來源：市場資訊

狗狗如何讓青少年不再那么焦慮

How dogs make teens

feel less anxious

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文本難度：考研

Dogs have been a part of human society for over 20,000 years. Whereas they first served people by supporting hunters, it did not take long before they became part of the home. Companion dogs may not help secure food, but for years, evidence has mounted that they help diminish anxiety and improve sociality.

狗與人類相伴已有兩萬多年。最初，它們協助人類狩獵；但沒過多久，便走進了千家萬戶。雖然作為伴侶的狗狗不再幫我們獲取食物，但多年來，越來越多的證據表明，它們能有效緩解焦慮、促進社交。

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Research led by Kikusui Takefumi at Azabu University in Japan, published recently in iScience, explains what might be going on. It reveals that the microbes found in the guts of dog owners are notably different from those who do not own dogs and that this is, at least partially, responsible for the behavioral differences.

日本麻布大學的菊水健史（Takefumi Kikusui）團隊近期在《交叉科學》（iScience）期刊發表的一項研究，揭示了其中可能的機制：養狗者的腸道微生物組成明顯異于不養狗的人，而這種差異至少在一定程度上解釋了兩類人行為上的不同。

The brain does not exist in isolation. The microbes found elsewhere, particularly in the gut, produce chemical compounds that influence how the brain works. Those microbes are heavily affected by diet, but are also shaped by factors like stress, pollutants, and exercise. Dr Kikusui knew from his own research that having a dog influenced the microbiota of the human gut, too. With this in mind, he wondered if microbe transfer from dogs might be helping confer psychological benefits on owners. Keen to find out, he set up an experiment with 343 participants in Tokyo.

大腦并非是孤立運作的。身體其他部位——尤其是腸道——的微生物會產生多種化學物質，從而影響大腦的運作。這些微生物深受飲食影響，同時也受到壓力、污染物和運動等因素的影響。菊水博士從前期研究中得知，養狗也會改變人體腸道菌群。由此，他想到：狗狗身上的微生物是否可能通過某種方式轉移給人類，并帶來心理上的益處？為了驗證這一猜想，他在東京開展了一項涉及343名參與者的研究。

Dr Kikusui specifically worked with teenagers. His reason for this was that adolescence is a crucial period of brain development, when social interactions often have lasting mental effects; if microbes from dogs were reducing teen anxiety and increasing teen sociality, then this would yield long-term benefits. He and his colleagues therefore psychologically analyzed 96 teens who were dog owners and 247 teens who were not. As expected, dog owners suffered from fewer social problems. More specifically, they showed reduced aggression, diminished delinquent behavior, and less social withdrawal.

菊水博士特意選擇了青少年作為研究對象，因為青春期是大腦發育的關鍵階段，這個時期的社交經歷往往會對心理健康產生長遠影響。如果來自狗狗身上的微生物真的能減輕青少年的焦慮、增強其社交能力，那么這種益處很可能會帶來長期影響。因此，他和同事對96名養狗的青少年與247名不養狗的青少年進行了心理評估。結果正如預期：養狗的青少年在社交方面遇到的問題更少。更具體地說，他們表現出的攻擊性更低，違紀行為更少，社交退縮傾向也更輕微。

Dr Kikusui and his colleagues then collected saliva samples from the participants and noted that several variants of Streptococcus and Prevotella 7 bacteria were significantly more abundant in samples from dog owners. They further found that participants in whom these key microbe variants were rare also tended to have more delinquent behaviors. This finding suggested that microbes, added to the human gut by dogs, may be influencing the brains of their owners in healthy ways.

隨后，菊水博士及其同事采集了參與者的唾液樣本，并發現：養狗青少年的樣本中，幾種鏈球菌（Streptococcus）和普雷沃氏菌屬第7類（Prevotella 7）的變體會多得多。他們進一步觀察到，那些體內缺乏這些關鍵微生物變體的參與者，往往有更多的違紀行為。這一發現表明，狗狗帶入人類腸道的微生物，可能正以有益的方式影響著主人的大腦功能。

The ideal next step for Dr Kikusui would have been to infuse dog microbes into the bodies of non-dog-owning teens. Since that is an ethically grey area, he worked instead with mice. He cultured microbe samples from both groups of teens in the lab and fed them to 24 mice. After six weeks, he monitored them as they were put through a series of murine sociality tests, which included examinations of how long they spent sniffing unfamiliar mice and how close they would get to a distressed mouse that had previously been their cage-mate.

理想情況下，菊水博士下一步本想將狗狗相關的微生物直接移植到不養狗的青少年體內，以驗證其效果。但鑒于這種做法涉及倫理爭議，他轉而采用小鼠進行實驗。研究團隊在實驗室中培養了兩組青少年的微生物樣本，并將其喂給24只小鼠。六周后，研究人員對這些小鼠進行了一系列社交行為測試，包括觀察它們花多長時間嗅探陌生小鼠，以及當曾經同籠的伙伴處于痛苦狀態時，它們會主動靠近到什么程度。

Remarkably, mice carrying the microbes of teen dog owners spent up to 14 seconds sniffing unfamiliar mice, whereas mice carrying the microbes of teens without dogs spent a paltry six seconds doing so. A similar result played out with the distressed mouse test—mice with the microbes of teen dog owners often spent more than 21 seconds checking on the distressed mouse, while the other mice never spent more than three seconds doing so. Dr Kikusui admits that making direct comparisons between murine and human behavior is not ideal, but his findings nonetheless indicate that the microbiotic changes brought about by dog ownership influence the brain. If the conclusions hold, it seems that the path to a healthier mind may begin not with introspection, but with a nuzzle and a few licks.

令人驚訝的是，攜帶養狗青少年的微生物的小鼠，會花多達14秒的時間去嗅探陌生小鼠；而攜帶不養狗青少年的微生物的小鼠，這一時間僅有6秒。在有關“靠近痛苦鼠友”的測試中，也出現了類似結果：前者常常花超過21秒的時間去查看處于痛苦狀態的鼠友，而后者從未超過3秒。菊水博士坦言，將小鼠行為直接與人類行為類比并不算理想，但研究結果依然清晰表明：養狗所引發的腸道菌群變化，確實會影響大腦功能。如果這些結論經得起進一步驗證，那似乎可以說，通往更健康的精神狀態的路，或許并非始于內省，而是始于狗狗的一次依偎和幾次舔舐。

詞匯

1. microbe n. 微生物

2. microbiota n. 微生物群

3. aggression n. 攻擊性

4. delinquent adj. 違法的；不良行為的

5. saliva n. 唾液

6. infuse v. 注入；灌輸

7. ethically adj. 倫理地；道德地

8. culture v. 培養（細胞或細菌）

9. paltry adj. 微不足道的；很少的

10. murine adj. 鼠類的；鼠的

11. introspection n. 內省；反省

12. nuzzle n. 用鼻子輕觸；依偎