Dmitri and Lyudmila decided that they should designate the small number of foxes that were displaying these new behaviors as the “elite.” They devised a strict categorization scheme. Class III were foxes that fled from experimenters, or were aggressive towards humans; Class II foxes were those that allowed themselves be handled, but showed no emotional response to the experimenters. Class I foxes were those that were friendly, displaying whining and tail wagging. And the elite, Class IE, displayed in addition to those two behaviors, a distinct whimpering for attention; they sniffed and licked Lyudmila when she came to observe them, displaying clear eagerness for human contact.
Ember sired another litter the following year, and Lyudmila had hoped that the pups in this clutch would be tail-waggers, but again, none of them was, but in the next year, 1966, Ember sired a third clutch, and several of these pups did wag their tails. Ember was not an anomaly, he was a pioneer. Now Belyaev and Lyudmila had some evidence that the tail wagging was heritable.
In the seventh generation of pups, several more displayed the whining, licking, and rolling over for belly rubs behavior, but none of these pups except those from Ember’s line were tail waggers. Changes were showing up differently in different litters. Something was going on in the genetic makeup of some of the tamer foxes that was leading them to spontaneously perform a whole set of brand new behaviors. And the changes were appearing in an increasing number of pups. In the sixth generation, 1.8% of the pups were elite. By this seventh generation, approximately 10% were. By the eight generation, tails were not only being wagged, but some of the tails of the tame foxes were curly, another remarkably dog-like characteristic.
That so many and such various changes in the behavior of animals could arise so early in their development was particularly notable. Natural selection stabilizes the developmental regime, and once a trait has entered this early development routine, it rarely changes, presumably because these stages of growth are so crucial in the fight for survival. That’s why all fox pups opened their eyes and emerged from their dens according to a relatively fixed timeline. But the tamest pups were breaking even that rule. Lyudmila’s meticulous observations revealed that tame pups were responding to sounds two days earlier and opening their eyes a day earlier than was normal. It was almost, she thought to herself, as if these little foxes were itching to start interacting with people.
As Lyudmila continued to observe the tamer pups with their new behaviors, she found that not only did they retain those new behaviors, they also held onto the characteristic puppy behaviors seen in all foxes much longer. While fox pups, like almost all animal pups, are curious, playful, and relatively carefree when they are very young, the behavior of foxes both in the wild and in captivity dramatically changes when they turn about forty-five days old. At that point, which is when wild pups begin exploring on their own more often, they become much more cautious and anxious. Lyudmila was finding that the tame pups were retaining the typical impishness and curiosity almost twice as long, for about three months, and after that, they stayed markedly calmer and more playful than is typical for foxes. These tamer foxes seemed to be resisting the mandate to grow up.
In less than a decade, the experiment had accomplished so much more than Dmitri had expected. Now it was time, he decided, to build an experimental fox farm in Akademgorodok and scale the experiment up further. Their own farm dedicated to the experiment would allow for a larger population of foxes, and Lyudmila would be able to observe them continually, not just four times a year. Belyaev could assign some research assistants and students at the Institute to help her with the work, and the Institute of Cytology and Genetics could conduct more extensive analyses of the changes underway in the foxes. What’s more, Dmitri would finally be able to visit the foxes regularly himself. Due to his heavy administrative load at the Institute and many trips he had to make for conferences and lectures, he’d still only been able to make time for a few short trips to Lesnoi to see the foxes for himself. With such strong results from the Lesnoi foxes, Belyaev could now justify the allocation of the considerable funds required for building and maintaining an experimental farm. He also now had the administrative clout to do so. He started to search for property to house the farm.
ONE DAY IN MAY OF 1967, after Dmitri had poured through her data from their seventh generation of foxes, he excitedly called Lyudmila into his office. He told her he hadn’t slept at all the night before because his mind had been racing. He had an idea about what was causing the changes in the foxes, and he asked her to gather a number of the researchers at the Institute to come to his office. Once they had settled in, Belyaev told them, “My friends, I think I have come close to understanding what we are observing in the domestication experiment.”
Belyaev had realized that most of the changes they’d seen in the foxes involved changes in the timing of when traits turn on and off. Many of the changes they were observing in the tamer foxes involved retaining a juvenile trait longer than normal. The whimpering was a youthful behavior that normally stopped as foxes matured. So was calmness; fox pups are serenely calm when they’re first born, but as they age, foxes typically become quite high-strung. A change in timing was also going on with some of the females’ reproduction systems. Their readiness for mating was occurring much earlier and was lasting considerably longer.
Hormones were known to be involved in regulating the timing of development and of the reproductive system. They were also known to regulate the levels of an animal’s stress, or calmness. Dmitri felt sure that changes in the production of hormones were unfolding in the tame foxes and that this must be central to the process of domestication. If this were true, it could explain why domesticated animals look more juvenile than their wild cousins, as well as why they can reproduce outside of the normal mating time, and why they are so calm around us.
The discovery of hormones back at the dawn of the twentieth century had shaken the foundation of animal biology. The basic operation of the nervous system was just starting to be pieced together at that time, and the brain and the nervous system were thought to be the communication system that regulated animal behavior. Then, suddenly, it seemed our bodies were also controlled by a chemical messaging system, and it operated through the bloodstream, not through the nerves. The first hormone discovered was secretin, which was involved with digestion. Shortly thereafter adrenaline was identified, given that name because it was created by one of the adrenal glands (it’s also called epinephrine). More and more hormones were steadily discovered. On Christmas Day in 1914, thyroxin—a hormone produced by the thyroid—was identified, and in the 1920s and ’30s, testosterone, estrogen, and progesterone and their roles in regulating reproductive activity were discovered. Over time research showed that changes in the levels of these hormones could dramatically interfere with the normal reproductive cycles, ultimately leading to the creation of the birth control pill, which hit the market in 1957.
Two other adrenal gland hormones, cortisone and cortisol, were identified in the mid-1940s, and along with adrenaline, they were dubbed the stress hormones, because they all regulate levels of stress. Levels of adrenaline and cortisol were found to rapidly ramp up in response to perceived danger, key to the “fight or flight” response. In 1958, the isolation of another hormone, melatonin, was announced. This hormone was produced by the pineal gland, and in addition to affecting the pigmentation of skin, it played a vital role in regulating sleep patterns as well as the timing of reproductive cycles.
Research had also shown that rarely, if ever, does a hormone have a single effect on an organism. Most hormones affect a suite of different morphological and behavioral characteristics. Testosterone, for example, is involved not just in the development of the testis, but in aggressive behavior, as well as in the development of muscles, bone mass, body hair, and many other traits.
Dmitri had studied the literature on hormones and he knew that research had shown hormone production was somehow, though exactly how was not clear, regula
ted by genes. He thought the genes or combinations of genes that regulated hormone production might be responsible for many—maybe all—of the changes they were seeing in the tame foxes. The selection for tameness had triggered changes in the ways those genes were operating. Natural selection had stabilized the hormonal recipe for building a fox and its behavior in the wild. Now the selection for tameness that he and Lyudmila were imposing was destabilizing that formula.
Why, Dmitri wondered, would that be happening? The stabilization of an animal’s behavior and physiology was suited specifically to its environment. Animals’ mating seasons had been selected to coincide with the time of year when food and daylight were most favorable for the survival of young ones. Their coat coloring was optimized to camouflage them in their natural environment. Their production of stress hormones was optimized to cause them to either fight or flee from the dangers of their environment. But, what if they were suddenly transported to a radically different environment, one with different conditions for survival? That’s what had been done with the foxes; their environment was now one in which being tame around humans was optimal. So the stabilization of their behavior and physiology that had been the result of natural selection in the wild was no longer the best formula, and adjustments had to be made. And Dmitri thought that under such pressure to change, the activity patterns of an animal’s genes—the ways in which they regulated body functioning—might be dramatically altered. A cascade of changes might be unleashed. And it made sense that key among these would be regulatory, timing, changes in the production of the hormones that played such a vital role in optimizing an animal to its environment. Later he would come to add changes to the nervous system to his formula as well. He called the new process he was describing destabilizing selection.5
Lyudmila and the others needed time to process the idea. This theory was radical. The concept that the activity of genes could be altered without mutation being involved had barely started making its way into the literature. Dmitri was way ahead of the scientific community in making this conjecture that some of the changes in animals could come not from changes to DNA, but from genes already present being activated or deactivated in new ways. Up to this point, in conducting the experiment, they had been flying blind in a scientific sense, operating without a true theory. Now they had one. They had no proof for it yet, but it was an intriguing idea that might explain much if correct, and hopefully, Dmitri thought, in time the fox experiment would allow them to test this idea.
BELYAEV SECURED A GOOD PLOT OF LAND cut out of a lovely pine, birch, and aspen forest just four miles northeast of the Institute, and supervised the building of the fox farm. It was a barebones operation. Five wooden sheds were built, which could each hold fifty large pens. Feeding was done with a pulley system that allowed the workers to move large buckets of food up and down the sheds. A 100 square foot fenced-in playground where the foxes were allowed out to run and play for a period each day sat behind each shed. Fifty-foot-tall wooden observation towers were soon built to allow Lyudmila to sit and watch them through her binoculars, recording how they played and interacted with one another without disturbing them. There was a veterinary clinic as well, so any sick or injured foxes could be cared for right away.
In late fall of 1967, Lyudmila arranged for the transport of fifty female and twenty male foxes from Lesnoi to the new experimental farm. More would follow, until 140 tame foxes, of which 5%–10% were elites, were shipped from Lesnoi. Lyudmila worked with a farm manager to hire a small team of caretakers for the foxes, who would feed them twice a day and let them out in the yards for play. She took great care in hiring workers because she wanted to be sure not only that they weren’t afraid of the foxes, but that they enjoyed being with them and would take very good care of them. She would find that these workers not only zealously cared for the foxes, many of them fell in love with them.
Most of the caretakers were local women, from the nearby town of Kainskaya Zaimka, and Dmitri arranged for a bus to pick them up and bring them back home each day. He was sure to chat with them a little when he visited the farm, as he did whenever he could spare a moment, which was not nearly as often as he wished. He was keen to meet these workers and he would walk up to them to introduce himself, seeking to shake their hands. One woman worker recounts that when she demurred, because she was embarrassed by how rough her hands were, making the excuse that they were too dirty, he took her hands in his and said to her, “Working peoples’ hands are never dirty.”6 She was struck that a man of such high standing, the head of a major scientific institute, would treat her with such warmth.
These workers quickly developed a great fondness for the foxes. They watched zealously over them and went well beyond the call of duty to care for them, saving the lives of many pups who might otherwise have frozen to death, by keeping such a close eye on them. Sometimes fox mothers would neglect their pups right after birth, leaving them exposed to the frigid early spring weather. Even in April, the temperature could drop well below zero. The women would take off their thick fur hats and cradle the helpless little balls of fur in them, or hold them under their shirts in their bosoms until they had warmed up and had begun wriggling around.
On rare occasions, if someone was visiting the farm, the workers would pet the tame foxes and pick them up to show a guest how docile they were. The tamest foxes, even as fully matured adults, would allow workers to cradle them in their arms, or hug them tight, which felt good in the bitter cold of the Siberian winter. Some foxes would wriggle around in their arms when they held them, but others stayed so calm they seemed to be almost mesmerized.
A few foxes would lick the caretakers’ hands when they reached into their cages on their daily rounds. But the workers didn’t instigate this behavior. They were given a strict rule to remain as objective as possible with all of the foxes, no matter how irresistible they were, or how loudly the foxes protested for attention. Sometimes that was a challenge as the tamest foxes would whine and cry, causing a great clamor when the women entered the sheds, as if competing for attention, calling out, “Don’t bother with her, come and see me!”
These tame foxes were establishing a strong sense of connection with the workers, and with Lyudmila and her research assistants as well. They would even allow people to look directly into their eyes, and they seemed to be looking back. With wild animals, included canids, staring directly at another member of a group is often taken as a challenge that leads to aggression. For a human to do so is to invite attack. But in domesticated species, as in many dogs, gazing into the eyes of humans is common.7 Now these tame foxes were doing it too.
Though the caretakers resisted petting the foxes, they did begin talking to them quite a bit, always addressing them by their names, which were written on pieces of wood hung above their cages. Some of the workers chatted with them almost constantly while moving through the sheds during feeding time or letting them out to the yard for their playtime. They became more and more devoted to the foxes and engaged in the work being done with them. Starting with the first litter born on the farm, the women began assisting Lyudmila in naming the pups, which could be quite a challenge, requiring coming up with yet another six or seven names for each litter that all started with the first letter of the mother’s name. They became Lyudmila’s trusted eyes and ears, alerting her right away if a pup wasn’t eating, seemed to have a cold, was scratching itself too often, or just didn’t seem to be itself. Many of them regularly worked longer hours than their shifts, never complaining. Most of them loved spending as much time as possible with the foxes.
So did Lyudmila. She always had a great deal of data analysis and writing up of results to do, so she started her days by heading to the Institute of Cytology and Genetics to do some of that. If Dmitri was available, she’d also check in with him about the latest with the foxes and the work she had planned. But then she could head over to the farm for her favorite part of the day. Her first stop was usually to the veterinarian’s office, to che
ck on any problems there might be with any of the foxes. Then she would check in with the workers, whom she now thought of more as caretakers, and begin making her rounds through the fox sheds, always greeted by a great ruckus as the foxes jumped to the front of their cages, many of them now whining for attention, intently following her progress as she made her way from cage to cage. With the foxes so close by now, Lyudmila would also find herself heading over to the farm at off-hours, especially when she felt the need for an emotional pick-me-up. “I would take to the farm,” she recalls, and “communicate with the foxes.”
Generally, she devoted three to four hours each day to the foxes. A good part of that was taken up by collecting her standard housekeeping data: behavior, size, and growth rates, fur color, general body shape, and for the pups, milestones like when they opened their eyes for the first time. She also took daily notes on the behavior of the foxes toward her, her assistants, and the workers: and when it came to the young pups, how they behaved toward each other, who licked a human hand, or who wagged their tails. While the “official” behavioral data that would determine who parented the next generation was taken once when an individual was a pup and once when it had matured, these day-to-day notes on the foxes’ behavior were critical, as they gave Lyudmila and Dmitri a fine-scale, deeper appreciation of the changes that were occurring.
How to Tame a Fox (and Build a Dog) Page 7
