Making Scents
First of all, extracting DNA at home? I thought this was very cool and I hope to try it one day. I loved the way Shubin explained how the odor is like a chord because it is the product of signals from lots of receptors keyed to different odor molecules. I also never knew that fish actually have a hole on top of their head where they scent smells. I have raised and caught fish before and never noticed that they have a hole on top of their head. Another shocking thing is how that the lungfish and the Tiktaalik have external and internal nostrils just like humans. I was surprise how we actually have the lungfish that were here even before the smelling genes split up. They’re like some kind of living fossil! It was also very surprising that humans have three hundred of these thousand odor genes that are completely functionless. Throughout of many years, humans have evolved to not use these genes just like how the dolphins decided to smell through their blowholes.
Vision
This chapter was like a review of how the eye functions, but it was informative because it gave background information on the ideas to come. Biology amazes me because the Pax 6 (eyeless) gene from the flies developed an eye anywhere on the flies. If you think about it, an eye on antenna, leg, and the wing??? That is kind of creepy if you think about it, but also very amazing. When Gehring put an eyeless gene of a mouse on a fly, it turned into another fly eye! It just comes to show that even between small creatures there are many similarities. The eye development was almost the same in the mouse and the fly. Also something interesting I learned was how scallops have eyes! In addition, humans have modified bits of ancient bacteria inside our retinas that help us see. It is quite shocking that there are traces of the change that humans have went through.
Ears
I’ve already known that we have three ear bones and it was fun reviewing the parts of the ear at first. Shubin tries really hard to present the material to the readers so that they can completely understand. As I further read, I learned that two of the ear bones in the mammals corresponded to the pieces of the jaw in the reptiles. How is that possible? When I observed the diagram of the tracing of the gill arches to our ears, I was amazed. The bones were used differently to help the creature in their own way! The mammals used the bone to assist in hearing while on the other hand, reptiles used it to chew. The primitive creature, the jellyfish, does not have either the Pax 6 or the Pax 2 gene. They seem to have remained the same and stuck to their primitive bodies and have not changed after that. Interestingly, Shubin explained how human birth defects afftect both the eyes and the inner ear because of the similarities between the jellyfish. Who knew?
The Meaning of it All
In this chapter, the comparison that Shubin used especially stood out to me. At first, the way he used the bozos to help the reader understand the way in which creatures change throughout time. When Shubin said, “This exercise is almost like peeling an onion, exposing layer after layer of history,” I was very amazed. The more we go through time, the closer we get to see how all the animals in this world came to be. The explanation of why people get obese was pretty cool. It made total sense that our bodies are not used to having food 24/7. We are more used to the boom-bust world of our ancestors. I especially related to the section that Shubin talks about the tadpoles because I actually have raised and currently raising tadpoles of my own. I have seen them stay underwater, but once in awhile they would shoot up to the surface to get a breath of air. I learned that they have an “extended form of a hiccup” to help them shut the breathing tube. What a way to end this book!
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