Reflections on Feathers: the Evolution of a Natural Miracle

As a lifelong casual bird watcher, the title Feathers drew me in right away. I grew up in and around an Audubon-designated bird sanctuary, and as I flipped through the book I started to think about how feathers might account for how birds had captured my attention. The brilliant colors, the beauty of flight, and the fascinating behaviors of birds are all best considered through the lens of feathers. In Feathers, Thor Hanson takes a seemingly narrow topic and surprises readers with all the directions it can lead. While the focus is the evolutionary biology of feathers, the book touches on fashion, aircraft, the down industry, pens, and the aviaries of the Aztecs.

Thor Hanson Feathers book cover

Thor Hanson is a field biologist, a self-descriptor he uses often in the book. While not all readers will immediately appreciate the distinction between “biologist” and “field biologist,” I think the subtle difference becomes apparent in his writing. He clearly has many of the hallmarks of the naturalists of an earlier era; he spends an ample amount of time outdoors in direct observation of animals, takes copious field notes, and has an inclination for hands-on exploration of anatomy and physiology. Reading about the University of Vermont’s field naturalist program, where he got his master’s, gives you a sense where he’s coming from. Though some of his projects in the “racoon shack”—his outdoor shed/office—might remind you of the pursuits of nature-obsessed ten-year-olds, I think they are illustrative of a different—more approachable—kind of scientist than most readers will be familiar with.

While Hanson’s research extends across many fields and industries, he continually comes back to the work of evolutionary ornithologist Rick Prum and his research group at Yale. His fluidly written descriptions of Prum’s research programs were the highlights of the book. Prum took a developmental approach to understanding feather evolution early on. His theory centered around the development and structure of feathers; the central insight was that feathers are tubes, not plates. The idea struck him while teaching:

I was giving my class the standard scales-to-feathers theory, and by the end of the lecture I realized it didn’t make any sense. Feathers couldn’t have evolved that way!

Neatly following Prum’s “eureka” moment, Hanson treats us to the exciting story of how the evidence to support Prum’s theory came rolling in, mainly through massive fossil discoveries in the Yixian formation in China.

In the pages that follow, Hanson makes an interesting choice in including a discussion of Alan Feduccia’s theories and his BAND (Birds Are Not Dinosaurs) group. To be clear, BAND members are not creationists—they are scientists in support of the theory that birds are more like second-cousins of theropod dinosaurs, rather than their direct descendants. However, given the abundant and continually growing evidence that modern birds did indeed evolve from theropods, many in paleobiology find it frustrating that this still gets talked about, especially in popular media. Yet Hanson uses this conflict to tell an important (and often ignored) story about the scientific process, argumentation, and evidence. He notes:

…continual reporting on the BAND’s minority viewpoint (in the interest of journalistic fairness) may be perpetuating a controversy that most scientists consider over and done with. But when I pressed him, Prum did admit that certain criticisms had helped refine his thinking, whatever the cost to his blood pressure.

Feathers does something else that too many popular science books fail to do: it remains accessible to non-scientists throughout. Hanson never lets himself stray too far into the technical aspects of the science, and maintains general appeal by including extensive discussion of human interest in feathers. The book manages to be broad enough that scientists will learn something new, and restrained enough that non-scientists will understand and enjoy it.

I particularly enjoyed Feathers because it was so personally relatable. My own childhood interest in science grew out of observations of nature and a love for the work of naturalists. I might have been a field biologist too, if I had ever really had the constitution for surviving Maine winters and African summers. For now, I am happy to sit back and read.