How to Tame a Fox (and Build a Dog)

Visionary Scientists and a Siberian Tale of Jump-Started Evolution

The University of Chicago Press

Contents

A Bold Idea

One afternoon in the fall of 1952, thirty-five- year-old Dmitri Belyaev, clad in his signature dark suit and tie, boarded the overnight train from Moscow to Tallinn, the capital of Estonia on the coast of the Baltic Sea. Across the waters from Finland, but at the time, a world away, Tallinn was shrouded behind the Iron Curtain that divided Eastern and Western Europe after World War II. Belyaev was on his way to speak with a trusted colleague, Nina Sorokina, who was the chief breeder at one of the many fox farms he collaborated with in developing breeding techniques. Trained as a geneticist, he was a lead scientist at the government-run Central Research Laboratory on Fur Breeding Animals in Moscow, charged with helping breeders at the many commercial fox and mink farms run by the government to produce more beautiful and luxurious furs. Belyaev was hoping that Sorokina would agree to help him test a theory he had about how the domestication of animals had come about, one of the most beguiling open questions in animal evolution.

He carried with him several packs of cigarettes, a simple meal of hard-boiled eggs and hard salami, and a number of books and scientific papers. A voracious reader, he always traveled with a good novel or book of plays or poems, along with a number of science books and papers, on his many long train rides to the fox and mink farms scattered across the vast expanses of the Soviet Union. Even as he was intent to keep up with the rush of important new findings and theories in genetics and animal behavior pouring out of labs in Europe and the US, he always made time for his love of Russian literature. He was a particular enthusiast of works reflecting on the hardships endured by his countrymen through hundreds of years of political turmoil, works that were all too relevant to the upheavals Stalin had inflicted on the Soviet Union since his ascent to power decades earlier.

Dmitri's taste in literature ranged from the cunning folktales of the country's beloved storyteller Nikolai Leskov, in which unschooled peasants often outwit their more learned superiors, to the mystical poetry of Alexander Blok, who wrote presciently shortly before the 1917 revolution that "a great event was coming." One of his favorite works was the play Boris Godunov, by Russia's great nineteenth- century poet and playwright Alexander Pushkin. A cautionary tale inspired by Shakespeare's Henry plays, it recounts the tempestuous reign of the popular reformist tsar, who opened up trade with the West and instituted educational reform, but also dealt harshly with his enemies. Godunov's sudden death from a stroke in 1605 ushered in the bloody era of civil war known as the Time of Troubles. That brutal period 350 years ago was mirrored in the terror and devastation Stalin had perpetuated as Dmitri was growing up in the 1930s and '40s. Stalin's purges and his ill-conceived agricultural policies produced wave after wave of famine.

Stalin had also supported a brutal crackdown on work in genetics, and in 1952 it was still a very dangerous time to be a geneticist in Russia. Belyaev followed the new developments in the field at great risk to himself and his career. With Stalin's backing, for more than a decade Trofim Lysenko, a charlatan who posed as a scientist, had wielded enormous influence over the Soviet scientific community, and one of his primary causes was a vehement crusade against genetics research. Many of the best researchers had been deposedfrom their positions, either thrown into prison camps or forced to resign and accept menial positions. Some had been killed, including Dmitri's older brother, who was a leading light in the field. Before Lysenko's rise to power, Russia was a world leader in genetics. A number of the best Western geneticists — such as American Herman Muller — had even made the long journey east for the chance to work with Soviet geneticists. Now Russian genetics was in a shambles, with any kind of serious research strictly prohibited.

But Dmitri was determined not to allow Lysenko and his thugs to keep him from conducting research. His work in fox and mink breeding had given him an idea about the great outstanding mystery of domestication, and it was simply too good for him not to find a way to test it.

The methods of breeding employed by our ancestors who domesticated the sheep, goats, pigs, and cows that were so vital to the development of civilization were well understood. Dmitri employed them in his work every day at fox and mink farms. But the question of how domestication had gotten started in the first place had remained a riddle. The ancestors of domesticated animals, in their wild state, would likely have simply run away in fear or attacked if a human had approached. What happened to change this and make breeding them possible?

Belyaev thought he might have found the answer. Paleontologists had argued that the first animal to be domesticated was the dog, and by this time, evolutionary biologists were sure that dogs evolved from wolves. Dmitri had become fascinated by the question how an animal as naturally averse to human contact, and as potentially aggressive as a wolf, had evolved over tens of thousands of years into the lovable, loyal dog. His work breeding foxes had provided him an important clue, and he wanted to test the theory he was still in the early stages of developing. He thought he knew what had first set the process in motion.

Belyaev was traveling to Tallinn to ask Nina Sorokina to help him get started on a bold and unprecedented project — he wanted to mimic the evolution of the wolf into the dog. Because the fox is a close genetic cousin of the wolf, it seemed plausible to him that whatever genes were involved in the evolution of wolves into dogs were shared by the silver foxes raised on the farms all over the Soviet Union. As a lead scientist at the Central Research Laboratory on Fur Breeding Animals, he was in the perfect position to conduct the experiment he had in mind. Dmitri's breeding work was of such importance to the Soviet government, because of the badly needed foreign currency the sale of furs brought into the government's coffers, that he believed as long as he explained the experiment as an effort to improve the production of furs, it could be run safely.

Even so, the fox domestication experiment he had in mind was sufficiently risky that it would have to be run far away from the prying eyes of Lysenko's goons in Moscow. That's why Dmitri had decided to ask Nina to help him get it started under the auspices of her breeding program at a fox farm in faraway Tallin. He had collaborated with her on several successful projects to produce shinier and silkier furs, and he knew she was very talented. They had developed a good relationship, and Dmitri believed he could trust her and that she would trust him.

His plan for the experiment was on a scale never before carried out in genetic research, which worked primarily with tiny viruses and bacteria, or fast-breeding flies and mice, not animals like foxes, which mate only once a year. Due to the time it would take to breed each generation of foxes, the experiment might take many years to produce results, perhaps even decades, or longer. But he felt launching it was worth both the long commitment and the risk. If it did produce results, they might well be groundbreaking.

DMITRI BELYAEV WAS NOT A MAN TO shy away from danger, and he understood how to use the considerable tools he had to negotiate the treacherous waters of Stalin's rule. When World War II broke out, he immediately joined the Soviet army and fought valiantly against the Germans on the front, rising to the rank of major by war's end, though he was only twenty-eight. Both his military service and his skill in fur breeding, producing gorgeous furs that fetched high prices, had won him the trust of his government superiors, and he had developed a reputation as both a first-rate scientist and a man who knew how to get things done. Dmitri also knew how to make good use of his considerable charm, and the mesmerizing effect he had on people, to burnish his reputation.

Belyaev was a strikingly handsome man, with a strong jaw, thick coal-black hair, and penetrating dark-brown eyes. His confidence and dignified bearing lent him a commanding presence, though he stood only five feet eight inches tall. No one who worked with him, or even just met him briefly, failed to comment about the extraordinary power of his eyes when asked to describe him. "When he was looking at you," one colleague recalled, "he was looking through you, reading your mind. Some people didn't like to go to his office, not because they had done something wrong or they were afraid of being punished. They were scared by his eyes, by his gaze." Belyaev understood this effect well and he would often intently lock people in his gaze when he spoke with them. It seemed impossible to keep anything from him or to deceive him.

His demanding standards of excellence were profoundly inspiring for some of his scientific colleagues and those who worked for him, and many of them were intensely devoted to him. He gave them confidence and pushed them to do their best work, constantly probing into new avenues of inquiry with them. A believer in lively debate, he encouraged open discussion of alternative views, and he loved volleying ideas back and forth. Some of those who worked with him weren't so enamored of his leadership, however, intimidated by his intensity and unbridled energy, while others feared his disdain for any shirking of responsibility or any sort of gossip or intrigue. He knew those he could expect first-rate work from and trust and those he could not. Nina Sorokina was one of those he could have faith in on both counts.

Disembarking from his long train journey to Tallinn, Dmitri boarded a local bus heading south, traveling roads so bumpy they barely merited the name, through many tiny villages. His destination was the little hamlet of Kohila, buried deep in the Estonian forest. Not so much a village as a corporate outpost, Kohila was typical of the dozens of these industrial-scale fur farms scattered across the region. Spread out over 150 acres, the farm housed about 1500 silver foxes in dozens of rows of metal-roofed long wooden sheds, each of which contained dozens of cages. The workers and their families lived a ten-minute walk away from the farm in a bare-bones settlement of drab housing units, a small school, a few shops, and a couple of social clubs.

Nina Sorokina struck a somewhat incongruous figure against the dreary backdrop of this remote outpost. She was a beautiful, dark-haired woman, also in her mid-thirties, keenly intelligent and intense about her work, commanding a powerful position for a woman in such a vital industry. A welcoming host, she enjoyed inviting Dmitri for tea in her office whenever he visited the farm. When he arrived after his long journey, they went right away to her office to talk in private. Over tea and cakes, with an ever-present cigarette dangling from his mouth, he told her what he was proposing — to domesticate the silver fox. She would not have been unreasonable to think her friend somewhat mad. Most of the foxes at the fur farms were so aggressive that when caretakers and breeders approached them, they bared their sharp canine teeth and lunged at them, snarling viciously. When foxes bite, they bite hard, and Nina and her team of breeders wore two-inch thick protective gloves that rode halfway up their forearms when they got anywhere near these animals. But Nina was intrigued, and she asked him why he wanted to attempt this.

He told her that he had been fascinated by the unanswered questions about domestication, and that he was especially taken by the puzzle as to why domesticated animals could breed more than once a year, but their wild ancestors rarely did. If he could domesticate foxes, they might also be able to breed more often, which would be very good for business. This answer was true, but it was also good cover for her and her breeding team. If anyone should ask what they were doing, they could say that they were studying fox behavior and fox physiology, which were acceptable areas of research to Lysenko, in order to see if they could increase fur quality and the number of pups born each year. How could the authorities object to that?

He didn't want to put Nina at risk by explaining more. The full truth was that if the experiment worked, it might provide the answers to many important outstanding questions about domestication in all species. The more Belyaev had researched what was known about how animals had become domesticated, the more intrigued he had become by the mysteries about it, and those were mysteries that only an experiment of the kind he was proposing would be able to solve. How else could the answer to how domestication got started possibly be found? No written accounts of this first stage of the process were available. And though fossils of the early stages of domesticates such as dog-like wolves and early versions of domesticated horses had been found, they could reveal little about how the process got going in the first place. Even if remains could eventually be found that established what the first changes in animals' physiology had been, that would not explain how and why they emerged.

A number of other puzzles about domestication also had not been solved. One was why so few animal species out of the millions on the planet had become domesticated — only a few dozen in all, most of which were mammals, but which also included a few species of fish and birds, and a few insects, including the silk moth and the honeybee. Then there was the question why so many of the changes that had taken place in domesticated mammals were so similar. As Darwin, one of Dmitri's intellectual idols, had noted, most of them developed patches of different coloring in their fur and on their hides — spots, patches, blazes, and other markings. Many also retained physical characteristics from childhood well into their adulthood that their wild cousins outgrew, such as floppy ears, curly tails, and babyish faces — referred to as the neotonic features, those that make young animals of so many species so adorable. Why would these characteristics have been selected for by breeders? Farmers raising cows, after all, had nothing to gain from their cows having black- and-white spotted hides. Why would pig farmers have cared whether their pigs had curly tails?

Perhaps these changes in the animals' characteristics had arisen not from the artificial selection process involved in breeding by humans, but through natural selection. After all, natural selection continues to operate on species after they've been domesticated, just to a lesser degree than in the wild. Animals in the wild develop all sorts of spots and stripes and other patterns in their fur and hides, which often serve the purpose of camouflaging them. The spots and patches domestic animals develop don't play this camouflaging role, though, so why would selection favor them? There must be another answer.

Another commonality among domesticated animals concerns their mating abilities. All wild mammals breed within a particular window of time each year, and only once a year. For some, that window is as narrow as a few days and for others it's weeks or even months. Wolves, for example, breed between January and March. The window for foxes is from January to late February. This time of year corresponds to the optimal conditions for survival; the young are born when the temperature, the amount of light, and the abundance of food offer them the best odds for a successful launch into the world. With many domesticated species, by contrast, mating can occur any time during the year and for many, more than once. Why had domestication led to such a profound change in the reproductive biology of animals?

Belyaev thought the answer to all of the puzzling questions about domestication had to do with the essential defining characteristic of all domesticated animals — their tameness. He believed that the process of domestication was driven by our ancestors selecting animals according to this one key trait — that they were less aggressive and fearful toward humans than was typical for their species. This characteristic of tameness would have been the essential requirement for working with the animals in order to breed them for other desirable traits. Humans needed their cows, horses, goats, sheep, pigs, dogs, and cats to be nice and gentle toward their masters, regardless of what they were trying to get from them — milk, meat, protection, or companionship. It wouldn't do to be trampled by their food or maimed by their protectors.

Belyaev explained to Nina that in his work in fox and mink breeding he had noted that while most of the minks and foxes on the fur farms were either quite aggressive or were nervous and fearful towards people, a few were quite calm when people approached them. They weren't bred to be calm, so the quality must have been part of the natural behavioral variation in a population. This, he posited, would have been true for the ancestors of all domesticates. And over evolutionary time, as our early ancestors had begun raising them and selecting for this innate tameness, the animals became more and more docile. He thought that all of the other changes involved in domestication had been triggered by this change in the behavioral selection pressure for tameness. Rather than either avoidance of humans or aggression towards them giving them the survival advantage, now being calm around humans gave them the edge. The animals living in human contact had more reliable access to food and were better protected from predators. He wasn't sure yet how selection for tameness would have caused all the genetic changes that must have happened in the animals, but he had conceived of an experiment he hoped would eventually provide the answer.