December 2018

Vol. 46, No. 6

About Books: Kids! Let’s Have Fun with Genes!

Mark Lynch

Unnatural Selection. Katrina van Grouw. 2018. Princeton, New Jersey: Princeton University Press.

"The fact is that, for me at this time, producing my own unique, very beautiful books about evolution, which communicate this most profound and exciting field in all biology, is the ultimate expression of creativity." (p. viii)

"Natural selection is indeed a terrifying concept to the human mind. But it also has a profound, breathtaking magnificence and an exquisite poetry." (p. xvi)

Some years back I was birding along the Connecticut River when we bumped into Tom Gagnon, well-known Valley birder, butterflier, and a longtime friend. After birding with him, he insisted on bringing us to a "poultry" show at the Big E in Springfield. Tom is a longtime breeder of show poultry. What I found there was mind-blowing. There were rows upon rows of cages in a huge exhibition building, each cage containing some breeder's prized chicken, duck, or turkey. Some chickens looked like, well, chickens, albeit very spiffy and healthy ones. Other breeds had wild feathering on their heads or on their feet or all over. Some looked like animated feather dusters. Some chickens were really huge, others minute. There was a crazy array of tail feather lengths and shapes. And they came in a startling array of colors and patterns. Some birds sported plumage in which each feather looked like it was perfectly outlined with a black Magic Marker. It wasn't just the chickens. Some ducks had pompadours. Others had carbuncles. It was as if H.G. Wells's Dr. Moreau had been let loose on a farm. It was an alternative reality of domestic fowl. These clearly were not chickens that were destined for a box of deep fried tenders, but these were birds that were doted upon by caring fanciers, many of whom were standing by their birds, anxiously awaiting a judge to pass a verdict. The question that immediately came to my mind was "How did they get a descendant of the Red Junglefowl to look like this?"

Typically, birders don't give domestic birds a second look in life or in print. Why should they? You can't count them on your list. eBird won't list your sighting of a prized onagadori as "mega!" It is the hope of artist and science writer Katrina van Grouw that her new book, Unnatural Selection, will change that attitude, particularly if the reader is interested in Darwin, evolution, and genetics.

Van Grouw is best known for her previous book The Unfeathered Bird. This is a large format collection of her exquisite study drawings of different species of birds, their feathers, skeletons, and musculature. In The Unfeathered Bird, the text supports the drawings. In Unnatural Selection, another outstanding collection of drawings really supports a more thorough and involved text.

Unnatural Selection is a book that begins with the basics of Darwinian natural selection and how Darwin described its central role in evolution over hundreds or thousands of years. But the bulk of Unnatural Selection is about how enterprising humans for centuries before Darwin have learned to accelerate and control this natural process to produce domestic animals in a myriad of forms through selective breeding. Van Grouw became interested in domestic breeds after she met her husband who has spent his life breeding exhibition varieties of pigeons, chickens, gerbils, canaries, budgies, and Barbary doves. Throughout the text, Katrina van Grouw's significant other is referred to as simply "Husband" in the manner of "Cher" or "Prince." The more van Grouw learned about selective breeding, the more she realized that these historic fanciers, through trial and error, and by keeping careful track of their crosses, were really masters of genetics long before Bateson and Mendel.

How foolish I was not to take fanciers more seriously. Oblivious was I to the fact that many of these men (and women too), in their own way, know at least as much about birds as any museum ornithologist or field birder. In their highly skilled hands pigeons are but putty that can, within a few generations, be molded into any shape and remade in virtually any color. Fanciers can fast forward evolution. (p. xiii)

Darwin had a life-long interest in domestic animals and even wrote a book on the subject: The Variation of Animals and Plants Under Domestication. But Darwin's central belief was always "natura non facit saltum," "Nature does not make jumps." Therefore, to Darwin, what fanciers did was interesting but had little relationship to what happened in the wild. But this was a long time before we understood genetics on the biochemical level. "Darwin believed that single-step evolution like this would be impossible in wild animals." (p. 109)

Unnatural Selection looks at domestic birds such as chicken, duck, finch, and particularly pigeon breeds, as well as dog, sheep, cattle, and pig breeds and asks a basic question: How did they come to look like this? And more specifically: Why does that bulldog have such an enormous mouth? What do Runner Ducks stand so straight? Dip randomly into Unnatural Selection and you will find Van Grouw's writing is engaging, opinionated, chatty, and often humorous. She also tells some great stories along the way. Her chapter on mutations begins this way:

Mutation; mutant; monstrosity; monster; deformity; freak—you can almost hear the barrel organ and the booming voice lyrically cajoling passers-by to roll up and see the two-headed lamb or the bearded lady. The word conjures up images of mad scientists conducting illicit experiments; creatures with too many body parts, or body parts in the wrong places, pickled in jars. Even the X-Men, superheroes of Marvel Comics, are social pariahs. "Mutation" it turns out, is a dirty, politically incorrect, word. The sort of word to get doors slammed in your face. (p. 134)

To sketch the numerous large fine drawings for the book, she visited some rather arcane places to find type specimens. These include the Albert Heim Foundation for Canine Research in Berne, Switzerland, which has the largest collection of dog skulls in the world. Included in Unnatural Selection is a fine drawing of a big box chock full of dog skulls from that museum. This is classic van Grouw artwork: unique, beautiful, with a dash of the macabre, like a contemporary Andreas Vesalius. A turn-spit dog is not a breed, but any small, short-legged pooch that spent a hellish life trapped walking in a wheel which turned various meats on a spit over a fire. Van Grouw tracks down the last extant specimen of a turn-spit dog in a modest local museum in a small town in Wales. Van Grouw's drawing of the poorly mounted body of Whiskey, the last turn-spit dog, conveys all the tragedy of Whiskey's hellish life.

Unnatural Selection is divided into four general topics: "Origins," "Inheritance," "Variation," and "Selection." These are further broken down into chapters on a variety of subjects. Though van Grouw often deals with some technical terms and concepts, don't let that dissuade you from reading this book. She often uses her illustrations to help the reader understand these complex ideas. To discuss genetic variation in breeds of pigeons, she presents a tour-de-force two-page spread (pp. 50-–51) of skulls of different pigeon breeds. To the average reader this looks like a collection of dramatically different species of doves from around the world, yet these are all breeds derived from one species of domestic pigeon. The caption reads,

Skulls of domesticated pigeons, all sharing a common ancestry with the Rock Dove and showing the enormous diversity of possible forms. Despite the apparent intermediate stages, all these birds are contemporary and represent the tips of evolutionary branches. From appearance alone, assumptions about which branch sprang from which would be merely guesswork—especially as many breeds were created by crossing. (p. 49) Keep in mind that all this genetic variation was accomplished long before knowledge of modern genetics and gene splicing techniques utilizing CRISPR (clustered regularly-interspaced short palindromic repeats).

Unnatural Selection celebrates how humans figured out how to change a rock pigeon into dramatically different fancy breeds like the Scandaroon, Frillback, Mokees, or Norwich Cropper through crossbreeding. Learning the odd breed names is just part of the fun in this book. Sometimes it wasn't simply a matter of selective breeding, but taking advantage of a spontaneous mutation. That was the case of a breed of sheep with very short legs called Ancon, or "otter sheep." A farmer in Dover, Massachusetts, decided to keep and breed these natural anomalies so he could save money on fences. Born in the wild, this mutation would probably have had a short life span. But if that mutation appeals to humans, it just might become a breed. For van Grouw, each domestic breed is as precious and worth "saving" as a wild species, because it is all about the importance of genetic diversity.

This is why it's so important to preserve rare breeds of livestock—not only for their historical or cultural importance but because they represent irreplaceable richness in genetic diversity for the entire animal kingdom. (p. 159)

Sometimes, some of the most startling traits of a breed are affected by the environment, and this is exploited by the fancier, often to extremes. Onagadori roosters are a rare and prized breed from Japan that is known for extremely long rectrices. Since light can affect molt, these onagadori roosters lead a unique life.

A range of stimuli can initiate molt: changes in day length, sudden stress, diet, and most of all, sex. The most prized onagadori roosters therefore live an austere, monastic life. They're traditionally kept in tall enclosed towers called tombaku, where their exposure to light can be closely monitored. (p. 205)

Most often the changes wrought by selective breeding seem harmless, are visually interesting or fun, and don't do the animal in question any real harm. Think of all the dramatically different dog breeds. But there are other times when what the fancier creates can seem a bit Frankensteinian. The Bokhara trumpeter pigeon "…has fully formed, asymmetric quill feathers on its feet to rival the flight feathers of wings." (p.194). This breed of pigeon looks like it has two sets of wings, one pair where they ought to be and the other on its feet! If that isn't enough, its head is all but invisible inside a dense ball of feathers. It is selective breeding like this that has had some readers criticizing Unnatural Selection for not condemning selective breeding altogether. Katrina van Grouw responds, in part, this way:

There are of course ethical issues involved in pushing these boundaries to their full capacity, and equally there's a certain amount of moral outrage about selective breeding in general. Some would even label all domesticated animals as monsters. To say that it's not about right and wrong is not the same thing as saying that it's right. Nevertheless, my response to anyone complaining, "Look what humans have done to the Pekinese" is to reply, "Look what flowers have done to Sword-billed Hummingbirds! (p. 159)

Unnatural Selection covers a lot of ground in describing the wonders of selective breeding. It is a great overview of Darwin's ideas and a history of genetics and evolution. It is also a unique account of how humans have domesticated animals and then manipulated their charges genes solely for our benefit and delight. Add to this an abundance of van Grouw's stunning detailed drawings and it is easy to see why Unnatural Selection is one of the best science and art books of the year.

Artificial selection is an excellent analogy for natural selection, even more so than Darwin had realized. But the similarity is more than just metaphorical. There are not "domesticated animals", "wild animals", and "humans". There are only animals. There's not a "natural environment" and a "man-made environment"; there's just the environment. Artificial selection is not merely analogous with evolution. It is evolution. And the process of domestication is just one of countless adaptations to changing environments, irrespective of the existence of man. (p. 278)


  • The Unfeathered Bird. Katrina van Grouw. 2013. Princeton, New Jersey: Princeton University Press.
  • The Variation of Animals and Plants Under Domestication. Charles Darwin. 1868. London, Britain: John Murray.

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