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The silver fox domestication experiment

• Lee Alan Dugatkin 1  

Evolution: Education and Outreach volume  11 , Article number:  16 ( 2018 ) Cite this article

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For the last 59 years a team of Russian geneticists led by Lyudmila Trut have been running one of the most important biology experiments of the 20th, and now 21st, century. The experiment was the brainchild of Trut’s mentor, Dmitri Belyaev, who, in 1959, began an experiment to study the process of domestication in real time. He was especially keen on understanding the domestication of wolves to dogs, but rather than use wolves, he used silver foxes as his subjects. Here, I provide a brief overview of how the silver fox domestication study began and what the results to date have taught us (experiments continue to this day). I then explain just how close this study came to being shut down for political reasons during its very first year.

Introduction, history and findings

Today the domesticated foxes at an experimental farm near the Institute of Cytology and Genetics in Novosibirsk, Siberia are inherently as calm as any lapdog. What’s more, they look eerily dog-like. All of this is the result of what is known as the silver fox, or farm fox, domestication study. It began with a Russian geneticist named Dmitri Belyaev. In the late 1930s Belyaev was a student at the Ivanova Agricultural Academy in Moscow. After he graduated he fought in World War II, and subsequently landed a job at the Institute for Fur Breeding Animals in Moscow.

Both as a result of his reading of Darwin’s The Variation of Animals and Plants Under Domestication (Darwin 1868 ), and his interaction with domesticated animals at the Ivanova Agricultural Academy and at the Institute for Fur Breeding Animals, Belyaev knew that many domesticated species share a suite of characteristics including floppy ears, short, curly tails, juvenilized facial and body features, reduced stress hormone levels, mottled fur, and relatively long reproductive seasons. Today this suite of traits is known as the domestication syndrome. Belyaev found this perplexing. Our ancestors had domesticated species for a plethora of reasons—including transportation (e.g., horses), food (e.g., cattle) and protection (e.g., dogs)—yet regardless of what they were selected for, domesticated species, over time, begin to display traits in the domestication syndrome. Why? Belyaev hypothesized that the one thing our ancestors always needed in a species they were domesticating was an animal that interacted prosocially with humans. We can’t have our domesticates-to-be trying to bite our heads off. And so he hypothesized that the early stages of all animal domestication events involved choosing the calmest, most prosocial-toward-human animals: I will refer to this trait as tameness, though that term is used in many different ways in the literature. Belyaev further hypothesized that all of the traits in the domestication syndrome were somehow or another, though he didn’t know how or why, genetically linked to genes associated with tameness.

Belyaev set out to test these hypotheses using a species he had worked with extensively at the Institute for Fur Breeding: the silver fox, a variant of the red fox ( Vulpes vulpes ). Every generation he and his team would test hundreds of foxes, and the top 10% of the tamest would be selected to parent the next generation. They developed a scale for scoring tameness, and how a fox scored on this scale was the sole criteria for selecting foxes to parent the next generation. Belyaev could then test whether, over generations, foxes were getting tamer and tamer, and whether the traits in the domestication syndrome appeared if they selected strictly based on tameness.

The experiment began in 1959 at the Institute of Cytology and Genetics in Novosibirsk, Siberia, shortly after Belyaev was appointed vice director there. Belyaev immediately recruited 25-year-old Lyudmila Trut to his team (Fig.  1 ). Trut quickly became the lead researcher on the experiment, working with Belyaev on every aspect from the practical to the conceptual. Trut turned 85 years old in November of 2018 and remains the lead investigator on the work to this day (Belyaev died in 1985).

Lyudmila Trut. a 1960 and b 2015

It is not possible here to do justice to all of the results this almost six-decade-long experiment has produced. Here I touch on some of the most salient (see Trut 1999 , Trut et al. 2009 and Dugatkin and Trut 2017 for more). Starting from what amounted to a population of wild foxes, within six generations (6 years in these foxes, as they reproduce annually), selection for tameness, and tameness alone, produced a subset of foxes that licked the hand of experimenters, could be picked up and petted, whined when humans departed, and wagged their tails when humans approached. An astonishingly fast transformation. Early on, the tamest of the foxes made up a small proportion of the foxes in the experiment: today they make up the vast majority.

Belyaev was correct that selection on tameness alone leads to the emergence of traits in the domestication syndrome. In less than a decade, some of the domesticated foxes had floppy ears and curly tails (Fig.  2 ). Their stress hormone levels by generation 15 were about half the stress hormone (glucocorticoid) levels of wild foxes. Over generations, their adrenal gland became smaller and smaller. Serotonin levels also increased, producing “happier” animals. Over the course of the experiment, researchers also found the domesticated foxes displayed mottled “mutt-like” fur patterns, and they had more juvenilized facial features (shorter, rounder, more dog-like snouts) and body shapes (chunkier, rather than gracile limbs) (Fig.  3 ). Domesticated foxes like many domesticated animals, have longer reproductive periods than their wild progenitors. Another change associated with selection for tameness is that the domesticated foxes, unlike wild foxes, are capable of following human gaze as well as dogs do (Hare et al. 2005 ). In a recent paper, a “hotspot” for changes associated with domestication has been located on fox chromosome 15 (Kukekova et al. 2018 ). SorCS , one gene in this hotspot, is linked with synaptic plasticity, which itself is associated with memory and learning, and so together these studies are helping us better understand how the process of domestication has led to important changes in cognitive abilities.

Mechta (Dream), the first of the domesticated foxes to have floppy ears 1969

The domesticated foxes have more juvenilized facial characters, including a shorter, rounder snout, than wild foxes

Right from the start of the experiment, Belyaev hypothesized that the process of domestication was in part the result of changes in gene expression patterns—when genes “turn on” and “turn off” and how much protein product they produce. A recent study examining expression patterns at the genome level, in both domesticated foxes and a second line of foxes that has been under long-term selection for aggressive, rather than tame, behavior, suggests Belyaev was correct (Wang et al. 2018 ). This study identified more than one hundred genes in the prefrontal cortex of the brain that showed different gene expression patterns between domesticated and aggressive foxes. Some of those genes are linked to serotonin receptor pathways that modulate behavioral temperament, including tame and aggressive temperaments.

When Belyaev proposed that the domestication syndrome was linked to tame behavior, he did not have a proposed mechanism, but today we are getting closer to understanding how this works. Very early on in animal development, what are known as neural crest cells migrate from the neural crest to a plethora of locations: glands in the endocrine system, bone, fur, cartilage, the brain and other spots in a developing embryo. The neural crest cell hypothesis for the domestication syndrome proposes that selection for tame behavior results in a reduction of the number of migrating neural crest cells, which subsequently leads to changes in fur coloration, facial structure, the strength of cartilage (floppy ears, curly tails and so on), hormone levels, the length of the reproductive season, and more. This hypothesis may provide the link that Belyaev was missing when he came up with the idea for the experiment (Wilkins et al. 2014 ).

Discussion: a cautionary tale

The silver fox domestication study is often lauded as one of the most important long-term studies ever undertaken in biology. Yet in 1959, the very year it commenced, the work came within a hair’s breath of being shut down by the premier of the Soviet Union. The problem for Belyaev and Trut was that their domestication experiment, like any experiment in domestication, was an experiment in genetics. But work in Mendelian genetics was essentially illegal at the time in the Soviet Union, because of a pseudo-scientific charlatan by the name of Trofim Lysenko (Joravsky 1979 ; Soyfer 1994 ).

In the mid-1920s, the Communist Party leadership, in an attempt to glorify the average citizen, began to promote uneducated men from the proletariat into the scientific community. Lysenko was one of those men. The son of peasant farmers in the Ukraine, Lysenko didn’t learn how to read until he was a teenager, and his education, as it was, amounted to a correspondence degree from gardening school. With no training, he still landed a middle-level job at the Gandzha Plant Breeding Laboratory in Azerbaijan in 1925. Lysenko convinced a Pravda reporter, who was writing a story about the regime’s glorious peasant scientists, that the yield from his pea crop he tended was far above average, and that his technique could save a starving USSR. In the Pravda article the reporter wrote glowingly that “the barefoot professor Lysenko has followers… and the luminaries of agronomy visit… and gratefully shake his hand.” Pure fiction, but the story propelled Lysenko to the national limelight, with Josef Stalin taking pride in what he read.

Over time Lysenko would claim to have done experiments creating grain crops, including wheat and barley, that produced high yields during cold periods of the year, if their seeds had been kept in freezing water for long stretches before planting. What’s more, Lysenko claimed offspring of these plants would also produce higher yields, down through the generations. This method, he said, could quickly double the yield of farmlands in the Soviet Union in just a few years. In truth, Lysenko never undertook any legitimate experiments on increased crop yield. Any “data” he claimed to have produced he simply fabricated.

Soon Stalin was his ally, and Lysenko began a crusade to discredit work in Mendelian genetics because proof of the genetic theory of evolution would likely expose him as a fraud. He denounced geneticists, both overseas and in the Soviet Union, as subversives. His star was rising and at a conference held at the Kremlin in 1935, after Lysenko finished a speech in which he branded Western geneticists as “saboteurs,” Stalin stood up to yell, “Bravo, Comrade Lysenko, bravo.”

Lysenko was placed in charge of all policy regarding the biological sciences in July 1948. The next month, at a meeting of the All-Union Lenin Academy of Agricultural Sciences, he presented a talk that today is regarded as the most disingenuous, dangerous speech in the history of Soviet science. In this speech, “The Situation in the Science of Biology,” Lysenko damned “modern reactionary genetics,” by which he meant Mendelian genetics. At the end of his ranting, the audience cheered wildly. Geneticists present were forced to stand up and refute their scientific knowledge and practices. If they refused, they were thrown out of the Communist Party. In the aftermath of that awful speech thousands of geneticists were fired from their jobs. Dozens, perhaps hundreds, were jailed, and a few were murdered by Lysenko’s henchmen.

Belyaev could not sit by idly. After reading of Lysenko’s speech in the newspaper, he was furious. His wife, Svetlana, remembers it well: “Dmitri was walking toward me with tough sorrowful eyes, restlessly bending and bending the newspaper in his hands.” Another colleague recalls running into him that day and how Belyaev had fumed that Lysenko was “a scientific bandit” (Dugatkin and Trut 2017 ). Ignoring the personal risk, Belyaev began speaking out about the dangers of Lysenkoism to all scientists, whether friend or foe.

The case of Nikolai Vavilov, one of Belyaev’s intellectual idols, illustrates just how dangerous it was to speak out against Lysenko (Medvedev 1969 ; Pringle 2008 ; Soyfer 1994 ). Vavilov studied plant domestication and was also one of the world’s leading botanical explorers, travelling to sixty-four countries collecting seeds. In his lifetime alone, three terrible famines in Russia killed millions of people and Vavilov had dedicated his life to finding ways to propagate crops for his country. His research program centered on finding crop varieties that were less susceptible to disease.

Vavilov’s collecting trips are the stuff of legend. On one of three expeditions, he was arrested at the Iran-Russia border and accused of being a spy, simply because he had a few German botany books with him. On another trip, this one to the border of Afghanistan, he fell as he was stepping between two train cars, and was left dangling by his elbows as the train roared along. On yet a different a trip to Syria he contracted malaria and typhus.

Vavilov collected more live plant specimens than any man or woman in history, and he set up hundreds of field stations for others to continue his work.

Vavilov had actually befriended the young Lysenko in the 1920s, before it became clear that Lysenko was a malevolent charlatan. Over time, Vavilov became suspicious of Lysenko’s results, and in a series of experiments trying to replicate what Lysenko said he had discovered, Vavilov proved to himself, and others that were willing to listen (though not many were), that Lysenko was a fraud. He then became Lysenko’s most fearless opponent. In retaliation, Stalin forbade Vavilov from any more travels abroad and he was denounced in the government newspaper, Pravda . Lysenko warned Vavilov that “when such erroneous data were swept away… those who failed to understand the implications” would also be “swept away.” Vavilov was undeterred, and at a meeting of the All-Union Institute of Plant Breeding declared, “We shall go into the pyre, we shall burn, but we shall not retreat from our convictions.”

In 1940, Vavilov was kidnapped up by four men wearing dark suits and thrown into the KGB’s dreaded Lubyanka Prison in Moscow. Next he was shipped off to an even more remote prison. There, over the course of 3 years, the man who had collected 250,000 domesticated plant samples to solve the puzzle of famine in his homeland was slowly starved to death.

Lysenko’s power had its ebbs and flows. In 1959, as the fox domestication experiment was just beginning, Lysenko was getting frustrated that his hold on Soviet biology was loosening. Something needed to be done. And The Institute of Cytology and Genetics, where the fox domestication experiment had just begun, where Belyaev was vice director, and where they had the audacity to put “Genetics” in the title of the institute, seemed a good place to attack.

The Institute of Cytology and Genetics was part of a new giant scientific city called Akademgorodok. Long before this city was built, Russian writer Maxim Gorky had written of a fictional “town of science… a series of temples in which every scientist is a priest… where scientists every day fearlessly probe deeply into the baffling mysteries surrounding our planet.” Here Gorky envisioned “…foundries and workshops where people forge exact knowledge, facet the entire experience of the world, transforming it into hypotheses, into instruments for the further quest of the truth.” Akademgorodok was what Gorky had in mind. It was home to thousands of scientists housed at the Institute of Cytology and Genetics, the Institute of Mathematics, the Institute of Nuclear Physics, the Institute of Hydrodynamics, and a half dozen other institutes.

In January 1959, a Lysenko-created committee from Moscow was sent to Akademgorodok. This committee had been authorized to determine just what sort of work was being done at the Institute of Cytology and Genetics, and Belyaev, Trut and their colleagues understood the gravity of the situation. “Committee members were, Trut said, “snooping in the laboratories,” and rumors were spreading that the committee was unhappy. When the committee met with Mikhail Lavrentyev, chief of all the institutes at Akademgorodok, they told him that “the direction of the Institute of Cytology and Genetics is methodologically wrong” (Dugatkin and Trut 2017 ). Ominous words from a Lysenkoist group.

Nikita Khrushchev, premier of the USSR, learned of the committee’s report about Akademgorodok. Khrushchev was a supporter of Lysenko, and he decided to see for himself what was happening. In September 1959, while returning from a visit to Mao Tse-Tung in China, he stopped off in Novosibirsk and went to Akademgordok.

The staff of all the science institutes at Akademgorodok gathered for this visit, and Trut remembers that the premier “walked by the assembled staff very fast, not paying any attention to them” as he proceeded to a meeting with administrators. “Khrushchev” Trut recalls was, “very discontented, with the intention to get everyone in trouble because of the geneticists.” What Khrushchev and Akademgorodok administrators said that day was not recorded, but accounts from the time make clear that the premier intended to shut down the Institute of Cytology and Genetics that day, and with it the nascent silver fox domestication experiment.

Fortunately for science, Khrushchev’s daughter, Rada, was with him in Akademgorodok. Rada, a well-respected journalist, had trained as a biologist, and understood very well that Lysenko was a fraud. She somehow managed to convince her father to let the Institute of Cytology and Genetics remain open. In an ironic twist, because Khrushchev felt he had to do something to show his discontent, the day after his visit, he fired the head of the Institute of Cytology and Genetics. Deputy Director Belyaev was now in charge of the institute.

If Rada Khrushchev had not taken a stand for science that day the fox domestication study would likely have ended before it even got off the ground. But, it survived and thrived and continues to shed new light on the process of domestication.

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Acknowledgements

I thank Lyudmila Trut for working with me on our book, How to Tame a Fox and Build a Dog (University of Chicago Press, 2017). Nikolai and Michael Belyaev provided much in the way of assistance, as did Aaron Dugatkin. I thank Dana Dugatkin for proofreading this paper.

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Dugatkin, L.A. The silver fox domestication experiment. Evo Edu Outreach 11 , 16 (2018). https://doi.org/10.1186/s12052-018-0090-x

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Fox experiment is replaying domestication in fast-forward.

New book recounts nearly 60-year effort to understand taming process

DOMESTICATION IN ACTION   How to Tame a Fox tells the story of a long-running experiment to domesticate silver foxes (a wild silver fox is shown).

Minette Layne/Flickr ( CC BY-NCE 2.0 )

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By Tina Hesman Saey

April 29, 2017 at 8:00 am

In 1959, Lyudmila Trut rode trains through Siberia to visit fox farms. She wasn’t looking for furs. She needed a farm to host an audacious experiment dreamed up by geneticist Dmitry Belyaev: to create a domestic animal as docile as a dog from aggressive, wily silver foxes.

Evolutionary biologist Lee Alan Dugatkin helps Trut recount this ongoing attempt to replay domestication in How to Tame a Fox . The mechanics of domestication are still a matter of intense scientific debate. Belyaev’s idea was that ancient humans picked wolves and other animals for docility and that this artificial selection jump-started an evolutionary path toward domestication.

Back in the 1950s, testing the idea was dangerous work, and not just because untamed foxes bite. In 1948, the Soviet Union, under the scientific leadership of Trofim Lysenko, outlawed genetics research. Lysenko had risen to power based on fabricated claims that freezing seeds in water could increase crop yields. “With Stalin as his ally, he launched a crusade to discredit work in genetics, in part, because proof of the genetic theory of evolution would expose him as a fraud,” Dugatkin and Trut write. Geneticists often lost their jobs, were jailed or even killed, as was Belyaev’s own brother. So Belyaev cloaked his domestication experiments in the guise of improving the fur-farming business.

Fox researchers started by testing the temperament of about 100 silver foxes each year. About a dozen of the foxes, slightly calmer than most, were bred annually. Within a few generations, some foxes were a bit more accepting of people than the starting population. That small difference convinced Belyaev of the experiment’s promise, and he recruited Trut to carry out a larger breeding program.

Trut and Dugatkin lovingly recount some of the experiment’s milestones, including the first fox born with a wagging tail and the first one with droopy ears — two hallmarks of domesticated animals. Trut recalls the foxes she’s lived with and, heartbreakingly, the ones she lost, or had to sacrifice to keep the experiment going after the collapse of the Russian economy in 1998 led to funding problems. At every step, the authors skillfully weave the science of domestication into the narrative of foxes becoming ever-more doglike.

Trut has kept Belyaev’s dream alive for nearly 60 years. Now in her 80s, she still runs the experiment and has eagerly collaborated with others to squeeze every drop of knowledge from the project. The work has shown that selecting for tameness alone can also produce a whole suite of other changes (curly tails, droopy ears, spotted coats, juvenile facial features) dubbed the domestication syndrome. With the help of geneticist Anna Kukekova, Trut is searching for the genes involved in this process.

The project now sells some of the foxes as pets to raise money, although one could argue they aren’t fully domesticated. The foxes may wag their tails and flop on their backs to get their bellies rubbed, but Trut says they still don’t follow commands like dogs do. It probably took Stone Age humans hundreds or thousands of years to domesticate wolves. The silver fox experiment has replayed the process in fast-forward. It may speed scientists’ quest to understand the DNA changes that transformed a wolf into a dog.

Buy   How to Tame a Fox (and Build a Dog) from Amazon.com. Sales generated through the links to Amazon.com contribute to Society for Science & the Public’s programs.

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Why Are These Foxes Tame? Maybe They Weren’t So Wild to Begin With

In a famous experiment, scientists bred Russian foxes without a fear of people. But the foxes’ ancestry raises new questions about when they became tame and what counts as domestication.

By James Gorman

In the 1950s, Dmitri K. Belyaev began one of the most famous experiments in animal domestication. Dr. Belyaev, a geneticist at the Institute of Cytology and Genetics in Novosibirsk, Russia, selectively bred foxes that he had acquired from a fur farm, concentrating only on reducing their fear of humans.

Within 10 generations, he wrote in 1979 , “Like dogs, these foxes seek contact with familiar persons, tend to get close to them, and lick their hands and faces.”

In a new paper in the journal Trends in Ecology and Evolution , several scientists have challenged a common interpretation of Dr. Belyaev’s results, and have questioned whether scientists who study domestication have any common understanding of what the word means.

The authors don’t dispute the essence of Dr. Belyaev’s work: the selection for tameness, which is regarded as profoundly important in exploring the genetics and evolution of behavior.

But that wasn’t all that Dr. Belyaev discovered. His foxes also showed physical changes, like piebald coats and floppy ears — characteristics shared by dogs, cows and other domesticated animals.

Dr. Belyaev and the researchers who followed up his work suggested, as had Charles Darwin before them, that there might be a collection of physical traits that go along with tameness called domestication syndrome.

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What DNA From Pet Foxes Teaches Us About Dogs—And Humans

A Soviet-era experiment to breed tame and aggressive foxes has produced surprising revelations about social behavior and domestication.

For nearly 60 years, Russian scientists have bred foxes to be tame—or aggressive. A new study looking at the genomes of the two groups shows that the experiment has changed the animals’ DNA in surprising ways. The research has relevance for understanding social behavior across animals and even humans.

It took a while to get to here. In 1959, a man named Dmitri Belyaev began an experiment designed to understand how dogs became domesticated . Belyaev and other biologists believed that domestic dogs were descended from wolves, but did not yet know how all the anatomical, physiological, and behavioral differences between the two animals could arise.

But Belyaev had a hunch. He suspected that the key component was the dog's tameness. Perhaps, he hypothesized, the biological changes in domesticated animals—white spots, curled tails, floppy ears, shortened skulls—were the result of an evolutionary selection process over behavioral traits rather than anatomical ones.

Fearful and Friendly

Belyaev believed that by breeding the friendliest foxes with each other, perhaps he could domesticate them, artificially mimicking the millennia-long process through which wolves became dogs. He bought up a group of silver foxes from a Canadian fur farm and got to work at his lab in the Soviet Union. ( See also: These foxes ‘grow’ their own gardens .)

Belyaev would eventually prove himself right. Breeding the least fearful foxes with each other resulted not only in animals that were eager to seek out a social connection with humans, but also in animals that displayed the suite of anatomical features associated with domestication: those characteristic white spots, curly tails, floppy ears, and so on.

The entire collection of modifications associated with domestication could be brought about simply by breeding foxes according to their response when approached by a human. Would they approach the experimenter with curiosity and permit physical contact? Or would they back away, hissing and yelping out of fear?

Belyaev died in 1985, but the experiment continues today. Researchers have bred more than 40 generations of friendly and aggressive foxes. And now, for the first time, they have a fully sequenced fox genome to help understand the genetics that underlie the transition from wild to tame, as described in a study published today in the journal Nature Ecology and Evolution .

The researchers sequenced the genes of 10 foxes from the aggressive and tame populations, and assembled a complete genome of the silver fox ( Vulpes vulpes ). This has and will continue to allow them to find genetic differences that could underlie different aspects of domestication, says University of Illinois biologist Anna Kukekova , who led the study.

Until now, researchers have had to rely on the domestic dog genome as a reference. But while wolves and foxes diverged only 10 million years ago, dogs and foxes have dramatically different lifestyles. (Related: Why are dogs so friendly? Science has an answer. )

Genetic Secrets

Kukekova and her colleagues zeroed in on one of the 103 genomic regions that differed between the tame and aggressive foxes. This analysis found that the tamest foxes had a version of a gene called SorCS1 that did not appear in either the aggressive or conventionally-bred foxes. Meanwhile, a different version of SorCS1 most common in aggressive foxes was incredibly uncommon in the other groups.

There was no prior reason to suspect that SorCS1 was associated with social behavior. "It was known to be associated with autism and Alzheimer's disease [in humans]," says Kukekova. And a mouse study recently found that SorCS1 is involved in synapse formation and neuronal signaling. This paves the way for understanding how the gene might affect social behavior, she says.

Domesticated animals experience less stress than wild creatures when confronted with unfamiliar people or objects, and the paper turned up genes that may be involved in this behavioral difference, which is tied to a blunted response in the hypothalamic-pituitary-adrenal, or HPA, axis. This series of biological structures form a connection between the brain and endocrine systems in the body that activates in response to stress.

The study also turned up one genomic region of interest that has been associated with domestication in dogs and with Williams-Beuren syndrome in humans, a genetic condition associated with exceptionally friendly behavior. Surprisingly, though, the "Williams-Beuren region" shows up in the aggressive foxes, rather than the tame ones.

Kukekova points out that Williams-Beuren syndrome is also characterized by extreme anxiety, however, and that is indeed consistent with the foxes' more fearful response to humans. And Princeton University evolutionary biologist Bridgett von Holdt, who was not associated with the study, points out that some dogs can be incredibly aggressive, even if they develop strong, friendly bonds with their owners. To really sort out the subtleties, she adds, will require a lot more research.

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How a Russian Scientist Bred the First Domesticated Foxes

In just five decades, an experiment in Russia has accomplished something that took ancient humans thousands of years.

On a farm in Novosibirsk, Russian geneticist Dmitry K. Belyaev selectively bred hundreds of foxes over multiple generations, eventually creating something never seen before: a domesticated fox. His goal was to recreate the process by which humans gradually turned wild dogs into workers and friends, hopefully learning something about the mechanism of domestication in the process.

Nice Foxes Only

To accomplish his goal, he selected the most docile foxes he could find from fur farms around Russia. He then bred them in successive generations, each time choosing only the tamest individuals. This is similar to the process today by which dog breeders select for desired traits, or how ancient farmers cultivated hardy crops with the highest yields.

Belyaev found that the process worked for fox domestication as well. His experiment started in the late 1950s, and by the early 2000s almost all of the foxes on the farm displayed remarkable changes in behavior,  according to an in-depth report  penned by Lucy Jones of the  BBC .

Foxes are considered notably hard to tame, but Belyaev’s foxes seemed preternaturally easygoing. They looked more like dogs than wild foxes — they would wag their tails and perk up in the presence of humans, and displayed none of the skittishness or aggressiveness usually associated with wild animals. In addition, they enjoyed being petted and would lick their handlers faces — all behaviors that socialized dogs display. And, all of this happened without any training on the part of the researchers. Their only intervention was to selectively breed those foxes that fit in with humans the best.

NPR   spoke to  Ceiridwen Terrill, a professor of Science Writing and Environmental Journalism at Concordia University in Portland, Oregon, who visited the farm and even got to pet the foxes.

“They’re genetically designed to crave human contact,” she says, “so that fox loved having its belly scratched.”

It wasn’t only behavioral changes either. The foxes started to look different over time: their ears got floppier, their legs, tails and snouts got shorter and their skulls got wider. Even their breeding patterns changed, they now mated out of season and had on average one more offspring per litter.

Changes Beyond Behavior

The reasons for this are likely rooted in neurological and endocrinological changes wrought in the foxes through selective breeding, according to  a 2009 paper  by Lyudmila Trut, of the Institute of Cytology and Genetics at the Russian Academy of Sciences, who now oversees the farm.

That paper reviewed the changes caused by domestication and found that, compared to wild foxes, the domesticated animals displayed different levels of certain chemicals in their brains. For example, their adrenal glands are not as active, but they have higher levels of serotonin. Serotonin likely plays a role in mediating aggressive behavior, writes Trut.

The physical alterations in the foxes, similar to the changes that happened in dogs, are likely a byproduct of behavioral selection. The droopiness of their ears may be caused by the slowing of their adrenal glands, says the  BBC , and the others physical disparities could similarly be related to the differences in hormone levels that lead to desirable traits. Dogs likely went through much the same process over the course of hundreds of generations as they gradually adapted to living with us.

Belyaev’s experiment is evidence that our theories of domestication are spot-on; we’ve bent the arc of evolution toward in our favor. Moreover, the process of taming a species affects more than their behavior, domestication alters their looks, and changes the rhythms of their lives.

Swing over to the  BBC   and check out Jones’s entire story , for more details about this decades-long study.

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Foxy Behavior: how a Russian fox farm uncovered the basis of canine domestication

by Drew Drabek figures by  Nicholas Lue

Foxes are not dogs. As a rule, dogs are docile and foxes are feral. You could say it’s in their DNA. But there are exceptions to every rule. A fox raised in captivity might learn to be gentle. A dog who was abused might lash out. Behavior: it’s complicated.

There has been great interest in the selective breeding of animals that can coexist with humans throughout history. In particular, biologists have been trying to understand the process of how dogs became domesticated, earning the mantle of “man’s best friend”. Taking up the challenge, scientists are searching for a specific gene, or set of genes, that predispose canines toward behaviors classified as “domestic.” In late 2018, two studies were published that helped shed some light on how these behaviors evolved. The scientists compared the genomes and brains of  tame and aggressive silver foxes – an animal closely related dogs – whose behavior was studied during an impressive 60 year-long experiment on a fox farm in Russia.

Evolution of foxes, wolves, and dogs

To understand the immense challenges facing these studies, one need only look to the evolution of the modern dog from other canines, a group that includes wolves, foxes, coyotes, jackals, and of course dogs. Between 10,000 and 30,000 years ago, our ancestors domesticated the wild dog. Scientists believe that the closest ancestor of all modern dogs is the modern-day gray wolf. As cousins to wolves and dogs, foxes are a great model for dog domestication. They diverged from the wolf lineage about 12 million years ago (a brief time period, evolutionarily). It is difficult to study the process of the dog’s domestication since its wild relatives, the fox and wolf, are now different species . This means that, even though the complete set of genes, or genomes, from a dog, gray wolf, and fox have been sequenced and are available for study, there are too many genetic differences that obfuscate the path to the answer of the “domestication question.”

Breeding a domesticated fox

More than 60 years ago, a group of researchers took a first step toward understanding the genetics of domestication by breeding wild foxes and selecting for domestication behaviors. This project, termed the “farm fox” experiment , was started in 1958 by Russian scientists Dmitri Belyaev and Lyudmila Trut, who bred wild silver foxes in an attempt to make them tamer.

Breeding is man’s attempt to control heredity, the inheritance of certain traits that are passed from parent to offspring via genes. Over tens of generations, the farm fox experiment successfully showed that careful breeding could select for certain behaviors in foxes, specifically the behavioral traits of gentleness or aggressiveness toward humans. Since these behaviors are passed on from generation to generation, subsequent biologists wanted to go deeper to discover which inherited genes predispose foxes to these opposing behaviors. As an example, animal biologists can clearly document genes that determine fur color or curliness of a tail. However, it is fundamentally more difficult to document a gene-to-behavior relationship, since behavior does not have not an unambiguous and discrete physical manifestation.  

Since the farm fox experiment has generated a wealth of documentation on the heredity of domestication, the direct descendants of the founder foxes have been subjected to high-profile genetic studies in an attempt to understand how specific genetic differences might contribute to their divergent behavior (Figure 1).

Genetic comparisons between tame and aggressive foxes

To identify specific genes that differentiate tame and aggressive foxes, teams of scientists from Cornell and the University of Copenhagen independently studied the genes of domesticated and aggressive Russian farm silver foxes.

The Cornell scientists compared the genes turned on in brains of the aggressive foxes with those turned on in the tame foxes, studying gene activity in two parts of the brain: the part responsible for memory and learning and the part responsible for arousal, attention, and decision making. They found hundreds of differences in the use of genes within each brain region, suggesting that molecular alterations within the brain could be the “switch” between tameness and aggression.

They also found a clue from genes that control how the brain responds to natural chemicals that affect mood. Differences in their mood-related brain chemistry could explain the tendency for tameness or aggression. For example, the chemical serotonin plays a role in feelings of contentment or happiness. And as it turns out, tame foxes use more of the genes responsible for forming feelings of happiness using serotonin, which is a possible explanation for their tolerance toward humans (Figure 2).

But serotonin is not the whole story. Glutamate, a chemical linked with aggression, is also involved. The genes affecting the brain’s response to glutamate changed directly, altering how the tame foxes’ brains respond to it. The scientists hypothesized that this change in glutamate sensing made the tame foxes more responsive toward their keepers. Together, these genetic differences predict that simultaneous changes in the equilibrium between glutamate and serotonin could contribute to “domestication-like” behaviors.

While the Cornell group looked at brain activity, the group from the University of Copenhagen instead looked for differences within the genomes of tame and aggressive foxes. Genes are the fundamental units of inheritance, and a genome is the complete collection of a  foxes’ genes. This is different from the Cornell group’s comparison of the sub-set of genes that are actively used just in the foxes’ brains. By documenting the genomes of several tame and aggressive foxes, the Copenhagen scientists were able to cross reference all the changes between the different animals.

They highlight changes, again, related to the mood altering chemical glutamate. Still other differences are linked to how the brain forms new connections called synapses.  Additionally, by comparing the genetic changes reported by the Copenhagen study with those found in the Cornell study, scientists discovered that there were 75 overlapping genes. This overlap indicates that the same genes that changed in foxes’ genomes were also used differently in their brains. Many of these genes were related to mood altering chemicals, like serotonin. This is an extremely valuable genetic list, and will be a key resource to allow scientists to define the gene-behavior relationship for fox domestication.

Together, these findings have given the field of animal behavior a huge hint for uncovering the molecular basis of behavior by curating a list of genes likely to directly affect a fox’s instinctual response to humans. However, more studies need to be performed to determine if a small number of genes and brain chemicals are critically important for such specific behaviors, not only in the fox, but also in other animal species.

The future of behavioral genetics

These recent genetic studies suggest that a relatively small set of genes can have a massive effect on the behavior of an animal. It is certainly possible that we might one day be able to look at a set of genes in a fox’s, or dog’s, DNA and predict certain personality traits. The possibilities for understanding the molecular basis of neurological function are tantalizing for man’s best friend. Maybe one day the gene-to-behavior relationship will be understood in humans, as well.

Despite these promises, there is still much to understand about the genetic basis of behavior. With the impressive work originating from a Russian, evolution-accelerated fox farm, we are one step closer to unraveling the mystery of how domestication evolved in canines.

Drew Drabek is a graduate student in the Harvard Chemical Biology Ph.D. Program studying mechanobiology jointly in the labs of Prof. Stephen C. Blacklow and Prof. Joseph J. Loparo at Harvard Medical School.

Nicholas Lue is a graduate student in the Chemical Biology PhD program at Harvard University. You can find him on Twitter as @nicklue8.

For more information:

• To learn more about early evolution of the domestic dog, check out  this piece in American Scientist
• Find more detail about the fox domestication and about Lyudmila Trut, herself, in this interview .
• A retrospective review of the farm fox experiment can be found in this technical article from the Russian Journal of Genetics

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11 thoughts on “ Foxy Behavior: how a Russian fox farm uncovered the basis of canine domestication ”

Fascinating article. Thank you

I love reading your blogs. Thanks for sharing!

One of the best and my favorite blog ever. Aala stuf and best quality.

One of the best and my favorite blog ever.

‘Scientists believe that the closest ancestor of all modern dogs is the modern-day gray wolf is wrong’. Both gray wolf and dog share a common ancestor that has long been extinct.

It certainly is wrong, but not for the reason you state. The DNA of “wolves” and “domestic dogs” is 99.9% the same. That doesn’t make them “cousins”, that makes them the same species. A spaniel and a greyhound are both dogs, as is a wolf, coyote and jackal. Every “breed” of dog has slightly varying DNA, appearance, abilities, etc. but you don’t blather about a “common ancestor” when you are discussing the same creature. This recurring old naturalists tale about wolves and dogs being different is disproved by DNA.

Living relative / common ancestor and direct ancestor are very different things. Just like a horse is not a zebra but they are both equids. Science is about using the right terms when speaking on a topic. Hypertension and hypotension are about the same body state but vastly different. Living relative does not affect the evolution of the entire population, at most there will be small subsets of those affected by admixture, like a direct ancestral line does. It’s why an individual’s doctor routinely asks about the health history of siblings, parents, grandparents etc and not cousins and aunts / uncles (unless due to a rare disease or condition is at play that is not exclusively passed along the direct line). But nice try.

You know this article isn’t relevant, so just take it down..

More information of why this article is now a bit incorrect.

https://www.nytimes.com/2019/12/03/science/foxes-tame-belyaev.html

Greetings, I’m studying at the Master’s University, and we have a group project in writing about the study between Dogs and foxes.  We are looking at Dr. Belyayev who did an experiment between these dogs and foxes. Website: https://blogs.scientificamerican.com/guest-blog/mans-new-best-friend-a-forgotten-russian-experiment-in-fox-domestication/ Here are some questions: 1). Your personal perspective?2) was this experiment helpful?3) would you do anything different?4) what are a few exciting or interesting characteristics you like about dogs and foxes which are similar?  Thank you

Dr. Belaev passed away in 1985. The experiment was continued by Lyudmila Trut.

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That Famous Russian Fox Domestication Study May Have Had a Few Crucial Flaws

In 1959, the Soviet zoologist Dmitry Belyaev began selectively breeding silver foxes. Those least afraid of people were chosen to reproduce. His goal was to simulate the process that turned fierce ancient wolves into the dogs now known as our best friends.

The experiment worked, famously well. In 10 generations, Belyaev's lineage of foxes became tame, seeking attention from people and wagging their tails when scientists approached.

But this wasn't the only way the foxes changed. In 1979, Belyaev noted that some of the foxes had begun to look different, developing curly tails, spotting on their coats and floppy, puppy-like ears.

Later, other scientists began noticing some of these same traits in other domesticated species - pigs and goats, birds and fish - which seemed to point to a common genetic path that animals take as they change from wild to tame to domesticated.

This tantalizing notion, now known as domestication syndrome, was first put forward by Charles Darwin, and it has become integral to our understanding of how animal domestication works. But in a new paper, some scientists have challenged its accuracy - and, along the way, common beliefs about what domestication means.

The authors of the paper do not doubt that Belyaev was able to breed tamer foxes. But the Russian experiment fell short of proving the existence of domestication syndrome, they argue, because Belyaev's first foxes were far from wild, and there's no proof certain physical features are common to domesticated species.

"The common story line is that when you select on tameness in an animal species, a whole suite of other traits change in a predictable way," said Elinor Karlsson , a genomic scientist at the University of Massachusetts Medical School and senior author on the study. "And we just couldn't find convincing evidence for that."

A major problem is that Belyaev started with foxes that weren't wild, said Kathryn Lord , an evolutionary biologist at the University of Massachusetts Medical School and lead author of the paper, published Tuesday in the journal Trends in Ecology and Evolution . Genetic testing indicated they originated in eastern Canada, probably at a fur farm on Prince Edward Island, which means the animals were already on the path toward domestication.

There's also evidence that Canadian fur farmers were seeking to produce unusual pelt colors, including with white spotting, which might fetch higher prices. So some of the traits held up by Belyaev as evidence of the domestication syndrome may already have been present in his first batch of foxes.

And those foxes' tendency to produce white spots likely would have become greater when they arrived in Russia, because Belyaev started his experiment with a rather small population of 130 animals, Karlsson said.

"You can get very rapid changes in the frequency or the prevalence of a trait without having done a whole lot of work, just by making the population really, really small," she said.

The other wrinkle is that evidence for the suite of physical traits long said to be shared by dogs, goats, rabbits and other domesticated species is thin, the authors say.

For instance, it's commonly said that domesticated animals have curlier, more upright tails - the difference between a Siberian husky's and a gray wolf's. But Lord and her colleagues found no conclusive evidence that domesticated dogs hold their tails differently from wolves, foxes or other wild canids. They also found little documentation of these traits for other animals.

"I know this is true! It's a thing!" Lord said, acknowledging that even she finds the lack of data frustrating. "But nobody's counted it."

This is important, Karlsson said, because while "tail carriage" is more common in less fearful foxes, it's also seen in some of their wild cousins. That means the adorable, dog-like tails seen in the Russian experiment's foxes may not be linked to genetic changes that enabled their tameness at all. It might just be sheer luck.

"Our main point is not that domestication syndrome doesn't exist, but just that we don't think there is enough evidence to be confident it does exist," said Karlsson in a follow-up email.

None of this matters much to how most of us relate to our dogs and cats (or pigs and goats). But the challenge to common wisdom about how those animals came to be has caused waves in the community of domestication scholars - and gotten a mixed reception.

"The fox experiment is the most celebrated one in studies of domestication, yet details of it have never been fully published or explained, much less critically assessed," said Marcelo Sánchez-Villagra , a paleobiologist at the University of Zurich who has studied domestication syndrome. "This paper to me shows that new, better designed experiments on domestication - of several kinds of animals - are needed to advance the field forward."

Melinda Zeder , senior scientist emeritus at the Smithsonian's National Museum of Natural History, said the Russian farm-fox experiment has "really been oversold," in that many popular portrayals make it out to be grander and more simplified than Belyaev and the scientists who succeeded him meant it to be.

"The caution that they offer here is very useful, to sort of pull back and say this is not the be-all, end-all," Zeder said. But she added that the "case is not as convincing as you would want it to be," in part because, she said, it places too much weight on a lack of studies documenting every domestication syndrome trait in every domesticated animal.

Belyaev was well aware that white spotting was present in his fox population and never claimed it was linked to tameness, said Anna Kukekova , a geneticist at the University of Illinois at Urbana-Champaign who has been studying these foxes for decades. Belyaev detailed this clearly in a paper he published in 1979, she said.

Kukekova said she had other qualms about the new paper, though she agrees that there doesn't seem to be evidence for one easy path to domestication.

"Genes rarely have a single function," she said in an email.

"I would strongly argue [the Russian farm-fox experiment] is still the gold standard," said Lee Dugatkin , a biologist at the University of Louisville and co-author of a book about the Russian experiment, " How to Tame a Fox (and Build a Dog) ."

Dugatkin said he had "major concerns" about the study. He said curly tails didn't show up in the foxes for nine to 10 generations and that the scientists did not select for them once they showed up.

But they grew more common with each tamer generation, he said. The project, which is now run by his co-author, Russian geneticist Lyudmila Trut, has since added two new lineages of foxes, one selected for aggression and another as a control, he said, and they haven't developed curly tails and spotting.

But just because those traits don't show up in other populations "doesn't prove that the traits are directly linked to tameness," said Karlsson, "just that those traits happened to also occur in the population that was selected for tameness. The most likely explanation is that this is due to random chance."

Lord makes no bones about how important Belyaev's work was. "It's an amazing behavioral experiment," she said.

But it could be stronger, Karlsson said.

"That was kind of what inspired us to write the paper," she said. "Because there's nothing more frustrating than when people just assume that something is true that hasn't been proved yet."

2019 © The Washington Post

This article was originally published by The Washington Post .

How Vladimir Demikhov Actually Made A Two-Headed Dog

Though it's hard to believe that soviet scientist vladimir demikhov actually made a two-headed dog, these surreal photos are the proof..

Calling Soviet doctor Vladimir Demikhov a mad scientist may be undercutting his contributions to the world of medicine, but some of his radical experiments certainly fit the title. Case in point — though it may seem like myth, propaganda, or a case of photoshopped history — in the 1950s, Vladimir Demikhov actually created a two-headed dog.

Vladimir Demikhov’s Pioneering Career In Medical Research

Even before creating his two-headed dog, Vladimir Demikhov was a pioneer in transplantology — he even coined the term. After transplanting a number of vital organs between dogs (his favorite experimental subjects) he aimed, amid much controversy, to see if he could take things further: He wanted to graft the head of one dog onto the body of another, fully intact dog.

Bettmann/Getty Images Laboratory assistant Maria Tretekova lends a hand as noted Russian surgeon Dr. Vladimir Demikhov feeds the two-headed dog he created by grafting the head and two front legs of a puppy onto the back of the neck of a full-grown German shepherd.

Starting in 1954, Demikhov and his associates set about performing this surgery 23 times, with varying degrees of success. The 24th time, in 1959, was not the most successful attempt, but it was the most publicized, with an article and accompanying photos appearing in LIFE Magazine . This is thus the two-headed dog that history remembers most.

For this surgery, Demikhov chose two subjects, one a large stray German Shepherd that Demikhov named Brodyaga (Russian for “tramp”) and a smaller dog named Shavka. Brodyaga would be the host dog, and Shavka would supply the secondary head and neck.

With Shavka’s lower body amputated below the forelegs (keeping her own heart and lungs connected until the last minute before the transplant) and a corresponding incision in Brodyaga’s neck where Shavka’s upper body would attach, the rest was mainly vascular reconstruction — other than attaching the vertebrae of the dogs with plastic strings, that is.

Bettmann/Getty Images Vladimir Demikhov’s lab assistants feed the two-headed dog made from Brodyaga and Shavka after the surgery.

Thanks to the team’s wealth of experience, the operation took a mere three and a half hours. After the two-headed dog was resuscitated, both heads could hear, see, smell, and swallow. Although Shavka’s transplanted head could drink, she was not connected to Brodyaga’s stomach. Anything she drank flowed through an external tube and onto the floor.

ancient history

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By All That's Interesting

The Sad Fate Of Demikhov’s Two-Headed Dog

In the end, this two-headed dog lived only for just four days. Had a vein in the neck area not accidentally gotten damaged, it may have lived even longer than Demikhov’s longest-living two-headed dog, which survived 29 days.

Even setting aside the deaths of the canine subjects, the moral implications of Demikhov’s experiment are tricky. This head transplantation, unlike some of his other advancements in the field of transplantology, had no real-life applications. Yet there were certainly very real implications for the dogs.

Keystone-France/Gamma-Keystone via Getty Images Vladimir Demikhov with his two-headed dog.

However, as outrageous as this all sounds, a head transplant wasn’t even that radical for the 1950s. As early as 1908, the French surgeon Dr. Alexis Carrel and his partner, American physiologist Dr. Charles Guthrie, attempted the same experiment. Their dual-headed canine initially showed promise, but degraded quickly and was euthanized within a few hours.

Today, Italian neurosurgeon Sergio Canavero believes that head transplants will be a reality in the very near future. He is closely involved in the first human attempt, which is slated to occur in China, where there are fewer medical and ethical regulations. Canavero said last year , “They have a tight schedule but the team in China say they are ready to do it.”

Nevertheless, most everyone else in the medical community believes that a transplant of this kind is still science-fiction fodder. But in the not-too-distant future, such a surgery may actually become a reality.

After this look at how Vladimir Demikhov created a two-headed dog, see some astounding photos of two-headed animals found in nature . Then, read up on Laika, the Cold War-era Soviet dog who was sent into space and became the first animal to orbit the Earth .

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Guarding the Fox House

A famous animal experiment is in peril, after 54 years of work..

Courtesy Ceiridwen Terrill

The battered Volga bounces us along the buckled roads, frozen and thawed over long Siberian winters. With me in the van are geneticist Lyudmila Trut and her assistant Anastāsiya Kharlamova, whom I met earlier that morning at the Institute of Cytology and Genetics in Siberia.  Now in her 70s, Trut, a petite woman in a blue pinstripe jacket and light gray pants, peers through thick glasses, trying to read a scientific paper as we drive. A few minutes later, the driver stops at the dented metal gate to the experimental farm, and Trut leads the way down dilapidated rows of narrow barracks-style sheds, morning glories sprouting from cracks in the paved walkways. The farm houses 3,000 foxes, each open-air wooden shed holding 100 or so animals in adjacent wire cages. The three of us put on white lab coats and prepare to greet the foxes.

When I open the door to one fox’s cage, the only home it will ever know, the little guy doesn’t shrink in fear as a wild creature could be expected to. Instead he lets me scoop him up, then nuzzles my neck and licks my fingers. Kharlamova, a slim young woman with shoulder-length brown hair, explains that the fox is “emotional” because I’m giving him the attention he wants. 

Although domestication of dogs took thousands of years, Russian geneticist Dmitry K. Belyaev tried to reproduce the whole messy process in one human lifetime, eliminating all the dead ends and inefficiencies of chance and human blunder. In 1957, he began a domestication experiment with the farmed fox Vulpes vulpes , a distant cousin of the dog. In March 2011, a National Geographic article described the experiment as if it were finally on the verge of completion. Researchers were scanning the genomes of the “domesticated silver foxes,” it said, in the hopes of finding “key domestication genes.” But there’s a problem with this narrative: Even after 54 years of research, we still don’t know whether the animals have reached the original end point set out by the project’s founder.

Belyaev, who died in 1985 and left Lyudmila Trut in charge of the project, was clear about his goal: The foxes would be considered fully domesticated only when they obeyed human commands as dogs do. That part of the experiment is still unfinished. No evidence exists to tell us whether the foxes can be trained to override their instincts, the way a dog might learn to avoid defecating on the carpet, or to stay at the heel instead of running off to seek the company of other canines. Belyaev would never have called the experiment over until a whole population of foxes had shown that they were biddable, eager to please, and able to pass those qualities to their offspring. Now Trut would like to put those qualities to the test, but her experiment has stalled for lack of money. After 51 generations of foxes, the world’s foremost domestication experiment languishes. If nothing is done to save it, we’ll have missed an opportunity to understand the mechanisms of domestication, of which genetic tameness—friendly behavior that is not learned but inherited—is only one component.

Belyaev began with several hypotheses: People created the dog, and they did it by selecting—first unintentionally and then intentionally—for behavior.  He could replicate and accelerate the dog’s domestication process with the fox, he theorized, by rigorously selecting for tameness, which would eventually allow him to uncover the genetic mechanisms responsible for changing the dog’s wild ancestor into our beloved Fido. From fur farms where foxes had been bred in captivity for more than 50 years, Belyaev chose 130 of the calmest animals, descendants of foxes who’d already passed an unintentional selection test for tameness simply by surviving the original lure, capture, and confinement that literally scares some wild foxes to death. Kits born to Belyaev’s founding population and each succeeding generation of kits were subjected to a standardized tameness test, each animal ranked according to its response to a human experimenter who tried to touch and feed it. Only those foxes that showed tolerance for the nearness of people were selected and bred to produce the next generation, while fearful or aggressive animals were culled. Each generation of foxes grew more approachable, many showing doglike yearning for human contact. The experimental farm presently houses a stable population of genetically tame foxes.

Results of testing by anthropologist Brian Hare and his team at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have shown that Belyaev’s foxes respond to pointing cues almost as well as dogs, which means they’re attuned to human interaction. But although we have the occasional anecdote of a fox walking on a leash or another sitting for a treat, no systematic socialization and training program has been launched to test the capacity and willingness of the foxes to respond to classic obedience cues— come , sit , down , stay , and settle — defining characteristics of a domestic canine. If fox kits are raised like dog puppies, put to the training test, and pass, then scientists would know that all the genes relevant to domestication are present in their genome. They’d just have to find them.

Unfortunately, the experiment is broke. Grant money is scarce in Russia, where economic crises hit in 1998 and again in 2008. Trut has resorted to selling some of the foxes into the exotic pet trade through SibFox Inc., a private company in Las Vegas. For $6,950, the U.S. distributor promises a tame four-month-old fox “delivered to your door in 90 days.” Since the foxes’ critical window of socialization—the period during which they form primary bonds—closes when the animals are about 60 to 65 days old, it’s no wonder the distributor advises housing the foxes in cages with bottoms or dig guards to prevent escape, because that’s what the foxes try to do. 

But the fact is, people aren’t lining up for pet foxes, and each year Trut and her team must either euthanize or sell several hundred foxes to fur farms because she can barely afford basic upkeep. As of this writing, fewer than five foxes have been sold in the United States as pets, and only a handful live with wealthy Russians. One sent to a home in Moscow went roaming and found himself a wild girlfriend whom he occasionally brought around for dinner. She wouldn’t go near the house, and he stayed only long enough to eat a bit of meat—less a pet than a roommate. Yet Trut soldiers on, trying to preserve the integrity of the genetic line in case funding should materialize for a rigorous socialization and training program. 

For the experiment to continue, fox kits would have to be systematically hand-reared and human-socialized. Then they could be trained and tested for their ability and eagerness to respond to classic obedience commands. If the foxes don’t prove trainable, then perhaps domestication, even when compressed for efficiency, takes longer than one human lifetime and is more complicated than merely selecting for a single behavioral trait. Or perhaps the dog’s ancestor possessed something unique in its genes that gave rise to our closest companion, something that can’t be replicated in the fox just because it’s a social canid. The point is, we won’t know until Belyaev’s experiment is finished. Unless the experiment is helped to reach its conclusion—to understand once and for all whether the foxes have achieved domesticity as Belyaev hoped—more than half a century of intellectual labor and the lives of more than 50,000 foxes will have been wasted.

Trut feels bad about the state of the farm and the plight of hundreds of foxes moaning and chattering for attention from their 3-foot wire cubes. On my last night in Siberia, over a meal of tsar’s hodgepodge—described in the menu as “grilled vegetables with secret sauce and garbage”—a man with his personal fifth of Beluga vodka tells me that getting by in Russia takes a lot of luck. I can’t help thinking those farm foxes need all the luck they can get. They’ve already surprised geneticists by suggesting that selection for a single behavioral trait can trigger “piggy-backing” changes in physiology and appearance, like increased levels of serotonin and piebald coats. There may be more surprises to come, but it will take a major infusion of cash, and a collaboration among scientists, adventurous dog trainers, and Lyudmila Trut to let Belyaev’s experiment—and eventually his foxes—out of the box.

Watch Soviet Scientists Bring a Dog’s Decapitated Head Back to Life

What was supposed to be the stuff of medical miracles ended up being a horror show..

A warning: the video above contains imagery of medical experiments conducted on animals that some might find disturbing.

In 1940, Soviet scientists reanimated a dead dog.

Dr. Sergei Brukhonenko had done pioneering work in blood transfusion several years earlier, a procedure which still remains essential in modern hospitals. But if you can move life-giving blood from one individual to another, why stop there?

While the Americans experimented on primates, the Soviet scientists experimented on dogs. Brukhonenko was able to isolate individual organs and maintain them in working order: a heart would keep pumping blood, lungs breathed on their own.

But those pieces, while important to life, do not a life make. The next step was to reanimate an entire head, brain, face and all, by pumping oxygenated blood through the arteries with the help of a contraption called the “autojektor.” With a blood supply to the brain, the head reacted to stimuli as it would in life, twitching its ears and eyes at pokes and prods. It even licked a substance off its own nose.

Next, another dog, this one completely intact, was given a clinical death, then brought back to life with the autojektor. “After the experiment,” the narrator of Experiments in the Revival of Organisms says over triumphant music, “the dogs live for years, they grow, they put on weight, and have families.”

Some have suggested that the whole thing is a hoax, an elaborate scheme to intimidate American scientists, but no evidence of fakery has been revealed. A contemporary video shows a puppy surgically attached to the torso of another dog , and images of a robot suit piloted by a dog’s head and brain have surfaced online. The only reason these experiments haven’t been recreated since is that the blatant animal abuse and disregard for modern standards of medical ethics would turn stomachs even more that this 1940 video does.

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A dog with two heads: How a Soviet doctor pioneered organ transplantation against the odds

"The son of a peasant, Demikhov initially trained as a mechanic and repairman before enrolling in the biology department at Moscow State University. Here he thrived."

On April 11, 1959 the Associated Press circulated a message from Moscow: Russian doctors had transplanted a puppy’s head to the neck of a German shepherd and the two-headed beast was in good health. However, the American public - surprised by the sensational news - had not yet seen the shocking images. Only later would the photos of the experiment become public.

The pictures (which are, fair to say, objectively repulsive) document the ground-breaking experiment of a Soviet scientist leading the way in organ transplantation. By the time the news of the operation hit America in 1959, the surgeon - Vladimir Demikhov, 43 at the time - had already been performing transplants on dogs for five years.

None of the previously operated dogs has lived for more than six days. Pirat (the Russian word for Pirate) - the German shepherd operated on April 11 - proved an exception, however. The two-headed dog lived for three weeks while reacting to stimuli around it!

"By the time the news of the operation hit America in 1959, the surgeon - Vladimir Demikhov, 43 at the time - had already been performing transplants on dogs for five years."

A heart for two hours

The son of a peasant, Demikhov initially trained as a mechanic and repairman before enrolling in the biology department at Moscow State University. Here he thrived.

Demikhov performed his first ground-breaking experiment less than two years into his studies. In 1937, he sent shockwaves through Russia’s medical community when he created an artificial heart and successfully implanted it into a dog. The dog lived for two hours after surgery, pushing the borders of organ transplantation, a science scarcely studied in 1937 but vital for today’s medical world.

Demikhov’s later and bolder experiments attracted attention from across the Atlantic, as well as from Europe. Scientists in the West mostly believed organ transplantation was not possible because the patient’s immune system would reject the new addition.

Likely, this general skepticism was the main reason why the work of an American professor at Washington University - Dr. Charles C. Guthrie - who performed an experiment similar to Demikhov’s in 1908, was not followed up by his American colleagues.

Everything changed though when news about Demikhov’s success reached the U.S. In the 1960s, American doctors traveled to the Soviet Union to learn about innovative techniques used by Soviet surgeons. One of the key innovations, later adopted by the U.S., Canada, and Japan, was the use of staples to compress veins and arteries during operations, which dramatically reduced surgery time.

By 1962, a consensus of the American medical community had shifted and U.S. doctors, who saw Demikhov at work, gradually warmed to the possibility of successfully transplanting human organs.

Concise obituary

In 1965 Demikhov attended a medical conference where he proposed the creation of a bank where human organs could be stored for the needs of surgeons. The futuristic proposal, unthinkable at the time, sparked much anger among Soviet academics who criticized Demikhov and demanded the closure of his laboratory.

This took a toll on his health, his wife later recalled, and despite the fact Demikhov remained a director at the Russian Health Ministry Republican Center for Human Reproduction, his research efforts in organ transplantation declined, and his international fame wilted.

The pioneering scientist died in a small apartment on the outskirts of Moscow in 1998 at the age of 82. The true value of his experiments, which were observed with suspicion by the Soviet medical elites, were acknowledged by the Russian state at the end of his life. Demikhov was awarded the Order for Services for the Fatherland in 1998, the year of his death. However, the countless lives subsequently saved by organ transplants are his real legacy.  

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