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Dogs cry with joy when their master returns, shows a Japanese study published on Monday August 22.
SCIENCE – Crying with joy. After each absence, the dogs stamp their feet with impatience at the idea of finding their master. Standing on their hind legs, they wag their tails and bark happily, but did you know your dog cries when you come back? This is what Japanese researchers discovered in a study published this Monday, August 22 in the journal Current Biology.
To find out, scientists measured the amount of tears produced using a widely used test, the Schirmer test (consisting of a strip placed under the eyelid). They took as a point of comparison a base level raised when the dog was in its usual environment, in the presence of its owner.
The hormone of love at its peak
After five to seven hours of separation, the amount of tears increased “significantly” within five minutes of reuniting the dog with its owner. On the other hand, the doggies did not cry when they met a familiar person who was not their owner.
“We had never heard of pets shedding tears in happy situations, like reuniting with their owner”one of the study’s authors, Takefumi Kikusui of Azabu University, said in a statement, citing a likely “world premiere”.
In humans, greater tear volume is linked to greater emotional arousal, and the current findings suggest that it is positive emotions that cause the extra tears in dogs as well. Indeed, the researchers observed an increase in oxytocin, the love hormone, when the dog found a loved one.
A way to appease us?
Besides this hypothesis of an excess of love, dogs could simply try to appease us. Dogs, domesticated like no other animal, have actually developed specific communication skills over time.
Eye contact has been shown to play a role in forming the relationship between a dog and its handler. “Dogs that exhibit misty eyes during their interactions with their owner may lead the owner to care for them more”advanced Takefumi Kikusui.
While finding tears of joy in our canine companions would be groundbreaking, “ other scientists are not convinced by this new experiment or its methodology”, nuance the site specialized in Sciences Sciencealert. Some animals use crying to clean their eyes, to remove dust for example. Further research will therefore need to be conducted to determine with certainty whether dogs cry as a reflex or to express their emotions.
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