How dogs became “Man’s best friend”

Although we do not know the origin of the domestication of dogs, it is assumed that certain factors were determining in their proximity to humans. Especially through the obedience and the dogs’ ability to forge social bonds with us. Researchers from the University of Azabu (Japan) are interested in the impact of domestication on dog behavior. They realized that current dog breeds had genetic specificities compared to older breeds. In addition, these specificities would be involved in changing 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 investigate whether there were behavioral differences between the old dog breeds 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 of food. After this heating, the experimenter presented the same container, but this time closed mechanically, therefore impossible to open. The dog’s behavior was recorded on video for analysis. The latency, duration, and number of glances from the dogs toward the test leaders were measured. The second was a double-choice test. Canids had two upturned bowls available, one containing food. During the warm-up, the dogs had to learn to recognize the dish that contained the food. For the test, the test leaders indicated to the dogs what was the “good dish” at different signals. By tapping the bowl, pointing the finger at the bowl or doing nothing (control mode). The number of correct responses was recorded and the dogs’ behavior 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 differences were determined by the genetic distance between different groups of dogs and wolves. As a result, for the problem-solving test, dogs of “old” breeds looked less often at the test leaders than dogs of “newer” breeds. On the other hand, the researchers did not observe a significant difference for the double-choice test. Dogs of “newer” breeds and “older” breeds showed similar abilities to understand human gestures and adapt their reactions accordingly. In this test, it was the dog’s ability to understand human commands and adapt their behavior accordingly that was tested. The researchers therefore assumed that this ability developed very early during the domestication of dogs.

Also read: Here’s why cats’ brains shrink because of us. Safe from danger in humans, tame cats’ brains would slowly but surely undergo a transformation: they would have shrunk.

Genetic analyzes on different groups of dogs

The researchers wanted to link their behavioral observations with genetic analyzes. 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 Biotechnological Information. After analysis, they discovered 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 dog breeds. The goal ? See if there is a difference 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 in the dog’s behavior

Previous studies have assumed that these genes are involved in dog behavior. The MCR2 gene is particularly involved in the production of cortisol. The drop in cortisol can ease dogs’ fearlessness towards humans. Oxytocin (OT) is thought to be involved in how dogs respond to human social signals, such as pointing the finger in the direction of an object. The genetic variation of oxytocin receptors (OTR) would be correlated with the search for proximity to humans. Finally, hypersociability, a key characteristic of the WBSCR17 gene, is also an element that distinguishes dogs and wolves. In fact, the dog presents a change in this gene. These changes would have emerged during the domestication process.

The consequences of domestication

But what is the connection between these genetic modifications and domestication? These modifications would have been chosen naturally or artificially – that is, when humans cross different dog breeds. The current hypothesis is that “old” wolves, exhibiting 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 show good communication skills with humans, genetic changes must have taken place during the domestication of dogs.

To elucidate the relationship between the identified genes and the observed behavior, it will be necessary to study the developmental processes of dogs and wolves. Then measure their hormone levels according to development. In addition, dogs’ social behaviors are complex. They can not be completely explained by the identified genes alone and must be controlled by multiple genes. It will therefore be necessary to search for other genes and verify their global effects.

Also read: Animals: they also feel rich and complex emotions. Attachment, grief, jealousy … Science today reveals a sensory palette that is almost as rich and complex as ours!

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