Even if we do not know the origin of the domestication of dogs, it is assumed that certain factors were determining in their proximity to humans. In particular through the docility and the ability of dogs to form social ties with us. Researchers from the University of Azabu (Japan) are interested in the impact of domestication on the behavior of dogs. They realized that current dog breeds had genetic specificities compared to older breeds. Moreover, these specificities would be involved in modifying the behavior of dogs. The team published their findings in the journal Scientific Reports.
Behavioral tests on different groups of dogs
The researchers first wanted to check whether there were any behavioral differences between the old breeds of dogs and the newer ones. To do this, they gave groups of dogs two tests. The first test was problem solving. The principle ? The dogs first learned the task of opening a container with food. After this heating, the experimenters presented the same container but this time closed mechanically, therefore impossible to open. The behavior of the dogs was recorded on video for analysis. The latency, duration and number of gazes of the dogs towards the experimenters were measured. The second was a double choice test. The canids had two upturned bowls available, one containing food. During the warm-up, the dogs had to learn to recognize the bowl that contained the food. For the test, the experimenters indicated to the canids which was the “good bowl” by different signals. By tapping on the bowl, pointing their finger at the bowl or doing nothing (control mode). The number of correct answers was recorded and the behavior of the dogs was also analyzed on video.
A comparison between “old” and “new” dog breeds
For these two tests, the researchers compared the behavior of dogs of “old” and “new” breeds by separating them into several groups. These distinctions were determined by the genetic distance of different groups of dogs from wolves. As a result, for the problem-solving test, dogs of “old” breeds looked at the experimenters less often than dogs of “recent” breeds. On the other hand, for the double-choice test, the researchers did not observe a significant difference. Dogs of “newer” breeds and “older” breeds showed similar abilities to understand human gestures and adapt their responses accordingly. In this test, it was the ability of canids to understand human commands and adapt their behavior accordingly that was tested. The researchers therefore hypothesized that this ability evolved very early during the domestication of dogs.
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Genetic analyzes on different groups of dogs
The researchers wanted to link their behavioral observations with genetic analyses. They looked at 4 genes: WBSCR17, MC2R, OT and OTR, which they assumed were involved in dog behavior. They then searched for genetic variations for these genes from the databases of Together and National Center for Biotechnology Information. After analysis, they detected several SNPs (Single Nucleotide Polymorphism), which are variations of a single base pair of the genome. Next, they determined the frequency of these variations within different breeds of dogs. The goal ? See if there are any differences between “old” and “newer” dog breeds. As a result, the researchers identified 5 SNPs that showed significant differences between these groups of dogs.
The consequences of hormonal differences on dog behavior
Previous studies have assumed that these genes are involved in dog behavior. The MCR2 gene is notably involved in the production of cortisol. The decrease in cortisol may facilitate dogs’ fearlessness of humans. Oxytocin (OT) is thought to be involved in dogs’ response to human social cues, such as pointing their finger at an object. The genetic variation of oxytocin receptors (OTR) would be correlated with the search for closeness with humans. Finally, hypersociability, a central characteristic of the WBSCR17 gene, is also an element that distinguishes dogs and wolves. Indeed, the dog presents an alteration of this gene. These modifications would have appeared during the process of domestication.
The consequences of domestication
But what is the link between these genetic modifications and domestication? These modifications would have been selected naturally or artificially – that is, when humans cross different breeds of dogs. The current hypothesis is that “ancient” wolves that exhibited low levels of fear and aggression began to approach human areas and evolved into dogs. Since wolves, which share the same ancestry as dogs, do not exhibit good communication skills with humans, genetic changes must have occurred during the domestication of dogs.
To elucidate the correlations between the types of genes identified and the behaviors observed, it will be necessary to study the developmental processes of dogs and wolves. Then measure their hormone levels after development. In addition, the social behaviors of dogs are complex. They cannot be completely explained by the identified genes alone and must be controlled by several genes. It will therefore be necessary to search for other genes and verify their global effects.
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