Evolution Within: Your Inner Fish

Neil Shubin's book about tracing the history of our bodies back to single-celled microbes shows a beautiful and enduring vision of humanity and all its relatives. Your Inner Fish: A Journey Into the 3.5-Billion-Year History of the Human Body starts with a personal account of an expedition that found fossils of Tiktaalik, an animal midway between a fish and a terrestrial animal. Shubin describes the differences in head type (flat vs conical), and points out how the bones of fins morph into the big bone -- two bones -- lots of blobs structure of land-living limbs.

The next chapters zoom in on the history of arms, heads (teeth were the first bones), bodies, describing how we are like other mammals, other limbed creatures, other vertebrates, other shaped animals, other multi-cellular groupings. Shubin looks at both anatomy and DNA, tracing the changes in both over the history of life. Then he looks at vision, hearing, and scent to again point out how we can judge similarities and the evolution of spectacularly complicated mechanisms. The chapters build a bit upon each other, although it's clear that Shubin is picking them to illustrate his points. His tone is clear and enthusiastic, with a mix of personal touches including stories of some of his own work and that of other scientists who pioneered the discoveries he chronicles.

It's a great overview of evolution and the scientific method, but I also treasure the little facts I gleaned along the way. I didn't know you could sieve a sponge and it would rearrange itself back together. I didn't know that the three-bone ear was a solid indicator of a mammal; probably better than hair. I hadn't thought of my body as being organized as a tube within a tube, but now I do. I understand the differences in bone structure between reptiles and mammals better, because Shubin traces the changes made and their effects. His last chapters sum up some reasons this is relevant -- why our bodies fail in some of the ways they do, why men get hernias and couch potatoes get sick. B

(This is an excellent book for my Science Book Challenge, because it is just brimful of science, both the making of and the love of.)