The Social Dog || On the Way to a Better Understanding of Dog Domestication

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<ul><li><p>35The Social Dog. 2014 Elsevier Inc. All rights reserved.</p><p>On the Way to a Better Understanding of Dog Domestication: Aggression and Cooperativeness in Dogs and Wolves</p><p>Zsfia Virnyi and Friederike RangeComparative Cognition, Messerli Research Institute, University of Veterinary Medicine, Vienna, Austria; Medical University of Vienna, Vienna, Austria; University of Vienna, Vienna, Austria; Wolf Science Centre, Ernstbrunn, Austria</p><p>2.1 DOG DOMESTICATION AND HUMAN EVOLUTION: THE ROLE OF WOLFDOG COMPARISONS</p><p>It has repeatedly been suggested that dogs can tell us about the evolution of human social behaviour and cognition (Miklsi et al., 2004; Hare &amp; Tomasello, 2005; Fitch et al., 2010). More precisely, we expect doghuman similarities based on the hypothesis that dogs and humans went through convergent evolu-tion, as has been proposed in the previous chapter. The core of this hypothesis is that during domestication, dogs have been selected to cooperate and com-municate with humans, to live and work as members of human groupsjust as has happened to humans as well. In response to the demands posed by the human environment, we expect that some genetic predispositions evolved in dogs allowing them to develop skills shared with humans. It is a mistake, how-ever, to automatically attribute all doghuman similarities to domestication, that is, to assume that they rely on genetic changes that occurred since the dog separated from its closest wild-living relative, the wolf. Alternatively or, more likely, additionally, because pet dogs and humans grow up and live essentially in the same social environment, similar socialisation and learning can take place. Consequently, we can be sure that doghuman similarities have been supported by evolutionary changes only if we can demonstrate that wolves socialized with humans do not show those skills that dogs and humans share.</p><p>Chapter 2</p></li><li><p>36 SECTION | I Theoretical Aspects</p><p>2.1.1 How to Compare Dogs and Wolves for This Aim?</p><p>Consequently, we need to compare dogs and wolves that grew up and live in an identical environment to make sure that their behaviour differences do not originate purely from their different individual experiences. Then we can dem-onstrate the effects of domestication on dog social behaviour and cognition and, thus, reason about human evolution. Few comparisons on dog and wolf social cognition exist, and even fewer satisfy this requirement. In a number of studies, wolves kept in an enclosure with daily but limited contact with humans were compared to pet dogs (Agnetta et al., 2000; Hare et al., 2002); or wolves that had received an early and intensive socialisation with humans were compared to stray dogs living in a shelter (Udell et al., 2008); or, although both grew up in human families, wolves that lived in this way only for 2 to 4 months and were then returned to enclosures where they had only limited contact with humans were compared at a later age to dogs that remained in their human families (Topl et al., 2009a). Because raising and keeping a sufficient sample of dogs and wolves socialized with humans under identical conditions and satisfying the animals needs at the same time require a lot of effort, it is understandable that many research groups work with more or less ad hoc study populations that do not allow correct comparisons. However, such comparisons of dogs and wolves with different experiences cannot provide conclusive evidence about evolution-ary questions, though they may be useful to create hypotheses and to explore the behavioural plasticity of dogs or wolves living in different environments. For this latter aim, it is, of course, important to make sure that subjects of different origins are tested with the same methods.</p><p>Up to now, few research projects have had the potential to detect evolu-tionary differences between dogs and wolves. In the 1960s, at the Institut fr Haustierkunde of the University of Kiel (Germany) led by Prof. Wolf Herre and later by Dorit Feddersen-Petersen, wolves and standard poodles (as well as coy-otes and miniature poodles and golden jackals and toy poodles) were crossed in order to study the genetics of brain size and other morphological features, such as fur structure and colour. The poodlewolf hybrids were called Puwos or Wopus, depending on whether the mother or the father was a wolf, respec-tively. The animals, including wolves and poodles together, were kept in packs in enclosures at the zoological garden of the institute (see Figure 2-1). The pups were raised by their natural mothers. Erik Zimen used this exceptional opportu-nity and began investigating the behaviour of these animals. He also hand-raised wolves, poodles, and their crosses, and compared the human-directed behaviour of these animals to the mother-raised animals (Zimen, 1987). In 1975, when the morphological studies ended, Dorit Feddersen-Petersen took over the behav-ioural observations of the animals at the institute. Since then, her group has collected observational data of social interactions on 189 canids (of whom 74 were hand-raised) including not only the institutes populations but also dogs of several different breeds (Feddersen-Petersen, 1991, 1994, 2000).</p></li><li><p>37Chapter | 2 On the Way to a Better Understanding of Dog Domestication</p><p>More or less in parallel, from 1979 to 1981, the University of Michigan canine information-processing project took place under the leadership of Martha and Harry Frank (Frank &amp; Frank, 1987). This research program was of a smaller scale (including a total of 11 wolf and 4 malamute pups), but focused on comparing dogs and wolves from a behavioural and cogni-tive perspective. Albeit with a small sample size, it otherwise fully satisfied the methodological requirements of searching for genetically based differ-ences between dogs and wolves. In two different years, the Franks raised 4 wolf and 4 malamute pups in the very same environment. From the age of 10 to 13 days on, all pups were taken care of by the same lactating wolf female and by two human hand-raisers. All animals were housed in the same facility, had contact with the same adult conspecifics, were fed the same diet, and were administered the same experimental tests following the same regime (Frank &amp; Frank, 1982). A year later, 7 additional wolf pups raised exclusively by humans were tested in the same tests, but their per-formance differed from the 4 mother- and human-raised wolf pups, which was attributed to motivational differences (Frank et al., 1989; Frank, 2011). The animals were tested in experiments addressing their physical problem-solving and learning abilities as well as their trainability (Frank &amp; Frank, 1988; Frank et al., 1989; Frank, 2011). Based on informal observations, their social interactions with conspecifics also were compared (Frank &amp; Frank, 1982).</p><p>More recent attempts using somewhat bigger samples have been made by the Family Dog Project of the Department of Ethology, Etvs Lornd Univer-sity, Budapest, Hungary, led by dm Miklsi in the early 1990s and currently </p><p>FIGURE 2-1 Wolves and poodles living in a captive pack established and observed by Dorit Feddersen-Petersens research group at the University of Kiel, Germany. Very often poodles took the leading positions in the dominance hierarchy, and the wolves readily submitted to them, as can be seen in this picture. Note the ear positions, averted gaze, and back posture of both wolves in this photo. See color plate section. (Courtesy of Dorit Feddersen-Petersen.)</p></li><li><p>38 SECTION | I Theoretical Aspects</p><p>at the Wolf Science Centre, Ernstbrunn, Austria, founded by Kurt Kotrschal and the two authors of this chapter. In both research programs, the dogs and wolves have been raised under identical conditions by humans, but their goals and accordingly their raising regimes differ. In Hungary, 13 European wolves and 11 dogs (mongrels) were raised individually, each by a specific human raiser, and lived in a family environment from their first week on. Because this project aimed at comparing dogs and wolves in their communication, interactions, and relationship with humans, the animals went through very intensive socialisation in an urban environment, lived in family homes, accompanied their raisers to the university, travelled on public transportation, and thus met unfamiliar people and dogs on a daily basisi.e., lived like well-socialized pet dogs (see Kubinyi et al., 2007, for a review). It was not possible, however, to maintain this form of keeping the wolves after the age of 2 to 4 months for reasons of safety and animal welfare. Accordingly, around this age, the wolves were returned to the captive facility where they had been born and were visited by their hand-raisers once or twice a week. Most of the dogs, however, stayed with their hand-raisers, and all continued living in a human family as a pet.</p><p>In contrast, at the Wolf Science Centre, both dogs (mongrels) and wolves (timber wolves) (currently 12 and 13, respectively) are kept in a way that is sustainable also for adult wolves: in packs in large enclosures in the Gamepark Ernstbrunn. The animals have been hand-raised in peer groups (wolves and dogs separately) and had close contact not only with a group of 6 to 10 human raisers but also with 4 to 6 pet dogs of the hand-raisers with whom the pups interacted as with adult conspecifics. The animals had continuous human con-tact till the age of 4 to 5 months when they were integrated in packs of older conspecifics. Importantly, the animals have continued to have daily interactions with their raisers: they receive basic obedience training and have a firm routine of being separated from the packs in order to participate in regular cognitive and behavioural testing. Because the animals are similarly well socialized with humans and with conspecifics, this raising regime allows for the comparison of intra- and interspecific interactions of the dogs and wolves using experiments as well as observations of spontaneous behaviour (see Range &amp; Viranyi, 2011, 2013, 2014, as examples).</p><p>2.1.2 What Can DogWolf Comparisons Really Tell Us?</p><p>Even if raised comparably, wolves and dogs do not necessarily gain the same experiences and go through the same learning processes, but may easily adapt their behaviour to different aspects of the same environment. Therefore, we can detect only epigenetic differences between wolves and dogs (Gcsi et al., 2009a; Miklsi &amp; Topl, 2011): genetically based differences potentially enlarged by differential learning processes, which are likely to be more pro-found the older the investigated animals are. Still, given that their environ-ment is identical, what dogs and wolves learn originates from their preferences </p></li><li><p>39Chapter | 2 On the Way to a Better Understanding of Dog Domestication</p><p>and sensitivities, and thus will inform us about the domestication process. In this sense, we can talk about genetically based differences between dogs and wolves, although we need to keep in mind that evolutionary arguments can hardly be made about the effect size of such dogwolf differences. Nonethe-less, these comparisons provide us with evidence that domestication has had an influence on the behaviour of dogs.</p><p>Finding such dogwolf differences does not mean, however, that domestica-tion is either necessary or sufficient to explain human-like behaviour in dogs (Udell et al., 2011). Udell and colleagues (2008) showed that human-raised wolves can outperform shelter dogs that have limited experiences with humans in their use of human-given cues. These results demonstrate that (1) socialisa-tion with and learning about humans can provide wolves with an alternative means to reach a certain dog-like performance, e.g., to pay attention to humans; and that (2) even in dogs, a minimal amount of socialisation and individual learning is needed to enable the use of some human-directed skills (see also Hare et al., 2010, for a discussion on this issue). At the same time, however, dogs can follow a difficult form of human pointing (momentary distal pointing) earlier than wolves, showing that they are genetically predisposed to develop this skill faster (Gcsi et al., 2009a). In sum, dogwolf comparisons have been used for different purposes. On the one hand, they have been used to demon-strate that developmental processes can either mask existing or compensate for missing genetic features; and on the other hand, they have been used to show that domestication has changed a genetic predisposition in dogs compared to wolves. Important to realize, however, is that these are two independent ques-tions and that the answer can be Yes to both.</p><p>2.2 HUMAN-LIKE BEHAVIOUR IN DOGS BUT NOT IN WOLVES: PART 1</p><p>The second question (has domestication changed a genetic predisposition in dogs compared to wolves?) is the relevant one when arguing for convergent evolution between humans and dogs. While numerous studies have reported human-like behaviour in dogs and pointed out the potential contribution of domestication (see Reid, 2009; Udell et al., 2010; Bensky et al., 2013, for reviews), only in very few cases wolves have been tested in the above- suggested rigorous manner and demonstrated to lack a similar ability. We sum-marise these dogwolf comparisons in two sections in this chapter ( Sections 2.2 and 2.6). The first section focuses on the performance of dogs and wolves in using a human-specific communicative cue, pointing to locate food in one of two hiding places. Interestingly, based on results produced with this single experimental paradigm, various evolutionary hypotheses have been put for-ward to theorise about the selection pressures that might have shaped dog social behaviour and cognition during the course of domestication. We review these hypotheses in the next section.</p></li><li><p>40 SECTION | I Theoretical Aspects</p><p>2.2.1 Following Human Pointing: A Simple Test and a Lot of Hypothesising</p><p>Quite intriguing, most studies investigated whether dogs and wolves can com-prehend a uniquely human hand signal and compared how skilled they are in fol-lowing human pointing. In this simple experiment (object-choice task), one of two containers is baited with food, and a human experimenter standing between them indicates to the subject where the food can be found with her extended arm and pointing finger (Figure 2-2). Many animals are successful in using simple versions of this human form of communication, but when the pointing is performed relatively far (&gt;50 cm) from the indicated container and is not there when the animal is released to make a choice (i.e., momentary distal pointing), dogs outperform most non-human species (Miklsi &amp; Soproni, 2006). Dogs can follow momentary distal pointing similarly to 2-year-old human infants (Laka-tos et al., 2009), better than chimpanzees (Hare et al., 2002), and they do so at an early age (Riedel et al., 2008; Gcsi et al., 2009b). The initial studies that teste...</p></li></ul>