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A Comparison of the Sensory Development of Wolves (Canis lupus lupus) and Dogs (Canis lupus familiaris)
Abstract
Little is known about the development of the sensory systems of wolves. The timing of sensory development in wolves is usually extrapolated from studies on dogs, since they are members of the same species. However, early developmental differences between these two subspecies have already been identified. For example, wolves tend to approach and investigate objects in their environment 2 wk before dogs. These changes in developmental timing may play an important role in the behavioral differences between adult wolves and dogs. The purpose of this study is to compare the development of the sensory systems in wolves and dogs.
Responses of seven wolf pups and 43 dog pups to familiar and novel olfactory, auditory, and visual stimuli were tested weekly from 2–7 wk of age. Eleven wolf pups were also observed for orientation towards auditory and visual stimuli during 2-h sessions, 5 d a week, from 2–8 wk of age. These observations were supplemented by the daily records of caretakers.
The results suggest that wolves and dogs both develop olfaction by 2 wk, audition by 4 wk, and vision by 6 wk on average, despite the 2-wk shift in their ability to explore. This means that when wolves begin to explore at 2 wk, they are blind and deaf, and must rely primarily on their sense of smell. Thus, there is a significant alteration of how these subspecies experience their environment during the critical period of socialization. These findings lead to an alternative explanation for the difference in dogs' and wolves' abilities to form interspecies social attachments, such as those with humans.
... Welsh terriers did not begin exhibiting social object play until 6.0 weeks of age, while poodles and vizslas started exhibiting social object play at 4.5 weeks of age . Lord (2013) found that there was a developmental difference in dogs vs. captive hand-reared wolf pup motor development, with wolf pups exploring their environments earlier than dog puppies. Wolf pups explore while still blind at 2 weeks of age, while dog pups do not start exploring the world around until approximately 4 weeks of age when their vision and other senses are fully functional (Lord, 2013). ...
... Lord (2013) found that there was a developmental difference in dogs vs. captive hand-reared wolf pup motor development, with wolf pups exploring their environments earlier than dog puppies. Wolf pups explore while still blind at 2 weeks of age, while dog pups do not start exploring the world around until approximately 4 weeks of age when their vision and other senses are fully functional (Lord, 2013). ...
... The subjects were handreared wolf pups from two litters tested with diverse commercial dog toys and focuses on some of the same topics as in the Burghardt et al. (2016) paper. We had the following predictions: (1) Given that Lord (2013) found wolves start to investigate environmental stimuli at 2.0 weeks of age, while dogs do not until 4.0 weeks of age, we predict the wolf pups will show the onset of object related play significantly before it emerges in dogs. (2) Since wolf motor development is more precocious than in dogs, the time spent playing, and the complexity shown will peak earlier in wolves than in dogs. ...
Studies exploring the development of object play of wolf pups are lacking. Comparisons of wolves vs. dogs can aid in teasing out the influences of domestication on any differences uncovered between wolves and various dog breeds. We investigated the development of object play from 2 to 9 weeks of age (14–63 days) in 2 litters of hand-reared wolf pups (Canis lupus). Both litters of pups were video-recorded in their home enclosures at week and mid-week timepoints. Each litter was given a separate set of the same five commercial dog (Canis lupus familiaris) toys with differing sensory and functional qualities. The first 10 min of activity from each session were analyzed using the Noldus Observer XT program and a previously developed ethogram of object related behaviors. The results were analyzed using repeated measures LMMs. Percent of time spent playing with toys, behavioral counts and behavioral diversity all increased significantly with age for wolf pups, and they were generally developmentally ahead of dog puppies. Wolves, like dogs, had preferences for some toys. These findings expand our grasp of infant wolf behavior, the comparative development of object play in canines, and provide a model for the study of domestication on play behavior.
... While such effects are ultimately based on the species-specific genetic make-up and, thus, evolutionary differences between species, the effects appear to increase with age, highlighting the advantages of testing puppies. However, cognitive abilities change over the lifespan, differentiating rapidly from infancy to young adulthood; thus, testing young animals could carry the risk of testing animals that are not cognitively fully developed as well as detecting 'false' differences, since dogs and wolves develop at different speeds [44]. ...
... Moreover, even human-socialized wolves (both as puppies and as adults) are more neophobic than are dogs toward objects. [41,44,[51][52][53]. ...
... However, wolf populations that were never extensively hunted by humans (e.g., Arctic wolves) show few fear reactions toward humans or their artifacts [54]. Moreover, once wolves have overcome their initial fear, they are more explorative [41,44,52,53], persistent in manipulating objects [55], and risk-prone [56] compared with dogs. These results are intriguing since they indicate that wolf-dog differences in fear reactions might be partly explained by selection for fear/shyness of humans in wolves due to the extensive persecution of these animals and not only selection against fear in dogs. ...
Based on claims that dogs are less aggressive and show more sophisticated socio-cognitive skills compared with wolves, dog domestication has been invoked to support the idea that humans underwent a similar ‘self-domestication’ process. Here, we review studies on wolf–dog differences and conclude that results do not support such claims: dogs do not show increased socio-cognitive skills and they are not less aggressive than wolves. Rather, compared with wolves, dogs seek to avoid conflicts, specifically with higher ranking conspecifics and humans, and might have an increased inclination to follow rules, making them amenable social partners. These conclusions challenge the suitability of dog domestication as a model for human social evolution and suggest that dogs need to be acknowledged as animals adapted to a specific socio-ecological niche as well as being shaped by human selection for specific traits.
... In recent years, advance in high-capacity genome examining techniques, especially whole genome sequencing, SNP genotyping array and comparative genomic hybridization (CGH) arrays have authorized the recognition of genome-wide structural variants. The arraymethods have limited resolution and low sensitivity because their performance is strongly depending on the marker frequency and particularly constructed non polymorphic markers [6,44,57], thus they cannot detect small copy number variations (CNVs) (< 10 kb) and cannot precisely identify boundaries of CNVs [77]. ...
... The terms "sensory perception of smell", "detection of chemical stimulus" and "Olfactory transduction" were enriched among the CNV gain regions in dog and wolf (over-represented, P<0.01), which are involved in sensory perception. Both wolf and dog develop olfaction, audition and vision by 2 weeks, 4 weeks and 6 weeks of age on average, respectively [44]. Wolf pups start to investigate their environment at 2 weeks of age while they are blind and deaf, and must depend mainly on sense of smell, while dog pups start to investigate their environment at 4 weeks of age [44]. ...
... Both wolf and dog develop olfaction, audition and vision by 2 weeks, 4 weeks and 6 weeks of age on average, respectively [44]. Wolf pups start to investigate their environment at 2 weeks of age while they are blind and deaf, and must depend mainly on sense of smell, while dog pups start to investigate their environment at 4 weeks of age [44]. In a previous study, the fraction of olfactory receptor pseudogenes in dog and wolf was 17.78 and 12.08%, respectively, however, difference between these values in dog and wolf was not significant [80]. ...
Background: Advances in genome technology have simplified a new comprehension of the genetic and historical processes crucial to rapid phenotypic evolution under domestication. To get new insight into the genetic basis of the dog domestication process, we conducted whole-genome sequence analysis of three wolves and three dogs from Iran which covers the eastern part of the Fertile Crescent located in Southwest Asia where the independent domestication of most of the plants and animals has been documented and also high haplotype sharing between wolves and dog breeds has been reported.
Results: Higher diversity was found within the wolf genome compared with the dog genome. A total number of 12.45 million SNPs were detected in all individuals (10.45 and 7.82 million SNPs were identified for all the studied wolves and dogs, respectively) and a total number of 3.49 million small Indels were detected in all individuals (3.11 and 2.24 million small Indels were identified for all the studied wolves and dogs, respectively). A total of 10,571 copy number variation regions (CNVRs) were detected across the 6 individual genomes, covering 154.65 Mb, or 6.41%, of the reference genome (canFam3.1). Further analysis showed that the distribution of deleterious variants in the dog genome is higher than the wolf genome. Also, genomic annotation results from intron and intergenic regions showed that the proportion of variations in the wolf genome is higher than that in the dog genome, while the proportion of the coding sequences and 3'-UTR in the dog genome is higher than that in the wolf genome. The genes related to the olfactory and immune systems were enriched in the set of the structural variants (SVs) identified in this work.
Conclusions: Our results showed more deleterious mutations and coding sequence variants in the domestic dog genome than those in wolf genome. By providing the first Iranian dog and wolf variome map, our findings contribute to understanding the genetic architecture of the dog domestication.
... In recent years, advance in high-capacity genome examining techniques, especially whole genome sequencing, SNP genotyping array and comparative genomic hybridization (CGH) arrays have authorized the recognition of genome-wide structural variants. The arraymethods have limited resolution and low sensitivity because their performance is strongly depending on the marker frequency and particularly constructed non polymorphic markers [6,44,57], thus they cannot detect small copy number variations (CNVs) (< 10 kb) and cannot precisely identify boundaries of CNVs [77]. ...
... The terms "sensory perception of smell", "detection of chemical stimulus" and "Olfactory transduction" were enriched among the CNV gain regions in dog and wolf (over-represented, P<0.01), which are involved in sensory perception. Both wolf and dog develop olfaction, audition and vision by 2 weeks, 4 weeks and 6 weeks of age on average, respectively [44]. Wolf pups start to investigate their environment at 2 weeks of age while they are blind and deaf, and must depend mainly on sense of smell, while dog pups start to investigate their environment at 4 weeks of age [44]. ...
... Both wolf and dog develop olfaction, audition and vision by 2 weeks, 4 weeks and 6 weeks of age on average, respectively [44]. Wolf pups start to investigate their environment at 2 weeks of age while they are blind and deaf, and must depend mainly on sense of smell, while dog pups start to investigate their environment at 4 weeks of age [44]. In a previous study, the fraction of olfactory receptor pseudogenes in dog and wolf was 17.78 and 12.08%, respectively, however, difference between these values in dog and wolf was not significant [80]. ...
Background: Advances in genome technology have simplified a new comprehension of the genetic and historical processes crucial to rapid phenotypic evolution under domestication. To get new insight into the genetic basis of the dog domestication process, we conducted whole-genome sequence analysis of three wolves and three dogs from Iran which covers the eastern part of the Fertile Crescent located in Southwest Asia where the independent domestication of most of the plants and animals has been documented and also high haplotype sharing between wolves and dog breeds has been reported.
Results: Higher diversity was found within the wolf genome compared with the dog genome. A total number of 12.45 million SNPs were detected in all individuals (10.45 and 7.82 million SNPs were identified for all the studied wolves and dogs, respectively) and a total number of 3.49 million small Indels were detected in all individuals (3.11 and 2.24 million small Indels were identified for all the studied wolves and dogs, respectively). A total of 10,571 copy number variation regions (CNVRs) were detected across the 6 individual genomes, covering 154.65 Mb, or 6.41%, of the reference genome (canFam3.1). Further analysis showed that the distribution of deleterious variants in the dog genome is higher than the wolf genome. Also, genomic annotation results from intron and intergenic regions showed that the proportion of variations in the wolf genome is higher than that in the dog genome, while the proportion of the coding sequences and 3'-UTR in the dog genome is higher than that in the wolf genome. The genes related to the olfactory and immune systems were enriched in the set of the structural variants (SVs) identified in this work.
Conclusions: Our results showed more deleterious mutations and coding sequence variants in the domestic dog genome than those in wolf genome. By providing the first Iranian dog and wolf variome map, our findings contribute to understanding the genetic architecture of the dog domestication.
... In recent years, advance in high-capacity genome examining techniques, especially whole genome sequencing, SNP genotyping array and comparative genomic hybridization (CGH) arrays have authorized the recognition of genome-wide structural variants. The arraymethods have limited resolution and low sensitivity because their performance is strongly depending on the marker frequency and particularly constructed non polymorphic markers [6, 44,57], thus they cannot detect small copy number variations (CNVs) (< 10 kb) and cannot precisely identify boundaries of CNVs [77]. Next-generation sequencing methods provide a high-accuracy base-by-base vision of the genome and capture all variants by different size that might otherwise be missed, and all these are important and have signi cant effects on an extensive range of traits in domesticated animals. ...
... The terms "sensory perception of smell", "detection of chemical stimulus" and "Olfactory transduction" were enriched among the CNV gain regions in dog and wolf (over-represented, P<0.01), which are involved in sensory perception. Both wolf and dog develop olfaction, audition and vision by 2 weeks, 4 weeks and 6 weeks of age on average, respectively [44]. Wolf pups start to investigate their environment at 2 weeks of age while they are blind and deaf, and must depend mainly on sense of smell, while dog pups start to investigate their environment at 4 weeks of age [44]. ...
... Both wolf and dog develop olfaction, audition and vision by 2 weeks, 4 weeks and 6 weeks of age on average, respectively [44]. Wolf pups start to investigate their environment at 2 weeks of age while they are blind and deaf, and must depend mainly on sense of smell, while dog pups start to investigate their environment at 4 weeks of age [44]. In a previous study, the fraction of olfactory receptor pseudogenes in dog and wolf was 17.78 and 12.08%, respectively, however, difference between these values in dog and wolf was not signi cant [80]. ...
Background Advances in genome technology have simplified a new comprehension of the genetic and historical processes crucial to rapid phenotypic evolution under domestication. To get new insight into the genetic basis of the dog domestication process, we conducted whole-genome sequence analysis of three wolves and three dogs from Iran which covers the eastern part of the Fertile Crescent located in Southwest Asia where the independent domestication of most of the plants and animals has been documented and also high haplotype sharing between wolves and dog breeds has been reported. Results Higher diversity was found within the wolf genome compared with the dog genome. A total of 10.45, 7.82, 3.11 and 2.24 million SNPs and small Indels were identified within wolf and dog genomes, respectively. A total of 10,571 copy number variation regions (CNVRs) were detected across the 6 individual genomes, covering 154.65 Mb, or 6.41%, of the reference genome. The genes related to olfactory and immune systems were enriched in the set of structural variants (SVs) identified in this work. Annotation of genomic variations showed that in general the proportion of genomic variations in the intron and intergenic regions in wolf genome is higher than that in dog genome while their proportion in the coding sequences and 3'-UTR in dog genome is higher than that in wolf genome. Generally, genes engaged in digestion and metabolism and neurological process had an important role in the process of dog domestication. Conclusions By providing the first Iranian dog and wolf variome map, our findings contribute to understanding the genetic architecture of the dog domestication.
... Based primarily on the findings in a long-term selection study on silver foxes (Vulpes vulpes), it has been suggested that domestication causes a shift in the sensitive period resulting in a delayed onset of fearful response in domesticated compared to non-domesticated animals (Belyaev et al., 1985;Trut et al., 2004; but see also Coppinger and Coppinger, 2001). While this might indicate that differences in fear expression between domesticated and non-domesticated animals arise already during early ontogeny, only a very limited body of studies have experimentally compared the ontogeny of fear in wild and domestic species under controlled conditions and with ambiguous results (Bilkó and Altbäcker, 2000;Lord, 2013). Therefore, it remains largely an open question whether the ontogeny of fear and the sensitive period have been altered by domestication. ...
... However, recent evidence suggests that the development of fear might be highly breed-specific and subject to considerable variation (Morrow et al., 2015), thereby highlighting substantial gaps in our knowledge of the ontogeny of fear in dogs. In wolves, consensus on when fear behavior is established is lacking, with the onset of fearful response reported to occur as varied as 4-8 weeks of age across studies (Scott and Marston, 1950;Fentress, 1967;Wooply and Ginsburg, 1967;Fox, 1972;Zimen, 1987;Lord, 2013). The ambiguity of these wolf studies is further complicated by the fact that the majority of them were conducted over a short period of time and/or focused on isolated individuals or single litters, thereby limiting our ability to generalize from these findings. ...
... Our longitudinal design allowed us to assess fear development and expression in juvenile wolves and dogs over an unprecedented period of time, and address our overall goal to test the hypothesis that domestication has altered fear responses in dogs compared to wolves. Based on studies reporting delayed onset of fear behavior in domestic species (Belyaev et al., 1985;Coppinger and Coppinger, 2001;Martin and Fitzgerald, 2005;Lord, 2013), we expected wolves to express exaggerated fearfulness compared to dogs already at 6 to 10 weeks of age by increasing their latency to approach the novel object. ...
Selection of behavioral traits holds a prominent role in the domestication of animals, and domesticated species are generally assumed to express reduced fear and reactivity toward novel stimuli compared to their ancestral species. However, very few studies have explicitly tested this proposed link between domestication and reduced fear responses. Of the limited number of studies experimentally addressing the alterations of fear during domestication, the majority has been done on canids. These studies on foxes, wolves, and dogs suggest that decreased expression of fear in domesticated animals is linked to a domestication-driven delay in the first onset of fearful behavior during early ontogeny. Thus, wolves are expected to express exaggerated fearfulness earlier during ontogeny compared to dogs. However, while adult dogs are less fearful toward novelty than adult wolves and wolf-dog hybrids, consensus is lacking on when differences in fear expression arise in wolves and dogs. Here we present the first extended examination of fear development in hand-raised dogs and European gray wolves, using repeated novel object tests from 6 to 26 weeks of age. Contrary to expectations, we found no evidence in support of an increase in fearfulness in wolves with age or a delayed onset of fear response in dogs compared to wolves. Instead, we found that dogs strongly reduced their fear response in the period between 6 and 26 weeks of age, resulting in a significant species difference in fear expression toward novelty from the age of 18 weeks. Critically, as wolves did not differ in their fear response toward novelty over time, the detected species difference was caused solely by a progressive reduced fear response in dogs. Our results thereby suggest that species differences in fear of novelty between wolves and dogs are not caused by a domestication-driven shift in the first onset of fear response. Instead, we suggest that a loss of sensitivity toward novelty with age in dogs causes the difference in fear expression toward novelty in wolves and dogs.
... Socialized adult wolves react with fear to humans, and if only partially socialized, fear can turn into aggression [20]. In addition, wolves who have socialized with humans (both puppies and adults) also show a greater neophobia than dogs toward objects [20,23,[73][74][75]. ...
... lupus arctos), show minimal reactions of fear toward humans and their artifacts [76]. Once the "initial fear" is overcome, wolves seem to be more exploratory [20,23,73,75], persistent in manipulating objects [77], and more prone to risk [78] in comparison to dogs. These findings are very interesting, as they suggest that the differences between the wolf and the dog in terms of fear reactions may be partly explained by the selection for human fear/shyness in wolves, due to the strong persecution that these animals have suffered over time, and not only due to the selection against fear in dogs [20]. ...
The process of canine domestication represents certainly one of the most interesting questions that evolutionary biology aims to address. A “multiphase” view of this process is now accepted, with a first phase during which different groups of wolves were attracted by the anthropogenic niche and a second phase characterized by the gradual establishment of mutual relationships between wolves and humans. Here, we provide a review of dog (Canis familiaris) domestication, highlighting the ecological differences between dogs and wolves, analyzing the molecular mechanisms which seem to have influenced the affiliative behaviors first observed in Belyaev’s foxes, and describing the genetics of ancient European dogs. Then, we focus on three Mediterranean peninsulas (Balkan, Iberian and Italian), which together represent the main geographic area for studying canine domestication dynamics, as it has shaped the current genetic variability of dog populations, and where a well-defined European genetic structure was pinpointed through the analysis of uniparental genetic markers and their phylogeny.
... Therefore, our pilot data used to create the ethogram and observer coding scheme listed below were enriched by this larger dataset. Researchers' classification of pup weeks varies [45,48]. Our meaning of week usage here is the same week scheme used in [27,28] and is clarified here by denoting the equivalent day age of each week timepoint as follows: 3.0 weeks (21 days); 4.0 weeks (28 days); 5.0 weeks (35 days); 6.0 weeks (42 days); and 7.0 weeks (49 days). ...
... However, there was an overall decrease in SOL play between 6-7 weeks of age as social object play peaked. Compared to wolf pups provided with the same objects during the same 3-7-week period [28], dogs began to exhibit object-directed behavior about one week later and displayed less object-related behavioral diversity, supporting the findings from Lord [45], in which wolves' sensory systems developed earlier than dogs. ...
Play behavior is a prominent aspect of juvenile behavior for many animals, yet early development, especially play with objects, has received little attention. Our previous study on object play introduced our general methods, focusing on litter differences in the developmental trajectory of object play and toy preferences. Here, we present a detailed ethogram of more than 30 observed object play behaviors. We focus on breed differences in the development of play in the three following breeds: Welsh Terriers, Vizslas, and standard Poodles. Puppies were video recorded from 3 to 7 weeks of age at half-week intervals upon the introduction of a standard set of five toys into their home environments. Ten minutes of video from each session for each puppy were analyzed using the Noldus Observer XT program. Aside from analyzing individual behaviors, they were also grouped into three behavioral categories. These were behaviors that occurred only in a solitary context, only in a social context, or in both contexts. Solitary object play developed first, and social object play developed later across breeds. There was a significant three-way interaction between breed, developmental age, and the context in which play occurred. Pairwise comparisons within each breed, age, and context are discussed, but a prominent result is that the onset of many behaviors occurred later in Welsh Terriers compared to the other breeds.
... It commences at around three weeks of age when puppies' eyes and ears become functional, and they become more mobile. Early in the socialisation period, puppies tend to fearlessly explore and investigate unfamiliar things in their environment, but they become increasingly wary of novelty with age [34,35]. From approximately three to six weeks, puppies exhibit a reflexive startle reaction (fast contraction of the muscles) in response to sudden/intense sounds [36], which is followed by immediate recovery. ...
... The first fear responses occur around six to seven weeks, although this may vary by up to two weeks between different litters and breeds [36][37][38]. Thus, Lord [35] would argue that the socialisation period ends at around eight weeks, when puppies often show initial fear responses to novelty. However, this fear of novelty (leading to increased avoidance) increases further until 12-14 weeks, which other authors consider as the end of the socialisation period [26,31,37,39]. ...
The socialisation period in dog puppies is one of the most important periods determining behavioural development in dogs. Here, we aimed to test the effect of providing stimulation (beyond mere exposure) early during the socialisation period (approx. 3–6 weeks) on puppies’ behaviour. Each of 12 litters (83 puppies) of various breeds was divided into a treatment and a control group. Between 3–6 weeks, the treatment group received age-appropriate “challenge” exercises (carefully graded noise exposure, novel objects, and problem-solving tasks) four times per week (total 12 times). The control group spent the same time with the trainer, who cuddled or played with the puppies. In a behaviour test at 6–7 weeks, two of four principal components, “social-startle” and “response to novelty”, differed significantly between the groups. Treatment puppies were bolder towards the novel object, showed a reduced startle reaction, and recovered more quickly after a loud noise. Furthermore, they accomplished the problem-solving task faster and were more persistent during problem-solving than the control group. The control group showed a higher interest in a friendly stranger. It is a possibility that increased handling experienced by the control group had beneficial effects on their sociability. No long-term effects of the treatment were found, as determined by a validated dog personality questionnaire, available for 67 dogs at the age of six months. Likely, a continuation of the treatment over a longer time period would be necessary to obtain lasting effects, since the training took place only during the first third of the socialisation period.
... Furthermore, behavioral development in these highly altricial animals can be theoretically and comparatively important. Dogs, wolves, and related canids are the focus of much developmental research [19][20][21][22][23][24], while bears, although less social as adults than many other carnivores, have a far longer period of maternal care, and can provide tests of hypotheses deriving from research on canids. ...
... Behavioral development of cubs in dens may be crucial to their survival after emergence. Being born in such an altricial state leads to the need to look at differences from wolves and dogs, for example, which are comparatively very well studied [20][21][22]. Even more so, however, we need comparative data among the various bear species, which are still sadly lacking, but which new technology may assist in studying. ...
Denning behavior has long remained the least observed aspect of bear behavior. During 2010–2013, we used webcams, microphones, the internet, and 14,602 h of archived video to document the denning behaviors of two adult wild black bears (Ursus americanus) as they gave birth and cared for four litters through six winters in northeastern Minnesota. Observations included types of dens, labor, pre-parturient genital swelling, birthing positions, post-partum vocalizations, mothers removing amniotic tissues and warming newborn cubs in sub-freezing temperatures, frequency of nursing, cubs establishing nipple order, yearlings suckling, the ingestion of snow and icicles, the ingestion of foot pads, urination and defecation in latrine areas, toilet-licking, eye opening, reciprocal tongue-licking, play, rapid eye movement (REM) sleep and possible dreaming, and reactions to wildlife intruders. The use of this new method for observing natural bear dens allowed the identification of many behaviors undescribed for any species of wild bear in dens. We also discuss the need for future studies and how the depth and duration of black bear hibernation varies with body condition and geographic region.
... The terms "sensory perception of smell", "detection of chemical stimulus" and "Olfactory transduction" are involved in sensory perception and were enriched among the CNV gains in dog and wolf and all of them were over-represented among the CNV gains in wolf (P<0.01). Both wolf and dog develop olfaction, audition and vision by 2 weeks, 4 weeks and 6 weeks of age on average, respectively [41]. Wolf pups start to investigate their environment at 2 weeks of age while they are blind and deaf, and must depend mainly on sense of smell, while dog pups start to investigate their environment at 4 weeks of age [41]. ...
... Both wolf and dog develop olfaction, audition and vision by 2 weeks, 4 weeks and 6 weeks of age on average, respectively [41]. Wolf pups start to investigate their environment at 2 weeks of age while they are blind and deaf, and must depend mainly on sense of smell, while dog pups start to investigate their environment at 4 weeks of age [41]. In a previous study, the fraction of olfactory receptor pseudogenes in dog and wolf was 17.78 and 12.08%, respectively, however, difference between these values in dog and wolf was not significant [76]. ...
Background Advances in genome technology have simplified a new comprehension of the genetic and historical processes crucial to rapid phenotypic evolution under domestication. To get new insight into the genetic basis of the dog domestication process, we conducted whole-genome sequence analysis of three wolves and three dogs from Iran which covers the eastern part of the Fertile Crescent located in Southwest Asia where the independent domestication of most of the plants and animals has been documented and also high haplotype sharing between wolves and dog breeds has been reported. Results Higher diversity was found within the wolf genome compared with the dog genome. A total of 12.45 million SNPs were detected in all individuals (10.45 and 7.82 million SNPs were identified for all the studied wolves and dogs, respectively) and a total of 3.49 million small Indels were detected in all individuals (3.11 and 2.24 million small Indels were identified for all the studied wolves and dogs, respectively). A total of 10,571 copy number variation regions (CNVRs) were detected across the 6 individual genomes, covering 154.65 Mb, or 6.41%, of the reference genome (canFam3.1). Further analysis showed that the distribution of deleterious variants in the dog genome is higher than the wolf genome. Also, annotation of genomic variations showed that the proportion of genomic variations in the intron and intergenic regions in the wolf genome is higher than that in the dog genome, while the proportion of the coding sequences and 3'-UTR in the dog genome is higher than that in the wolf genome. The genes related to the olfactory and immune systems were enriched in the set of the structural variants (SVs) identified in this work. Generally, genes engaged in digestion and metabolism and neurological process had an important role in the process of dog domestication. Conclusions Our results showed more deleterious mutations and coding sequence variants in the domestic dog genome than those in wolf genome. By providing the first Iranian dog and wolf variome map, our findings contribute to understanding the genetic architecture of the dog domestication.
... The terms "sensory perception of smell", "detection of chemical stimulus" and "Olfactory transduction" were enriched among the CNV gain regions in dog and wolf (over-represented, P < 0.01), which are involved in sensory perception. Both wolf and dog develop olfaction, audition and vision by 2 weeks, 4 weeks and 6 weeks of age on average, respectively [44]. Wolf pups start to investigate their environment at 2 weeks of age while they are blind and deaf, and must depend mainly on sense of smell, while dog pups start to investigate their environment at 4 weeks of age [44]. ...
... Both wolf and dog develop olfaction, audition and vision by 2 weeks, 4 weeks and 6 weeks of age on average, respectively [44]. Wolf pups start to investigate their environment at 2 weeks of age while they are blind and deaf, and must depend mainly on sense of smell, while dog pups start to investigate their environment at 4 weeks of age [44]. In a previous study, the fraction of olfactory receptor pseudogenes in dog and wolf was 17.78 and 12.08%, respectively, however, difference between these values in dog and wolf was not significant [80]. ...
Background:
Advances in genome technology have simplified a new comprehension of the genetic and historical processes crucial to rapid phenotypic evolution under domestication. To get new insight into the genetic basis of the dog domestication process, we conducted whole-genome sequence analysis of three wolves and three dogs from Iran which covers the eastern part of the Fertile Crescent located in Southwest Asia where the independent domestication of most of the plants and animals has been documented and also high haplotype sharing between wolves and dog breeds has been reported.
Results:
Higher diversity was found within the wolf genome compared with the dog genome. A total number of 12.45 million SNPs were detected in all individuals (10.45 and 7.82 million SNPs were identified for all the studied wolves and dogs, respectively) and a total number of 3.49 million small Indels were detected in all individuals (3.11 and 2.24 million small Indels were identified for all the studied wolves and dogs, respectively). A total of 10,571 copy number variation regions (CNVRs) were detected across the 6 individual genomes, covering 154.65 Mb, or 6.41%, of the reference genome (canFam3.1). Further analysis showed that the distribution of deleterious variants in the dog genome is higher than the wolf genome. Also, genomic annotation results from intron and intergenic regions showed that the proportion of variations in the wolf genome is higher than that in the dog genome, while the proportion of the coding sequences and 3'-UTR in the dog genome is higher than that in the wolf genome. The genes related to the olfactory and immune systems were enriched in the set of the structural variants (SVs) identified in this work.
Conclusions:
Our results showed more deleterious mutations and coding sequence variants in the domestic dog genome than those in wolf genome. By providing the first Iranian dog and wolf variome map, our findings contribute to understanding the genetic architecture of the dog domestication.
... Esta población de perros también ha experimentado un escaso nivel de contacto con los humanos. En los perros domésticos se considera que el periodo crítico de socialización comienza a las cuatro semanas y puede prolongarse hasta la semana 16, siendo las semanas siete y ocho las más importantes (Fox & Stelzner, 1966, 1967Freedman et al., 1961;Lord, 2013;Wright, 1983). Esto significaría que los cachorros a evaluar estarían atravesando la etapa crítica de socialización. ...
... Sin embargo, dado que prefirieron al EG por sobre el egoísta, esta explicación es poco probable. Asimismo, debemos considerar el incompleto desarrollo motor de los cachorros de las edades evaluadas(Lord, 2013). Sería posible que los cachorros diferencien a los Es pero esto no se refleje en las latencias a acercarse a uno y otro E dadas sus dificultades de control (por ejemplo, los cachorros en ocasiones tropezaban al acercarse rápidamente a uno de los Es). ...
En ciertas ocasiones la cooperación requiere incurrir en un costo para
beneficiar a un tercero. Uno de los mecanismos posibles para explicar este tipo de
conductas aparentemente altruistas, entre no parientes, es la reciprocidad (i.e. un
acto cooperativo inicial podría ser retribuido luego por el beneficiado o un tercero).
Esto permitiría el establecimiento de vínculos a largo plazo, beneficiosos para todos
los agentes involucrados. Como consecuencia, uno de los problemas principales es
elegir a los compañeros sociales con quienes interactuar para evitar a los tramposos
o no-reciprocadores. El mecanismo propuesto para realizar esta evaluación se
denomina atribución de reputación.
Se evaluó la habilidad evaluar la reputación de las personas de forma directa
en perros domésticos. El perro se ha convertido en un modelo privilegiado para el
estudio comparativo de la cognición social debido a: 1) Sus sorprendentes
habilidades comunicativas interespecíficas, 2) su historia filogenética y 3) su
inclusión en las sociedades humanas.
Se diseñó un protocolo para evaluar la habilidad de discriminar las personas
generosas o egoístas definidas como aquellas que le permiten o le niegan el acceso
a la comida al perro en un contexto comunicativo. El mismo consto de dos fases. En
una fase de entrenamiento un experimentador, (generoso), le señalaba un recipiente
con comida al perro y luego le permitía comer. En cambio, el otro experimentador
(egoísta) le señalaba el recipiente correcto, pero cuando el perro se acercaba al
mismo, sacaba la comida y ostensiblemente la comía a la vista del animal. Luego, en
una fase de prueba se le permitía al perro elegir a uno de los dos experimentadores.
Los resultados muestran que los perros son capaces de reconocer las
actitudes humanas luego de interacciones directas con las personas y esta
discriminación probablemente implique el reconocimiento individual de los
experimentadores. Tanto la dificultad de la tarea discriminativa (semejanza o
diferencia entre los experimentadores) como la cantidad y variedad de claves
presentes (verbales y gestuales) modulan la velocidad de aprendizaje en esta tarea.
Asimismo, los perros con escaso contacto con los humanos, como los peros de
refugio, mostraron un desempeño similar al de los de familia, si bien presentaron
mayores conductas de evitación. Por último, los cachorros de entre 45 y 60 días de
edad también lograron resolver la tarea aunque requirieron más entrenamiento que
los adultos. Estos datos sugieren que, desde muy temprano en la ontogenia y con
poco contacto previo con las personas, los perros son capaces de aprender a
discriminar actitudes humanas.
El conjunto de los hallazgos son discutidos en función de las diversas
hipótesis respecto de los orígenes de las habilidades comunicativas entre perros y
personas.
... Their critical period of socialization ends when they are about six weeks old. Exposure to other species during this period can permit social attachments ( Lord, 2013 ;Hall et al., 2015 ) to, in this case, humans. The Upper Palaeolithic hunter-gatherers probably let only the most docile wolf pups live into adulthood; the more aggressive ones were eliminated. ...
... Recent studies have shown that hand-reared wolves, removed from their mother when about 10 days old, can become attached to their human caregivers (e.g. Lord, 2013;Hall et al., 2015 ) ( Table 2.2 ). However, human-socialized adult wolves can display offensive aggression towards humans as they sometimes fight for their dominance (Klinghammer and Goodmann, 1987). ...
... Second, the ear canal is closed until about 3 weeks of age in dogs (e.g. 33 ), therefore we can exclude the effect of intrauterine and early postnatal exposure to female voice on dogs' preference for female addressee-specific prosody. ...
When addressing preverbal infants and family dogs, people tend to use specific speech styles. While recent studies suggest acoustic parallels between infant- and dog-directed speech, it is unclear whether dogs, like infants, show enhanced neural sensitivity to prosodic aspects of speech directed to them. Using functional magnetic resonance imaging on awake unrestrained dogs we identify two non-primary auditory regions, one that involve the ventralmost part of the left caudal Sylvian gyrus and the temporal pole and the other at the transition of the left caudal and rostral Sylvian gyrus, which respond more to naturalistic dog- and/or infant-directed speech than to adult-directed speech, especially when speak by female speakers. This activity increase is driven by sensitivity to fundamental frequency mean and variance resulting in positive modulatory effects of these acoustic parameters in both aforementioned non-primary auditory regions. These findings show that the dog auditory cortex, similarly to that of human infants, is sensitive to the acoustic properties of speech directed to non-speaking partners. This increased neuronal responsiveness to exaggerated prosody may be one reason why dogs outperform other animals when processing speech.
... At this point the pups are still blind, the mother leaves the den more often, and she is more easily distracted (Packard, 2003). These individuals, from a developmental perspective, would have still been within the critical period of socialization during which wild wolf pups can potentially be socialized to humans (Klinghammer and Goodmann, 1987;Lord, 2013;Hall et al., 2015). The implicit assumption here is that in Eurasia the captive wolf pups were selected by Late Pleistocene hunter-gatherers from a very young age for their human-friendly behavior, and potentially also for favored morphological features, such as particular coat colors that humans found aesthetically appealing (Germonpré et al., 2018(Germonpré et al., , 2021a. ...
The historically known relationship of interspecies companionship between Aboriginal foraging communities in Australia and free-ranging dingoes provides a model for understanding the human-canid relations that gave rise to the first domesticated dogs. Here, we propose that a broadly similar relationship might have developed early in time between wild-living wolves and mobile groups of foragers in Late Pleistocene Eurasia, with hunter-gatherers routinely raiding wild wolf dens for pre-weaned pups, which were socialized to humans and kept in camp as tamed companions (“pets”). We outline a model in which captive wolf pups that reverted to the wild to breed when they were sexually mature established their territories in the vicinity of foraging communities — in a “liminal” ecological zone between humans and truly wild-living wolves. Many (or most) of the wolf pups humans took from the wilderness to rear in camp may have derived from these liminal dens where the breeding pairs had been under indirect human selection for tameness over many generations. This highlights the importance of the large seasonal hunting/aggregation camps associated with mammoth kill-sites in Gravettian/Epigravettian central Europe. Large numbers of foragers gathered regularly at these locations during the wild wolf birthing season. We infer that if a pattern of this kind occurred over long periods of time then there might have been a pronounced effect on genetic variation in free-ranging wolves that denned and whelped in the liminal zones in the vicinity of these human seasonal aggregation sites. The argument is not that wolves were domesticated in central Europe. Rather, it is this pattern of hunter-gatherers who caught and reared wild wolf pups gathering seasonally in large numbers that might have been the catalyst for the early changes leading to the first domesticated dogs — whether in western Eurasia or further afield.
... Last, compared with more traditional animal models that have specific limitations to their senses (e.g., rats and visual acuity, pigeons and olfactory acuity, etc.), wolves possess adequate visual and olfactory senses (Peichl, 1992). Olfaction plays a major role in the life history of gray wolves (Briscoe et al., 2002;Lord, 2013;Mech, 1970;Peters & Mech, 1975;Rothman & Mech, 1979), which have outperformed domestic dogs purposefully bred for odor detection in a food-finding task (Polg ar et al., 2016). ...
Conceptual behavior represents a type of complex stimulus control where an organism differentially responds to examples and nonexamples of instances within a stimulus class. Different species have demonstrated conceptual behavior both in their natural environments and through experimental investigations. The current paper investigates preliminary methods to teach conceptual behavior to gray wolves (Canis lupus). The researchers used a match-to-sample arrangement to teach three shapes: a triangle, square, and cross varying in size, color, and positions. Probe trials used a novel set of stimuli to test for the emergence of conceptual behavior. Although the wolves did not show an immediate transfer to novel stimuli following initial match-to-sample training, they did show improvement after explicit discrimination training. We discuss the implications of these results as well as future methods that may enhance experimental procedures investigating concept learning in canids.
... Therefore, it makes sense to follow dogs to find new food sources given their highly developed sense of smell (Lord 2012). Black Vultures use dogs to locate food and then steal it from them. ...
... Therefore, it makes sense to follow dogs to find new food sources given their highly developed sense of smell (Lord 2012). Black Vultures use dogs to locate food and then steal it from them. ...
Kleptoparasitism is recognized as an important ethological feeding strategy that enables many animals to feed on a limited resource. Research on avian scavengers is significant because their consumption of carrion and food discarded by humans helps reduce foci of infection due to animals that die from disease, thereby preventing the spread of infection through the ecosystem. Scavenging birds provide key environmental and hygienic services valued at billions of dollars and here we document, analyze, and discuss the first cases of inter-and intraspecific kleptoparasitism reported in the American Black Vulture Coragyps atratus within the context of Calceta garbage dump (Manabí, Ecuador). The sampling work was documented with photos and videos over a period of 69 hours. A total of 48 events of intraspecific kleptoparasitism and 19 of interspecific kleptoparasitism were recorded. The intraspecific kleptoparasitism was triggered by the discharge of large amounts of waste from trucks, while the interspecific kleptoparasitism occurred when the Black Vultures took advantage of domestic dogs and their olfactory abilities to accurately locate food and then steal it. The efficiency of interspecific kleptoparasitism indicates that cooperative groups with more vultures are more likely to succeed in obtaining food. The data suggest that there is an optimal size beyond which larger group sizes will begin to incur foraging costs. This acquired behavior shows a high tolerance to anthropogenic conditions and illustrates the great adaptive phenotypic plasticity of this species.
... Therefore, it makes sense to follow dogs to find new food sources given their highly developed sense of smell (Lord 2012). Black Vultures use dogs to locate food and then steal it from them. ...
Kleptoparasitism is recognized as an important ethological feeding strategy that enables many animals to feed on a limited resource. Research on avian scavengers is significant because their consumption of carrion and food discarded by humans helps reduce foci of infection due to animals that die from disease, thereby preventing the spread of infection through the ecosystem. Scavenging birds provide key environmental and hygienic services valued at billions of dollars and here we document, analyze, and discuss the first cases of inter-and intraspecific kleptoparasitism reported in the American Black Vulture Coragyps atratus within the context of Calceta garbage dump (Manabí, Ecuador). The sampling work was documented with photos and videos over a period of 69 hours. A total of 48 events of intraspecific kleptoparasitism and 19 of interspecific kleptoparasitism were recorded. The intraspecific kleptoparasitism was triggered by the discharge of large amounts of waste from trucks, while the interspecific kleptoparasitism occurred when the Black Vultures took advantage of domestic dogs and their olfactory abilities to accurately locate food and then steal it. The efficiency of interspecific kleptoparasitism indicates that cooperative groups with more vultures are more likely to succeed in obtaining food. The data suggest that there is an optimal size beyond which larger group sizes will begin to incur foraging costs. This acquired behavior shows a high tolerance to anthropogenic conditions and illustrates the great adaptive phenotypic plasticity of this species.
... For prey-like stimulus, we opted for the light of a laser pointer. At least in the case of cats, there is evidence that this type of stimulus elicits the typical locomotor components of the hunting sequence (stare, chase and pounce) [47], and dogs have also been shown to be interested in visual stimulation by static or moving laser dots [48]. However, when the subjects could observe the red dot from a laser pointer that moved in a 'detouring' fashion around the V-shaped fence, we predicted that cats would perform better than dogs because this type of stimulus may be more suitable for cats more than for dogs, as dogs are considered to be more motivated by social stimuli [28]. ...
We tested companion cats and dogs in similar indoor conditions using identical procedures in the classic detour task around a V-shaped transparent wire-mesh fence. Besides the control group, we used two types of laser light-pointing demonstration (moving around the fence, or pointing straight at the reward). We found that dogs reached the food reward faster than cats; across consecutive trials, only the dogs showed improvement in their speed and dogs continued to use the same side for detouring after a preceding successful attempt, while cats chose the side for detouring irrespective of their previous successful trials. In addition, ‘demonstrating’ a detour with the laser did not influence the speed or direction of the detour of the subjects; and dogs looked back to their owner more frequently than the cats did. We discuss the possibility that for dogs, detouring along a transparent obstacle represents a more problematic task than for cats; therefore, dogs strongly rely on their previous experiences. This is the first time that cats were successfully tested in this detour paradigm in direct comparison with dogs. The results are relevant from the aspect of testing cognitive performance in companion cats, which are known to be notoriously reluctant to engage with novel experimental situations.
... In many cases, the animal collects information about a food resource using acute sensory capabilities that exceed those of humans. For example, dolphins use echolocation to locate prey in murky water, while wolves and potentially honeyguides use olfaction to locate dispersed prey and cryptic bees' nests, respectively (Lord, 2013;Parker, 2018). These sensory abilities, combined with their locomotion (e.g. ...
1. Human-wildlife cooperation is a type of mutualism in which a human and a wild, free-living animal actively coordinate their behaviour to achieve a common beneficial outcome. 2. While other cooperative human-animal interactions involving captive coer-cion or artificial selection (including domestication) have received extensive
... In many cases, the animal collects information about a food resource using acute sensory capabilities that exceed those of humans. For example, dolphins use echolocation to locate prey in murky water, while wolves and potentially honeyguides use olfaction to locate dispersed prey and cryptic bees' nests, respectively (Lord, 2013;Parker, 2018). These sensory abilities, combined with their locomotion (e.g. ...
Human‐wildlife cooperation is a type of mutualism in which a human and a wild, free‐living animal actively coordinate their behaviour to achieve a common beneficial outcome.
While other cooperative human‐animal interactions involving captive coercion or artificial selection (including domestication) have received extensive attention, we lack integrated insights into the ecology and evolution of human‐wildlife cooperative interactions.
Here, we review and synthesise the function, mechanism, development, and evolution of human‐wildlife cooperation.
Active cases involve people cooperating with greater honeyguide birds and with two dolphin species, while historical cases involve wolves and orcas.
In all cases, a food source located by the animal is made available to both species by a tool‐using human, coordinated with cues or signals.
The mechanisms mediating the animal behaviours involved are unclear, but they may resemble those underlying intraspecific cooperation and reduced neophobia.
The skills required appear to develop at least partially by social learning in both humans and the animal partners. As a result, distinct behavioural variants have emerged in each type of human‐wildlife cooperative interaction in both species, and human‐wildlife cooperation is embedded within local human cultures.
We propose multiple potential origins for these unique cooperative interactions, and highlight how shifts to other interaction types threaten their persistence.
Finally, we identify key questions for future research. We advocate an approach that integrates ecological, evolutionary and anthropological perspectives to advance our understanding of human‐wildlife cooperation. In doing so, we will gain new insights into the diversity of our ancestral, current and future interactions with the natural world.
Read the free Plain Language Summary for this article on the Journal blog.
... The latter is a facet particularly important in wolf sociality and life history (Packard, 2003). Wolf pups in captivity show a very early propensity for exploration and novel stimuli (Lord, 2013). ...
Some animals use humanmade objects for building and constructing nests or shelter and even for play. Gray wolves (Canis lupus) gather and use humanmade objects discovered in their natural environment. Gathering humanmade objects is a peculiar behavior particularly when there is no immediately apparent benefit to survival or reproduction. I opportunistically documented 46 different types of humanmade objects with plastic bottles and aluminum cans being the most common items found at wolf pup-rearing sites. Many objects were made of materials that appeared suitable to alleviate pain in teething pups. For some objects, however, it was not immediately obvious that they would alleviate teething pain due to their unpliable material. Additionally, such objects were quite rare in wolves' natural environment although it was not uncommon to find them at pup-rearing sites. Rare humanmade objects may provide a novelty that stimulates pups more than common objects. I hypothesize that objects used by wolf pups 1) alleviate pain from teething, and 2) provide adults respite from energetic pups. The latter is an important distinction because it implies the benefit of object play is to the adults and not the pups per se. Gathering novel objects that occupy energetic and hungry pups may influence the overall ability of social carnivores to leave young unattended while they hunt, to rest upon their return, and ultimately rear young successfully.
... Nos enquêtes nous ont permis d'identifier quatre situations-types chez les éleveurs, selon la taille du parc (petit, moyen, grand), l'occupation de la surface du parc par le troupeau, et la visibilité (présence de lisière forestière, landes hautes, rupture de pente) (figure 2). 30 Étant donné les grandes capacités olfactives des canidés (Lord, 2013 ;Rosell, 2018), les CPTs sont capables de repérer les loups bien avant que ceux-ci ne soient en contact du parc. Pour les chiens appréciant « d'aller au contact » comme disent des éleveurs enquêtés, il est probablement frustrant de ne pas être autorisés à repousser le ou les loup(s) activement avant qu'il(s) ne franchissent la clôture. ...
La prédation par les loups affecte tous les systèmes d’élevage, y compris ceux avec plusieurs lots d'animaux mis à pâturer dans différents parcs clôturés, parfois distants et dispersés dans le paysage. La protection d’animaux en l’absence d’un humain responsable à leurs côtés, éleveur ou berger, et par la seule combinaison de clôtures et de chiens, est une pratique nouvelle n’ayant pas reçu beaucoup d'attention dans les recommandations de politiques publiques. A partir de plusieurs sources de connaissances, depuis les écrits de scientifiques jusqu’au recueil d’expériences auprès d’éleveurs des Alpes du sud, nous analysons trois questions afin d’améliorer l’efficacité de la pratique : le nombre de chiens nécessaires, la complémentarité des chiens dans un groupe, l’espace à protéger. Plusieurs chiens sont en effet nécessaires. Au sein d'un groupe, les chiens peuvent assurer des rôles complémentaires et ceci optimise la protection. La recomposition des groupes au cours de l’année peut engendrer des difficultés. Il peut s’avérer pertinent de permettre aux chiens de parfois franchir les clôtures, afin qu’ils n’aient pas à attendre que des loups sautent ou creusent par dessous. Mais dans un pays densément peuplé et fréquenté, le travail des chiens en périphérie des parcs est confronté à un risque élevé de conflit avec d’autres usagers de l’espace. Lorsque les espaces de pâturage deviennent zones à risque pour des randonneurs ou chasseurs confrontés aux chiens, la pérennité des élevages peut être remise en question.
... In situation 3b, the flock moved temporarily along a fence on the edge of a forest or a high and dense scrubland. 30 Given the great olfactory abilities of canids (Lord, 2013;Rosell, 2018), LGDs are able to spot wolves long before they come close to a fenced pasture. For dogs that enjoy "going to contact" as interviewed breeders say, it is likely frustrating that they are not allowed to actively repel the wolf or wolves before they cross the fence. ...
Predation by wolves affects all livestock farming systems, including those having different batches of animals being simultaneously grazed in distinct and sometimes distant fenced pastures scattered over a landscape. In the absence of a responsible human herding and watching over his flock or herd, livestock protection by the sole combination of fences and guard dogs is a new practice in France, that has not yet received much attention in public policy recommendations. We used several sources of knowledge, from the scientific literature to experiences of breeders interviewed in the Southern Alps, to analyse three issues to improve the effectiveness of the practice: the number of guard dogs required per batch of animals, the complementarity of dogs within their working group, and the land area to be protected by dogs. In each case, several dogs are necessary. Within their group, the guard dogs can play complementary roles and this optimizes protection. The rearrangement of dog groups during the year can cause difficulties. It may be appropriate sometimes to allow guard dogs to cross fences, so that they do not have to wait for wolves to jump or dig underneath. But in a densely populated and frequented country such as France, allowing protection by dogs on the periphery of fenced pastures faces a high risk of conflict with other land users. When grazing lands become risky areas for hikers or hunters confronted with guard dogs, the sustainability of outdoor livestock farming may be called into question.
... Nos enquêtes nous ont permis d'identifier quatre situations-types chez les éleveurs, selon la taille du parc (petit, moyen, grand), l'occupation de la surface du parc par le troupeau, et la visibilité (présence de lisière forestière, landes hautes, rupture de pente) (Figure 2). Étant donné les grandes capacités olfactives des canidés (Lord, 2013 ;Rosell, 2018), les CPTs sont capables de repérer les loups bien avant que ceux-ci ne soient en contact du parc. Pour les chiens appréciant « d'aller au contact » comme disent des éleveurs enquêtés, il est probablement frustrant de ne pas être autorisés à repousser le ou les loup(s) activement avant qu'il(s) ne franchissent la clôture. ...
La prédation par les loups affecte tous les systèmes d'élevage, y compris ceux avec plusieurs lots d'animaux mis à pâturer dans différents parcs clôturés, parfois distants et dispersés dans le paysage. La protection d'animaux en l'absence d'un humain responsable à leurs côtés, éleveur ou berger, et par la seule combinaison de clôtures et de chiens, est une pratique nouvelle n'ayant pas reçu beaucoup d'attention dans les recommandations de politiques publiques. A partir de plusieurs sources de connaissances, depuis les écrits de scientifiques jusqu'au recueil d'expériences auprès d'éleveurs des Alpes du sud, nous analysons trois questions afin d'améliorer l'efficacité de la pratique : le nombre de chiens nécessaires, la complémentarité des chiens dans un groupe, l'espace à protéger. Plusieurs chiens sont en effet nécessaires. Au sein d'un groupe, les chiens peuvent assurer des rôles complémentaires et ceci optimise la protection. La recomposition des groupes au cours de l'année peut engendrer des difficultés. Il peut s'avérer pertinent de permettre aux chiens de parfois franchir les clôtures, afin qu'ils n'aient pas à attendre que des loups sautent ou creusent par dessous. Mais dans un pays densément peuplé et fréquenté, le travail des chiens en périphérie des parcs est confronté à un risque élevé de conflit avec d'autres usagers de l'espace. Lorsque les espaces de pâturage deviennent zones à risque pour des randonneurs ou chasseurs confrontés aux chiens, la pérennité des élevages peut être remise en question.
... Given the great olfactory abilities of canids (Lord, 2013;Rosell, 2018), LGDs are able to spot wolves long before they come close to a fenced pasture. For dogs that enjoy "going to contact" as interviewed breeders say, it is likely frustrating that they are not allowed to actively repel the wolf or wolves before they cross the fence. ...
Predation by wolves affects all livestock farming systems, including those having different batches of animals being simultaneously grazed in distinct and sometimes distant fenced pastures scattered over a landscape. In the absence of a responsible human herding and watching over his flock or herd, livestock protection by the sole combination of fences and guard dogs is a new practice in France, that has not yet received much attention in public policy recommendations. We used several sources of knowledge, from the scientific literature to experiences of breeders interviewed in the Southern Alps, to analyse three issues to improve the effectiveness of the practice: the number of guard dogs required per batch of animals, the complementarity of dogs within their working group, and the land area to be protected by dogs. In each case, several dogs are necessary. Within their group, the guard dogs can play complementary roles and this optimizes protection. The rearrangement of dog groups during the year can cause difficulties. It may be appropriate sometimes to allow guard dogs to cross fences, so that they do not have to wait for wolves to jump or dig underneath. But in a densely populated and frequented country such as France, allowing protection by dogs on the periphery of fenced pastures faces a high risk of conflict with other land users. When grazing lands become risky areas for hikers or hunters confronted with guard dogs, the sustainability of outdoor livestock farming may be called into question.
... The best way to socialize a wolf is to remove the pups from their mother and hand-rear them before they open their eyes when they are 12 days old. At this tender age they can become attached to their human caretakers (Gaćsi et al. 2005;Hall et al. 2015;Lord 2013;Ujfalussy et al. 2017). One main question is how these young animals could have been fed and taken care of at Palaeolithic camp sites. ...
Several hypotheses have been proposed to explain the initial steps in the domestication process of the wolf. We discuss the human-initiated model in which wolf pups were brought to camp sites by male hunters and cared for by nursing women. A good relation between the more sociable and playful pups and the women and their children likely formed affiliative bonds and led to the survival of such pups into maturity. Some of these animals could have reproduced and delivered at least one litter. A selection on the behaviour of subsequent generations could ultimately have led to Palaeolithic dogs.
... Functional olfaction in dogs develops between 8 and 13 days after birth (Lord, 2013). Olfactory epithelium, nasal cavity receptor cells, vomeronasal organ (VNO), which is an olfactory chamber rich in receptors and olfactory bulb, are major components of dog's nose (Jenkins et al., 2018;Marcus, 2012). ...
... The breed is the outcome of a military hybridization attempt conducted in former Czechoslovakia in 1958 to create a new line of dogs showing the positive traits of the GSs (e.g. temperament and trainability) but also some characteristics of the wolf including health, strength, and night vision (Lord, 2013). The first breeding involved a female Carpathian wolf and a male GS dog; then, only four additional crossings with wolves occurred, with the last crossed breeding in 1983. ...
Through domestication and subsequent selection dogs’ morphological and behavioural traits have been selected for functional purposes beyond companionship. Since dogs are kept as pets worldwide and live in close contact with humans, gathering information on the behavioural characteristics of breeds either potentially problematic or obtained through hybridization appears particularly relevant. In the current study, the C-BARQ questionnaire was used to examine the behaviour of the Czechoslovakian wolfdog, a recent breed obtained through hybridization of the Carpathian wolf and the German shepherd dog and rapidly growing in popularity. One thousand four hundred twenty owners, 1119 from Italy and 301 from the Czech Republic completed the online questionnaire providing data on Czechoslovakian wolfdogs (CWDs), their sister breed, i.e. German shepherd dogs (GSs), and Labrador retrievers (LRs).
Overall some behavioural differences among the breeds emerged together with discrepancies between Italian and Czech owners in the evaluation of some behavioural traits.
Italian owners outlined only a few breeds and/or sex differences. Regardless of breed and training male dogs were rated as more aggressive towards other dogs, more excitable and active, more prone to show attention-seeking behaviour, less trainable, and less prone than females to engage in chasing than females. CWDs showed less stranger-directed fear than GSs and LRs and less non-social fear than GSs. According to Czech owners, males were generally more aggressive than females and CWDs and GSs were significantly more aggressive towards strangers and other dogs than LRs. CWDs showed more stranger-directed fear and separation-related behaviour and were less trainable than both GSs and LRs. The training was generally reported to reduce aggressive and separation-related behaviour, fear of strangers and non-social stimuli, and chasing tendencies. Taken together these findings suggest that CWDs could be more similar to ancient breeds (more wolf-like) for some behavioural traits and like modern breeds for others. Different breeding practices and/or social/environmental conditions such as socialization, handling, training methods but also owners’ perceptions and expectations about a given breed could explain the differences in rating that emerged between the two countries.
... The selection of survey methods will directly influence the accuracy and comprehensiveness of survey outcomes (Nussear et al. 2008). It is well known that dogs have a remarkable olfactory sensory system (Jezierski et al. 2010, Lord 2013, and have been used for a variety of scent related assignments, such as the detection of drugs and explosives in forensics (criminal investigation) and for hunting (Browne et al. 2006, Hurt & Smith 2009, Adamkiewicz et al. 2013. Domestic dogs are also used to screen for cancer (Walczak et al. 2012) and to locate larger wildlife (like bears) by means of detecting scat (Wasser et al. 2004). ...
Efficient and systematic survey methods are essential for wildlife researchers and conservationists
to collect accurate ecological data that can be used to make informed conservation decisions. For endangered
and elusive species, that are not easily detected by conventional methods, reliable, time- and cost-efficient
methodologies become increasingly important. Across a growing spectrum of conservation research projects,
survey outcomes are benefitting from scent detection dogs that assist with locating elusive species. This paper
describes the training methodology used to investigate the ability of a scent detection dog to locate live riverine
rabbits (Bunolagus monticularis) in their natural habitat, and to determine how species-specific the dog was
towards the target scent in a controlled environment. The dog was trained using operant conditioning and a
non-visual methodology, with only limited scent from roadkill specimens available. The dog achieved a 98%
specificity rate towards the target scent, indicating that the dog was able to distinguish the scent of riverine
rabbits from the scent of other lagomorph species. The dog has already been able to locate ten of these elusive
individuals in the wild. The training method proved successful in the detection of this critically endangered
species, where scent for training was only available from deceased specimens.
... However, fishers (Martes pennanti), a species also experiencing delayed implantation, show a relatively delayed postnatal development of deciduous teeth (~40 days old) and simultaneous opening of eyes and ears (~48 days old- Frost and Krohn 2005). Although domestic dogs and wolves (Canis lupus lupus) experience opening of eyes and ear canals around the same time (eyes ~13 and ears ~19 days old), both species display a 5-to 10-day delay in responding to visual and auditory stimuli (Bekoff and Jamieson 1975;Lord 2013). Despite the relative delay in postnatal eye and ear development in black bears (e.g., ~44 days of age), cubs have a ~21-day period to achieve complete functionality of these sensorial organs when they emerge from the den (~65 days of age) and they appear fully responsive to auditory and visual cues upon emergence. ...
We assessed the effects of cub age, litter size, and sex, on body mass (BM), absolute and relative growth rates (AGR, RGR), opening of ears and eyes, and deciduous teeth eruption from 129 cubs of American black bears (Ursus americanus) born at Virginia Tech’s Black Bear Research Center. Specific ages, related to maternal food consumption, and litter size, best described BM, AGR, RGR, and ear and eye development. Overall, newborns weighed ~0.44 kg at birth and increased ~9-fold by ~14 weeks. Twins were greater in BM than single cubs and triplets. Single and triplet cubs had higher AGR and RGR than twins after mothers resumed food consumption post-hibernation. Newborns displayed RGR > 3.5% that decreased until den emergence (RGR < 3.5% after emergence). RGR differed among litter sizes, particularly after den emergence. Ear and eye opening occurred concurrently at ~44 days of age, while teeth erupted ~10 days later. Single cubs experienced delayed development of these organs compared to other litter sizes. Postnatal developmental differences between black bears and other carnivores likely stem from strategies allowing black bears to minimize energy expenditure during the gestational period when hibernating.
... It is still possible, however, that early and intensive socialization either masked or enlarged genetically based differences between dogs and wolves. If equipped with different genetic predispositions and learning preferences, wolves and dogs, even if raised under identical conditions, likely gain different experiences, go through different learning processes, and, ultimately, adapt their behaviour to different aspects of the same environment 5,30 . Therefore, even if comparing animals raised in the same way, we can detect epigenetic differences between wolves and dogs that are likely to be more profound the older the investigated animals are 11,31 . ...
Dogs live in 45% of households, integrated into various human groups in various societies. This is certainly not true for wolves. We suggest that dogs' increased tractability (meant as individual dogs being easier to control, handle and direct by humans, in contrast to trainability defined as performance increase due to training) makes a crucial contribution to this fundamental difference. In this study, we assessed the development of tractability in hand-raised wolves and similarly raised dogs. We combined a variety of behavioural tests: fetching, calling, obeying a sit signal, hair brushing and walking in a muzzle. Wolf (N = 16) and dog (N = 11) pups were tested repeatedly, between the ages of 3-24 weeks. In addition to hand-raised wolves and dogs, we also tested mother-raised family dogs (N = 12) for fetching and calling. Our results show that despite intensive socialization, wolves remained less tractable than dogs, especially in contexts involving access to a resource. Dogs' tractability appeared to be less context dependent, as they followed human initiation of action in more contexts than wolves. We found no evidence that different rearing conditions (i.e. intensive socialization vs. mother rearing) would affect tractability in dogs. This suggests that during domestication dogs might have been selected for increased tractability, although based on the current data we cannot exclude that the differential speed of development of dogs and wolves or the earlier relocation of wolves to live as a group explains some of the differences we found.
... Despite minimal initial preference in the olfactory discrimination task (54% correct, measured as the first response option approached), puppies spent the majority of the time investigating the baited option (62% of the 20 s trial time at the baited option versus 18% at the nonbaited option) and had chosen this option 73% of the time by the end of the trial. Previous work has shown that dogs' behaviour is guided by olfaction by 2 weeks of age, audition by 4 weeks of age and vision by 6 weeks of age (Lord, 2013), and the current study suggests that by 8 weeks of age, dogs are able to adequately use these senses to discriminate between multiple response options in an object choice task. ...
To characterize the early ontogeny of dog cognition, we tested 168 domestic dog, Canis familiaris, puppies (97 females, 71 males; mean age = 9.2 weeks) in a novel test battery based on previous tasks developed and employed with adolescent and adult dogs. Our sample consisted of Labrador retrievers, golden retrievers and Labrador × golden retriever crosses from 65 different litters at Canine Companions for Independence, an organization that breeds, trains and places assistance dogs for people with disabilities. Puppies participated in a 3-day cognitive battery that consisted of 14 tasks measuring different cognitive abilities and temperament traits such as executive function (e.g. inhibitory control, reversal learning, working memory), use of social cues, sensory discriminations and reactivity to and recovery from novel situations. At 8–10 weeks of age, and despite minimal experience with humans, puppies reliably used a variety of cooperative-communicative gestures from humans. Puppies accurately remembered the location of hidden food for delays of up to 20 s, and succeeded in a variety of visual, olfactory and auditory discrimination problems. They also showed some skill at executive function tasks requiring inhibitory control and reversal learning, although they scored lower on these tasks than is typical in adulthood. Taken together, our results confirm the early emergence of sensitivity to human communication in dogs and contextualize these skills within a broad array of other cognitive abilities measured at the same stage of ontogeny.
... Therefore, control tests have been commonly set up to rule out this possibility in adult dogs (Ward and Smuts 2007;Miletto Petrazzini and Wynne 2016;Baker et al. 2011;Horowitz et al. 2013). Dogs develop olfaction by the second week of life (Lord 2013). Hence, to reduce the possibility that puppies could rely on olfactory rather than visual information when making their choices an opaque pierced container (14 × 12 × 4.5 cm) that concealed the food was attached below each plate with a piece of Velcro. ...
There is considerable evidence that animals are able to discriminate between quantities. Despite the fact that quantitative skills have been extensively studied in adult individuals, research on their development in early life is restricted to a limited number of species. We, therefore, investigated whether 2-month-old puppies could spontaneously discriminate between different quantities of food items. We used a simultaneous two-choice task in which puppies were presented with three numerical combinations of pieces of food (1 vs. 8, 1 vs. 6 and 1 vs. 4), and they were allowed to select only one option. The subjects chose the larger of the two quantities in the 1 vs. 8 and the 1 vs. 6 combinations but not in the 1 vs. 4 combination. Furthermore, the last quantity the puppies looked at before making their choice and the time spent looking at the larger/smaller amounts of food were predictive of the choices they made. Since adult dogs are capable of discriminating between more difficult numerical contrasts when tested with similar tasks, our findings suggest that the capacity to discriminate between quantities is already present at an early age, but that it is limited to very easy discriminations.
... For the purpose of standardization across years, the same unfamiliar female puppy assessor conducted the tests all three years. Unlike dogs, wolves do not seem to generalize familiarity with human hand-raisers to strangers (Zimen 1987;Lord 2013) and the use of an unfamiliar person, and not a caregiver, as the puppy assessor in the test further served to eliminate potential bias caused by familiarity between puppy assessor and wolf. ...
Domestication dramatically alters phenotypes across animal species. Standing variation among ances-tral populations often drives phenotypic change during domestication, but some changes are causedby novel mutations. In dogs (Canis familiaris) specifically, it has been suggested that the ability tointerpret social-communicative behavior expressed by humans originated post-domestication andthis behavior is thus not expected to occur in wolves (Canis lupus). Here we report the observationof three 8-week-old wolf puppies spontaneously responding to social-communicative behaviorsfrom an unfamiliar person by retrieving a ball. This behavioral expression in wolves has significant im-plications for our understanding and expectations of the genetic foundations of dog behavior. Impor-tantly, our observations indicate that behavioral responses to human social-communicative cues arenot unique to dogs. This suggests that, although probably rare, standing variation in the expressionof human-directed behavior in ancestral populations could have been an important target for earlyselective pressures exerted during dog domestication.
... For instance, working lines of dogs are created by starting with dogs who exhibit desirable behavioral characteristics (e.g., herding or not killing livestock) and then selectively breeding those that best exemplify the characteristic [19], yielding behavioral change in as few as three generations [75]. The change in the critical period of socialization in the selected foxes is more like the difference between more and less easily socialized dog breeds [76,77] than between dogs and wolves [78]. ...
The Russian Farm-Fox Experiment is the best known experimental study in animal domestication. By subjecting a population of foxes to selection for tameness alone, Dimitry Belyaev generated foxes that possessed a suite of characteristics that mimicked those found across domesticated species. This 'domestication syndrome' has been a central focus of research into the biological pathways modified during domestication. Here, we chart the origins of Belyaev's foxes in eastern Canada and critically assess the appearance of domestication syndrome traits across animal domesticates. Our results suggest that both the conclusions of the Farm-Fox Experiment and the ubiquity of domestication syndrome have been overstated. To understand the process of domestication requires a more comprehensive approach focused on essential adaptations to human-modified environments.
... One or more of the six most familiar senses may exhibit an exaggerated capacity [79]; this enables the affected species to successfully engage with what would otherwise be insurmountable challenges posed by their ecological niche [54,66]. Examples include the exaggerated acuity of sight in eagles [80], smell and ultrasonic hearing in dogs [81][82][83][84][85][86], and sight, smell and ultrasonic hearing in cats [85,87]. In addition to enhancing the scope of effective behavioural responses in particular environments, such exaggerated sensory capacities likely also influence the modes of communication utilised by these animals. ...
The focus of this opinion is on the key features of sentience in animals which can experience different states of welfare, encapsulated by the new term ‘welfare-aligned sentience’. This term is intended to exclude potential forms of sentience that do not enable animals in some taxa to have the subjective experiences which underlie different welfare states. As the scientific understanding of key features of sentience has increased markedly during the last 10 to 15 years, a major purpose here is to provide up-to-date information regarding those features. Eleven interconnected statements about sentience-associated body functions and behaviour are therefore presented and explained briefly. These statements are sequenced to provide progressively more information about key scientifically-supported attributes of welfare-aligned sentience, leading, in their entirety, to a more comprehensive understanding of those attributes. They are as follows: (1) Internal structure–function interactions and integration are the foundations of sentience; (2) animals posess a capacity to respond behaviourally to a range of sensory inputs; (3) the more sophisticated nervous systems can generate subjective experiences, that is, affects; (4) sentience means that animals perceive or experience different affects consciously; (5) within a species, the stage of neurobiological development is significant; (6) during development the onset of cortically-based consciousness is accompanied by cognitively-enhanced capacities to respond behaviourally to unpredictable postnatal environments; (7) sentience includes capacities to communicate with others and to interact with the environment; (8) sentience incorporates experiences of negative and positive affects; (9) negative and positive affective experiences ‘matter’ to animals for various reasons; (10) acknowledged obstacles inherent in anthropomorphism are largely circumvented by new scientific knowledge, but caution is still required; and (11) there is increasing evidence for sentience among a wider range of invertebrates. The science-based explanations of these statements provide the foundation for a brief definition of ‘welfare-aligned sentience’, which is offered for consideration. Finally, it is recommended that when assessing key features of sentience the same emphasis should be given to positive and negative affective experiences in the context of their roles in, or potential impacts on, animal welfare.
... Among tyrannosaurs, the large taxa had larger OR repertoires than any other non-avian dinosaurs, whereas Dilong paradoxus falls within the inner 95th quantiles of the modern bird distribution, even if the outlier taxa (zebra finch, chicken and budgerigar) are excluded. This overall increase in olfactory capability within Tyrannosauroidea may reflect ecological adaptation, allowing the tracking of prey over large distances, as in modern wolves [36], or to effectively scavenge carrion, as in the modern turkey vulture (electronic supplementary material, table S1). ...
The olfactory bulb (OB) ratio is the size of the OB relative to the cerebral hemisphere, and is used to estimate the proportion of the forebrain devoted to smell. In birds, OB ratio correlates with the number of olfactory receptor (OR) genes and therefore has been used as a proxy for olfactory acuity. By coupling OB ratios with known OR gene repertoires in birds, we infer minimum repertoire sizes for extinct taxa, including non-avian dinosaurs, using phylogenetic modelling, ancestral state reconstruction and comparative genomics. We highlight a shift in the scaling of OB ratio to body size along the lineage leading to modern birds, demonstrating variable OR repertoires present in different dinosaur and crown-bird lineages, with varying factors potentially influencing sensory evolution in theropods. We investigate the ancestral sensory space available to extinct taxa, highlighting potential adaptations to ecological niches. Through combining morphological and genomic data, we show that, while genetic information for extinct taxa is forever lost, it is potentially feasible to investigate evolutionary trajectories in extinct genomes.
... The sociability period changes with domestication. For instance, the sociability or sensitive period for wolves comes earlier than that of dogs; it is longer for domesticated silver foxes (Belyaev et al. 1985;Lord 2013). It can be assumed that in the past donkeys were initially captured earlier than they are at present, given that the domestication of wild asses had just begun. ...
Several factors may underlie the ability of animals to solve problems in the physical environment including motivation, attention and inhibitory control. Here we review studies comparing wolves and dogs on these aspects. The data available to date suggest that while wolves are more neophobic than dogs, they are also more explorative and manipulative when encountering new objects in their environment. These are important differences since they are likely to affect results in many (social and non-social) tasks. Indeed, these results would suggest that, even if wolves and dogs do not differ in their cognitive abilities, wolves would outperform dogs in all sorts of physical tasks just because they have a better chance to stumble on the solution during their more persistent exploration. In combination with being more sensitive towards details of a situation and maybe better working memory capacities, wolves should be in general better problem-solvers. This is indeed what emerges, although a number of aspects still require further investigation. With regard to inhibitory control, dogs outperform wolves in situations where humans are involved, potentially because they are more sensitive to human social inhibition than wolves. But in contexts where humans are not involved, wolves and dogs inhibitory control abilities do not differ.
In this chapter, we review studies comparing the social learning and cooperative abilities of wolves and dogs, both with conspecifics and humans. As regards social learning, their performance is similar in basic tasks involving local enhancement and observational memory. But when it comes to paying attention to the exact details of a demonstration and imitating a specific action, wolves clearly outperform dogs. Whether these differences stem from differences in cognitive abilities or rather from differences in general purpose mechanisms such as attention, working memory, inhibition or motivation still needs to be explored. As regards cooperation, the studies reviewed show that wolves and dogs share with us at least some of the abilities that seem to be important for cooperation: they show some prosocial tendencies, are inequity averse, can coordinate their actions with conspecific partners, and have a basic understanding of the role of their partner in cooperative interactions. However, the studies show that while wolves cooperate successfully with conspecifics as well as with human partners, dogs only succeeded with humans. This suggests that the dogs’ failure to cooperate with conspecifics is not due to cognitive limitations but rather due to limited tolerance towards each other in feeding contexts. While both species cooperate with humans, their behaviour revealed some remarkable differences suggesting that wolves rather lead (and perhaps just expect humans to follow), whereas dogs are more inclined to wait for the human partners to take the initiative and then follow their lead.
Although body sniffing is the most frequent canine interaction in public places, little is known about olfactory behaviors between walking dogs. The aim of this study was to examine the association of dog, human and behavior characteristics with the number of sniffing dogs within a dyad, with the initiation and termination of sniffing, with the first and last area sniffed on the recipient’s body and with the number of areas sniffed on the recipient’s body in walking dogs in public places. We observed 538 dyadic encounters between sexually intact dogs, each led by one owner. We randomly selected one dog from each of 538 dyads, yielding 486 focal dogs actively involved in sniffing for analysis. Interacting dogs were more likely to engage in mutual than single dog sniffing when the owners communicated with each other than when they did not. Dogs more likely initiated sniffing than not when a male dog encountered a female than vice versa. Dogs more likely sniffed the rear than the head as the first area on the recipient’s body when only one dog sniffed the other than when both dogs sniffed each other; and also when they initiated sniffing than when they did not. Dogs more likely sniffed more than one area than only one area on the recipient’s body when they sniffed the head or abdomen than the rear as the first area on the recipient’s body; when both dogs sniffed one another than when only one dog sniffed the other; and also when they initiated sniffing than when they did not. Dogs more likely sniffed the abdomen or rear than the head as the last area on the recipient’s body, when only one dog sniffed the other than when both dogs sniffed one another; and also when they sniffed more than one area on the recipient’s body than when they sniffed only one area. Dogs more likely terminated sniffing than not when an adult dog encountered a puppy than vice versa. In conclusion, dyadic sniffing behaviors between sexually intact dogs, each walking with one owner, were mainly associated with the owners’ communication, the number of sniffing dogs within a dyad, the dog’s sex and age and with the initiation of sniffing.
A prolonged stress hyporesponsive period (SHRP) due to the mother's presence may delay the timing of glucocorticoid (GC) elevation in infants, thereby reducing the excessive stress response that would affect post-growth temperament. In dogs, the SHRP has been suggested to persist until postnatal week (PW) 4; therefore, PW 5, which SHRP may be prolonged by the mother dog, may be a critical point in the developmental stage of dogs to establish stress responsiveness. We conducted a long-term survey on the development of dogs to investigate i) whether the degree of the stress response at PW 5 is determined by maternal behavior and ii) whether it can predict post-growth stress responses and temperament in dogs. As a result, the offspring of mother dogs who had more delivery experience and exhibited more maternal behavior showed higher basal cortisol concentrations at PW 5. These offspring may have acquired less fear response as an individual trait and had relatively quick adaptability, albeit with high cortisol concentrations during exposure to novel environments post-growth, suggesting that high cortisol concentrations at PW 5 are linked to resilience post-growth. Basal cortisol concentrations at PW 7 were not affected by maternal variables and were not associated with cortisol response to novel environments post-growth. GCs are essential hormones that increase the probability of survival. Therefore, the high hypothalamic pituitary adrenal activities of the mother dogs and their offspring in this study may not immediately indicate negative states, and these results prompt a reconsideration of the role of GC in organisms.
Animal-assisted therapy (AAT) is highly heterogeneous at many levels, for example with regards to the setting itself, recipients of the intervention, species involved as therapy animals and their therapeutic potential. Dogs are the most commonly involved species in this work, and there may be good reasons for this beyond their availability. Some specific characteristics such as their cognitive and emotional capacities and biases, their evolutionary connection with humans, as well as a natural attraction and emotional connection between both species make dogs particularly suitable for AAT and many other forms of AAI. In this chapter, we elaborate on the significance of these characteristics and discuss the attributes required of an ideal dog working in this sort of context. Furthermore, we provide suggestions for strategies and approaches to optimally prepare, help, and support therapy dogs for and during their work in order to minimise risks, maximise therapeutic potential, and secure the well-being of all involved parties.
This chapter contextualizes the dog-human relationship in the dog's origin as a scavenger on the fringes of human settlements over 15,000 years ago. It then reviews the evidence for unique evolved cognitive structures in dogs that could explain their success in a human-dominated world. Failing to find evidence of unique human-like social-cognitive capacities I then review uncontroversial facts of dogs' basic behavioral biology, including reproductive and foraging behavior and, particularly, affiliative and attachment-related behaviors. This leads to consideration of dogs' social behavior, both conspecific and toward other species, especially humans. I draw attention to a seldom-noted apparent contradiction between dogs' stronger affectional bonds toward humans than toward members of their own species. Dogs' social groups also show steeper social hierarchies accompanied by more behaviors indicating formal dominance than do other canid species including wolves. I resolve this contradiction by proposing that dogs' intense sensitivity to social hierarchy contributes to their willingness to accept human leadership. People commonly control resources that dogs need and also unknowingly express behaviors which dogs perceive as formal signs of dominance. This may be what Darwin was referring to when he endorsed the idea that a dog looks on his master as on a god. Whatever the merits of this idea, if it serves to redirect behavioral research on dogs in human society more toward the social interactions of these species in their diverse forms of symbiosis it will have served a useful function.
Behavioural and brain lateralization is widespread among non-human vertebrates. Motor lateralization has been investigated in the domestic dog, revealing that “pawedness” in this species seems to be sex and task related; however, few if any studies considered this asymmetry in wolves (Canis lupus). The aim of this study was to investigate the paw preference of seven wolves housed at Parco Natura Viva – Italy, during the interaction with food-related (FD) and olfactory (OLF) environmental enrichment devices. Eleven sessions were done (22 session in total) per condition (FD and OLF), and data about enrichment manipulation were collected. Most of the wolves manipulated the enrichment devices using one paw rather than both paws. At the individual level, all subjects were lateralized in paw use, six were right pawed, one was left pawed (the alpha male) regardless of the enrichment condition. The fact that one paw rather than both was frequently involved in manipulation could indicate a practical advantage for each individual in being lateralized in paw use. Despite the small sample size, our results provide interesting insights about lateralization in wolves, deserving further investigations. More studies are needed considering factors such as temperament, social rank and task complexity on canid motor lateralization.
Twenty-five puppies, 7 males and 11 females from 3 litters of German Shepherds and 5 males and 2 females from 1 litter of Beagles, were assigned to either a hand-reared or litter-reared condition. Pups were individually tested for 10 min at 5.5 and 8.5 weeks of age in an arena with novel objects and wall patterns. Stimulus objects were different for each test session, and included the following: a mirror, metronome, balloon, clock, an empty rat cage, soiled rat litter, and a mouse in a cage. A principal components factor analysis done on scores of 5 measures of exploratory behavior showed 1 primary factor (exploratory behavior) operating at 5.5 weeks and 2 factors existing at 8.5 weeks. One of the latter factors was identified as locomotor activity, whereas the other factor involved reactions to novel objects, and was identified as stimulus reactivity. There were no differences in exploratory behavior due to sex, rearing, or their interaction at 5.5 weeks, or in locomotor activity at 8.5 weeks of age. Only stimulus reactivity was significantly affected by rearing at 8.5 weeks (P < 0.05); the hand-reared pups investigated and spent more time in the presence of the novel objects than the litter-reared subjects. An application of the findings is discussed.
Social development and behavior are compared for 4 Eastern timber wolves (C. lupus lycaon) and 4 Alaskan Malamutes (C. familiaris). The two groups were born a year apart, but all were fostered at approximately 10 days of age on the same lactating female wolf, reared jointly by the authors and the foster mother, housed in the same facility, and subjected to the same regimen of maintenance and social contact with adult members of the animal colony. It is suggested that many of the observed group differences can be attributed to selection in domestic dogs for prolongation of juvenile behavior and morphological characteristics. Discussion then focuses on the evolution and ontogeny of ritualized aggression in wolves and the effects of domestication on agonistic behavior in domestic dogs. It is suggested that the disintegration of ritualized aggression in dogs is, in part, a consequence of neotenization. Also implicated in the breakdown of this behavioral system is human provision of food, which relaxes (1) the behavioral consequences of injuries sustained in fighting and (2) the selective advantage enjoyed by group-hunting species who have evolved social systems of population regulation.
Recordings of averaged brain stem auditory-evoked potentials were obtained from 13 Beagle pups of both genders to document the postnatal development of the response from age 1 to 76 days. Responses were recorded between needle electrodes placed on the vertex and the ipsilateral ear, with ground at the interorbital line. Recordings were performed without sedation. Low-amplitude responses to high-intensity stimuli could be recorded from animals prior to opening of the ear canals. Peak latencies did not change after day 20 for peak I, day 30 for peaks II and III, and day 40 for peak V. As a result, the interpeak latencies between peaks I and III did not change after day 30, but continued to decrease until day 40 for peaks III-V and I-V. Peak amplitudes reached plateau values by day 20 (peak I) or day 30 (peaks II, III, and V). All of the measured latency and amplitude values had significant (P less than 0.001) linear regression lines of latency vs age and amplitude vs age. The brain stem auditory-evoked potential thresholds were mature by day 20.
The most commonly kept domestic animal in the developed world, the cat has been a part of human life for thousands of years. Cats have been both worshipped and persecuted over this long period - either loved or hated for their enigmatic self-reliance and the subject of numerous myths and fables. Highlighting startling discoveries made over the last ten years, this new edition features contributions from experts in a wide range of fields, providing authoritative accounts of the behaviour of cats and how they interact with people. Thoroughly revised and updated to include information on the basic features of cat development and social life, the history of their relations with humans, health and welfare problems, and the breeding of cats for sale and for show. It is intended for all those, whether specialist or general reader, who love or are simply intrigued by these fascinating animals.
The main aim of this book is to provide a basis for a complete dog behavioural biology based on concepts derived from contemporary ethology. Thus, dog behaviour is viewed from both functional (evolution and ecology) and mechanistic and developmental points of view. The study of dogs is placed in a comparative context which involves comparison with their ancestors (wolves), as well as with humans with which dogs share their present environment. Instead of advocating a single theory which would explain the emergence of dogs during the last 20,000 years of human evolution, this book gives an overview of present knowledge which has been collected by scientists from various fields. It aims to find novel ways to increase our understanding of this complex evolutionary process by combining different methods originating from different scientific disciplines. This is facilitated by describing complementing knowledge provided by various field of science, including zooarchaeology, cognitive and comparative ethology, human-animal interaction, behaviour genetics, behavioural physiology and development, and behavioural ecology. This interdisciplinary approach to the study of dogs deepens our biological understanding of dog behaviour, but also utilizes this knowledge to reveal secrets to behavioural evolution in general, even with special reference to the human species.
Thesis (M.S.)--Idaho State University, 1966. Bibliography: l. 79-82.
The effects of early weaning on the sexual behavior and reproductive success of ranch mink (Mustela vison) were tested. Male and female mink were weaned at various ages from 5 to more than 10 weeks after birth. the behavior associated with reproduction during their first breeding season was analyzed and a critical socialization period for exhibition of this behavior delimited. Females weaned prior to 8 weeks post-partum were significantly easier to breed than females weaned at 8 weeks of age or older. Successful breeding performances by the males apparently depended on a critical period of socialization in the litter environment occurring within 5 to 8 weeks after birth. Visual isolation appeared to inhibit reproductive behavior somewhat, possibly due to an asynchrony in physiological development.
A detailed analysis was made of the process by which the wolf comes from a state of unfamiliarity and fear of humans to a state of familiarity and friendliness. The nature of the process was found to depend on the age of the animal as well as the technique employed by the experimenter. Although young cubs were found to respond positively to almost any form of human contact, the older cubs and juveniles required much more time and effort to socialize, and fully matured adults offered very special problems which required specialized techniques to overcome. Periods beyond which no socialization could occur were not found. Wolves socialized as cubs had to be reinforced repeatedly in order to maintain their social bond with humans; however, adult wolves retained their socialized behavior even after being left with unsocialized animals and not handled for 18-22 months. Wolves socialized with the aid of tranquilizing drugs (chlorpromazine, librium, and reserpine) did not retain their socialization when the drugs were withdrawn on a variety of schedules. The development of fear responses as the animals grow older, and the association of fear with the unfamiliar, closely parallel the increasing difficulty of acquiring socialized behavior as well as the decreasing difficulty of retaining that behavior once it is acquired. Socialization is viewed as a conditioning process which must take place after the development and in the presence of the free expression of the subjective components of fear, a separable aspect of the general phenomenon of genetic wildness.
Observations on the behavioral development of a male timber wolf, hand-reared from the age of four weeks, have been continued for a period of three years. Data include the following: (1) Adjustment to human companionship has been successful even after sexual maturity. (2) Behavior towards strange persons and objects is cautious. (3) The animal remains more independent and aloof to persons than similarly reared dogs. (4) Interaction with dogs, including males and young puppies, is marked by gregariousness and lack of aggression. (5) Small domestic species have been attacked occasionally, the response depending largely upon the behavior of these animals. (6) Large species are avoided, chased, or ignored. (7) Numerous motor patterns, postures, and communicative signals are closely similar to siblings and other wolves and contrast with dog companions. (8) Sharp behavioral changes occurred at eight and 12 weeks, the former initiating aggressive tendencies, the latter extreme avoidance in the presence of new objects. Restlessness, then calming, followed in later months, and slight seasonal fluctuations have been noted. (9) Rudiments of many adult motor patterns occurred at an early age, e.g., small prey-pounces and pelvic thrusts seen by eight weeks. (10) Vocalizations include a wide repertoire of howls, squeaks, growls, and barks.
In recent years much interest has been focused on early experiences and numerous studies have been carried out in order to understand their effects on the behaviour of adult animals. The aim of this preliminary study was to assess the effects of early gentling and early environment on the emotional stability of puppies. Forty-three dogs (16 females and 27 males) from seven litters were used. Four of these litters (in total 23 puppies) were raised in a professional breeding kennel, while the remaining litters lived in their owner's home, in a family atmosphere. Half of every litter was gently handled daily from the 3rd day postpartum until the 21st. In order to assess the puppies’ emotionality, an isolation test followed by an arena test were conducted on every puppy at the age of 8 weeks. Video recording of the tests allowed the measurement of each puppy's vocalization and exploratory activity. Data were analysed with the Newmann–Keuls’ test comparing four groups: non-handled puppies raised in family (NHF); handled puppies raised in family (HF); non-handled puppies raised in a professional breeding kennel (NHB); handled puppies raised in a professional breeding kennel (HB).The results suggest that early environment strongly influences the emotional stability of puppies when put in isolation: latency to the first yelp was longer (p
Restricted experience in early life is known to contribute to long-lasting predispositions to fear and anxiety in mammals. It is commonplace for young domestic dogs not to experience many features of the environment in which they will spend their adult lives until after 8 weeks of age: simulations of that environment presented before 8 weeks might therefore reduce subsequent fear and anxiety. A series of experiments tested whether fearful and exploratory behaviour up to 8 weeks of age is reduced by exposure to audiovisual playback between 3 and 5 weeks of age. First, it was demonstrated that puppies between 3 and 5 weeks of age do respond to video images. Second, the reactions of puppies, exposed to audiovisual playbacks for 30min per day for 14 days between 3 and 5 weeks old, to test objects in both familiar and unfamiliar environments, were compared with those of control, unexposed puppies; the unexposed puppies visited most of the objects significantly more frequently than did the exposed puppies. Third, another sample of puppies given the same treatments was tested at 7–8 weeks of age; the unexposed puppies were significantly more fearful than the exposed, and also tended to visit the objects more frequently. Audiovisual simulations therefore appear to be worthy of further investigation as a way of enhancing coping strategies in dogs.
At an experimental farm in Novosibirsk, Siberia, geneticists have been
working for four decades to turn foxes into dogs. They are not trying to
create the next pet craze. Instead, author Trut and her predecessors
hope to explain why domesticated animals such as pigs, cattle and dogs
are so different from their wild ancestors. Selective breeding alone
cannot explain all the differences. Trut's mentor, the eminent Russian
geneticist Dmitri Belyaev, thought that the answers lay in the process
of domestication itself, which might have dramatically changed wolves'
appearance and behavior even in the absence of selective breeding. To
test his hypothesis, Belyaev and his successors at the Institute have
been breeding another canine species, silver foxes, for a single trait:
friendliness toward people. Although no one would mistake them for dogs,
the Siberian foxes appear to be on the same overall evolutionary
path—a route that other domesticated animals also may have
followed while coming in from the wild.
Social behavior of dogs raised singly with cats from 25 days to 16 weeks of age was studied. A series of tests evaluated the effects of such restricted social experience and later recovery and comparisons were made between cats and dogs that had or had not prior social experience with an alien species. Dogs raised with cats showed a marked intra-species avoidance and lack of species or self-identity. The intra-specifically directed greeting was absent but reappeared following intra-species socialization, together with species or self-identity. Only cats with prior experience with a dog interacted socially with dog raised dogs while the latter always solicited play from cats.
Hediger reports field observations and experimental studies of the behavior of a wide variety of animals, from paramecium to elephants. Pertinent literature is reviewed. Among the chapters are: "The animal's daily life," "The animal and its enemies," "Flight and hypnosis" and discussions of social and maternal behavior, contrasting traits of wild and domestic animals, "animal psychology in the circus," training of animals and the expressions of animals. 198-item bibliography. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
The development of auditory localization in dogs was investigated in a litter of 12 pups. Behavioral auditory localization consisted of orienting responses to dog vocalizations presented from loudspeakers 90 degrees to each side. Sounds were presented in two configurations, single source (only one loudspeaker) and precedence effect (both loudspeakers, with one slightly leading the other). Localization began around 16 days after birth, for single-source sounds. This is consistent with previous observations and with findings on dogs' auditory neural development. Single-source sounds were localized earlier during development than precedence-effect sounds. This ordering resembles findings on human infants and can be related to neuroanatomical investigations of mammalian brain structures mediating single source versus precedence effect localization.
Visual deprivation in dogs during the first 5 weeks of life resulted in marked structural, biochemical, and electrophysiological changes which were not apparent in dogs similarly treated between 5 and 10 weeks of age or for 5 weeks as adults. These findings are discussed in relation to the period of integration, when structuro-functional relationships of neural elements begin to reach adult-like levels of organization. It was postulated that lack of stimulation of a sensory modality during this period would result in arrested development of the system so treated. This hypothesis was partially supported; although there was complete visual deprivation, some neuronal and myelin development occurred independent of visual stimulation. Visual evoked potentials were markedly abnormal in the youngest age group only. The findings suggest a “sensitive” period in the pathodevelopmental sense; development of a particular system is retarded if stimulation is inadequate. This period corresponds to the period of integration when structuro-functional organization of component systems of the central nervous system occurs.
Feeding young mammals is often used as a way to increase their affinity to their human caregiver. However, feeding is not always necessary, which raises questions as to the feeding method used (bottle, bucket) and to the importance of contacts surrounding feeding compared to an absence of human contact. These questions are the focus of this study.At early age, lambs were divided into 4 treatments: no contact, holding, holding and hand-feeding with a bottle (hand bottle-fed), or feeding using a bottle attached to a stand (wall bottle-fed). The treatment sessions (5min) were repeatedly applied every day for 1 week and then twice-a-week for 2 weeks. Contacts to the caregiver were measured during the treatments. Then, from 3 weeks of age, the lambs were tested in an unfamiliar pen to measure their attraction to the caregiver and the effects of caregiver presence and departure on distress behaviours. Exploration of objects and response to a sudden event in the presence of the caregiver were also measured.During the treatments, hand bottle-fed lambs interacted more with their caregiver (54±2% of the observations) than held lambs (25±3%, p
Using chronically implanted electrodes in the visual and auditory cortex, the development of evoked responses was studied in restrained but unanesthetized dogs of various ages. Neuronal development was evaluated from Golgi-Cox preparations of visual and auditory cortex. Development of both visual and auditory evoked responses was rapid during the first 3 weeks of life, attaining relatively mature characteristics by 4-5 weeks. Similarly, neuronal development in both cortical areas approximated adult complexity by 4-5 weeks, the most rapid development occurring during the first 3 weeks in both the deeper and more superficial cell layers. Subsequent developmental changes after 5 weeks were more gradual, and contrasted the rapid development of all parameters studied during the period from birth to 3 weeks of age. The significance of qualitative differences in the ontogeny of visual and auditory evoked responses and of the different neuronal layers is discussed.
Prenatal chemosensory learning has been demonstrated in a wide variety of mammals, including humans, sheep, rabbits, rats and mice, and it may help to shape development and behaviour. The domestic dog, Canis familiaris, is renowned for its olfactory acuity. Furthermore, it belongs to an order of mammals (Carnivora) for which there has been no evidence of prenatal learning. We examined how prenatal exposure to a chemosensory stimulus (aniseed), via the mother's diet, affected the chemosensory preferences of neonatal pups. Pups received two-choice tests of aniseed versus water and vanilla (a novel odour) versus water. Twenty-four-hour-old pups exposed to aniseed during gestation preferred aniseed more than did pups not exposed to this odour (experiment 1) but showed no preference for vanilla over water (experiment 2). Thus, the preference was specific to the stimulus experienced in utero. Pups tested 15 min after birth showed a similar preference for aniseed (experiment 3), thus ruling out the possibility that postnatal exposure influenced the preference. The results indicate that prenatal chemosensory learning is present in the Carnivora and suggest that such learning may be present in all mammals, serving an important function in early mammalian development.
Herbivore damage is generally detrimental to plant fitness, and the evolu- tionary response of plant populations to damage can involve either increased resistance or increased tolerance. While characters that contribute to resistance, such as secondary chem- icals and trichomes, are relatively well understood, characters that contribute to a plant's ability to tolerate damage have received much less attention. Using Helianthus annuus (wild sunflower) and simulated damage of Haplorhynchites aeneus (head-clipping weevil) as a model system, we examined morphological characters and developmental processes that contribute to compensatory ability. We performed a factorial experiment that included three levels of damage (none, the first two, or the first four inflorescences were clipped with scissors) and eight sires each mated to four dams. We found that plants compensated fully for simulated head-clipper damage and that there was no variation among plant families in compensatory ability: seed production and mean seed mass did not vary among treat- ments, and sire X treatment interactions were not significant. Plants used four mechanisms to compensate for damage: (1) Clipped plants produced significantly more inflorescences than unclipped plants. Plants produced these additional inflorescences on higher order branches at the end of the flowering season. (2) Clipped plants filled significantly more seeds in their remaining heads than did unclipped plants. (3) Clipped plants, because they effectively flowered later than unclipped plants, were less susceptible to damage by seed- feeding herbivores other than Haplorhynchites. (4) In later heads, seed size was greater on clipped plants, which allowed mean seed size to be maintained in clipped plants. Although there was genetic variation among the families used in this experiment for most of the characters associated with compensation for damage (seed number, mean seed size, mean flowering date, length of the flowering period, and branching morphology), in analyses of these characters, no sire X treatment interactions were significant indicating that all of the families relied on similar mechanisms to compensate for damage.
The physiological boundaries of the sensitive period of primary socialization were studied in the silver fox (Vulpes fulvus Desm). A total of 273 farm-bred foxes from 59 litters were observed from 1976 to 1978; pups were produced by vixens from two populations, one selected for domesticated behaviour and the other unselected. Results indicate that the age when the eyes are fully open, when the response to sound first appears and when exploratory behaviour is first shown in strange surroundings is 3 weeks, on average. The age when the socialization period starts appears to be 20–25 days old. The optimum period of the formation of primary social bonds appears to be 30–35 days, when maximum exploration in a novel situation is shown. The 40–45 days period appears to be the upper boundary of primary socialization in unselected foxes because pups show fear in response to novel stimuli, which prevents exploration. In pups from the population of domesticated foxes, the sensitive period of socialization is prolonged to over 60–65 days old.
The classic study of dog behavior gathered into one volume. Based on twenty years of research at the Jackson Laboratory, this is the single most important and comprehensive reference work on the behavior of dogs ever complied. "Genetics and the Social Behavior of the Dog is one of the most important texts on canine behavior published to date. Anyone interested in breeding, training, or canine behavior must own this book."âWayne Hunthausen, D.V.M., Director of Animal Behavior Consultations "This pioneering research on dog behavioral genetics is a timeless classic for all serious students of ethology and canine behavior."âDr. Michael Fox, Senior Advisor to the President, The Humane Society of the United States "A major authoritative work. . . . Immensely rewarding reading for anyone concerned with dog-breeding."âTimes Literary Supplement "The last comprehensive study [of dog behavior] was concluded more than thirty years ago, when John Paul Scott and John L. Fuller published their seminal work Genetics and the Social Behavior of the Dog."âMark Derr, The Atlantic Monthly "Genetics and the Social Behavior of the Dog is essential reading for anyone involved in the breeding of dogs. No breeder can afford to ignore the principles of proper socialization first discovered and articulated in this landmark study."-The Monks of New Skete, authors of How to Be Your Dog's Best Friend and the video series Raising Your Dog with the Monks of New Skete.
Discusses neural activity and stimulation crucial in fetal brain development and the formation of the mind. Focuses on activity-dependent remodeling related to development of the visual system and retinal activity. (MCO)
The general theory of critical periods applies to organizational processes involved in the development of any living system on any level of organization and states that the time during which an organizational process is proceeding most rapidly is the time when the process may most easily be altered or modified. Complex organizational processes involving 2 or more interdependent subprocesses may show 1 to several critical periods, depending on the time relationships of the subprocesses. The nature of the relationships between interdependent processes operating on different levels is again dependent on time and is a more meaningful formulation than that of the old “innate-acquired” dichotomy. These theoretical considerations lead to the conclusion that understanding a critical-period phenomenon rests on analyzing the nature of the organizational process or processes involved. An example is given in a review of research on the critical period for primary socialization (social attachment) in the dog. Evidence that attachment has taken place consists of discriminative behavior in relation to familiar and unfamiliar objects and rests on a minimum of 3 processes: (1) organization of the separation distress response; (2) visual and auditory sensory capacities; and (3) long-term associative memory capacities. Once these capacities are developed, the overall attachment process proceeds very rapidly (the critical period for such attachment). Thus the critical periods for the organizational subprocesses precede or slightly overlap that for the overall process. Deeper analyses of these processes must rest on neurophysiological research. The theory of critical periods is a general one that should apply to any developmental organizational process which proceeds at grossly different rates at different times.
The reaction of dogs toward a monochrome painting of an adult conspecific were evaluated developmentally at 6, 8, 10, 12, and 16 weeks of age. Highest frequencies of interaction toward the head and inguinal regions of the model occurred at 6 and 8 wk and increased at these ages following food deprivation. These findings are discussed in relation to the development of social behavior in the dog.
CLASSICAL, imprinting of precocial birds has been studied in the laboratory for some 20 years. Suggestions have also been made over a similar period about the imprinting of precocial mammals, but no systematic experiments specifically concerned with imprinting have been reported so far. Although Shipley's study of guinea-pigs1 referred to imprinting, in reality it was concerned with the approaches and following responses of these animals to moving objects. Imprinting involves more than that, namely an attachment to a given figure, and this can be readily assessed in a discrimination test2. The experiment reported here describes imprinting in young guinea-pigs, judged in terms of the animals' preference for familiar, compared with strange, objects.
The effects of handling from birth to 5 weeks and isolation from 4 to 5 weeks were studied in twenty-tow dogs and contrasted with the behaviour of control subjects raised under normal rearing conditions. Differences in behaviour, heart rate and