What did you think of the reading?
Continuing the journey through different body organs and their evolution from a primitive past, Shubin’s last chapters discussed the senses of smell, vision, and hearing. These pages provided insight as to the shift of organs and organ functions from their origins in fish and simpler organisms to their modern counterparts found in mammals like humans today. The last chapter, entitled “The Meaning of It All,” brilliantly tied all the evidence together to make connections that shocked me, as the reader. These revelations expertly explained our convoluted mammalian body layout, and previously inexplicable ailments, from the hiccups to hernias.
What did you learn from the reading?
The chapter about vision made some startling links between eyes in various species. I found it shocking how our camera-like eye emerged from the rudimentary light-capturing device found in limpets, nautili, and scallops. Even more astonishing were the discovered parallels between the eyeless gene of a fly and the Pax 6 gene in a mouse. When the focus shifted to our ears and their development, I learned about the exact internal processes that each part of this organ is responsible for, i.e. how it senses balance, perceives acceleration, and processes sounds. Shubin’s diagram adeptly conveyed the astounding alteration that transformed a reptilian jaw bone into a mammalian ear bone.
I found the last chapter to be the most intriguing, as it really tied together all the loose ends, and- more importantly- described why all of this is relevant. Shubin utilized the effective analogy of the “bozo family tree” to exhibit how evolution is an editing process. In other words, he explained how small, subtle alterations between generations can yield such a dramatic species change, such as that from a humorless species to a “full bozo.” I was also interested in another analogy that likened looking at the human body to looking back in time; changing features within our bodies reflect changes in our atmosphere at points in our history. A branch off of this analogy consisted of attributing our various ailments to our fish ancestry. The origins of common medical conditions like hemorrhoids (due to our body’s incompatibility with a sedentary lifestyle) and hiccups (derived from an amphibian’s gill breathing) were expounded upon. These explanations were definitely the most eye-opening to me.
What questions do you still have?
One question I had from previous chapters still baffles me: can these connections between species be used in medical areas regarding congenital abnormalities like missing limbs? After the Pax 6 gene and the eyeless gene (seen in different animals) were proven interchangeable, the ability to restore amputated or ungrown limbs seemed more plausible to me.