飼い主の存在、犬同士での遊びを後押し　米研究

【ワシントンＡＦＰ＝時事】ペットとして飼育されている犬は、飼い主がそばにいて、犬のことを気にかけている時に、より犬同士で遊ぶ傾向にあるとの研究論文がこのほど、発表された。（写真は資料写真）
　動物行動学者で、ドイツの専門誌「Ａｎｉｍａｌ　Ｃｏｇｎｉｔｉｏｎ（動物の認知）」に掲載された論文の筆頭著者であるリンジー・マーカム氏は９日、人が示す関心に飼い犬が応えることは、よく知られているとＡＦＰに語った。
　「しかし、人に見られていることが、犬たちの行動──今回の場合は犬同士の遊び──に影響を与えることを明確に示した研究はこれまで見たことがない」
　米モンマス大学のマーカム助教（心理学）は今回、飼育期間６か月以上の犬１０組を対象に実験を行った。
　研究者らは、「飼い主がいない場合」、「飼い主はいるが犬を無視している場合」、「飼い主が犬を気にかけ、言葉で褒めたりなでたりしている場合」の３通りの条件下で、犬たちの行動を記録した。実験は７日間にわたって行われ、それぞれの条件が３回ずつ繰り返された。
　「実験の結果、飼い主が気にかけることで、犬の遊びが促される様子は全体的に見て取れた」とマーカム助教は話す。「プレイングバウ」と呼ばれる上半身を伏せておしりを高く上げる姿勢、おしりを相手に押し付ける行為、さらにはじゃれ合い、追いかけっこ、あまがみなど、その頻度と強度がいずれも高まったと説明した。
　研究者らは、考え得る理由をいくつか挙げている。
　一つは、幼い子どもが自分のできることを親に見せたがるのと同様に、飼い主からの注目は犬が求めるご褒美だというもの。
　飼い主が犬を安心させるという見方もある。動物たちは遊びを通じて絆を強めるが、時に緊張が生まれ攻撃的になることもある。人がそばにいれば、けんかに発展したとしても安心というわけだ。
　その他、飼い主の存在が周囲の雰囲気をよくするきっかけとなり、愛情ホルモンのオキシトシンが放出されてポジティブな気分が高まり、それが遊びという形で表れるということも考えられるという。【翻訳編集ＡＦＰＢＢＮｅｗｓ】

〔ＡＦＰ＝時事〕（2021/02/17-15:07）

Pet dogs are far more likely to play with one another when their owner is present and being attentive, according to a new study, raising the intriguing possibility that they are putting on a show for our benefit.
That our canine companions are keenly attuned to the level of interest humans are showing them is well established, Lindsay Mehrkam, an animal behaviorist and lead author of the paper that appeared in Animal Cognition, told AFP Tuesday.
But we weren't aware of any research that has really shown the effect of a human audience impacting species typical behavior, in this case dog-dog play.
Mehrkam oversaw an experiment involving 10 pairs of pet dogs that had lived together for at least six months.
The duos ordinarily engaged in play at least once a day, according to their owners.
The researchers videotaped the dog pairs under three conditions: where the owner was absent, where the owner was present but ignoring them, and where the owner was present and showering them with attention in the form of verbal praise and petting.
To ensure the experiment was robust, they ran each of the conditions three times over the course of several days.
We found overall that the availability of owner attention did in fact facilitate play, said Mehrkam, with human attention increasing both the frequency and intensity of behaviors like bowing, hip nudges, wrestling, chasing, gentle bites and so on.
It's really quite striking that dogs who have the chance to play with each other whenever they want to, nonetheless are much more likely to get up off their butts and start playing when a person is just paying attention to them, said co-author Clive Wynne of Arizona State University.
- Seeking attention like children? -
The researchers offered several ideas for what might be driving the effect.
One possibility is that an owner's attention might be a reward the dogs are seeking, like young children pleading with their parents to watch them as they show off what they can do.
The dogs might have also learned that playing among themselves leads to bigger prizes, such as the owner joining in the fun, or taking them outside.
Or, their owner might provide the dogs a sense of safety, because although animals use play to strengthen bonds, it can sometimes turn tense and lead to aggression. Having a person around is insurance against a fight.
Their human's presence could also be a trigger that enriches the general environment, perhaps causing a rush of the love hormone oxytocin, which leads to a more positive emotional state that in turn manifests as play.
It's one of those types of studies that leads to a lot more questions than answers, said Mehrkam, adding she was working on untangling the various threads in ongoing experiments.