How to make foxes pets

I am 83 years old. And when I look at my past, at the experiment to which I dedicated three quarters of my life, my mind sometimes wanders to Antoine de Saint-Exupéry's classic story, "The Little Prince" and the fox's warning to the prince that "a man never guarantees the safety of the one he tames." [Translation: Aryeh Lerner, with Oved 1971]

That's how I became a guarantor for the safety of those foxes shortly after I met my teacher and my friends Dimitri Live in 1958. I was at the end of my studies at the University of Moscow when I heard that Blaev was going to Novosibirsk to join a new institute for cell research and genetics, and that he was looking for students to participate in an animal domestication experiment that he was about to open.

In my first meeting with Live, I was surprised that he treated me as an equal, and I'm just an undergraduate student. He explained the basic idea of ​​the experiment, to investigate the domestication process at an accelerated pace: "I want to make a dog from a fox," he said. Generation after generation, we will selectively breed only the foxes whose relations with humans will be the most positive. If the process works as we hypothesize, domestication, perhaps similar to the exchange that happened to wolves that were to dogs, will unfold before our eyes.

When I left Blaev's office, I already wanted to participate, a participation that would involve moving to Novosibirsk, the largest city in Siberia. I was excited by the thought that I would be part of the first generation of scholars inAkademgorodok, the new "city of science" that was established in Novosibirsk and where the new institute was located, and from the thought that I would work alongside a man who I felt was a revolutionary thinker. Soon, my husband, my baby daughter and I left Moscow for the east on a long train ride.

Blaive's hypothesis about animal domestication was radical and at the same time simple. He concluded that the common characteristic of all domesticated animals is their agreeable temperament. Therefore, from an evolutionary point of view, our ancestors drove the domestication process by favoring the less aggressive individuals and those that were less afraid of humans. Convenience of temper, or the tendency to domesticate, was the secret to working with animals and cultivating desirable traits. Our dogs, cows, horses, goats, sheep and cats had to be obedient and comfortable whether we asked for their protection, their milk, their meat, their company or any other product or quality.

Furthermore, Live believed that most of the other traits that characterize many domestic and farm animals, what is known today as the domestication syndrome: rounded tail, drooping ears, variegated fur, retention of childish facial features (roundness and blunt snout) even in adulthood, and relatively little dependence on seasonal reproduction Hardiness, were created because of the selection of the most comfortable animals. And so, generation after generation, under Blaive's guidance but with quite a bit of independence in the day-to-day experimental matters, I selectively bred only the most temperamental foxes I selected from a starting group of foxes brought from fur farms throughout the Soviet Union.

Meet the elite

Every year I did initial tests for hundreds of foxes in a regular procedure that we developed. Wearing protective gloves that were five centimeters thick, I approached each fox in its cage, stood by the closed cage, opened the cage door and put a stick in it. I rated the fox's response on a scale where the calmest individuals received the highest overall score.

In the first year, almost all the foxes looked less like dogs and more like fire-breathing dragons: they were very aggressive when I approached and when I put the stick in the cage. I'm sure even the foxes who received the low ratings longed to rip my hand off with their teeth. Other low-scoring foxes were those that retreated in fear to the edge of the cage. But there were some who kept their cool throughout the ordeal. They watched, but did not react, neither this way nor that way. These individuals were chosen to mate and give birth to the next generation. I managed a detailed follow-up of every stage of the development of the foxes from the moment they were born until they reached adulthood. We were very careful about residual breeding that could have occurred due to hybridization between relatives. We hoped to avoid the negative genetic effects of the reproduction of the remnants that could disrupt the experiment.

In the early generations, even the peaceful foxes were not very friendly towards humans. It would seem that they are tolerant of the presence of humans but do not enjoy it. But in the fourth and fifth generation I already saw hints of what was to come: puppies that had just learned to walk wagged their tails in anticipation as I approached. Then came the sixth generation.

As my colleague and I wrote in the journal Bioessays in 2009, "In the sixth generation, puppies appeared that were eager for contact with humans, not only with tail wagging, but also with whining, whining and licking, similar to dogs." The appearance of this cluster of behaviors was so impressive that we called these animals "the elite". These little foxes even raised their heads when their name was called. It seemed that they "crave for human company," as we mentioned in the chapter we contributed in 2012 to the second edition of the book The genetics of the dog. These easy-going cubs responded to sounds two days earlier than usual for foxes and opened their eyes a day earlier, almost as if they were preparing to begin their relationship with humans as soon as possible.

The elite charmed every person he met, no matter how tough he was. One evening, after the crew members had finished their work, Labev brought General Lukov, who was a famous army officer, to the test compound. Lukov was a man of official manners that the horrors of the war hardened him. But when I opened the cage of one of the elite females and she jumped at me and lay down next to me, the general's cloak of dignity melted away. With a look of astonishment, he approached the fox, knelt down and caressed her head for a long time.

Only 2% of these sixth generation foxes were among the elite, but their proportion increased with each generation. Today it stands at about 70%.

Embryo transplants

Blaive and I are geneticists by training, and every domestication experiment is a study in evolutionary genetics. We had to make sure that the changes we saw in the domesticated foxes had a genetic root. Therefore, we developed a test involving easy-tempered foxes and foxes from another group that we isolated in the experiment: individuals chosen because of their aggression towards humans. Generations of breeding created a fox that we saw as an eye Cerberus, the same multi-headed dog that guards the gates of Hades in Greek mythology. They were evil foxes.

The idea was to transfer embryos from comfortable mothers to implant them at the mercy of aggressive females, and vice versa. If the young puppies behave like their biological mother and not like the surrogate, we will know for sure that the good temperament and aggression are fundamentally genetic.

Two females participate in each transplant, one is temperamental and one is aggressive, both around the end of the first week of their pregnancy. After anesthetizing the two females, I cut into the lower abdomen of one of them and found the uterus and the two fallopian tubes, each of which had embedded embryos. I then removed the embryos from one of the fallopian tubes of the donor female and carefully placed it in a nutrient solution. Then I repeated the operation and removed the embryos from one fallopian tube of the receiving female, but this time I replaced them with those of the donor. In some of the transplants, the donor was temperamental and the recipient aggressive, and in some the opposite.

Seven weeks later the puppies were born. But how do we know which of the puppies in the litter is the genetic offspring of the mother and which were transplanted? The foxes themselves helped in this: the color of the fur is a genetic trait in them, so with the help of a careful recording of the fur colors of the parents, the fur of the puppies was used to identify their lineage.

My friend and colleague for many years, Tamara Kuzhutova, and I documented the behavior of the puppies from the moment they began to respond to humans. In particular, I remember one aggressive female and her cubs, only some of whom were aggressive. Her adopted offspring, easy-going, still found it difficult to walk and as soon as someone stood by the cage, they rushed to its doors and wagged their tails. This inappropriate behavior seems to have upset the mother. She growled at the friendly pups, grabbing them by the neck and throwing them back onto the bed.

In that litter, the genetic offspring of the aggressive mother behaved as their mother expected. They growled aggressively and ran themselves to their beds. We saw this pattern over and over again: puppies behaved like their genetic mother and not like their surrogate mother. It therefore seems that agreeable temperament and aggression towards humans are genetic traits.

Pushinka

In 1974 there were already 15 generations for the experiment. Many of the good-natured foxes were classified as elite and were characterized by a variety of traits characteristic of domesticated species, as predicted by Leib. Their faces became younger looking, their tails were hairier, their stress hormone levels were lower and their reproductive cycles were longer. Some of them, including Macheta (Dream) which I particularly liked, even had droopy ears.

Most domesticated species do not bond with certain humans, but dogs do. Is it possible that this emotional attachment to people is a change that can appear quickly, similar to so many other changes we have seen in foxes? And will living among humans be natural for the foxes in our home? To answer this, I suggested to Bleiv that we use our foxes, whose genetics have made them friendly, to examine deep emotional bonds similar to those formed between humans and dogs.

In the fox farm where we conducted the experiment there was a small house. I suggested that I move into this house with one of the elite foxes to see what connections would develop between us. Live happily agreed. And so, on March 28, 1974, we moved to Pushinka, which in Russian means "plum ball", and I moved in together.

Pushinka had jet black eyes, black fur with silver tips and a white stripe on her left cheek. A short time before she turned one year old, and she was pregnant, only about a week or two before calving. Therefore, I could observe not only Pushinka's adaptation to living in my midst, but also check whether puppies born in a human environment connect with them differently from other homes, even elite homes.

Our new house had three rooms, a kitchen and a bathroom. I took one room to be used as a bedroom and study, and in another room I built a den for Pushinka. The third room, with several chairs and a table, served as a common area. In order for me to have leisure to be with my human family as well, Kozhutova and several others came to my aid and replaced me for several days and nights. Whoever was on duty kept a detailed record of Pushinka's behavior, in all its aspects, throughout the day and evening.

The first days were stormy. When Pushinka came in, she ran all over the house and it was obvious that she was upset. She didn't eat anything until I gave her some cheese and an apple that I made for me. On the second day there was an improvement. When I returned after a short exit from the house, Pushinka greeted me at the door, as dogs do. But Pushinka's moods did not disappear during the day. My new friend was so frantic at times that it seemed like she was on the verge of a nervous breakdown, but the next day she quietly jumped on the bed and snuggled up next to me.

Although the adaptation was harder than I expected, about a week later Pushinka calmed down. She lay at my feet as I sat at my desk and worked. It seemed that she enjoyed going for walks with me. One of her favorite games was that I hide a prize in my pocket, and she tries to take it out and grab it. Sometimes she lay on her back and invited caresses on her bare belly.

On April 6, Pushinka gave birth to six puppies. And to my amazement, she brought one of the puppies to me and placed it in front of me. I remember saying "Shame on you! Your puppy will catch a cold!” But when I returned the cub to the den, Pushinka returned and introduced him to me. This went back and forth several times until I gave up and stopped returning the puppy to its nest.

I gave names to the puppies, all of which begin with P in honor of their mother: Perlest ("wonderful"), Pesnia ("song"), Plaska ("whiny"), Palma ("palm"), Penka ("skin") and Pushok ("ball of fluff"). "). Within a few weeks the cubs started running out of the den when I entered the room.

Each of them had their own personality: Pushok demanded a lot of attention, Palma liked to jump on tables, Pesnia was stoic, Prelest bullied her brother sometimes, Plaska made mumbling noises when she wandered around the house, and Penka, my favorite, was a master at napping.

Despite Lev Tolstoy's claim that "all happy families are alike," Pushinka and her cubs were a happy but also special family.

I played ball with everyone or ran and let the little ones chase me. Penka especially liked the catch and used to jump on top of me when she caught me. Excessive romp outside would tire the puppies. In one of the diary entries I described them like this: "Asleep, without worries and without fear."

When Pushinka's children grew up and she didn't have to watch over them all the time, the bond between us got tighter. She would lie at my feet and wait for me to scratch her neck. When I left the house for a moment, Pushinka would sit by the window and look at him, waiting for my return. When she saw me approaching the house, she would wait by the door with a wagging tail.

Despite all these signs of a connection between us, I was not prepared for what happened on July 15, 1974. I was reading a book on the bench outside the house, as I often did, and Pushinka rested at my feet. I heard footsteps in the distance, but I didn't notice them. Pushinka, on the other hand, felt in danger. But instead of hiding or seeking my protection, she ran at full speed to the apparent intruder and did something I had never seen her do before and never again: she barked and sounded exactly like a guard dog.

I have never seen Pushinka behave towards any person in a real aggressive manner, and certainly not wildly. I ran after her and discovered that the one who scared Pushinka was just the night watchman patrolling the compound. I started talking to him in a calm voice. Pushinka probably felt that everything was fine and stopped barking.

We moved into the house three and a half months earlier to see if living next to a human would inspire the loyalty of a dog in the elite fox, the product of about 15 years of genetic selection. For me that evening provided a decisive answer.

at the DNA level

Pushkina has long since passed away. But the experiment, and my involvement in it, continue to this day. 43 generations have been born since Pushinka's generation. (If we go back 43 generations of humans we will reach the peak of the Middle Ages.) The descendants of Pushinka and her easy-going friends provided many insights into the domestication process. These insights are described in our book How to tame a fox (and make a dog), but let's just say that today these foxes are even more friendly and affectionate towards humans. They naturally follow the looks and movements of humans, and they are becoming strangely similar to dogs: their snouts have become rounder and their limbs are shorter and thicker.

With the development of research in genetics, it was possible for our team to examine the domestication process at the DNA level. Most of the chromosomal regions in which genetic changes have occurred related to the behaviors and characteristics unique to comfortable foxes, although certainly not all, have been identified on chromosome number 12 in the fox genome. In particular, we discovered in chromosome 12 some DNA fragments (QTLs) that can be linked quantitatively to the obedient behavior scale. (In humans, for example, it is possible to link in a similar quantitative manner between genetic segments and between gradual traits such as height and skin color.)

By comparing these DNA fragments with what is known about the genetics of dog domestication, I was able to Anna Kukkokova And I have, with our colleagues, to confirm the hypothesis that in many cases the QTLs on chromosome 12 in foxes are similar to the QTLs associated with dog domestication. We therefore concluded that through artificial selection over several dozen generations, we loosely reproduced the genetic mutation that made wild wolves domesticated.

The foxes also start telling us things, almost literally. When Svetlana Gogoleva and I analyzed the voices of the friendly foxes and compared them with the voices of the aggressive foxes, we found that the voices of the friendly foxes are unique to them. The acoustic dynamics of the sounds they make are remarkably similar to human laughter. We don't know how and why the good-natured foxes "laugh", but it's hard to imagine a more pleasant way to bond between one species than another.

Lyudmila Tratt in conversation with Lee Dugatkin