Your Inner Fish

The evolutionary history of animal development is producing some thrilling science these days. Like Endless Forms Most Beautiful, by Sean Carroll, Your Inner Fish is written for a general audience by one of the pioneering scientists in the field.
Neil Shubin is a paleontologist and developmental biologist whose team discovered Tiktaalik, a Devonian fish that is evolving toward tetrapod. The stage of tetrapod evolution is intriguing on its own — the creature jointed fins with ends that bend and splay, and a neck, allowing it to do “pushups” in shallow water to catch prey or watch for predators.
Picture 184.png
Carroll has more in-depth information than Shubin about the core of evo devo, the evolution of the developmental program that builds creatures with bodies. Where Shubin’s book shines is exploring the deep evolutionary history of different parts of the body, such as teeth, eyes, ears, and the head. The developmental program for teeth, out of the interaction between layers of skin in the embryo, also generates hair, feathers, and breasts. The bones, cartilage, and nerves in the human jaw, ears, and throat, expanded from tissues that served as gills in fish; the straightforward nerve routes in fish became convoluted in mammals now that the location of the tissues has been rearranged.
One of the most interesting chapters in the book covered the evolution of the building materials of bodies: collagen, cartilage, bone, intercellular communication. One fascinating hypothesis in this section is that one of the key bodybuilding materials, collagen, requires a lot of oxygen to produce. Therefore, a key factor in the explosion of animals with bodies in the Cambrian era was a rapid rise in the amount of oxygen in the atmosphere.
To follow up on this idea, I’m now reading Oxygen, the Molecule that Made the World.

Leave a Reply

Your email address will not be published. Required fields are marked *