狗鼻子可以靈敏到什么地步？狗狗不但能聞出糖尿病，聞出藥品和毒品，還能聞出人類情緒的變化。新研究證實，狗可以通過嗅覺來識別一個人是否精神緊張。

Whether it’s a tricky maths problem or an unexpected bill, daily life is full of stressful experiences. Now researchers have found that humans produce a different odour when under pressure – and dogs can sniff it out.

無論是棘手的數學題還是意想不到的賬單，日常生活中總是有各種事讓人壓力山大。如今研究人員發現，人類在壓力下會產生一種不同的體味，而狗狗可以嗅到這種味道。

While previous studies have suggested canines might pick up on human emotions, possibly through smell, questions remained over whether they could detect stress and if this could be done through scent.

先前的研究表明，狗可以識別人類的情緒，可能是通過氣味，但是對于狗狗能否通過氣味識別人的精神壓力還未有定論。

"This study has definitively proven that people, when they have a stress response, their odour profile changes,” said Clara Wilson, a PhD student at Queen’s University Belfast, and first author of the research.

該研究的第一作者、貝爾法斯特女王大學的博士生克拉拉·威爾遜說：“這項研究明確證實了人們在應對壓力時體味會改變。”

Wilson added the findings could prove useful when training service dogs, such as those that support people with post-traumatic stress disorder (PTSD).

威爾遜說道，這一研究結果在訓練服務犬尤其是協助創傷后應激障礙患者的狗狗時會很有用。

Writing in the journal Plos One, Wilson and colleagues report how they first constructed a stand bearing three containers, each topped by a perforated lid.

這份發表在《公共科學圖書館期刊》上的研究報告中寫道，威爾遜和她的同事搭建起一個放著三個容器的臺子，每個容器的蓋子上都有孔。

The researchers report they were able to train four dogs to indicate the container holding a particular breath and sweat sample, even when the line-up included unused gauze, samples from another person, or samples from the same person taken at a different time of day.

研究人員報告稱，他們訓練四只狗識別裝有特殊氣味和汗液樣本的容器，其他容器中則盛放著沒用過的紗布、另一個人的氣味和汗液樣本，或在不同時間段從同一個人身上采集的樣本。

Then the team turned to breath and sweat samples collected from 36 people asked to count backwards from 9,000 in units of 17. The participants reported feeling stressed by the task and, for the 27 who carried it out in the laboratory, their blood pressure and heart rate rose.

然后研究團隊要求36個人從9000開始以17為單位倒數并從他們身上采集了氣味和汗液樣本。參與者報告稱這個任務讓他們感到緊張，其中在實驗室執行任務的27人的血壓和心率都有所上升。

The dogs were taught to pick out samples taken just after the task from a line-up that included two containers holding unused gauze.

在任務結束后，研究人員讓狗從三個容器中挑出裝有樣本的容器，另外兩個容器裝的是沒用過的紗布。

The researchers then tested whether the dogs could do the same when the line-up included not only unused gauze but samples taken from the same participant just before the task, when they were more relaxed. Each set of samples was shown to a single dog in 20 trials.

接著，研究人員又測試了這些狗能否在其他容器不止裝有未用紗布的情況下還能挑出有目標樣本的容器。研究人員在裝有未用紗布的容器中放入了同一個參與者在執行任務前精神較為放松時被采集的樣本，然后用每一組樣本對每只狗進行了20次測試。

The results reveal that the dogs chose the “stressed” sample in 675 out of the 720 trials.

結果顯示，狗狗們在720次測試中共有675次選擇了“壓力”樣本。

The team say while it was unclear what chemicals the dogs were picking up on, the study shows humans produce a different odour when stressed.

研究團隊表示，盡管尚不清楚這些狗嗅到了什么化學物質，但是研究表明，人類在情緒緊張時確實會產生不同的體味。

英文來源：衛報

翻譯&編輯：丹妮