Week 5: Needy Noses and Closing Remarks

We humans can pick out 10,000 different odors with our noses. This amazing level of specificity is only possible by the highly specialized proteins in our noses that attach to a unique odor and tell our brain what we're smelling. Shubin not only discusses the extraordinary function of noses, but also talks of the nose's function as an indicator of relatedness. He says,

"inside our noses is a veritable tree of life."

This is analogous to the saying "a picture is worth a thousand words." In humans specifically, we can determine the amount of scents we have and the amount we've lost due to mutations. Shubin points out that interestingly enough, organisms more closely related to humans have lost the exact same scent receptors from the same mutations that removed them from humans. I found it really interesting that mutations removing scent receptors that occurred further down the line of descent of mammals were conserved in humans and could be used as a biological clock to track moments of divergence.

As I finish Your Inner Fish, I'm left with a sense of fascination by the magnitude of examples that Shubin was able to provide throughout his text that supports evolution and the fact that all life descends from a common ancestor. Whether it was about similar body plans or the structure of our hands, Shubin continually connected everything back to this main argument. I found reading his book a breeze because of the constant connections he'd always make to common descent. Each chapter had a formulaic format to it: Shubin would present a discovery, give background information about the discovery, go back to discovery, then connect it to the larger picture. By being able to follow this formula, I was able to more easily comprehend the different enigmas he'd give and not be muddled down in new terminology or concepts.