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Do foxes growl like dogs7/13/2023 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. 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. Genetic comparisons between tame and aggressive foxes To what extent do genetics underlie the differences between wild foxes (left) and domesticated dogs (right)? Scientists are trying to pinpoint the genes that contribute to these behavioral effects. 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). 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. As an example, animal biologists can clearly document genes that determine fur color or curliness of a tail. 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. 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. 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.īreeding is man’s attempt to control heredity, the inheritance of certain traits that are passed from parent to offspring via genes. 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 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 It is difficult to study the process of the dog’s domestication since its wild relatives, the fox and wolf, are now different species. They diverged from the wolf lineage about 12 million years ago (a brief time period, evolutionarily). As cousins to wolves and dogs, foxes are a great model for dog domestication. Scientists believe that the closest ancestor of all modern dogs is the modern-day gray wolf. Between 10,000 and 30,000 years ago, our ancestors domesticated the wild dog. 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. 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. 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. In particular, biologists have been trying to understand the process of how dogs became domesticated, earning the mantle of “man’s best friend”. There has been great interest in the selective breeding of animals that can coexist with humans throughout history. A fox raised in captivity might learn to be gentle. As a rule, dogs are docile and foxes are feral.
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