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Belyaev’s experimental method was simple in the extreme. Out of the thousands of silver foxes held at a fur farm, he simply selected for ones that were calmer than normal in the presence of humans. After just a few generations of selective breeding, some offspring of these slightly tamer foxes started to seek out human company. Breeding these individuals produced foxes that showed changes in their reproductive systems that are typical of domesticated animals, which often bear more than one litter per year. Astonishingly, a few of the selected foxes even began to wag their tails and bark—characteristics otherwise seen only in dogs. Eventually foxes were produced that had varied color patterns in their fur, curly tails, and floppy ears, all of which are characteristic of domesticated animals, but not wild ones. A few even began vocalizing with a sound that was reminiscent of human laughter. None of these traits had been selected for—Belyaev’s team selected only for a fox’s degree of comfort around humans. Extensive checks, including experiments in which embryos from normal foxes were transplanted into the uteruses of selected females, were undertaken, in order to demonstrate that genes rather than learned cues were responsible for the changes. Despite the undoubted genetic basis of the change, the precise mechanisms remain poorly understood, though clearly hormonal regulation—particularly of stress hormones—is important. By demonstrating that a simple selection mechanism could, over an exceedingly brief time, have such a large effect, Belyaev’s experiment had a major impact on our understanding of how the dog–human relationship began. http://www.nybooks.com/articles/2018/04/05/raised-by-wolves/ _________________________________________________________ Full posting guidelines at: http://www.marxmail.org/sub.htm Set your options at: http://lists.csbs.utah.edu/options/marxism/archive%40mail-archive.com
