals sent from the nose and remembers the scent. Many creatures have one or more holes to bring the scent inside the body, where special tissues chemically interact with the neurons to recognize the smell. The narrator expressed his idea of evolution, proving that fish, mammals, and reptiles have nasal receptor systems, water-based ones for fish and air-based ones for mammals and reptiles. Shubin points out that the number of odor genes have dramatically increased from the era of the jawless fish to the time of mammls, highly speacialized and effective animals. The reason of having a large number of olfactory genes can be explained by our ancestors; our body still contains left over smell genes from the past.
Chapter Nine: Vision
Shubin explains the roles of the eyes by stating that we have little cameras in the back of our brain, capturing light and processing images that our eyes capture. The light must pass through certain tissues such as cornea, iris, lens, retina for the lights to convert to an image. The structures of an eye is very complex; different opsins are used to differentiate the black, the while, and the colored images. Shubin, once again reemphasizes the similarities of human and animals; "Insects, humans, clams, and scallops all use opsins" (160). I gasped at Gehring's experiment of swapping genes between different species. The mouse gene was able to produce a fly's eye anywhere. We, the different creatures and humans, share similar complexities of the eyes.
Chapter Ten: Ears
Unlike the nose and the eyes, the ears of mammals differ from those of other creatures; our ears contain three middle ear bones called malleus, incus, and stapes, which allow us to hear higher frquency sounds. The fact that the stapes in human ears and the upper jaw of the fish blew me away: I have never guessed such transformations of the bones. The inner ear has two functions in a body: one for hearing and the other for balancing and noticing the movements of the head. When you tilt your head to the right and to the left, the eyes stay focused on one point because the muscles recognize and respond to the kinetic changes.
Chapter Eleven: The Meaning of it All
The author concludes the book with the idea that every living creature has or once had parents who are genetically similar to its own. The very first creature on this planet reproduced, its offspring reproduced, and continued the process until we, the humans, were evolved from different species. Based on different appearances, structures, and roles, creatures are grouped in many ways but the point of this division is to illustrate the fact that these creatures came from teh same ancestors. Not effectively using our bodies, humans have developed miserable ways to death; diseases such as diabetes and heart attacks are cause by our sedentary lifestyle. Unlike us, the ancient animals were active for survival, however we tend to depend on the lifestyle that is "easier." I didn't like how the author concluded the novel because towards the end, I felt that he was off topic, discussing about random facts like the hiccups and the mitochondrial diseases. Despite this fact, this book helped me view evolution differently; My perspective has changed through this experience, I learned to view different species similarly. The examples Shubin used were entertaining and educating at the same time. I disliked how the author wrote 20 pages to explain his main point but his points regarded the topic and were worth reading.
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