The Russian geneticist Dmitry K. Belyaev (1917–1985) demonstrated in real time the process by which wild animals become domesticated, in particular how wolves became dogs. Belyaev's research population of wild foxes, bred for domestication, evidenced in only a few decades the behavioral and physiological changes that could occur over thousands of years in the wild.
During a time when it was illegal and dangerous to do so in the Soviet Union, geneticist Dmitry Belyaev quietly proved and advanced Czech scientist Gregor Mendel's theory of genetic selection and British naturalist Charles Darwin's theory of evolution. Carefully cloaking his genetics research as an attempt to improve the quality of Russian fox fur, Belyaev was able to shed light on how and why species become domesticated, that is, adapt to life with humans. His breeding population of foxes came to resemble and behave like domestic dogs in a remarkably short time. They showed the sort of physiological changes that would otherwise take thousands of years and only be recognized by the study of fossils. Belyaev's work was arguably the greatest genetics experiment of the 20th century.
Born July 17, 1917, in Protasovo, a village northeast of Moscow, Dmitry Konstantinovich Belyaev was the fourth and youngest son of Konstantin Pavlovich, the village priest. A peasant family, they raised livestock and grew corn, but they also valued learning. Belyaev's oldest brother, Nikolai, was 18 years his senior and already a scientist by the time Belyaev entered school. After second grade, the younger son was sent to live with Nikolai in Moscow in order to continue his education.
As a city rich in art and intellectual energy, Moscow inspired the young student. Over the next decade, Belyaev followed in his brother's footsteps, studying biology at the Ivanovo Agricultural Institute and spending time with Nikolai and his scientist friends. Nikolai Belyaev was a prominent researcher in the field of population genetics. By this time, scientists had linked two important theories: Darwin's theory of evolution, which stated that all organisms progress and survive as species through “natural selection,” or the inheritance of small variations that help that species compete for survival, and Mendel's theory of biological inheritance. These theories formed the foundation for genetics: the passing on of traits through genes. Further combined with early chromosome theory, this line of research led to the new science of population genetics. The Belyaev brothers and their colleagues devoted themselves to advancing the field, sharing ideas and research results freely with each other.
By this time, however, a political noose was tightening around the free exchange of knowledge in Russia. Government and society had gone through extreme upheaval since the dawn of the 20th century. Communist revolutionaries, or Bolsheviks, followed the teachings of German philosopher Karl Marx and wanted to overthrow the Russian tsar (or king) and pass control to the peasants. They finally overthrew Tsar Nicholas II and the royal family in 1917, while Russia's government and society were strained due to the country's involvement in World War I (1914–1918). The Great War, as it was then called, ultimately involved 32 countries around the world and left Russia devastated.
In 1937, a year before Belyaev graduated from the Ivanovo Agricultural Institute, Nikolai was arrested by the state police and executed without trial. Stalin and his advisors did not like genetics research, considering it to be a tool to oppress the working class. Stalin's leading advisor on agriculture, Trophim Lysenko, advocated long-disproven methods—which he claimed to have invented—of improving crop yields and livestock, areas usually helped by genetic research. Lysenko claimed that his methods could create huge improvements in a short time and involve farmers in an agricultural revolution. Because the slow, methodical work of genetics in the mode of Mendel, Darwin, and others could not promise such speedy results, they fell out of favor, and scientists were forced from their jobs, arrested, or worse.
Despite this atmosphere of fear and suspicion, Belyaev continued his research, strategically picking a subject for his dissertation—the improvement of silver fox fur—that would please the authorities. Foxes from Russia's Arctic north were bred in captivity for their thick, dark fur, which was prized in the manufacture of winter coats. Belyaev framed his research as a study in animal physiology. However, he quietly used Mendelian ideas and methods and supported other scientists doing the same.
Over the next 20 years, amid the brutality that characterized the Stalin era, Belyaev persevered. Hired by the USSR's Department of Fur Animal Breeding in Moscow, he was assigned a government fur farm, where he slowly progressed on his dissertation. In 1941, however, Belyaev was drafted into the Russian Army to fight Nazi Germany in World War II. He set his research aside and fought bravely, starting as a machine gunner, rising through the ranks to major and receiving several medals for valor and service. Because of his outstanding military record, Belyaev was able to return to his job, soon becoming head of the department.
Adhering to his belief in evolutionary genetics put Belyaev in an awkward position, despite his caution. His now-completed dissertation, titled “The Variation and Inheritance of Silver-Coloured Fur in Silver-Backed Foxes,” fairly shouted its basis in Mendelian genetics. The persecution of geneticists had never abated; in fact, Nazi Germany's use of genetics in creating a “master race” convinced the Soviets that the study of genetics was evil and must be abolished. In 1948, practice in the field was banned within the USSR and Belyaev was dismissed from his position as director of the Department of Fur Animal Breeding. If he continued his work openly, he would likely be arrested and taken to a political prison, or gulag, located in the farthest reaches of frozen Siberia.
For the next ten years, Belyaev remained cautious, knowing that he was at serious risk of arrest. Even after the death of Stalin in 1953, Lysenko remained in power. However, he continued to study animal physiology, secretly performing genetics research at the same time. A step forward came in 1958, when he was hired by the Siberian division of the USSR's Academy of Sciences to continue his experiments. Headquartered in Novosibirsk, a large city in Siberia on the banks of the Ob River, he could conduct his genetic research, far away from the politics of Moscow.
By now Belyaev had become deeply interested in the domestication of wild animals, specifically the evolution from wolf to the incredible variety of domestic dogs in the modern world. According to Darwin's notes on the physiological changes involved, wolves gradually lost their upright ears; most domestic breeds have floppy ears. Largely dependent on humans for survival, domesticated dogs developed facial expressions and postures that communicate to people: they whimper and bark, whereas wolves are largely silent. Over time, dogs' tails curled and they lost their wild, musky scent, all while remaining genetically identical to their wild forebears. Although dogs are basically wolves, domestication caused significant physical differences, and Belyaev determined to study this process.
Belyaev's long acquaintance with the silver fox suggested a perfect subject for study. Russian silver foxes were of the same species as the more typical red foxes found across the Northern Hemisphere, so his research could have wide application. In Russia, these dark foxes were bred in captivity but were never tamed or trained. They lived short lives, slaughtered for their pelts as soon as they matured at seven or eight months. Fox farms were plentiful across Russia, so there would be a large and diverse population from which to draw subjects.
Belyaev suspected that the physical changes in domesticated animals resulted from gene modifications during selection for tamability. In other words, animals that naturally felt comfortable around humans would tend to produce offspring that felt the same way, leading to physical changes in succeeding generations. Wild foxes—normally silent, sharp-eared, straight-tailed, and averse to human contact—should, therefore, become friendlier, vocalize, and have floppy ears and a curling tail, among other attributes. Belyaev decided on a brilliantly simple approach: he would select foxes from across Russia that were already calm and unafraid of humans. Making tameability his sole criteria for selection would allow him to observe a whole range of possible changes over succeeding generations of foxes.
Following Belyaev's research criteria, Trut located a remote, successful fox farm willing to host the research, and she traveled to many other fox farms to select the initial breeding population. She was initially taken aback by the savagery of the animals, many which snarled and snapped at her as she approached their cages. Others cowered at the back of the cage. She gathered her breeding population based on tameability, selecting calmer foxes that did not seem to mind her presence.
In her experiments, Trut followed strict guidelines laid down by Belyaev. Once each month, each fox was tested for its response to human contact. The researcher would offer the pup food from her hand while attempting to pet it. Notes were taken and pups were classified accordingly. From each new generation of foxes, Trut selected the calmest and friendliest to start the next generation. Breeding occurred each October, with new pups arriving from April through June.
Progress was seen as early as 1964, with the fourth generation of pups, when young foxes showed signs of affection, and by the sixth generation a new category, for extremely friendly foxes, was created. As the years passed, the foxes began to show the predicted changes in physiology. Along with being friendly and approachable, their ears changed, they began to whimper for attention like dog puppies, and their tails began to curl and wag.
Meanwhile, in 1959, Belyaev was appointed director of the academy's Institute of Cytology and Genetics (ICG). During the late 1950s, the political atmosphere in the USSR changed as new leaders adopted more tolerant attitudes toward the sciences. Since coming to power in 1954, Communist Party leader Nikita Khrushchev reversed Stalinist policies in an attempt to modernize the USSR. Moving into the 1960s, under Belyaev's leadership the Institute was able to resume the study of classic genetics, as well as that of the newer molecular genetics.
As his genetics research expanded, Belyaev established a new fox farm near the ICG. A longtime tobacco smoker, he died of cancer on November 14, 1985, leaving Trut to continue his work. She attracted international attention through a series of published articles, and by 1999, with 45,000 foxes now studied, she reported in American Scientists that “a group of animals had emerged that were as tame and as eager to please as a dog.” Other researchers grasped the enormity of the implications of Belayev's domestication research, given the questions it raised. How is it that relatively few species, out of thousands, are domesticated? Can we learn about human development from our earlier origins? Which genes influence tameness and aggression?
Trut's ability to publicize the ICG research proved useful when political conditions again threatened it. By 1992, the USSR had collapsed and the newly formed Russian Federation was now struggling to build its economy. Fortunately, researchers in the United States were very interested, and financial support for the fox studies was provided by the National Institutes of Health (NIH). German researchers also joined the project, channeling funding through the Max Planck Institute. National Geographic took a keen interest as well, helping to make Belyaev's secret genetic studies known internationally.
Dugatkin, Lee Alan, and Lyudmila N. Trut, How to Tame a Fox (and Build a Dog): Visionary Scientists and a Siberian Tale of Jump-Started Evolution, University of Chicago Press, 2017.
Hare, Brian, and Vanessa Woods, The Genius of Dogs, Oneworld Publications, 2014.
American Scientist, April 1999, Lyudmila N. Trut, “Early Canid Domestication: The Farm-Fox Experiment”; July-August 2017, Lee Dugatikin and Lyudmila Trut, “How to Tame a Fox and Build a Dog,” p. 240.
LiveScience Expert Voices, https://www.livescience.com/38241-how-wolf-turned-to-dog.html/ (July 17, 2013), Brian Hare, “Darwin's Dark Knight: Scientist Risked Execution for Fox Study.”
Scientific American, https://blogs.scientificamerican.com/guest-blog/mans-new-best-friend-a-forgotten-russian-experimentin-fox-domestication/ (September 6, 2010), Jason G. Goldman, “Man's New Best Friend? A Forgotten Russian Experiment in Fox Domestication.”
SciELO Chile, http://www.scielo.cl/pdf/gayana/v73s1/art06.pdf (July 12, 2017), Claudio Bidau, “Domestication through the Centuries: Darwin's Ideas and Dmitry Belyaev's Long-Term Experiment in Silver Foxes.”□