Canid Domestication: Early The Farm-Fox Experiment Foxes hredfortamability in a AO-yearexperiment exhibit remarkable transformations thatsuggest an interplaybetween behavioral genetics and development Lyudmila N. Trut scientists ponder how animals came mon? Do they stem from a single cause, and if When to be domesticated, they almost in so, what is it? In the case of the dog, Morey evitably wind up thinking about dogs. The dog identifies one common factor as pedomorphosis, was probably the firstdomestic animal, and it is the retention of juvenile traitsby adults. Those the one inwhich domestication has progressed traits include both morphological ones, such the furthest?far enough to turnCants lupus into as skulls that are unusually broad for their Canis famili?ris.Evolutionary theoristshave long length, and behavioral ones, such as whining, speculated about exactly how dogs' association barking and submissiveness?all characteris with human beings may have been linked to tics thatwolves outgrow but that dogs do not. theirdivergence from theirwild wolf forebears, Morey considers pedomorphosis in dogs a by a topic that anthropologist Darcy Morey has dis product of natural selection for earlier sexual cussed in some detail in the pages of thismaga maturity and smaller body size, features that, zine (July-August 1994). according to evolutionary theory, ought to in As Morey pointed out, debates about the crease the fitness of animals engaged in colo origins of animal domestication tend to focus nizing a new ecological niche. on "the issue of intentionality"?the extent to The common patterns are not confined to a which domestication was the result of deliber single species. In a wide range ofmammals? ate human choice. Was domestication actually herbivores and predators, large and small? "self-domestication," the colonization of new domestication seems to have brought with it ecological niches by animals such as wolves? strikinglysimilar changes in appearance and be Or did it result from intentional decisions by havior: changes in size, changes in coat color, answer even in the animals' human beings? How you those ques changes reproductive cy tionswill determine how you understand the cles. Our research group at the Institute of Cy and that and Genetics in has Lyudmila N. Trut is head of morphological physiological changes tology Novosibirsk, Siberia, as the research group at the domestication has brought about?whether spent decades investigating such patterns and Institute of Cytology and the results of the pressure of natural selection other questions of the early evolution of domes Genetics the Siberian of in a new niche, or as deliberately cultivated ad tic animals. Our work grew out of the interests theRussian our Department of vantageous traits. and ideas of the late director of institute, the Sciences, in Academy of Inmany ways, the question of inten K. Novosibirsk. She received her though, geneticist Dmitry Belyaev. is beside the Domestication was Like believed that the doctoral in 1980. Her tionality point. Morey, Belyaev pat degree not a event but rather a terns of observed in domesticated ani current research interests are single long, complex changes process. Natural selection and artificial selection mals resulted from that oc the patterns of evolutionary genetic changes both have at different times or curred in the course of selection. transformations at the early may operated Belyaev, even at the same time. For even if believed that the factor selected steps of animal domestication. example, pre however, key Her is historic set out to was not size or research group develop people deliberately domesti for reproduction, but behavior? ing the problem of domestica cate wolves, natural selection would still have specifically amenability to domestication, or tion as an event evolutionary been at work. The selective regime may have tamability.More than any other quality, Belyaev with the use of experimental changed drastically when wolves started living believed, tamabilitymust have determined how models, the silver including with but selective pressure continued well an animal would to life among hu theAmerican the people, adapt fox, mink, of Homo chose to do. man Because behavior is rooted in biol river otter and thewild regardless anything sapiens beings. gray Another with the debate over in for tameness and rat. Address: Institute problem ogy, selecting against aggres of is that it can overshadow other im sion means for Cytologyand Genetics of the tentionality selecting physiological changes For in in the that the hormones Russian Academy of Sciences, portant questions. example, becoming systems govern body's a 630090Novosibirsk 90, domesticated, animals have undergone host and neurochemicals. Those changes, in turn, Russia. Internet: of changes inmorphology, physiology and be could have had far-reaching effects on the de [email protected]. havior. What do those changes have in com velopment of the animals themselves, effects 160 American Scientist, Volume 87 This content downloaded from 128.208.80.176 on Mon, 10 Feb 2014 21:02:47 PM All use subject to JSTOR Terms and Conditions 1. In a a Figure the late 1950s, the Russian geneticist Dmitry K. Belyaev began decades-long effort to breed population of tame foxes. Belyaev, then director of the Institute of Cytology and Genetics of the U.S.S.R. (now Russian) Academy of Sciences in Novosibirsk, Siberia, hoped to as show that physical and morphological changes in domestic animals such dogs could have resulted from selection for a single behavioral trait, friendliness toward people. Fourteen years after his death, the experiment continues, and the results appear to support Belyaev's hypothesis. (All photographs courtesy of the author.) thatmight well explain why different animals years after his death, it is still in progress. would respond in similar ways when subjected Through genetic selection alone, our research same to the kinds of selective pressures. group has created a population of tame foxes To test his hypothesis, Belyaev decided to fundamentally different in temperament and be turn back the clock to the point at which ani havior from theirwild forebears. In the process we mals received the first challenge of domestica have observed some striking changes in tion. By replaying theprocess, he would be able physiology, morphology and behavior, which see to how changes inbehavior, physiology and rnirrorthe changes known in other domestic an came morphology first about. Of course, repro imals and bear out many of Belyaev's ideas. ducing the ways and means of those ancient transformations, even in the roughest outlines, Belyaev's Hypothesis a as would be formidable task. To keep things Belyaev began his experiment in 1959, a time clear and simple as possible, Belyaev designed a when Soviet genetics was starting to recover a selective-breeding program to reproduce sin from the anti-Darwinian ideology of Trofim gle major factor, strong selection pressure for Lysenko. Belyaev's own career had suffered. In tamability.He chose as his experimental model 1948 his commitment to orthodox genetics had a species taxonomically close to the dog but cost him his job as head of the Department of never before domesticated: Vulpes vulpes, the sil Fur Animal Breeding at the Central Research ver fox. Belyaev's fox-breeding experiment oc Laboratory of Fur Breeding inMoscow. During cupied the last 26 years of his life. Today, 14 the 1950s he continued to conduct genetic re 1999 March-April 161 This content downloaded from 128.208.80.176 on Mon, 10 Feb 2014 21:02:47 PM All use subject to JSTOR Terms and Conditions wavy or curly hair rolled tails shortened tafIs, fewervertebrae floppyears changes in reproduc? cycle similar mor Figure 2. Early in the process of domestication, Darwin noted long ago, animals often undergo selection phological and physiological changes. Because behavior is rooted in biology, Belyaev believed that broader effects on the ani for behavior implied selection for physiological characteristics that would have to mals' development. These effects might explain patterns in the responses of various animals domestication. search under the guise of studying animal except the elephant. Another major evolution physiology. He moved toNovosibirsk, where ary consequence of domestication is loss of the an he helped found the Siberian Department of seasonal rhythmof reproduction. Most wild are the Soviet (now Russian) Academy of Sciences imals inmiddle latitudes genetically pro once a and became the director of the Department's grammed tomate year, during mating Institute of Cytology and Genetics, a post he seasons cued by changes in daylight. Domestic held from 1959 until his death in 1985. Under animals at the same latitudes, however, now can more once a his leadership the institute became a center of mate and bear young than year season. basic and applied research in both classical ge and in any netics and modern molecular genetics. His Belyaev believed that similarity in the pat was own work included ground-breaking investi ternsof these traits the result of selection for re gations of evolutionary change in animals un amenability to domestication. Behavioral are a der extreme conditions (including domestica sponses, he reasoned, regulated by fine tion) and of the evolutionary roles of factors balance between neurotransmitters and hor such as stress, selection for behavioral traits mones at the level of thewhole organism. The a and the environmental photoperiod, or dura genes that control that balance occupy high tion of natural daylight. Animal domestication level in the hierarchical system of the genome. were was his lifelong project, and fur bearers Even slight alterations in those regulatory genes can a in his favorite subjects. give rise to wide network of changes Early in the process of domestication, thedevelopmental processes theygovern. Thus, Belyaev noted, most domestic animals had un selecting animals forbehavior may lead to oth devel dergone the same basic morphological and er, far-reaching changes in the animals' physiological changes.