The bond­ing power of puppy-dog eyes

Los Angeles Times - - CALIFORNIA - MELISSA HEALY melissa.healy@la­times.com Twit­ter: @LATMelis­saHealy

The long, lov­ing gazes. The rit­u­al­ized, of­ten high­pitched ex­pres­sions of af­fec­tion. The heroic self­sac­ri­fice one would read­ily en­dure for the other.

What is it about the bond be­tween hu­man and dog that is not like the re­la­tion­ship be­tween par­ent and child?

Science of­fers a new ex­pla­na­tion for the sim­i­lar­ity. When our dogs gaze into our eyes with that “you are ev­ery­thing to me” look, our bod­ies — and theirs as well — are flooded with oxy­tocin, the hor­mone of love and nur­ture that ce­ments the bonds be­tween peo­ple.

In fact, the more that dog own­ers and their ca­nine com­pan­ions gazed into each other’s eyes, the more con­cen­trated the burst of oxy­tocin both hu­man and ca­nine pro­duced, Ja­panese re­searchers dis­cov­ered. And the more we hu­mans re­turn a pet’s gaze and the greater the re­sult­ing surge of oxy­tocin, the more em­phat­i­cally we be­lieve ours is the best dog in the whole wide world. (Yes, she is!)

Th­ese find­ings, pub­lished last week in the jour­nal Science, come cour­tesy of 30 beloved pets — in­clud­ing golden and Labrador re­triev­ers, minia­ture schnauzers and dachshunds, stan­dard and toy poo­dles, and a boxer, bor­der col­lie, Ger­man shep­herd and Shet­land sheep­dog.

For the sake of com­par­i­son, the re­searchers also an­a­lyzed the spon­ta­neous in­ter­ac­tions be­tween 11 wolves and the an­i­mal man­age­ment pro­fes­sion­als who had raised, fed and played with them. In those en­coun­ters, they saw nei­ther the mu­tual gaze (not sur­pris­ing, since wolves gen­er­ally lock eyes with other wolves to threaten them) nor the oxy­tocin surge.

In a sep­a­rate ex­per­i­ment, the re­searchers gave a dose of oxy­tocin to dogs be­fore they spent 30 min­utes with their own­ers. The hor­mone boost in­creased the num­ber of times and the du­ra­tion for which fe­male dogs locked eyes with their own­ers, in turn send­ing more oxy­tocin into their own­ers’ blood. The re­sponse was not noted with male dogs, pos­si­bly be­cause oxy­tocin plays a lesser role in re­pro­duc­tion for them.

The find­ings — “that hu­mans may feel af­fec­tion for their com­pan­ion dogs sim­i­lar to that felt to­ward hu­man fam­ily mem­bers,” as the re­searchers put it — are likely to be greeted by dog lovers with a “duh.”

But for sci­en­tists, the ex­per­i­ments help solve a perplexing evo­lu­tion­ary mys­tery: How did two species from very dif­fer­ent branches of the evo­lu­tion­ary tree come to live to­gether in such close har­mony?

The an­swer is that over eons of co-evo­lu­tion, dogs prob­a­bly in­sin­u­ated them­selves into hu­man so­ci­ety by adopt­ing the be­hav­ior and the neu­ral ma­chin­ery that draw hu­mans to­gether in tight pair-bonds.

The study high­lights the power and ver­sa­til­ity of oxy­tocin, said Stan­ford Uni­ver­sity neu­ro­bi­ol­o­gist Robert M. Sapol­sky, who was not in­volved in the Ja­panese re­search. Across many species, the neu­ropep­tide plays a key role in mother-in­fant bond­ing. But its in­flu­ence doesn’t stop there, he said.

“Evo­lu­tion is a tin­kerer, and when a small sub­set of species came up with the novel busi­ness of form­ing monog­a­mous pair-bonds, the oxy­tocin sys­tem got co-opted to fuel the bond­ing,” Sapol­sky said. “When hu­mans and dogs came up with this even stranger, more unique re­la­tion­ship, it looks like oxy­tocin got coopted for that as well.”

In­deed, oxy­tocin’s ef­fect may help ex­plain why “look­ing at cute pup­pies and cute ba­bies ac­ti­vates the same re­ward sys­tem in the brain,” Sapol­sky said.

That strik­ing sim­i­lar­ity may go a long way to­ward ex­plain­ing why and how oxy­tocin could be use­ful in the treat­ment of a wide range of neu­ropsy­cho­log­i­cal prob­lems, ac­cord­ing to a pair of an­i­mal cog­ni­tion re­searchers from Duke Uni­ver­sity who wrote an es­say that ac­com­pa­nied the study.

Ser­vice dogs, which are bred and trained to de­velop par­tic­u­larly pow­er­ful bonds with their own­ers, are prov­ing their worth with pa­tients, wrote Evan L. MacLean and Brian Hare. It’s prob­a­bly no co­in­ci­dence, they sug­gested, that sup­ple­men­tal oxy­tocin is also show­ing prom­ise help­ing peo­ple with post-trau­matic stress dis­or­der re­duce anx­i­ety, and help­ing those on the autism spec­trum build so­cial skills.

Big­ger stud­ies with more di­verse pop­u­la­tions of dogs and peo­ple will be needed to con­firm that pets and ser­vice an­i­mals can func­tion as furry, four-legged oxy­tocin dis­pensers, Hare and MacLean wrote.

In the mean­time, they added, the Ja­panese re­searchers “have pro­vided more ev­i­dence that when your dog is star­ing at you, she may not just be af­ter your sand­wich.”

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