Researching Evolution, She Bred Foxes Into Pets

"How, exactly, did the wolves lurking around ancient humans' campfires turn into the pugs and cockapoos that sleep in our beds?

For 66 years, Lyudmila Trut worked to find out. On a remote fox farm in Siberia, the Russian evolutionary geneticist ran an extraordinary science experiment to uncover the process by which something wild changes into something docile.

Trut, who died Oct. 9 at age 90, devoted her career to squeezing the millennia-long process of domestication into a single lifetime -- Trut's lifetime -- so that it could be methodically observed.

Lyudmila Nikolaevna Trut was born Nov. 6, 1933, just outside Moscow and grew up amid the hardships of World War II. Even so, she recalled, her mother preserved small amounts of their food rations to feed stray dogs.

In 1958, after studying animal physiology at Moscow State University, Trut met Dmitri K. Belyaev, an accomplished scientist who was about to become director of Russia's Institute of Cytology and Genetics. He was hatching an odd and ambitious plan. "He told me that he wanted to make a dog out of a fox," Trut wrote in "How to Tame a Fox (And Build a Dog)," a 2017 book co-written with Lee Alan Dugatkin.

Belyaev's hypothesis was that a suite of physical traits common in domesticated species but not in their wild counterparts -- including curly or wavy hair, coiled tails and floppy ears -- had basically hitchhiked along genetically as humans bred those species to be tame. In short, our ancestors wanted to make an animal that behaved a certain way but wound up with one that looked a certain way, too.

Belyaev would test this hypothesis by simulating the long process of domestication with silver foxes, close relatives of wolves that he had access to because he was researching how they could produce better fur coats, a lucrative export for the Soviet government.

It was an unprecedented undertaking that he wanted Trut to run. It was also dangerous. Genetics had been denounced in the Soviet Union under Stalin as a destructive, Western pseudoscience. Many geneticists, including Belyaev's older brother, had been sent to die in labor camps or murdered.

Even several years after Stalin's death, Belyaev was compelled to disguise the purpose of his project as a physiology study aligned with his official research. Trut, grasping how important the work could be, was undaunted by the risk.

She had spent her whole life in or around Moscow at that point and only recently married Vladimir Trut, an aviation mechanic, and had a newborn baby girl. (Vladimir died in 2007; their daughter, Marina Diyomina, survives Trut.) Nevertheless, that spring, the family of three, along with Trut's mother, relocated to the Siberian city of Novosibirsk, where winter temperatures routinely reach minus-30 Fahrenheit.

Trut toured remote fur farms, gathering up 130 of the most docile foxes she could find. She sorted them for tameness after assessing their temperaments. (The technique involved reaching into the fox cages while wearing a 2-inch-thick protective glove and gauging how eager each animal was to chew off her fingers.) She bred the very tamest foxes together, then bred the tamest of their offspring together -- and on and on, aggressively streamlining and accelerating a process that would have unfolded more haphazardly in prehistoric times.

By the fourth generation, several pups shocked Trut by wagging their tail when she approached. Two generations later, the young animals "eagerly sought contacts with [humans], not only wagging, also whining, whimpering, and licking in a dog-like manner," Trut wrote in a 2009 paper.

Meanwhile, physical changes were also taking hold: The foxes' snouts gradually became rounder and shorter, their ears turned floppy and their tails curled, mirroring the metamorphosis of wolves into dogs. Trut and colleagues also tracked shifts in the animals' hormone levels and neurochemistry. Trut earned a Ph.D. in genetics while she ran the project and taught herself to surgically transplant embryos from tame fox mothers into aggressive ones, to show that the behavioral changes were a function of nature, not nurture.

By the 15th generation of foxes, so many animals seemed puppylike that Trut wondered about living with one as a pet. "And so," she later wrote with Dugatkin in Scientific American, "on March 28, 1974, Pushinka, Russian for 'tiny ball of fuzz,' and I moved in together." In a small house on the farm, the fox "would lie by my feet and wait for me to scratch her neck. If I popped out of the house for a bit, Pushinka would sometimes sit at the window, looking out in anticipation of my return." At night, Pushinka leapt into Trut's bed to snuggle. A few years later, one of Trut's employees took a fox named Coca home temporarily, and she and her husband taught it to return to them when they whistled.

Trut habitually gave Belyaev, who had envisioned the study, all the credit. But Dugatkin, Trut's co-author, noted that she had been running the experiment for many years by the time her boss died in 1985, and its leadership officially passed to her.

In addition to being an exacting and intuitively talented scientist, Dugatkin said, Trut had a gift for getting things done. "She was tough as nails," he said -- a barely-five-foot-tall woman who, on Dugatkin's first visit to the farm, thought nothing of trudging through more than two feet of snow to show him around.

Along with the lovable foxes, Trut bred a second, parallel population of foxes at the farm selected for aggressiveness: a horde of unruly, nasty animals as demonic as the others were cuddly and sweet. Journalists who visited the operation often described walking over to this other barn like a descent into the underworld. ("I still have nightmares," Dugatkin said.)

In a 2010 documentary, "Dogs Decoded," Trut shows off these malevolent foxes. As she walks down the rows of pens, the animals all bark at her and lunge forward recklessly, slamming their bodies into the metal bars.

Somehow, Trut gets bitten. "I didn't even open the cage," she tells the camera through an interpreter. "I just put my hand up, and it managed to bite me through the bars!" She's smiling -- intrigued, even impressed, by what these creatures are capable of. Then, wrapping her wound in a bandage, she continues the tour." [1]

1. REVIEW --- Obituaries: Researching Evolution, She Bred Foxes Into Pets --- The Russian geneticist helped show that choosing the tamest wild animals to reproduce, generation after generation, can produce domesticated animals within a human lifetime. Mooallem, Jon.  Wall Street Journal, Eastern edition; New York, N.Y.. 30 Nov 2024: C.6.