The Silver Fox Domestication Experiment

“Baelaev’s team tested hundreds of foxes and selected the top 10% tamest individuals for breeding…researchers found that after only about six generations, many of the focus would like the scientists hands, allow themselves to be picked up and petted… Some of them also showed traits from the domestication syndrome and started to look different from their wild relatives… they had less stress hormones and had increased serotonin (which makes you happy).”

The Silver Fox Domestication Experiment

The silver fox domestication experiment started in 1959 with the goal of recreating the domestication process, but using foxes. Dmitri Belyaev, the leader of the experiment, wanted to find out if domestication was linked to an animal’s genetic makeup. The experiment consisted of breeding the tamest individuals in each generation of foxes, to hopefully create a fully domesticated fox after many generations. Belyaev also hypothesized that many of the traits that domesticated animals share, such as floppy ears, curly tails, or rounder bodies, are genetically linked to the traits that cause tameness. After only six generations, the experimenters found that not only were the majority of foxes domesticated and drawn to humans, but many also featured the traits previously mentioned. This showed that Belyaev’s hypothesis was indeed correct, and that domestication is a genetic process associated with a multitude of traits. ​(Dugatkin)

The silver fox domestication experiment started in 1959 at the Institute of Cytology and Genetics in Novosibirsk, Siberia. The team of researchers working on the experiment were led by Dmitri Belyaev, a Russian geneticist who became the director of the Institute after his predecessor was fired due to Lysenkoism. Lysenkoism was a movement against genetic research that occured in the Soviet Union during the mid-1900s, where hundreds of scientists were imprisoned or executed. Luckily for Belyaev, he and his experiment were spared from this fate, and the experiment is still happening today. ​(Dugatkin)

Belyaev’s goal was to recreate the domestication process, specifically the evolution from wolf to dog. ​(Dugatkin) ​He chose to use foxes because they were a close relative of the dog, and he had also worked with them during his work as a fur breeder. ​(PBS NewsHour) Belyaev knew that domesticated animals often share a group of traits called the “Domestication Syndrome”, which include floppy ears, mottled fur, short and curly tails, rounder features, reduced stress hormone levels, and relatively long reproductive seasons. He hypothesized that “tameness”, which humans looked for when selecting the animals to domesticate, was actually a genetic trait, and that it was genetically linked to the other traits in the domestication syndrome. ​(Dugatkin)

Belyaev’s team tested hundreds of foxes and selected the top 10% tamest individuals for breeding. They also selected a group of aggressive, defensive foxes to breed, to prove that tameness was inherited genetically. Belyaev wanted to see if the tame foxes would get tamer and tamer over generations, and if the traits in the domestication syndrome would start showing up more and more. He would continue to breed the tamest foxes from each generation so that their gene(s) would become more and more common. ​(Dugatkin)

The researchers found that after only about six generations, many of the foxes would lick the scientists hands, allow themselves to be picked up and petted, whine when the humans left, and wag their tails when they returned. Some of them also showed traits from the domestication syndrome and started to look different from their wild relatives. Over each generation, more and more of the foxes became tame. They developed less stress hormones and had increased serotonin (which makes you happy.) ​(Dugatkin)​ The most tame foxes were known as “elite”. Lyudmila Trut, one of the researchers for the experiment

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who continues to work on it to this day, explained:​ ​“By the tenth generation, 18 percent of fox pups were elite; by the 20th, the figure had reached 35 percent… Today elite foxes make up 70 to 80 percent of our experimentally selected population.” (PBS NewsHour)

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These results show that Belyaev’s hypothesis was correct, even though he didn’t live to see the results. Thanks to this experiment, we now know that domestication is a genetic process, and it causes a multitude of other traits to appear along with tameness. ​(Dugatkin) This knowledge will help scientists to better understand the domestication process, and in the future, it might even be possible to rearrange the DNA of an animal to domesticate it in a lab. ​(Verge Science) ​ ​ For now, scientists continue to study the foxes from Belyaev’s experiment, and they have already started to decode the fox genome to develop an even further understanding of the genes that cause domestication. ​(PBS NewsHour)

Mechta, the first domesticated fox to have floppy ears, 1969.

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Works Cited

1. Dugatkin, Lee Alan. “The Silver Fox Domestication Experiment.” ​Evolution: Education and Outreach​, vol. 11, no. 1, Dec. 2018, evolution-outreach.biomedcentral.com/articles/10.1186/s12052-018-0090-x, 10.1186/s12052-018-0090-x. Accessed May 2020.

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2. PBS NewsHour. “Why Domesticated Foxes Are Genetically Fascinating (and Terrible Pets).” ​PBS NewsHour​, 31 Mar. 2017, www.pbs.org/newshour/science/domesticated-foxes-genetically-fascinating-terrible-p ets. Accessed May 2020.

3. Verge Science. “We Met the World’s First Domesticated Foxes.” ​YouTube​, 11 Sept. 2018, www.youtube.com/watch?v=4dwjS_eI-lQ. Accessed May 2020.

Image: “Mechta (Dream), the first of the domesticated foxes to have floppy ears, 1969” ​Biomed Central​, 1969, evolution-outreach.biomedcentral.com/articles/10.1186/s12052-018-0090-x/figures/2.

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