Humans have remarkable skill in shaping the world to their needs. Throughout our history as a species, we’ve altered the shape of the land, changed the make-up of ecology, and even guided evolution of plants and animals to better serve our survival.
Somewhere between 27 – 40 thousand years ago humans domesticated the dog from a wolf-like ancestor. Since then, we’ve domesticated all sorts of different crops, food animals, and pets. Our world today would be very different without domestication!
What does it mean to domesticate a species?
During the process of domestication, plants or animals are bred in order to enhance desirable traits. Over the course of many generations, differences build up between wild populations and the ones in the process of domestication. These differences can become so great that domesticated plants or animals are no longer able to survive in the wild, or even reproduce without the assistance of humans.
For animals, one trait common among domesticated species is comfort in the presence of humans. Even for farm animals that are not kept as pets, it is important that the animal be able to tolerate human handling. Some wild animals can be tamed- taught to accept, or even welcome, human interaction. Domesticated animals don’t need to be tamed; they are genetically predisposed to human contact. Domestication has created the plants and animals that feed the world, give us company, and provide the cornerstones for many cultures around the world. Domestication is integral to our success as a global species, and one Russian scientist devised an ingenious experiment to test how this process may have happened.
The domesticated fox experiment
In the early 20th century, the demand for fur began to outpace the availability of furs acquired through traditional trapping. The first red fox fur farms were built to meet this demand and could even supply the highly valued silver color variant. The fur farming industry exists to this day and has since expanded to include a variety of animals with economically significant fur, such as chinchillas and mink.
In 1959, Soviet Scientist Dmitri Belyaev put together a fox farm for a new purpose: Studying domestication. He hoped that by attempting to domesticate the red fox that he could better understand how wolves were domesticated into dogs tens of thousands of years ago. He knew that domestic dogs were different from their ancestors in two major ways: In behavior and physical features. Dogs clearly look rather different from wolves and Belyaev thought these physical changes were an accidental byproduct of breeding for a domestic temperament.
He began to selectively breed the foxes that responded best to a human presence and contact. Only the most amiable foxes of each generation were used to produce the next batch. Belyaev wanted to be certain that any friendliness was the result of genetics and not of personal handling history, so foxes were not trained or encouraged to be tame.
As the breeding project continued, fascinating results began to emerge. Foxes of the fourth generation would wag their tails to signify pleasure at seeing humans, a behavior not normally found in foxes. Higher generations acquired even more doglike behaviors. Now, after 50 years of breeding for friendly foxes, the experimental animals are downright delighted when they receive human attention and enjoy a belly rub just as much as a dog might.
Just like Belyaev predicted, physical changes accompanied the behavioral ones. In the 1980s, foxes began to be born with spotted coats, floppy ears, and curled tails. Later foxes developed shorter legs and overbites. After 40 generations these changes were even more pronounced. Their tails grew shorter, their reproductive seasons grew longer, their litters grew bigger, and their smell became less pungent. These changes are remarkably similar to the traits seen amongst other domesticated animals, leading scientists to conclude that there must be some link between docile behavior and physical appearance.
The domestic fox experiment still runs today. A line of aggressive foxes have been bred too, further showing the linkage between genetics and behavior. The affectionate domesticated foxes have captured the imagination of many, and some are sold as pets to help fund the continued work of these scientists. Just don’t expect to find floppy-eared foxes in pet stores anytime soon. Only a very limited number are sold per year, and they don’t come cheap!
- Kate Dzikiewicz, Paul Griswold Howes Fellow