How to Tame a Fox and Build a Dog

A decades-long experiment opens up like a set of Russian nesting dolls, to reveal story after story, each embedded within the one that preceded it.

Evolution Animal Behavior

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July-August 2017

Volume 105, Number 4
Page 240

DOI: 10.1511/2017.105.4.240

Deep inside my soul,” says Lyudmila Trut, “is a pathological love for animals.” She inherited this from her mother, who was a great dog lover. Lyudmila had grown up with dogs as pets, and even during World War II, when food was horribly scarce, her mother would feed starving stray dogs, telling her, “If we don’t feed them, Lyudmila, how will they survive? They need people.” Following her mother’s example, Lyudmila always carries some kind of treat in a pocket in case she encounters a stray dog. And she’s never forgotten that domesticated animals need people. She knows that this is how we’ve designed them.

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Unless otherwise indicated, all photographs are courtesy of Lyudmila Trut and the Institute of Cytology and Genetics.

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In 1958, Lyudmila was just finishing up her studies at Moscow State University, home of Leonid Krushinsky, a pioneering Russian researcher in animal behavior. Dmitri Belyaev was friends with Krushinsky and admired his work. Belyaev had recently accepted a position as vice director of a new research institute in a giant Soviet city of science called Akademgorodok, near Novosibirsk, Siberia. He was searching for someone to lead an experiment he would begin in earnest at Akademgorodok. Dmitri intended to run an experiment domesticating silver foxes, and so the person he sought needed the kind of sophisticated skills in animal behavior that Krushinksy taught.

Belyaev went to visit Krushinsky at his office at Moscow State’s Sparrow Hill campus for advice about who might work with him on this experiment. Ensconced in the grand setting of Krushinsky’s building, with its palatial ceilings, marble floors, ornate columns, and fine art statues, he described his plans for the experiment and explained that he was looking for talented graduates to assist with the work. Krushinsky put the word out, and when Lyudmila heard about the opportunity, she was immediately captivated. Her own undergraduate work had been on the behavior of crabs, and as fascinating as their complex behavior could be, the prospect of working with foxes, so closely related to her beloved dogs, and with such a well-respected scientist as Belyaev, was tantalizing.

In early 1958, Lyudmila went to meet with Belyaev at his office. She was immediately struck by how unusual he was for a male Soviet scientist, especially one of his rank. Many were quite high-handed, and condescending to women. Lyudmila, who has a genial, smiling manner and stands just five feet tall, with her wavy brown hair cropped quite short, looked young for her age, and she hadn’t even finished her undergraduate studies, but Dmitri spoke to her as an equal. She was riveted, she recalls, by his piercing blue eyes, which so strongly communicated his intelligence and drive, but also emanated an extraordinary empathy.

She felt privileged to be invited into the confidence of this extraordinary man, who shared with her so openly about the bold work he was proposing. She had never experienced such a distinctive combination of confidence and warmth in a person. Dmitri told Lyudmila what he had in mind. “He told me that he wanted to make a dog out of a fox,” she recalls. Probing how creative she would be about conducting the experiment, Belyaev asked her, “You are now located on a fox farm that has several hundred foxes, and you need to select the 20 calmest ones for the experiment. How will you do it?” She had no experience whatsoever with foxes, and had only a vague notion of what the fox farms might be like and what sort of welcome she might receive at them. But she was a confident young woman, and she did the best she could to suggest some reasonable possibilities. She would try different methods, she said, talk to people who had worked with foxes, read up on what was known in the literature. Dmitri sat back and listened, gauging how committed she would be to the work and to developing techniques for such a novel study. She must be not only rigorously scientific, but also quite inventive. Was she really ready to go to Novosibirsk, to move to Akademgorodok, he asked her? After all, moving to the heart of Siberia was a life change not to be taken lightly.

Illustration by Barbara Aulicino.

Belyaev was also clearly concerned about the risk she would be taking, and he didn’t mince words about the dangers of being involved. This would be an experiment in genetics, but to ward off the dangers linked to a charlatan named Trofim Lysenko, who had made it essentially illegal to study Mendelian genetics in the USSR, Dmitri explained, the work would be described as research in fox physiology. No mention of genetics would be made in regard to the experiment, at least for the time being. He also assured her that he could, and would, speak out against Lysenko when necessary. But Lysenko and his crowd still had the power to make an example of a team of geneticists, even those in far-off Siberia, and punish them and ruin their careers and reputations.

Lyudmila knew that. Everyone knew that. Still, she was touched that he insisted that she be fully apprised. Another major concern he expressed was about the fate of her scientific career. Dmitri wanted to be very clear; he said with great seriousness, looking directly and intensely into her eyes, that the experiment might not produce any meaningful results. He hoped that it would, and he believed that it would. But even if it did, that might take many, many years, even as long as the rest of her life. Her job would be to select the calmest foxes for breeding and to observe and record the details of all changes in both their physiology and their behavior from generation to generation. In addition, she would need to travel great distances away from Novosibirsk to visit fox farms scattered in remote terrain, because he could not yet set up an experimental fox farm at Akademgorodok. He hoped he could one day, but not yet.

Lyudmila thought carefully about his admonitions, but she had no real doubt. This work would be a great challenge, she could see, and Belyaev would demand nothing short of excellence of her, which was greatly inspiring. Although she was a woman of great warmth and an unassuming demeanor, Lyudmila’s formidable energy and determination made her a force to be reckoned with. She had pursued her dream of becoming a scientist with great passion and had excelled at every step, despite Soviet science being almost entirely male-dominated. She wanted nothing more than to do path-breaking work.

The fox team remains hard at work, studying everything from the domesticated foxes’ love for humans, to the new vocalizations they now use to express that love, to the underlying molecular genetics of that passion.

Belyaev had made it clear that she would be given a good deal of latitude and responsibility in developing her methods for working with the foxes, and that was enormously appealing. She had found, as she would later say, a “winning ticket.” Not only would she be one of the first generation of researchers in a new scientific city, which might become the very center of Soviet science, but she would do extraordinary work with this remarkable man. She was sure of it. She could see it in those mesmerizing eyes of his. She trusted him.

Lyudmila had never dreamed she would leave Moscow to live in Siberia. She had grown up outside of Moscow and she loved the city. All of her family lived there, and they were very close, getting together regularly for dinners and outings. What’s more, she had just married and had a baby girl. Taking her daughter, Marina, so far away from such a close circle of loving family members would be difficult. Meanwhile, who knew what sort of work her husband, Volodya, an aviation mechanic, could find, or what sort of living conditions they could expect. The only thing she knew about living in Akademgorodok was that, being in the heart of Siberia, it would be bone-chillingly cold for much of the year. But she had to go. As it turned out, her husband heartily supported the move and felt confident he could find work there. To her great delight, her mother also decided that she would join them once they had gotten situated. She would live with them and look after the baby while Lyudmila did her work. In the spring of 1958 they took the Trans-Siberian Railway and headed to their new home.

Because there was no experimental fox farm yet in Akademgorodok, in the fall of 1959, Lyudmila found herself traveling on slow trains through vast expanses of Soviet wilderness, passing through village after village that modernity had not yet touched. She disembarked at tiny rail stations buried deep in forests and walked down dirt pathways to visit one industrial fox farm after another, looking for the best location for running the experiment.

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Photograph courtesy of Aaron Dugatkin.

When she arrived at a fox farm, she explained to the director the nature of the experiment that she and Belyaev wanted to start. They’d need some space of their own and access to hundreds of foxes to test, though, she explained, they would only end up using a very small percentage of those for the breeding they’d do in their experiment— just those that were the calmest. Many at the commercial farms were mystified why anyone would want to take the time to do what Lyudmila was describing. “It is quite possible,” she recalls with amusement, “that before people knew that Belyaev had sent me, they thought I was crazy, thinking, What is she up to, wanting to pick out the tamest foxes!” But as soon as she mentioned whom she was working with, their attitude changed completely. “A single word from Dr. Belyaev,” Lyudmila recalls, “was enough to guarantee respect.”

Eventually Lyudmila settled on a giant commercial fox farm called Lesnoi in remote terrain about halfway down to where the borders of Kazakhstan and Mongolia meet, about a 225-mile ride southwest of her home base in Novosibirsk. Like all commercial farms in the Soviet Union, it was owned by the state, and at any given time, it housed thousands of reproductive female foxes and tens of thousands of young pups. Lesnoi was a cash cow for the government, and the tiny space the director allocated for Lyudmila to keep the foxes she would breed would hardly change that.

The Lesnoi farm took some getting used to. It was an enormous complex, with rows and rows of open-air sheds—each one holding hundreds of cages, with one fox per cage. Even that wasn’t enough space, with fox cages seemingly covering every spare inch of space. The smell, especially for Lyudmila, who was a novice, was overwhelming. And the noise, a cacophony of yelps and screeches, especially at meal times, could often be deafening. The small armies of workers who fed the foxes and cleaned their cages paid little attention at first to this intense young woman methodically going about her strange testing of the foxes. They had little time for curiosity; each was responsible for the care of about 100 foxes.

The majority of foxes reacted aggressively when approached. A much smaller number cowered in fear. The smallest number stayed calm throughout. Foxes from that 10 percent of the population were selected for the experiment.

Having had no prior experience with foxes, Lyudmila was taken aback at first by how aggressive they were. Becoming acquainted with these “fire-breathing dragons,” as she called them, snarling and lunging at her when she approached their cages, she found it hard to believe that they could ever be domesticated. Now she understood why Belyaev had warned her that the experiment they were starting might take a very long time.

At Lyudmila’s behest, the manager of Lesnoi agreed to construct some large pens for the female foxes with wooden dens built into the front corner for them to give birth in, cushioned with wood chips to make the dens comfortable for the mothers and their pups.

Lyudmila’s first order of business at Lesnoi was to increase the number of foxes in the study, and to do that, she would select them from the large population there. She would have to travel from the Institute of Cytology and Genetics in Novosibirsk four times a year, starting in October, to select the calmest, most human-friendly foxes for mating, then in late January to oversee the mating process, again in April to observe the pups shortly after birth, and finally in June, to make more observations of the pups and how they were maturing. And she would do this year after year. Although Lesnoi was only 225 miles away, given the state of the Soviet train system, the trip was exhausting. Lyudmila would leave Novosibirsk at 11 P.M. and reach the small city of Biysk, an hour from Lesnoi, the next morning at about 11 A.M., where she caught a bus for the last leg of the journey.

Each day, starting at 6 A.M., Lyudmila made her way methodically from cage to cage. Wearing two-inch-thick protective gloves, she gauged how each fox reacted to her presence as she approached its cage, as she stood by the closed cage, as she opened the cage, and as she placed a stick inside the cage. Each fox was given a score on a scale of 1 to 4 for each interaction, and those with the highest aggregate scores were designated the calmest. She tested about 50 foxes every day, which was both physically and mentally grueling.

The majority of foxes reacted aggressively when she approached or when she put the stick into their cages. Given the chance, Lyudmila felt sure, they would have loved to rip her hand off. A much smaller number cowered in fear at the rear of their cages, also far from being calm. The smallest number stayed calm throughout, observing her intently but not reacting. She selected foxes from that 10 percent of the population to become the new parents for the next generation.

Lyudmila would take a short break for lunch in the middle of the afternoon at the little restaurant in the village, which served delicious borscht, Russian meatballs, and pancakes; then she’d head back to the farm for several more hours of testing, and after that, in the small room she was given at the quarters of the breeding researchers on the farm, she would record every detail of her observations that day. Finally, at about 11 P.M., she would unwind with a light dinner in the kitchen, sharing stories and jokes with the others at the house. Most of her time was spent alone with the foxes, and although she was developing a rapport with them, she often felt quite lonely.

Her visit to oversee the first mating of the foxes, in January 1960, was challenging. She had written a detailed plan during her October visit for which foxes to breed with which, pairing the calmest males with the calmest females while also avoiding any inbreeding. Most of the animals complied when they were brought together for mating, but some of the females rejected their proposed partners and Lyudmila had to act quickly to find another suitable mate: She did not want to let Belyaev down.

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Photograph courtesy of Aaron Dugatkin.

She was out in the unheated sheds for hours and hours in temperatures that regularly dipped to −40 or −50 degrees Celsius, and she missed her husband and daughter terribly. Although she knew her mother was taking good care of Marina, she felt horrible that she was missing so many of the exciting moments of her daughter’s early development. She couldn’t even call home very often, as there was no phone at the Lesnoi farm, and long-distance calls from the private phone of the director of the farm were next to impossible to arrange. The letter service between Lesnoi and Novosibirsk was also notoriously slow and unreliable.

Fortunately, Lyudmila’s visits to Lesnoi in April and June offered compensation. Observing the fox pups as they first opened their eyes and made their way out of their dens in April was a wonderful treat. As are the young of so many animals, fox pups are adorable. When first born, they are a little bigger than the size of a human hand and weigh only about 4 ounces. They are entirely helpless at first, both deaf and blind, and they don’t open their eyes until 18 or 19 days after birth. They look like little balls of puffy fur.

To simulate the normal rearing process, Lyudmila kept the pups in the experiment in their mother’s pen at all times until they were two months old, and they stayed bundled up together in the den for the first month, just as in the wild. Once they started venturing out of the den, they were allowed out into a yard by the shed to play for some time each day.

Lyudmila arrived within days of their births in April, and she wrote detailed descriptions of each of the pups, including their fur color, size, and weight, and made note of every little step of their growth: when they opened their eyes, when they could hear, when they first began to play.

The domestication experiment was off to a good start, and Lyudmila loved her time with the foxes, but the work was taking a heavy toll on her. The long absences from her daughter continued to weigh on her, and she sometimes wondered whether she shouldn’t try to find another research project.

Three domesticated fox pups sitting in a field (above), along with one holding a leash in its mouth (center), and one peeking through plants (right), show the range of variation in pigmentation that is possible with domesticated foxes. The process of domestication can alter the timing of development in the earliest stages. One gene the team identified, called Star, affects the migration rate of an embryo’s melanoblasts, precursors to pigment cells that color fur. Researchers in the study have also observed that domesticated foxes have lower levels of stress hormones (called corticosteroids), and produce higher levels of serotonin, sometimes dubbed the “happiness chemical.”

One day during her second January trip to Lesnoi, Lyudmila was waiting at the small train station in the town of Seyatel where she caught a bus to the Institute of Cytology and Genetics. The temperature was about 40 degrees below zero, and the station was barely heated. When it was announced that there would be no buses for quite a long time, she decided that was it—she would give Belyaev her resignation the next day and her family would move away from this horrid land. But the next morning, after a cup of hot coffee, she realized she couldn’t leave. She had fallen in love with the work.

Fast forward two decades and Lyudmila, Belyaev, and the whole fox team had accomplished more than they could have imagined in their wildest dreams. They had their own experimental farm near the Institute of Cytology and Genetics, and their domesticated foxes were as tame and playful as the cutest dog. And they now looked like dogs too, almost eerily so. They had begun to look so doglike, in fact, that one of the domesticated foxes, a female named Coco, who was something of a favorite at the experimental farm, was mistaken for a stray dog one day by a young man from a suburb of Novosibirsk in the vicinity of the farm. Coco then went on quite an odyssey.

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Coco was so appealing in part because from early on, she made a lovable chattering noise that sounded something like “co co co co co.” Lyudmila says fondly of Coco, “She gave herself her own nickname.” Everyone on the farm had followed Coco’s fate with great concern her first few weeks after birth. She was so tiny and weak that it looked like she wasn’t going to survive. Even after the veterinarian gave her glucose supplements and vitamins every day, and hand-fed her milk, she was still failing. Every morning when workers showed up at the fox farm, their first question was “How is Coco?” Even staff members over at the Institute of Cytology and Genetics, 20 minutes away, wanted daily updates.

One staff member, Galya, always told her animal-loving husband, Venya, about how Coco was progressing when she got home at night. The two of them had discussed that if the veterinarian determined Coco had no hope, they wanted to make their small apartment into a fox hospice, allowing her to die with loving humans caring for her. Lyudmila agreed that they could take her in, and when the word came from the vet that there was nothing more he could do, they came to the farm to collect her. To their great surprise, when they got her home, Coco perked up and began to eat more. Within days, she was a new fox, and miraculously, she survived. Rather than bringing her back to the fox farm, Lyudmila was happy for Coco to live with Galya and Venya, who had become deeply attached to her. Coco, in turn, would become deeply bonded to them, especially to Venya.

Venya was so enamored with Coco that he wanted to bring her into work with him, but that wasn’t possible. Every evening when he got home, he would take her for a long walk in the nearby woods, keeping a firm grip on her leash. Coco was fine with the leash, and behaved well. But one evening when Venya got stuck late at work and Galya was walking Coco instead, the fox spotted a man walking way off in the woods and bolted toward him, breaking free from Galya. In a moment, Galya lost sight of her. Coco probably thought that the male figure in the distance was Venya and ran away when she discovered otherwise. Galya called out to her, but Coco didn’t return, and Galya rushed home, hoping to find Venya so they could search for her.

The domesticated foxes were as tame and playful as the cutest dog. And they looked like dogs too, almost eerily so.

For the next several days, Venya went back to the woods frantically searching for his dear friend, asking anyone he encountered if they had seen Coco. Finally someone told him they had heard that a young man from the town had found a dog that looked like a fox, or maybe it was a fox that looked like a dog, and taken it in. But by the time Venya tracked him down, Coco was gone. Later they learned that the very first night, Coco had screamed and scratched at the man’s door so relentlessly that he finally just let her out.

Venya then heard rumors circulating among the kids at a local playground that Coco had been picked up by a woman who lived in the same building as the young man who had first taken the fox in. Venya managed to get the woman’s name and went to her apartment, but she refused to open the door. When he pleaded with her that Coco was a special fox, part of an experiment at The Institute, she only opened her chained door a crack and said tersely, “I do not have it.” But later that night, she apparently got nervous about holding on to such a special animal, and she also let Coco out. The odyssey still wasn’t over.

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Venya now got word that the kids at the playground had seen Coco with a local teenage boy, who was known to be a bully, but they said they didn’t know the boy’s name or where he lived. All they could say is that they thought he was about 12 years old. So with Lyudmila’s help, Venya set up an appointment with the principal of the middle school, and he and Lyudmila explained the situation. Right then, the teachers were instructed to make an announcement to every class that Coco was a special fox and if anyone had any information that would help find her, they should speak up. It paid off. The boy’s name was quickly coughed up, and Venya and Lyudmila rushed to his apartment. They arrived just in time to find the boy’s mother in the process of sedating Coco, apparently preparing to kill her for her beautiful fur. Venya tore Coco away from the woman and ran out to the street with her limp body in his arms. As Coco breathed the fresh air, she began to revive.

Coco lived happily in Venya and Galya’s apartment for six more months, but when mating season came around, she became restless. She began scratching at the apartment door and keeping Venya and Galya up all night. Clearly she was longing to find a mate, so they consulted with Lyudmila and worked out a plan. They would bring her back to the experimental fox farm to mate. All of the hundreds of foxes in the domestication experiment were kept on one part of the farm. But Coco was moved into a special house, separate from the experiment, where she could interact with both foxes and humans. To smooth over the transition to a different home, she was first placed in the human half of the house, and then in time, joined the other foxes over on their side.

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For years Coco lived in that house, and Venya would visit every weekend, occasionally spending the night on a couch there. They also took regular walks together. Years later, when Coco’s health started to fail, Venya and Galya brought her back to their apartment to spend the last days of her life in their loving care.

Lyudmila remembers Coco “behaving peacefully and spending that last period of her life very content and happy.” Coco’s greatest joy was sitting on a chair with Venya and looking out the window. On one such occasion she jumped off of the chair and fractured her right front paw. Shortly after that, she developed a bone sarcoma. Venya cared for her, but he knew it was the beginning of the end. Soon thereafter, Coco had a heart attack and died, with Venya and Galya by her side. They buried her on a small hill in the woods where she and Venya loved to walk.

Fast forward another 30 years to today. Venya still visits Coco’s grave on occasion. The fox team remains hard at work, studying everything from the domesticated foxes’ love for humans, to the new vocalizations they now use to express that love, to the underlying molecular genetics of that passion. And having recently celebrated her 83rd birthday, Lyudmila is still working with these remarkable creatures almost every day. Her dream is to establish a secure and loving future for the foxes. “I hope that it is possible to register them as a new pet species,” Lyudmila says. “One day I will be gone, but I want my foxes to live forever.” She knows that won’t be easy. But easy doesn’t matter to Lyudmila. Easy never has mattered. Possible is what matters.


Editors’ note: The authors of this article worked together, with Trut describing her experiences to Dugatkin, to produce this third-person account of the story behind Trut’s research. This article has been adapted from the authors’ book How to Tame a Fox (And Build a Dog): Visionary Scientists and a Siberian Tale of Jump-Started Evolution, ©2017, with permission from the University of Chicago Press. For more information about the results of Trut’s research, see her article “Early Canid Domestication: The Farm-Fox Experiment” in the March–April 1999 issue of American Scientist.